chamilo-lms2/main/inc/lib/sessionmanager.lib.php

<?php
/* For licensing terms, see /license.txt */
/**
* This is the session library for Chamilo.
* All main sessions functions should be placed here.
* This class provides methods for sessions management.
* Include/require it in your code to use its features.
* @package chamilo.library
*/
/**
 * Class SessionManager
 */
class SessionManager
{
    public function __construct()
    {
    }

    /**
    * Fetches a session from the database
    * @param   int     Session ID
    * @return  array   Session details
    */
    public static function fetch($id)
    {
        $t = Database::get_main_table(TABLE_MAIN_SESSION);
        if ($id != strval(intval($id))) {
            return array();
        }
        $s = "SELECT * FROM $t WHERE id = $id";
        $r = Database::query($s);
        if (Database::num_rows($r) != 1) {
            return array();
        }
        return Database::fetch_array($r,'ASSOC');
    }

    /**
    * Create a session
    * @author Carlos Vargas <carlos.vargas@beeznest.com>, from existing code
    * @param	string 		name
    * @param 	integer		Start year (yyyy)
    * @param 	integer		Start month (mm)
    * @param 	integer		Start day (dd)
    * @param 	integer		End year (yyyy)
    * @param 	integer		End month (mm)
    * @param 	integer		End day (dd)
    * @param 	integer		Number of days that the coach can access the session before the start date
    * @param 	integer		Number of days that the coach can access the session after the end date
    * @param 	integer		If 1, means there are no date limits
    * @param 	mixed		If integer, this is the session coach id, if string, the coach ID will be looked for from the user table
    * @param 	integer		ID of the session category in which this session is registered
    * @param  integer     Visibility after end date (0 = read-only, 1 = invisible, 2 = accessible)
    * @param  string      Start limit = true if the start date has to be considered
    * @param  string      End limit = true if the end date has to be considered
    * @param  string $fix_name
    * @todo use an array to replace all this parameters or use the model.lib.php ...
    * @return mixed       Session ID on success, error message otherwise
    **/
    public static function create_session(
        $sname,
        $syear_start,
        $smonth_start,
        $sday_start,
        $syear_end,
        $smonth_end,
        $sday_end,
        $snb_days_acess_before,
        $snb_days_acess_after,
        $nolimit,
        $coach_username,
        $id_session_category,
        $id_visibility,
        $start_limit = true,
        $end_limit = true,
        $fix_name = false
    ) {
		global $_configuration;

		//Check portal limits
        $access_url_id = 1;
        if (api_get_multiple_access_url()) {
            $access_url_id = api_get_current_access_url_id();
        }
        if (is_array($_configuration[$access_url_id]) && isset($_configuration[$access_url_id]['hosting_limit_sessions']) && $_configuration[$access_url_id]['hosting_limit_sessions'] > 0) {
            $num = self::count_sessions();
            if ($num >= $_configuration[$access_url_id]['hosting_limit_sessions']) {
                return get_lang('PortalSessionsLimitReached');
            }
        }

        $name                 = Database::escape_string(trim($sname));
        $year_start           = intval($syear_start);
        $month_start          = intval($smonth_start);
        $day_start            = intval($sday_start);
        $year_end             = intval($syear_end);
        $month_end            = intval($smonth_end);
        $day_end              = intval($sday_end);
        $nb_days_acess_before = intval($snb_days_acess_before);
        $nb_days_acess_after  = intval($snb_days_acess_after);
        $id_session_category  = intval($id_session_category);
        $id_visibility        = intval($id_visibility);
        $tbl_user		      = Database::get_main_table(TABLE_MAIN_USER);
        $tbl_session	      = Database::get_main_table(TABLE_MAIN_SESSION);

		if (is_int($coach_username)) {
			$id_coach = $coach_username;
		} else {
			$sql = 'SELECT user_id FROM '.$tbl_user.' WHERE username="'.Database::escape_string($coach_username).'"';
			$rs = Database::query($sql);
			$id_coach = Database::result($rs,0,'user_id');
		}

		if (empty($nolimit)) {
			$date_start  ="$year_start-".(($month_start < 10)?"0$month_start":$month_start)."-".(($day_start < 10)?"0$day_start":$day_start);
			$date_end    ="$year_end-".(($month_end < 10)?"0$month_end":$month_end)."-".(($day_end < 10)?"0$day_end":$day_end);
		} else {
			$id_visibility   = 1; // by default session visibility is read only
			$date_start      ="0000-00-00";
			$date_end        ="0000-00-00";
		}

        if (empty($end_limit)) {
            $date_end ="0000-00-00";
            $id_visibility   = 1; // by default session visibility is read only
        }

        if (empty($start_limit)) {
            $date_start ="0000-00-00";
        }

		if (empty($name)) {
			$msg=get_lang('SessionNameIsRequired');
			return $msg;
		} elseif (empty($coach_username))   {
			$msg=get_lang('CoachIsRequired');
			return $msg;
		} elseif (!empty($start_limit)  && empty($nolimit) && (!$month_start || !$day_start || !$year_start || !checkdate($month_start,$day_start,$year_start))) {
			$msg=get_lang('InvalidStartDate');
			return $msg;
		} elseif (!empty($end_limit)  &&  empty($nolimit) && (!$month_end || !$day_end || !$year_end || !checkdate($month_end,$day_end,$year_end))) {
			$msg=get_lang('InvalidEndDate');
			return $msg;
		} elseif(!empty($start_limit) && !empty($end_limit)  && empty($nolimit) && $date_start >= $date_end) {
			$msg=get_lang('StartDateShouldBeBeforeEndDate');
			return $msg;
		} else {
		    $ready_to_create = false;
		    if ($fix_name) {
		        $name = self::generate_nice_next_session_name($name);
		        if ($name) {
		            $ready_to_create = true;
		        } else {
		            $msg=get_lang('SessionNameAlreadyExists');
    				return $msg;
		        }
		    } else {
    		    $rs = Database::query("SELECT 1 FROM $tbl_session WHERE name='".$name."'");
    			if (Database::num_rows($rs)) {
    				$msg=get_lang('SessionNameAlreadyExists');
    				return $msg;
    			}
    			$ready_to_create = true;
		    }

			if ($ready_to_create) {
				$sql_insert = "INSERT INTO $tbl_session(name,date_start,date_end,id_coach,session_admin_id, nb_days_access_before_beginning, nb_days_access_after_end, session_category_id,visibility)
							   VALUES('".$name."','$date_start','$date_end','$id_coach',".api_get_user_id().",".$nb_days_acess_before.", ".$nb_days_acess_after.", ".$id_session_category.", ".$id_visibility.")";
				Database::query($sql_insert);
				$session_id = Database::insert_id();

                if (!empty($session_id)) {
                    /*
                    Sends a message to the user_id = 1

                    $user_info = api_get_user_info(1);
                    $complete_name = $user_info['firstname'].' '.$user_info['lastname'];
                    $subject = api_get_setting('siteName').' - '.get_lang('ANewSessionWasCreated');
                    $message = get_lang('ANewSessionWasCreated')." <br /> ".get_lang('NameOfTheSession').' : '.$name;
                    api_mail_html($complete_name, $user_info['email'], $subject, $message);
                    *
                    */
    				//Adding to the correct URL
                    $access_url_id = api_get_current_access_url_id();
                    UrlManager::add_session_to_url($session_id,$access_url_id);

    				// add event to system log
    				$user_id = api_get_user_id();
    				event_system(LOG_SESSION_CREATE, LOG_SESSION_ID, $session_id, api_get_utc_datetime(), $user_id);
    		    }
				return $session_id;
			}
		}
	}

    /**
     * @param string $name
     * @return bool
     */
    public static function session_name_exists($name)
    {
        $name = Database::escape_string($name);
        $sql = "SELECT COUNT(*) as count FROM ".Database::get_main_table(TABLE_MAIN_SESSION)."
                WHERE name = '$name'";
        $result = Database::fetch_array(Database::query($sql));
        return $result['count'] > 0;
	}

    /**
     * @param string $where_condition
     * @return mixed
     */
    public static function get_count_admin($where_condition = null)
    {
        $tbl_session            = Database::get_main_table(TABLE_MAIN_SESSION);
        $tbl_session_category   = Database::get_main_table(TABLE_MAIN_SESSION_CATEGORY);
        $tbl_user               = Database::get_main_table(TABLE_MAIN_USER);
        $table_access_url_rel_session = Database::get_main_table(TABLE_MAIN_ACCESS_URL_REL_SESSION);
        $tbl_session_rel_user 	= Database::get_main_table(TABLE_MAIN_SESSION_USER);

        $where = 'WHERE 1=1 ';
        $user_id = api_get_user_id();

        $extraJoin = null;

        if (api_is_session_admin() &&
            api_get_setting('allow_session_admins_to_manage_all_sessions') == 'false'
        ) {
            $where .= " AND (
                            s.session_admin_id = $user_id  OR
                            sru.id_user = '$user_id' AND
                            sru.relation_type = '".SESSION_RELATION_TYPE_RRHH."'
                            )
                      ";

            $extraJoin = " INNER JOIN $tbl_session_rel_user sru
                            ON sru.id_session = s.id ";
        }

        $today = api_get_utc_datetime();
        $today = api_strtotime($today, 'UTC');
        $today = date('Y-m-d', $today);

        if (!empty($where_condition)) {

            $where_condition = str_replace('category_name', 'sc.name', $where_condition);
            $where_condition = str_replace(
                array("AND session_active = '1'  )", " AND (  session_active = '1'  )"),
                array(') GROUP BY s.name HAVING session_active = 1 ', " GROUP BY s.name HAVING session_active = 1 " )
                , $where_condition
            );
            $where_condition = str_replace(
                array("AND session_active = '0'  )", " AND (  session_active = '0'  )"),
                array(') GROUP BY s.name HAVING session_active = 0 ', " GROUP BY s.name HAVING session_active = '0' "),
                $where_condition
            );
        } else {
            $where_condition = " AND 1 = 1";
        }

        $courseCondition = null;
        if (strpos($where_condition, 'c.id')) {
            $table = Database::get_main_table(TABLE_MAIN_SESSION_COURSE);
            $tableCourse = Database::get_main_table(TABLE_MAIN_COURSE);
            $courseCondition = " INNER JOIN $table course_rel_session ON (s.id = course_rel_session.id_session)
                                 INNER JOIN $tableCourse c ON (course_rel_session.course_code = c.code)
                                ";
        }

        $sql = "SELECT count(id) as total_rows FROM (
                SELECT
                 IF (
					(s.date_start <= '$today' AND '$today' <= s.date_end) OR
                    (s.nb_days_access_before_beginning > 0 AND DATEDIFF(s.date_start,'".$today."' ".") <= s.nb_days_access_before_beginning) OR
                    (s.nb_days_access_after_end > 0 AND DATEDIFF('".$today."',s.date_end) <= s.nb_days_access_after_end) OR
                    (s.date_start  = '0000-00-00' AND s.date_end  = '0000-00-00' ) OR
					(s.date_start <= '$today' AND '0000-00-00' = s.date_end) OR
					('$today' <= s.date_end AND '0000-00-00' = s.date_start)
				, 1, 0)
				as session_active,
				s.id,
                count(*) as total_rows
                FROM $tbl_session s
                    LEFT JOIN  $tbl_session_category sc ON s.session_category_id = sc.id
                    INNER JOIN $tbl_user u ON s.id_coach = u.user_id
                    $courseCondition
                    $extraJoin
                $where $where_condition ) as session_table";

        if (api_is_multiple_url_enabled()) {

            $access_url_id = api_get_current_access_url_id();
            if ($access_url_id != -1) {
				$where.= " AND ar.access_url_id = $access_url_id ";

                $sql = "SELECT count(id) as total_rows FROM (
                SELECT
                  IF (
					(s.date_start <= '$today' AND '$today' <= s.date_end) OR
                    (s.nb_days_access_before_beginning > 0 AND DATEDIFF(s.date_start,'".$today."' ".") <= s.nb_days_access_before_beginning) OR
                    (s.nb_days_access_after_end > 0 AND DATEDIFF('".$today."',s.date_end) <= s.nb_days_access_after_end) OR
                    (s.date_start  = '0000-00-00' AND s.date_end  = '0000-00-00' ) OR
					(s.date_start <= '$today' AND '0000-00-00' = s.date_end) OR
					('$today' <= s.date_end AND '0000-00-00' = s.date_start)
				, 1, 0)
				as session_active,
				s.id
                 FROM $tbl_session s
                    LEFT JOIN  $tbl_session_category sc ON s.session_category_id = sc.id
                    INNER JOIN $tbl_user u ON s.id_coach = u.user_id
                    INNER JOIN $table_access_url_rel_session ar ON ar.session_id = s.id
                    $courseCondition
                    $extraJoin
                 $where $where_condition) as session_table";
            }
        }

        $result_rows = Database::query($sql);
        $row = Database::fetch_array($result_rows);
        $num = $row['total_rows'];

        return $num;
    }

    /**
     * Gets the admin session list callback of the admin/session_list.php page
     * @param array $options order and limit keys
     * @return array
     */
	public static function get_sessions_admin($options)
    {
		$tbl_session            = Database::get_main_table(TABLE_MAIN_SESSION);
		$tbl_session_category   = Database::get_main_table(TABLE_MAIN_SESSION_CATEGORY);
		$tbl_user               = Database::get_main_table(TABLE_MAIN_USER);
        $tbl_session_rel_user 	= Database::get_main_table(TABLE_MAIN_SESSION_USER);
        $table_access_url_rel_session = Database::get_main_table(TABLE_MAIN_ACCESS_URL_REL_SESSION);

		$where = ' WHERE 1=1 ';
		$user_id = api_get_user_id();

        $extraJoin = null;

		if (api_is_session_admin() && api_get_setting('allow_session_admins_to_manage_all_sessions') == 'false') {
            $where .= " AND (
                            s.session_admin_id = $user_id  OR
                            sru.id_user = '$user_id' AND
                            sru.relation_type = '".SESSION_RELATION_TYPE_RRHH."'
                            )
                      ";

            $extraJoin = " INNER JOIN $tbl_session_rel_user sru
                            ON sru.id_session = s.id ";
		}

		$coach_name = " CONCAT(u.lastname , ' ', u.firstname) as coach_name ";

		if (api_is_western_name_order()) {
			$coach_name = " CONCAT(u.firstname, ' ', u.lastname) as coach_name ";
		}

        $options['where'] = str_replace(
            array("AND session_active = '1'  )", " AND (  session_active = '1'  )"),
            array(') GROUP BY s.name HAVING session_active = 1 ', " GROUP BY s.name HAVING session_active = 1 " )
            , $options['where']
        );

        $options['where'] = str_replace(
            array("AND session_active = '0'  )", " AND (  session_active = '0'  )"),
            array(') GROUP BY s.name HAVING session_active = 0 ', " GROUP BY s.name HAVING session_active = '0' "),
            $options['where']
        );

		$today = api_get_utc_datetime();
        $today = api_strtotime($today, 'UTC');
        $today = date('Y-m-d', $today);

        $courseCondition = null;
        if (strpos($options['where'], 'c.id')) {
            $table = Database::get_main_table(TABLE_MAIN_SESSION_COURSE);
            $tableCourse = Database::get_main_table(TABLE_MAIN_COURSE);
            $courseCondition = " INNER JOIN $table course_rel_session ON (s.id = course_rel_session.id_session)
                                 INNER JOIN $tableCourse c ON (course_rel_session.course_code = c.code)
                                ";
        }

		$select = "SELECT * FROM (SELECT
                IF (
					(s.date_start <= '$today' AND '$today' <= s.date_end) OR
                    (s.nb_days_access_before_beginning > 0 AND DATEDIFF(s.date_start,'".$today."' ".") <= s.nb_days_access_before_beginning) OR
                    (s.nb_days_access_after_end > 0 AND DATEDIFF('".$today."',s.date_end) <= s.nb_days_access_after_end) OR
                    (s.date_start  = '0000-00-00' AND s.date_end  = '0000-00-00' ) OR
					(s.date_start <= '$today' AND '0000-00-00' = s.date_end) OR
					('$today' <= s.date_end AND '0000-00-00' = s.date_start)
				, 1, 0)
				as session_active,
				s.name,
                nbr_courses,
                s.nbr_users,
                s.date_start,
                s.date_end,
                $coach_name,
                sc.name as category_name,
                s.visibility,
                u.user_id,
                s.id";

        $limit = null;
        if (!empty($options['limit'])) {
            $limit = " LIMIT ".$options['limit'];
        }

        if (!empty($options['where'])) {
		   $where .= ' '.$options['where'];
		}

        $order = null;
        if (!empty($options['order'])) {
            $order = " ORDER BY ".$options['order'];
        }

		$query = "$select FROM $tbl_session s
				LEFT JOIN $tbl_session_category sc ON s.session_category_id = sc.id
				LEFT JOIN $tbl_user u ON s.id_coach = u.user_id
				$courseCondition
				$extraJoin
                $where $order $limit";

		if (api_is_multiple_url_enabled()) {
			$access_url_id = api_get_current_access_url_id();
			if ($access_url_id != -1) {
				$query = " $select
                           FROM $tbl_session s
                               LEFT JOIN  $tbl_session_category sc ON s.session_category_id = sc.id
                               LEFT JOIN $tbl_user u ON s.id_coach = u.user_id
                               INNER JOIN $table_access_url_rel_session ar ON ar.session_id = s.id AND ar.access_url_id = $access_url_id
                               $courseCondition
                               $extraJoin
				 $where $order $limit";
			}
		}

		$query .= ") AS session_table";

		$result = Database::query($query);
		$formatted_sessions = array();
		if (Database::num_rows($result)) {
			$sessions = Database::store_result($result);
			foreach ($sessions as $session) {
				$session['name'] = Display::url($session['name'], "resume_session.php?id_session=".$session['id']);
				$session['coach_name'] = Display::url($session['coach_name'], "user_information.php?user_id=".$session['user_id']);

				if ($session['date_start'] == '0000-00-00' && $session['date_end'] == '0000-00-00') {
				//    $session['session_active'] = 1;
				}

				if ($session['session_active'] == 1) {
					$session['session_active'] = Display::return_icon('accept.png', get_lang('Active'), array(), ICON_SIZE_SMALL);
				} else {
					$session['session_active'] = Display::return_icon('error.png', get_lang('Inactive'), array(), ICON_SIZE_SMALL);
				}

				if ($session['date_start'] == '0000-00-00') {
					$session['date_start'] = '';
				}
				if ($session['date_end'] == '0000-00-00') {
					$session['date_end'] = '';
				}

				switch ($session['visibility']) {
					case SESSION_VISIBLE_READ_ONLY: //1
						$session['visibility'] =  get_lang('ReadOnly');
					break;
					case SESSION_VISIBLE:           //2
						$session['visibility'] =  get_lang('Visible');
					break;
					case SESSION_INVISIBLE:         //3
						$session['visibility'] =  api_ucfirst(get_lang('Invisible'));
					break;
                }
                $formatted_sessions[] = $session;
			}
		}
		return $formatted_sessions;
	}
    /**
     *  Get total of records for progress of learning paths in the given session
     *  @param int session id
     *  @return int
     */
    public static function get_count_session_lp_progress($sessionId = 0) {
        $tbl_lp         = Database::get_course_table(TABLE_LP_MAIN);
        $tbl_lp_view    = Database::get_course_table(TABLE_LP_VIEW);
        $tbl_user       = Database::get_main_table(TABLE_MAIN_USER);
        $tbl_course     = Database::get_main_table(TABLE_MAIN_COURSE);

        $sql =  "select  count(*) as total_rows
                FROM $tbl_lp_view v
                INNER JOIN $tbl_lp l ON l.id = v.lp_id
                INNER JOIN $tbl_user u ON u.user_id = v.user_id
                INNER JOIN $tbl_course c";
        $sql .= ' WHERE v.session_id = ' . $sessionId;
        $result_rows = Database::query($sql);
        $row = Database::fetch_array($result_rows);
        $num = $row['total_rows'];
        return $num;
    }
    /**
     *  Get the progress of a exercise
     *  @param int session id
     *  @return array
     */
    public static function get_exercise_progress($sessionId = 0, $courseId = 0, $exerciseId = 0, $answer = 2, $options = array())
    {
        $session                = Database::get_main_table(TABLE_MAIN_SESSION);
        $user                   = Database::get_main_table(TABLE_MAIN_USER);
        $quiz                   = Database::get_course_table(TABLE_QUIZ_TEST);
        $quiz_answer            = Database::get_course_table(TABLE_QUIZ_ANSWER);
        $quiz_question          = Database::get_course_table(TABLE_QUIZ_QUESTION);
        $table_stats_exercises  = Database::get_statistic_table(TABLE_STATISTIC_TRACK_E_EXERCICES);
        $table_stats_attempt    = Database::get_statistic_table(TABLE_STATISTIC_TRACK_E_ATTEMPT);

        require_once api_get_path(SYS_CODE_PATH).'exercice/exercise.lib.php';

        $course = api_get_course_info_by_id($courseId);
        $exercise = current(get_exercise_by_id($exerciseId));

        $where = " WHERE a.course_code = '%s'";
        if (!empty($sessionId)) {
            $where .= " AND a.session_id = %d AND q.id = %d";
        } else {
            $where .= " AND q.title = '%s'";
        }

        //2 = show all questions (wrong and correct answered)
        if ($answer != 2) {
            $where .= sprintf(' AND qa.correct = %d', $answer);
        }

        $limit = null;
        if (!empty($options['limit'])) {
            $limit = " LIMIT ".$options['limit'];
        }

        if (!empty($options['where'])) {
           $where .= ' '.$options['where'];
        }

        $order = null;
        if (!empty($options['order'])) {
            $order = " ORDER BY ".$options['order'];
        }

        $sql = "SELECT
            s.name as session,
            CONCAT (q.c_id, q.id) as exercise_id,
            q.title as quiz_title,
            u.username,
            u.lastname,
            u.firstname,
            a.tms as time,
            qa.question_id,
            qq.question,
            qa.answer,
            qa.correct
        FROM $table_stats_attempt a
        LEFT JOIN $quiz_answer qa ON a.answer = qa.id_auto
        LEFT JOIN  $quiz_question qq ON qq.id = qa.question_id
        INNER JOIN $table_stats_exercises e ON e.exe_id = a.exe_id
        INNER JOIN $session s ON s.id = a.session_id
        INNER JOIN $quiz q ON q.id = e.exe_exo_id
        INNER JOIN $user u ON u.user_id = a.user_id
        $where $order $limit";

        if (!empty($sessionId)) {
            $sql_query = sprintf($sql, $course['code'], $sessionId,  $exerciseId);
        } else {
            $sql_query = sprintf($sql, $course['code'], $exercise['title']);
        }

        $rs = Database::query($sql_query);
        while ($row = Database::fetch_array($rs)) {
            $row['correct'] = ($row['correct'] == 1) ? get_lang('Yes') : get_lang('No');
            $data[] = $row;
        }

        return $data;
    }
    /**
     * Gets the progress of learning paths in the given session
     * @param int   session id
     * @param array options order and limit keys
     * @return array table with user name, lp name, progress
     */
    public static function get_session_lp_progress($sessionId = 0, $courseId = 0, $options)
    {
        //tables
        $session_course_user    = Database::get_main_table(TABLE_MAIN_SESSION_COURSE_USER);
        $user                   = Database::get_main_table(TABLE_MAIN_USER);
        $tbl_course_lp_view     = Database::get_course_table(TABLE_LP_VIEW);

        $course = api_get_course_info_by_id($courseId);


        //getting all the students of the course
        //we are not using this because it only returns user ids
        /*if (empty($sessionId)
        {
            // Registered students in a course outside session.
            $users = CourseManager :: get_student_list_from_course_code($course_code);
        } else {
            // Registered students in session.
            $users = CourseManager :: get_student_list_from_course_code($course_code, true, $sessionId);
        }*/
        $where = " WHERE course_code = '%s'
        AND s.status <> 2 and id_session = %s";

        $limit = null;
        if (!empty($options['limit'])) {
            $limit = " LIMIT ".$options['limit'];
        }

        if (!empty($options['where'])) {
           $where .= ' '.$options['where'];
        }

        $order = null;
        if (!empty($options['order'])) {
            $order = " ORDER BY ".$options['order'];
        }

        $sql = "SELECT u.user_id, u.lastname, u.firstname, u.username, u.email, s.course_code
        FROM $session_course_user s
        INNER JOIN $user u ON u.user_id = s.id_user
        $where $order $limit";

        $sql_query = sprintf($sql, $course['code'], $sessionId);

        $rs = Database::query($sql_query);
        while ($user = Database::fetch_array($rs))
        {
            $users[$user['user_id']] = $user;
        }

        //Get lessons
        require_once api_get_path(SYS_CODE_PATH).'newscorm/learnpathList.class.php';
        $lessons = LearnpathList::get_course_lessons($course['code'], $sessionId);

        $table = array();
        foreach ($users as $user)
        {
            $data = array(
                'lastname'  => $user[1],
                'firstname' => $user[2],
                'username'  => $user[3],
            );

            //Get lessons progress by user
            $sql = "SELECT v.lp_id as id, v.progress
            FROM  $tbl_course_lp_view v
            WHERE v.session_id = %d
            AND v.c_id = %d
            AND v.user_id = %d";
            $sql_query = sprintf($sql, $sessionId, $courseId, $user['user_id']);

            $result = Database::query($sql_query);

            $user_lessons = array();
            while ($row = Database::fetch_array($result))
            {
                $user_lessons[$row['id']] = $row;
            }

            //Match course lessons with user progress
            $progress = 0;
            $count = 0;
            foreach ($lessons as $lesson)
            {
                $data[$lesson['id']] = (!empty($user_lessons[$lesson['id']]['progress'])) ? $user_lessons[$lesson['id']]['progress'] : 0;
                $progress += $data[$lesson['id']];
                $data[$lesson['id']]  = $data[$lesson['id']] . '%';
                $count++;
            }

            $data['total'] = round($progress / $count, 2) . '%';

            $table[] = $data;
        }
        return $table;
    }
    /**
     * Gets the survey answers
     * @param int   session id
     * @param int   course id
     * @param int   survey id
     * @param array options order and limit keys
     * @return array table with user name, lp name, progress
     */
    public static function get_survey_overview($sessionId = 0, $courseId = 0, $surveyId = 0, $options)
    {
        //tables
        $session_course_user    = Database::get_main_table(TABLE_MAIN_SESSION_COURSE_USER);
        $user                   = Database::get_main_table(TABLE_MAIN_USER);
        $tbl_course_lp_view     = Database::get_course_table(TABLE_LP_VIEW);

        $course = api_get_course_info_by_id($courseId);

        $where = " WHERE course_code = '%s'
        AND s.status <> 2 and id_session = %s";

        $limit = null;
        if (!empty($options['limit'])) {
            $limit = " LIMIT ".$options['limit'];
        }

        if (!empty($options['where'])) {
           $where .= ' '.$options['where'];
        }

        $order = null;
        if (!empty($options['order'])) {
            $order = " ORDER BY ".$options['order'];
        }

        $sql = "SELECT u.user_id, u.lastname, u.firstname, u.username, u.email, s.course_code
        FROM $session_course_user s
        INNER JOIN $user u ON u.user_id = s.id_user
        $where $order $limit";

        $sql_query = sprintf($sql, $course['code'], intval($sessionId));

        $rs = Database::query($sql_query);
        while ($user = Database::fetch_array($rs))
        {
            $users[$user['user_id']] = $user;
        }

        //Get survey questions
        $questions = survey_manager::get_questions($surveyId, $courseId);
        $table = array();
        foreach ($users as $user)
        {
            $data = array(
                'lastname'  => $user[1],
                'firstname' => $user[2],
                'username'  => $user[3],
            );

            //Get questions by user
            $sql = "SELECT sa.question_id, sa.option_id
            FROM c_survey_answer sa
            INNER JOIN c_survey_question sq ON sq.question_id = sa.question_id
            WHERE sa.survey_id = %d AND sa.c_id = %d AND sa.user = %d";

            $sql_query = sprintf($sql, $surveyId, $courseId, $user['user_id']);

            $result = Database::query($sql_query);

            $user_questions = array();
            while ($row = Database::fetch_array($result))
            {
                $user_questions[$row['question_id']] = $row;
            }

            //Match course lessons with user progress
            foreach ($questions as $question_id => $question)
            {
                $data[$question_id] = $user_questions[$question_id]['option_id'];
            }

            $table[] = $data;
        }
        return $table;
    }

    /**
     * Gets the progress of the given session
     * @param int   session id
     * @param array options order and limit keys
     * @return array table with user name, lp name, progress
     */
    public static function get_session_progress($sessionId, $courseId, $options)
    {
        //tables
        $session_course_user    = Database::get_main_table(TABLE_MAIN_SESSION_COURSE_USER);
        $user                   = Database::get_main_table(TABLE_MAIN_USER);
        $workTable              = Database::get_course_table(TABLE_STUDENT_PUBLICATION);
        $workTableAssignment    = Database::get_course_table(TABLE_STUDENT_PUBLICATION_ASSIGNMENT);
        $forum                  = Database::get_course_table(TABLE_FORUM);
        $forum_post             = Database::get_course_table(TABLE_FORUM_POST);
        $tbl_course_lp          = Database::get_course_table(TABLE_LP_MAIN);
        $wiki                   = Database::get_course_table(TABLE_WIKI);
        $table_stats_default    = Database::get_statistic_table(TABLE_STATISTIC_TRACK_E_DEFAULT);
        $table_stats_access     = Database::get_statistic_table(TABLE_STATISTIC_TRACK_E_ACCESS);

        $course = api_get_course_info_by_id($courseId);

        //getting all the students of the course
        //we are not using this because it only returns user ids
        /*if (empty($sessionId)
        {
            // Registered students in a course outside session.
            $users = CourseManager :: get_student_list_from_course_code($course_code);
        } else {
            // Registered students in session.
            $users = CourseManager :: get_student_list_from_course_code($course_code, true, $sessionId);
        }*/
        $where = " WHERE course_code = '%s'
        AND s.status <> 2 and id_session = %s";

        $limit = null;
        if (!empty($options['limit'])) {
            $limit = " LIMIT ".$options['limit'];
        }

        if (!empty($options['where'])) {
           $where .= ' '.$options['where'];
        }

        $order = null;
        if (!empty($options['order'])) {
            $order = " ORDER BY ".$options['order'];
        }

        $sql = "SELECT u.user_id, u.lastname, u.firstname, u.username, u.email, s.course_code
        FROM $session_course_user s
        INNER JOIN $user u ON u.user_id = s.id_user
        $where $order $limit";
        $sql_query = sprintf($sql, $course['code'], $sessionId);

        $rs = Database::query($sql_query);
        while ($user = Database::fetch_array($rs))
        {
            $users[$user['user_id']] = $user;
        }

        /**
         *  Lessons
         */
        $sql = "SELECT * FROM $tbl_course_lp
        WHERE c_id = %s ";  //AND session_id = %s
        $sql_query = sprintf($sql, $course['id']);
        $result = Database::query($sql_query);
        $lessons_total = 0;
        while ($row = Database::fetch_array($result))
        {
            if (api_get_item_visibility(api_get_course_info($course['code']), 'learnpath', $row['id'], $sessionId))
            {
                $lessons_total++;
            }
        }

        /**
         *  Exercises
         */
        require_once api_get_path(SYS_CODE_PATH).'exercice/exercise.lib.php';
        $exercises = get_all_exercises($course, $sessionId);
        $exercises_total = count($exercises);

        /**
         *  Assignments
         */
        //total
        $sql = "SELECT count(w.id) as count
        FROM $workTable w
        LEFT JOIN  $workTableAssignment a ON (a.publication_id = w.id AND a.c_id = w.c_id)
        WHERE w.c_id = %s
        AND parent_id = 0
        AND active IN (1, 0)
        AND  session_id = %s";
        $sql_query = sprintf($sql, $course['real_id'], $sessionId);
        $result = Database::query($sql_query);
        $row = Database::fetch_array($result);
        $assignments_total = $row['count'];

        /**
         * Wiki
         */
        $sql = "SELECT count(distinct page_id)  as count FROM $wiki
            WHERE c_id = %s and session_id = %s";
        $sql_query = sprintf($sql, $course['real_id'], $sessionId);
        $result = Database::query($sql_query);
        $row = Database::fetch_array($result);
        $wiki_total = $row['count'];

        /**
         * Surveys
         */
        $survey_user_list = array();
        $survey_list = survey_manager::get_surveys($course['code'], $sessionId);

        $surveys_total = count($survey_list);
        $survey_data = array();
        foreach ($survey_list as $survey)
        {
            $user_list = survey_manager::get_people_who_filled_survey($survey['survey_id'], false, $course['real_id']);
            foreach ($user_list as $user_id)
            {
                isset($survey_user_list[$user_id]) ? $survey_user_list[$user_id]++ : $survey_user_list[$user_id] = 1;
            }
        }
        /**
         * Forums
         */
        //total
        $sql = "SELECT count(*) as count
        FROM $forum f
        where f.c_id = %s and f.session_id = %s";
        $sql_query = sprintf($sql, $course['real_id'], $sessionId);
        $result = Database::query($sql_query);
        $row = Database::fetch_array($result);
        $forums_total = $row['count'];


        //process table info
        foreach ($users as $user)
        {
            //Course description
            $sql = "SELECT count(*) as count
            FROM $table_stats_access
            WHERE access_tool = 'course_description'
            AND access_cours_code = '%s'
            AND access_session_id = %s
            AND access_user_id = %s ";
            $sql_query  = sprintf($sql, $course['code'], $sessionId, $user['user_id']);
            $result     = Database::query($sql_query);
            $row        = Database::fetch_array($result);
            $course_description_progress = ($row['count'] > 0) ? 100 : 0;

            //Lessons
            //TODO: Lessons done and left is calculated by progress per item in lesson, maybe we should calculate it only per completed lesson?
            $lessons_progress   = Tracking::get_avg_student_progress($user['user_id'], $course['code'], array(), $sessionId);
            $lessons_done       = ($lessons_progress * $lessons_total) / 100;
            $lessons_left       = $lessons_total - $lessons_done;

            //Exercises
            $exercises_progress     = str_replace('%', '', Tracking::get_exercise_student_progress($exercises, $user['user_id'], $course['code'], $sessionId));
            $exercises_done         = ($exercises_progress * $exercises_total) / 100;
            $exercises_left         = $exercises_total - $exercises_done;

            //Assignments
            $assignments_done       = Tracking::count_student_assignments($user['user_id'], $course['code'], $sessionId);
            $assignments_left       = $assignments_total - $assignments_done;
            $assignments_progress   =  round((( $assignments_done * 100 ) / $assignments_total ), 2);

            //Wiki
            //total revisions per user
            $sql = "SELECT count(*) as count
            FROM $wiki
            where c_id = %s and session_id = %s and user_id = %s";
            $sql_query  = sprintf($sql, $course['real_id'], $sessionId, $user['user_id']);
            $result     = Database::query($sql_query);
            $row        = Database::fetch_array($result);
            $wiki_revisions =  $row['count'];
            //count visited wiki pages
            $sql = "SELECT count(distinct default_value) as count
            FROM $table_stats_default
            WHERE default_user_id = %s
            AND default_cours_code = '%s'
            AND default_event_type = 'wiki_page_view'
            AND default_value_type = 'wiki_page_id'
            AND c_id = %s";
            $sql_query  = sprintf($sql, $user['user_id'], $course['code'], $course['real_id']);
            $result     = Database::query($sql_query);
            $row        = Database::fetch_array($result);

            $wiki_read          = $row['count'];
            $wiki_unread        = $wiki_total - $wiki_read;
            $wiki_progress      = round((( $wiki_read * 100 ) /  $wiki_total), 2);

            //Surveys
            $surveys_done       = (isset($survey_user_list[$user['user_id']]) ? $survey_user_list[$user['user_id']] : 0);
            $surveys_left       = $surveys_total - $surveys_done;
            $surveys_progress   = round((( $surveys_done * 100 ) /  $surveys_total), 2);

            //Forums
            #$forums_done = Tracking::count_student_messages($user['user_id'], $course_code, $session_id);
            $sql = "SELECT count(distinct f.forum_id) as count FROM $forum_post p
            INNER JOIN $forum f ON f.forum_id = p.forum_id
            WHERE p.poster_id = %s and f.session_id = %s and p.c_id = %s";
            $sql_query  = sprintf($sql, $user['user_id'], $sessionId, $course['real_id']);
            $result     = Database::query($sql_query);
            $row        = Database::fetch_array($result);

            $forums_done        = $row['count'];
            $forums_left        = $forums_total - $forums_done;
            $forums_progress    = round((( $forums_done * 100 ) /  $forums_total), 2);

            //Overall Total
            $overall_total =  ($course_description_progress + $exercises_progress + $forums_progress + $assignments_progress + $wiki_progress + $surveys_progress) / 6;

            $table[] = array(
                'lastname'  => $user[1],
                'firstname' => $user[2],
                'username'  => $user[3],
                #'profile'   => '',
                'total'     => round($overall_total,2) . '%',
                'courses'   => $course_description_progress . '%',
                'lessons'   => $lessons_progress . '%',
                'exercises' => $exercises_progress . '%',
                'forums'    => $forums_progress . '%',
                'homeworks' => $assignments_progress . '%',
                'wikis'     => $wiki_progress . '%',
                'surveys'   => $surveys_progress . '%',
                //course description
                'course_description_progress' => $course_description_progress . '%',
                //lessons
                'lessons_total'      => $lessons_total,
                'lessons_done'       => $lessons_done,
                'lessons_left'       => $lessons_left,
                'lessons_progress'   => $lessons_progress . '%',
                //exercises
                'exercises_total'       => $exercises_total,
                'exercises_done'        => $exercises_done,
                'exercises_left'        => $exercises_left,
                'exercises_progress'    => $exercises_progress . '%',
                //forums
                'forums_total'      => $forums_total,
                'forums_done'       => $forums_done,
                'forums_left'       => $forums_left,
                'forums_progress'   => $forums_progress . '%',
                //assignments
                'assignments_total'     => $assignments_total,
                'assignments_done'      => $assignments_done,
                'assignments_left'      => $assignments_left,
                'assignments_progress'  => $assignments_progress . '%',
                //wiki
                'wiki_total'        => $wiki_total,
                'wiki_revisions'    => $wiki_revisions,
                'wiki_read'         => $wiki_read,
                'wiki_unread'       => $wiki_unread,
                'wiki_progress'     => $wiki_progress . '%',
                //survey
                'surveys_total'     => $surveys_total,
                'surveys_done'      => $surveys_done,
                'surveys_left'      => $surveys_left,
                'surveys_progress'  => $surveys_progress . '%',
                );
        }
        return $table;
    }
    function get_number_of_tracking_access_overview() {
        // database table definition
        $track_e_course_access = Database :: get_main_table(TABLE_STATISTIC_TRACK_E_COURSE_ACCESS);
        return Database::count_rows($track_e_course_access);
    }

    /**
     * Get the ip, total of clicks, login date and time logged in for all user, in one session
     * @todo track_e_course_access table should have ip so we dont have to look for it in track_e_login
     *
     * @author César Perales <cesar.perales@beeznest.com>, Beeznest Team
     * @version Chamilo 1.9.6
     */
    function get_user_data_access_tracking_overview($sessionId, $courseId, $studentId = 0, $profile = '', $date_from = '', $date_to = '', $options)
    {
        // database table definition
        $user                   = Database :: get_main_table(TABLE_MAIN_USER);
        $course                 = Database :: get_main_table(TABLE_MAIN_COURSE);
        $track_e_login          = Database :: get_main_table(TABLE_STATISTIC_TRACK_E_LOGIN);
        $track_e_course_access  = Database :: get_main_table(TABLE_STATISTIC_TRACK_E_COURSE_ACCESS);

        global $export_csv;
        if ($export_csv) {
            $is_western_name_order = api_is_western_name_order(PERSON_NAME_DATA_EXPORT);
        } else {
            $is_western_name_order = api_is_western_name_order();
        }

        if (isset($sessionId) && !empty($sessionId)) {
            $where = sprintf(" WHERE a.session_id = %d", intval($sessionId));
        }
        if (isset($courseId) && !empty($courseId)) {
            $where .= sprintf(" AND c.id = %d", intval($courseId)) ;
        }
        if (isset($studentId) && !empty($studentId)) {
            $where .= sprintf(" AND u.user_id = %d", intval($studentId));
        }
        if (isset($profile) && !empty($profile)) {
            $where .= sprintf(" AND u.status = %d", intval($profile));
        }

        if (!empty($date_to) && !empty($date_from)) {
            //FIX THIS
            $to     = substr($date_to, 0, 4) .'-' . substr($date_to, 4, 2) . '-' . substr($date_to, 6, 2);
            $from   = substr($date_from, 0, 4) . '-' . substr($date_from, 4, 2) . '-' . substr($date_from, 6, 2);
            $where .=  sprintf(" AND a.login_course_date >= '%s 00:00:00'
                        AND a.login_course_date <= '%s 23:59:59'", $to, $from);
        }
        $limit = null;
        if (!empty($options['limit'])) {
            $limit = " LIMIT ".$options['limit'];
        }

        if (!empty($options['where'])) {
           $where .= ' '.$options['where'];
        }

        $order = null;
        if (!empty($options['order'])) {
            $order = " ORDER BY ".$options['order'];
        }

        //TODO add course name
        $sql = "SELECT
                a.login_course_date ,
                u.username ,
                ".($is_western_name_order ? "
                    u.firstname,
                    u.lastname,
                    " : "
                    u.lastname,
                    u.firstname,
                ")."
                a.logout_course_date,
                c.title,
                c.code,
                u.user_id
            FROM $track_e_course_access a
            INNER JOIN $user u ON a.user_id = u.user_id
            INNER JOIN $course c ON a.course_code = c.code
            $where $order $limit";
        $result = Database::query(sprintf($sql, $sessionId, $courseId));

        $clicks = Tracking::get_total_clicks_by_session();
        $data = array ();
        while ($user = Database::fetch_assoc($result)) {
            $data[] = $user;
        }

        // Foreach
        foreach ($data as $key => $info) {
            #building array to display
            $return[] = array(
                'logindate' => $info['login_course_date'],
                'username' => $info['username'],
                'firstname' => $info['firstname'],
                'lastname' => $info['lastname'],
                'clicks' => $clicks[$info['user_id']],
                'ip' => '',
                'timeLoggedIn' => gmdate("H:i:s", strtotime($info['logout_course_date']) - strtotime($info['login_course_date'])),
            );
        }

        //Search for ip, we do less querys if we iterate the final array
        foreach ($return as $key => $info) {
            $sql = sprintf("SELECT login_ip FROM $track_e_login WHERE ('%s' BETWEEN login_date AND logout_date)", $info['logindate']); //TODO add select by user too
            $result = Database::query($sql);
            $ip = Database::fetch_assoc($result);
            #add ip to final array
            $return[$key]['ip'] = $ip['login_ip'];
        }
        return $return;
    }
    /**
     * Creates a new course code based in given code
     *
     * @param string	wanted code
     * <code>
     * $wanted_code = 'curse' if there are in the DB codes like curse1 curse2 the function will return: course3
     * if the course code doest not exist in the DB the same course code will be returned
     * </code>
     * @return string	wanted unused code
     */
    public static function generate_nice_next_session_name($session_name)
    {
        $session_name_ok = !self::session_name_exists($session_name);
        if (!$session_name_ok) {
           $table = Database::get_main_table(TABLE_MAIN_SESSION);
           $session_name = Database::escape_string($session_name);
           $sql = "SELECT count(*) as count FROM $table WHERE name LIKE '$session_name%'";
           $result = Database::query($sql);
           if (Database::num_rows($result) > 0 ) {
		       $row = Database::fetch_array($result);
		       $count = $row['count'] + 1;
		       $session_name = $session_name.'_'.$count;
		       $result = self::session_name_exists($session_name);
		       if (!$result) {
		           return $session_name;
		       }
           }
           return false;
        }
        return $session_name;
    }

	/**
	 * Edit a session
	 * @author Carlos Vargas from existing code
	 * @param	integer		id
	 * @param	string 		name
	 * @param 	integer		year_start
	 * @param 	integer		month_start
	 * @param 	integer		day_start
	 * @param 	integer		year_end
	 * @param 	integer		month_end
	 * @param 	integer		day_end
	 * @param 	integer		nb_days_acess_before
	 * @param 	integer		nb_days_acess_after
	 * @param 	integer		nolimit
	 * @param 	integer		id_coach
	 * @param 	integer		id_session_category
     * @param   int $id_visibility
     * @param bool
     * @param bool
     * @param string $description
     * @param int  $showDescription
	 * @return $id;
	 * The parameter id is a primary key
	**/
	public static function edit_session (
        $id,
        $name,
        $year_start,
        $month_start,
        $day_start,
        $year_end,
        $month_end,
        $day_end,
        $nb_days_acess_before,
        $nb_days_acess_after,
        $nolimit,
        $id_coach,
        $id_session_category,
        $id_visibility,
        $start_limit = true,
        $end_limit = true,
        $description = null,
        $showDescription = null
    ) {
		$name = trim(stripslashes($name));
		$year_start=intval($year_start);
		$month_start=intval($month_start);
		$day_start=intval($day_start);
		$year_end=intval($year_end);
		$month_end=intval($month_end);
		$day_end=intval($day_end);
		$id_coach= intval($id_coach);
		$nb_days_acess_before= intval($nb_days_acess_before);
		$nb_days_acess_after = intval($nb_days_acess_after);
		$id_session_category = intval($id_session_category);
		$id_visibility = intval($id_visibility);

		$tbl_session	= Database::get_main_table(TABLE_MAIN_SESSION);

		if (empty($nolimit)) {
			$date_start  = "$year_start-".(($month_start < 10)?"0$month_start":$month_start)."-".(($day_start < 10)?"0$day_start":$day_start);
			$date_end    = "$year_end-".(($month_end < 10)?"0$month_end":$month_end)."-".(($day_end < 10)?"0$day_end":$day_end);
		} else {
			$date_start  = "0000-00-00";
			$date_end    = "0000-00-00";
			$id_visibility = 1;//force read only
		}

        if (!empty($no_end_limit)) {
        	$date_end   = "0000-00-00";
        }

        if (empty($end_limit)) {
            $date_end ="0000-00-00";
            $id_visibility = 1;//force read only
        }

        if (empty($start_limit)) {
            $date_start ="0000-00-00";
        }

		if (empty($name)) {
			$msg=get_lang('SessionNameIsRequired');
			return $msg;
		} elseif (empty($id_coach))   {
			$msg=get_lang('CoachIsRequired');
			return $msg;
		} elseif (!empty($start_limit) && empty($nolimit) && (!$month_start || !$day_start || !$year_start || !checkdate($month_start,$day_start,$year_start))) {
			$msg=get_lang('InvalidStartDate');
			return $msg;
		} elseif (!empty($end_limit) && empty($nolimit) && (!$month_end || !$day_end || !$year_end || !checkdate($month_end,$day_end,$year_end))) {
			$msg=get_lang('InvalidEndDate');
			return $msg;
		} elseif (!empty($start_limit) && !empty($end_limit) && empty($nolimit) && $date_start >= $date_end) {
			$msg=get_lang('StartDateShouldBeBeforeEndDate');
			return $msg;
		} else {

			$rs = Database::query("SELECT id FROM $tbl_session WHERE name='".Database::escape_string($name)."'");
			$exists = false;
			while ($row = Database::fetch_array($rs)) {
				if ($row['id'] != $id) {
                    $exists = true;
                }
			}

			if ($exists) {
				$msg = get_lang('SessionNameAlreadyExists');
				return $msg;
			} else {

                $sessionInfo = SessionManager::fetch($id);

                $descriptionCondition = null;
                if (array_key_exists('description', $sessionInfo)) {
                    $descriptionCondition = ' description = "'.Database::escape_string($description).'" ,';
                }

                $showDescriptionCondition = null;
                if (array_key_exists('show_description', $sessionInfo)) {
                    $showDescriptionCondition = ' show_description = "'.Database::escape_string($showDescription).'" ,';
                }

				$sql = "UPDATE $tbl_session " .
					"SET name='".Database::escape_string($name)."',
						date_start='".$date_start."',
						date_end='".$date_end."',
						id_coach='".$id_coach."',
						nb_days_access_before_beginning = ".$nb_days_acess_before.",
						nb_days_access_after_end = ".$nb_days_acess_after.",
						session_category_id = ".$id_session_category." ,
                        $descriptionCondition
                        $showDescriptionCondition
						visibility= ".$id_visibility."
					  WHERE id='$id'";
				Database::query($sql);
				return $id;
			}
		}
	}

	/**
	 * Delete session
	 * @author Carlos Vargas  from existing code
	 * @param	array	id_checked an array to delete sessions
	 * @param   boolean  optional, true if the function is called by a webservice, false otherwise.
     * @return	void	Nothing, or false on error
	 **/
	public static function delete_session($id_checked, $from_ws = false)
    {
		$tbl_session=						Database::get_main_table(TABLE_MAIN_SESSION);
		$tbl_session_rel_course=			Database::get_main_table(TABLE_MAIN_SESSION_COURSE);
		$tbl_session_rel_course_rel_user=	Database::get_main_table(TABLE_MAIN_SESSION_COURSE_USER);
		$tbl_session_rel_user=				Database::get_main_table(TABLE_MAIN_SESSION_USER);
		$tbl_url_session                  = Database::get_main_table(TABLE_MAIN_ACCESS_URL_REL_SESSION);
		$t_sfv = Database::get_main_table(TABLE_MAIN_SESSION_FIELD_VALUES);

		$userId = api_get_user_id();

		if (is_array($id_checked)) {
			$id_checked = Database::escape_string(implode(',',$id_checked));
		} else {
			$id_checked = intval($id_checked);
		}

		if (!api_is_platform_admin() && !$from_ws) {
			$sql = 'SELECT session_admin_id FROM '.Database :: get_main_table(TABLE_MAIN_SESSION).' WHERE id='.$id_checked;
			$rs  = Database::query($sql);
			if (Database::result($rs, 0, 0) != $userId) {
				api_not_allowed(true);
			}
		}

		Database::query("DELETE FROM $tbl_session WHERE id IN($id_checked)");
		Database::query("DELETE FROM $tbl_session_rel_course WHERE id_session IN($id_checked)");
		Database::query("DELETE FROM $tbl_session_rel_course_rel_user WHERE id_session IN($id_checked)");
		Database::query("DELETE FROM $tbl_session_rel_user WHERE id_session IN($id_checked)");
		Database::query("DELETE FROM $tbl_url_session WHERE session_id IN($id_checked)");

		$sql_delete_sfv = "DELETE FROM $t_sfv WHERE session_id = '$id_checked'";
		Database::query($sql_delete_sfv);

		// Add event to system log
		event_system(LOG_SESSION_DELETE, LOG_SESSION_ID, $id_checked, api_get_utc_datetime(), $userId);
	}

    /**
     * @param int $id_promotion
     * @return bool
     */
    public static function clear_session_ref_promotion($id_promotion)
    {
        $tbl_session = Database::get_main_table(TABLE_MAIN_SESSION);
        $id_promotion = intval($id_promotion);
        $update_sql = "UPDATE $tbl_session SET promotion_id=0 WHERE promotion_id='$id_promotion'";
        if (Database::query($update_sql)) {
            return true;
        } else {
            return false;
        }
    }

    /**
     * Subscribes students to the given session and optionally (default) unsubscribes previous users
     *
     * @author Carlos Vargas from existing code
     * @author Julio Montoya. Cleaning code.
     * @param int $id_session
     * @param array $user_list
     * @param int $session_visibility
     * @param bool $empty_users
     * @param bool $send_email
     * @return bool
     */
    public static function suscribe_users_to_session(
        $id_session,
        $user_list,
        $session_visibility = SESSION_VISIBLE_READ_ONLY,
        $empty_users = true,
        $send_email = false
    ) {

	  	if ($id_session != strval(intval($id_session))) {
            return false;
        }

	   	foreach ($user_list as $intUser){
	   		if ($intUser!= strval(intval($intUser))) {
                return false;
            }
	   	}

	   	$tbl_session_rel_course				= Database::get_main_table(TABLE_MAIN_SESSION_COURSE);
		$tbl_session_rel_course_rel_user	= Database::get_main_table(TABLE_MAIN_SESSION_COURSE_USER);
	   	$tbl_session_rel_user 				= Database::get_main_table(TABLE_MAIN_SESSION_USER);
	   	$tbl_session						= Database::get_main_table(TABLE_MAIN_SESSION);

		$session_info 		= api_get_session_info($id_session);
		$session_name 		= $session_info['name'];

		// from function parameter
	   	if (empty($session_visibility)) {
	   		$session_visibility	= $session_info['visibility']; //loaded from DB
	   		//default status loaded if empty
			if (empty($session_visibility))
				$session_visibility = SESSION_VISIBLE_READ_ONLY; // by default readonly 1
	   	} else {
	   	    if (!in_array($session_visibility, array(SESSION_VISIBLE_READ_ONLY, SESSION_VISIBLE, SESSION_INVISIBLE))) {
	   	        $session_visibility = SESSION_VISIBLE_READ_ONLY;
	   	    }
	   	}

        $sql = "SELECT id_user FROM $tbl_session_rel_course_rel_user WHERE id_session = '$id_session' AND status = 0";
		$result = Database::query($sql);
		$existingUsers = array();
		while ($row = Database::fetch_array($result)) {
			$existingUsers[] = $row['id_user'];
		}

		$sql = "SELECT course_code FROM $tbl_session_rel_course WHERE id_session = '$id_session'";
		$result = Database::query($sql);
		$course_list = array();
		while ($row = Database::fetch_array($result)) {
			$course_list[] = $row['course_code'];
		}

		if ($send_email) {
			// Sending emails only
			if (is_array($user_list) && count($user_list)>0) {
				foreach ($user_list as $user_id) {
				    if (!in_array($user_id, $existingUsers)) {
                        $subject = '['.get_setting('siteName').'] '.get_lang('YourReg').' '.get_setting('siteName');
                        $user_info = api_get_user_info($user_id);
                        $content	= get_lang('Dear')." ".stripslashes($user_info['complete_name']).",\n\n".sprintf(get_lang('YouAreRegisterToSessionX'), $session_name) ." \n\n" .get_lang('Address') ." ". get_setting('siteName') ." ". get_lang('Is') ." : ". api_get_path(WEB_PATH) ."\n\n". get_lang('Problem'). "\n\n". get_lang('Formula').",\n\n".get_setting('administratorName')." ".get_setting('administratorSurname')."\n". get_lang('Manager'). " ".get_setting('siteName')."\nT. ".get_setting('administratorTelephone')."\n" .get_lang('Email') ." : ".get_setting('emailAdministrator');
                        MessageManager::send_message($user_id, $subject, $content, array(), array(), null, null, null, null, null);
					}
				}
			}
		}

		foreach ($course_list as $enreg_course) {
			// for each course in the session
			$nbr_users = 0;
	        $enreg_course = Database::escape_string($enreg_course);
		    // delete existing users
			if ($empty_users) {
				foreach ($existingUsers as $existing_user) {
					if (!in_array($existing_user, $user_list)) {
						$sql = "DELETE FROM $tbl_session_rel_course_rel_user WHERE id_session='$id_session' AND course_code='$enreg_course' AND id_user='$existing_user' AND status = 0";
						Database::query($sql);
						if (Database::affected_rows()) {
							$nbr_users--;
						}
					}
				}
			}

			// Replace with this new function
			// insert new users into session_rel_course_rel_user and ignore if they already exist
			foreach ($user_list as $enreg_user) {
				if(!in_array($enreg_user, $existingUsers)) {
	                $enreg_user = Database::escape_string($enreg_user);
					$insert_sql = "INSERT IGNORE INTO $tbl_session_rel_course_rel_user(id_session, course_code, id_user, visibility, status) VALUES('$id_session','$enreg_course','$enreg_user','$session_visibility', '0')";
					Database::query($insert_sql);
					if(Database::affected_rows()) {
						$nbr_users++;
					}
				}
			}
			// Count users in this session-course relation
			$sql = "SELECT COUNT(id_user) as nbUsers FROM $tbl_session_rel_course_rel_user WHERE id_session='$id_session' AND course_code='$enreg_course' AND status<>2";
			$rs = Database::query($sql);
			list($nbr_users) = Database::fetch_array($rs);
			// update the session-course relation to add the users total
			$update_sql = "UPDATE $tbl_session_rel_course SET nbr_users=$nbr_users WHERE id_session='$id_session' AND course_code='$enreg_course'";
			Database::query($update_sql);
		}

		// Delete users from the session
		if ($empty_users===true) {
			Database::query("DELETE FROM $tbl_session_rel_user WHERE id_session = $id_session AND relation_type<>".SESSION_RELATION_TYPE_RRHH."");
		}

		// Insert missing users into session
		$nbr_users = 0;
		foreach ($user_list as $enreg_user) {
	        $enreg_user = Database::escape_string($enreg_user);
			$nbr_users++;
			$insert_sql = "INSERT IGNORE INTO $tbl_session_rel_user (id_session, id_user) VALUES ('$id_session', '$enreg_user')";
			Database::query($insert_sql);
		}

		// update number of users in the session
		$nbr_users = count($user_list);
        if ($empty_users) {
            // update number of users in the session
            $update_sql = "UPDATE $tbl_session SET nbr_users= $nbr_users WHERE id='$id_session' ";
            Database::query($update_sql);
        } else {
            $update_sql = "UPDATE $tbl_session SET nbr_users= nbr_users + $nbr_users WHERE id='$id_session'";
            Database::query($update_sql);
        }
	}

    /**
     * Subscribe a user to an specific course inside a session.
     *
     * @param array $user_list
     * @param int $session_id
     * @param string $course_code
     * @param int $session_visibility
     * @return bool
     */
    public static function subscribe_users_to_session_course(
        $user_list,
        $session_id,
        $course_code,
        $session_visibility = SESSION_VISIBLE_READ_ONLY
    ) {
        $tbl_session_rel_course				= Database::get_main_table(TABLE_MAIN_SESSION_COURSE);
        $tbl_session_rel_course_rel_user	= Database::get_main_table(TABLE_MAIN_SESSION_COURSE_USER);

        if (empty($user_list) || empty($session_id) || empty($course_code)) {
            return false;
        }

        $session_id = intval($session_id);
        $course_code = Database::escape_string($course_code);
        $session_visibility = intval($session_visibility);

        $nbr_users = 0;
        /*AND
        visibility = $session_visibility*/
        foreach ($user_list as $enreg_user) {
            $enreg_user = intval($enreg_user);
            $sql = "SELECT count(id_user) as count
                    FROM $tbl_session_rel_course_rel_user
                    WHERE id_session = $session_id AND
                          course_code = '$course_code' and
                          id_user = $enreg_user ";
            $result = Database::query($sql);
            $count = 0;

            if (Database::num_rows($result) > 0) {
                $row = Database::fetch_array($result, 'ASSOC');
                $count = $row['count'];
            }

            if ($count == 0) {
                $insert_sql = "INSERT IGNORE INTO $tbl_session_rel_course_rel_user(id_session,course_code,id_user,visibility)
                               VALUES ('$session_id','$course_code','$enreg_user','$session_visibility')";
                Database::query($insert_sql);
                if (Database::affected_rows()) {
                    $nbr_users++;
                }
            }
        }

        // count users in this session-course relation
        $sql = "SELECT COUNT(id_user) as nbUsers FROM $tbl_session_rel_course_rel_user
                WHERE id_session='$session_id' AND course_code='$course_code' AND status<>2";
        $rs = Database::query($sql);
        list($nbr_users) = Database::fetch_array($rs);
        // update the session-course relation to add the users total
        $update_sql = "UPDATE $tbl_session_rel_course SET nbr_users=$nbr_users
                       WHERE id_session='$session_id' AND course_code='$course_code'";
        Database::query($update_sql);
    }

	/**
	 * Unsubscribe user from session
	 *
	 * @param int Session id
	 * @param int User id
	 * @return bool True in case of success, false in case of error
	 */
	public static function unsubscribe_user_from_session($session_id, $user_id)
    {
		$session_id = (int)$session_id;
		$user_id = (int)$user_id;

		$tbl_session_rel_course_rel_user = Database::get_main_table(TABLE_MAIN_SESSION_COURSE_USER);
		$tbl_session_rel_course	= Database::get_main_table(TABLE_MAIN_SESSION_COURSE);
		$tbl_session_rel_user = Database::get_main_table(TABLE_MAIN_SESSION_USER);
		$tbl_session = Database::get_main_table(TABLE_MAIN_SESSION);

		$delete_sql = "DELETE FROM $tbl_session_rel_user
		               WHERE    id_session = '$session_id' AND
		                        id_user ='$user_id' AND
		                        relation_type <> ".SESSION_RELATION_TYPE_RRHH."";
		Database::query($delete_sql);
		$return = Database::affected_rows();

		// Update number of users
        $sql = "UPDATE $tbl_session SET nbr_users = nbr_users - $return WHERE id='$session_id' ";
		Database::query($sql);

		// Get the list of courses related to this session
		$course_list = SessionManager::get_course_list_by_session_id($session_id);
		if (!empty($course_list)) {
			foreach($course_list as $course) {
				$course_code = $course['code'];
				// Delete user from course
                $sql = "DELETE FROM $tbl_session_rel_course_rel_user
                        WHERE id_session='$session_id' AND course_code='$course_code' AND id_user='$user_id'";
				Database::query($sql);
				if (Database::affected_rows()) {
					// Update number of users in this relation
                    $sql = "UPDATE $tbl_session_rel_course SET nbr_users=nbr_users - 1
                            WHERE id_session='$session_id' AND course_code='$course_code'";
					Database::query($sql);
				}
			}
		}
		return true;
	}

	 /** Subscribes courses to the given session and optionally (default) unsubscribes previous users
	 * @author Carlos Vargas from existing code
     * @param	int		Session ID
     * @param	array	List of courses IDs
     * @param	bool	Whether to unsubscribe existing users (true, default) or not (false)
     * @return	void	Nothing, or false on error
     **/
     public static function add_courses_to_session($id_session, $course_list, $empty_courses = true)
     {
     	// Security checks
     	if ($id_session!= strval(intval($id_session))) {
            return false;
        }

		$tbl_session_rel_course_rel_user	= Database::get_main_table(TABLE_MAIN_SESSION_COURSE_USER);
		$tbl_session						= Database::get_main_table(TABLE_MAIN_SESSION);
		$tbl_session_rel_user				= Database::get_main_table(TABLE_MAIN_SESSION_USER);
		$tbl_session_rel_course				= Database::get_main_table(TABLE_MAIN_SESSION_COURSE);
		$tbl_course							= Database::get_main_table(TABLE_MAIN_COURSE);
     	// get general coach ID
		$id_coach = Database::query("SELECT id_coach FROM $tbl_session WHERE id=$id_session");
		$id_coach = Database::fetch_array($id_coach);
		$id_coach = $id_coach[0];
		// get list of courses subscribed to this session
		$rs = Database::query("SELECT course_code FROM $tbl_session_rel_course WHERE id_session=$id_session");
		$existingCourses = Database::store_result($rs);
		$nbr_courses=count($existingCourses);
		// get list of users subscribed to this session
		$sql="SELECT id_user
			FROM $tbl_session_rel_user
			WHERE id_session = $id_session AND relation_type<>".SESSION_RELATION_TYPE_RRHH."";
		$result=Database::query($sql);
		$user_list=Database::store_result($result);

		// remove existing courses from the session
		if ($empty_courses===true) {
			foreach ($existingCourses as $existingCourse) {
				if (!in_array($existingCourse['course_code'], $course_list)){
					Database::query("DELETE FROM $tbl_session_rel_course WHERE course_code='".$existingCourse['course_code']."' AND id_session=$id_session");
					Database::query("DELETE FROM $tbl_session_rel_course_rel_user WHERE course_code='".$existingCourse['course_code']."' AND id_session=$id_session");

				}
			}
			$nbr_courses=0;
		}

		// Pass through the courses list we want to add to the session
		foreach ($course_list as $enreg_course) {
			$enreg_course = Database::escape_string($enreg_course);
			$exists = false;
			// check if the course we want to add is already subscribed
			foreach ($existingCourses as $existingCourse) {
				if ($enreg_course == $existingCourse['course_code']) {
					$exists=true;
				}
			}
			if (!$exists) {
				//if the course isn't subscribed yet
				$sql_insert_rel_course= "INSERT INTO $tbl_session_rel_course (id_session,course_code) VALUES ('$id_session','$enreg_course')";
				Database::query($sql_insert_rel_course);
				//We add the current course in the existing courses array, to avoid adding another time the current course
				$existingCourses[]=array('course_code'=>$enreg_course);
				$nbr_courses++;

				// subscribe all the users from the session to this course inside the session
				$nbr_users=0;
				foreach ($user_list as $enreg_user) {
					$enreg_user_id = Database::escape_string($enreg_user['id_user']);
					$sql_insert = "INSERT IGNORE INTO $tbl_session_rel_course_rel_user (id_session,course_code,id_user) VALUES ('$id_session','$enreg_course','$enreg_user_id')";
					Database::query($sql_insert);
					if (Database::affected_rows()) {
						$nbr_users++;
					}
				}
				Database::query("UPDATE $tbl_session_rel_course SET nbr_users=$nbr_users WHERE id_session='$id_session' AND course_code='$enreg_course'");
			}
		}
		Database::query("UPDATE $tbl_session SET nbr_courses=$nbr_courses WHERE id='$id_session'");
     }

	/**
	 * Unsubscribe course from a session
	 *
	 * @param int Session id
	 * @param int Course id
	 * @return bool True in case of success, false otherwise
	 */
	public static function unsubscribe_course_from_session($session_id, $course_id)
    {
		$session_id = (int)$session_id;
		$course_id = (int)$course_id;

		$tbl_session_rel_course = Database::get_main_table(TABLE_MAIN_SESSION_COURSE);
		$tbl_session_rel_course_rel_user	= Database::get_main_table(TABLE_MAIN_SESSION_COURSE_USER);
		$tbl_session = Database::get_main_table(TABLE_MAIN_SESSION);

		// Get course code
		$course_code = CourseManager::get_course_code_from_course_id($course_id);
		if($course_code == 0) {
			return false;
		}

		// Unsubscribe course
	    Database::query("DELETE FROM $tbl_session_rel_course WHERE course_code='$course_code' AND id_session='$session_id'");
	    $nb_affected = Database::affected_rows();

	    Database::query("DELETE FROM $tbl_session_rel_course_rel_user WHERE course_code='$course_code' AND id_session='$session_id'");
	    if($nb_affected > 0) {
			// Update number of courses in the session
			Database::query("UPDATE $tbl_session SET nbr_courses= nbr_courses + $nb_affected WHERE id='$session_id' ");
			return true;
		} else {
			return false;
		}
	}

    /**
    * Creates a new extra field for a given session
    * @param	string	Field's internal variable name
    * @param	int		Field's type
    * @param	string	Field's language var name
    * @return int     new extra field id
    */
	public static function create_session_extra_field ($fieldvarname, $fieldtype, $fieldtitle)
    {
		// database table definition
		$t_sf 			= Database::get_main_table(TABLE_MAIN_SESSION_FIELD);
		$fieldvarname 	= Database::escape_string($fieldvarname);
		$fieldtitle 	= Database::escape_string($fieldtitle);
		$fieldtype = (int)$fieldtype;
		$time = time();
		$sql_field = "SELECT id FROM $t_sf WHERE field_variable = '$fieldvarname'";
		$res_field = Database::query($sql_field);

		$r_field = Database::fetch_row($res_field);

		if (Database::num_rows($res_field)>0) {
			$field_id = $r_field[0];
		} else {
			// save new fieldlabel into course_field table
			$sql = "SELECT MAX(field_order) FROM $t_sf";
			$res = Database::query($sql);

			$order = 0;
			if (Database::num_rows($res)>0) {
				$row = Database::fetch_row($res);
				$order = $row[0]+1;
			}

			$sql = "INSERT INTO $t_sf SET
                    field_type = '$fieldtype',
                    field_variable = '$fieldvarname',
                    field_display_text = '$fieldtitle',
                    field_order = '$order',
                    tms = FROM_UNIXTIME($time)";
			Database::query($sql);

			$field_id = Database::insert_id();
		}
		return $field_id;
	}

    /**
    * Update an extra field value for a given session
    * @param	integer	Course ID
    * @param	string	Field variable name
    * @param	string	Field value
    * @return	boolean	true if field updated, false otherwise
    */
	public static function update_session_extra_field_value ($session_id,$fname,$fvalue='')
    {

		$t_sf 			= Database::get_main_table(TABLE_MAIN_SESSION_FIELD);
		$t_sfv 			= Database::get_main_table(TABLE_MAIN_SESSION_FIELD_VALUES);
		$fname = Database::escape_string($fname);
		$session_id = (int)$session_id;
		$fvalues = '';
		if (is_array($fvalue)) {
            foreach ($fvalue as $val) {
                $fvalues .= Database::escape_string($val).';';
			}
			if (!empty($fvalues)) {
				$fvalues = substr($fvalues,0,-1);
			}
		} else {
			$fvalues = Database::escape_string($fvalue);
		}

		$sqlsf = "SELECT * FROM $t_sf WHERE field_variable='$fname'";
		$ressf = Database::query($sqlsf);
		if (Database::num_rows($ressf)==1) {
		    //ok, the field exists
			//	Check if enumerated field, if the option is available
			$rowsf = Database::fetch_array($ressf);

			$tms = time();
			$sqlsfv = "SELECT * FROM $t_sfv WHERE session_id = '$session_id' AND field_id = '".$rowsf['id']."' ORDER BY id";
			$ressfv = Database::query($sqlsfv);
			$n = Database::num_rows($ressfv);
			if ($n>1) {
				//problem, we already have to values for this field and user combination - keep last one
				while($rowsfv = Database::fetch_array($ressfv)) {
					if($n > 1) {
						$sqld = "DELETE FROM $t_sfv WHERE id = ".$rowsfv['id'];
						$resd = Database::query($sqld);
						$n--;
					}
                    $rowsfv = Database::fetch_array($ressfv);
					if($rowsfv['field_value'] != $fvalues) {
						$sqlu = "UPDATE $t_sfv SET field_value = '$fvalues', tms = FROM_UNIXTIME($tms) WHERE id = ".$rowsfv['id'];
						$resu = Database::query($sqlu);
						return($resu?true:false);
					}
					return true;
				}
			} else if ($n==1) {
				//we need to update the current record
				$rowsfv = Database::fetch_array($ressfv);
				if($rowsfv['field_value'] != $fvalues)
				{
					$sqlu = "UPDATE $t_sfv SET field_value = '$fvalues', tms = FROM_UNIXTIME($tms) WHERE id = ".$rowsfv['id'];
					//error_log('UM::update_extra_field_value: '.$sqlu);
					$resu = Database::query($sqlu);
					return($resu?true:false);
				}
				return true;
			} else {
				$sqli = "INSERT INTO $t_sfv (session_id,field_id,field_value,tms) " .
					"VALUES ('$session_id',".$rowsf['id'].",'$fvalues',FROM_UNIXTIME($tms))";
				//error_log('UM::update_extra_field_value: '.$sqli);
				$resi = Database::query($sqli);
				return($resi?true:false);
			}
		} else {
			return false; //field not found
		}
	}

	/**
	* Checks the relationship between a session and a course.
	* @param int $session_id
	* @param int $course_id
	* @return bool Returns TRUE if the session and the course are related, FALSE otherwise.
	* */
	public static function relation_session_course_exist ($session_id, $course_id)
    {
		$tbl_session_course	= Database::get_main_table(TABLE_MAIN_SESSION_COURSE);
		$return_value = false;
		$sql= "SELECT course_code FROM $tbl_session_course WHERE id_session = ".Database::escape_string($session_id)." AND course_code = '".Database::escape_string($course_id)."'";
		$result = Database::query($sql);
		$num = Database::num_rows($result);
		if ($num>0) {
			$return_value = true;
		}
		return $return_value;
	}

	/**
	* Get the session information by name
	* @param string session name
	* @return mixed false if the session does not exist, array if the session exist
	* */
	public static function get_session_by_name ($session_name)
    {
		$tbl_session = Database::get_main_table(TABLE_MAIN_SESSION);
        $session_name = trim($session_name);
        if (empty($session_name)) {
            return false;
        }

		$sql = 'SELECT *
		        FROM '.$tbl_session.'
		        WHERE name = "'.Database::escape_string($session_name).'"';
		$result = Database::query($sql);
		$num = Database::num_rows($result);
		if ($num>0) {
			return Database::fetch_array($result);
		} else {
			return false;
		}
	}

	/**
	  * Create a session category
	  * @author Jhon Hinojosa <jhon.hinojosa@dokeos.com>, from existing code
	  * @param	string 		name
	  * @param 	integer		year_start
	  * @param 	integer		month_start
	  * @param 	integer		day_start
	  * @param 	integer		year_end
	  * @param 	integer		month_end
	  * @param 	integer		day_end
	  * @return $id_session;
	  **/
	public static function create_category_session($sname,$syear_start,$smonth_start,$sday_start,$syear_end,$smonth_end, $sday_end)
    {
		$tbl_session_category = Database::get_main_table(TABLE_MAIN_SESSION_CATEGORY);
		$name= trim($sname);
		$year_start= intval($syear_start);
		$month_start=intval($smonth_start);
		$day_start=intval($sday_start);
		$year_end=intval($syear_end);
		$month_end=intval($smonth_end);
		$day_end=intval($sday_end);

        $date_start = "$year_start-".(($month_start < 10)?"0$month_start":$month_start)."-".(($day_start < 10)?"0$day_start":$day_start);
        $date_end = "$year_end-".(($month_end < 10)?"0$month_end":$month_end)."-".(($day_end < 10)?"0$day_end":$day_end);

		if (empty($name)) {
			$msg=get_lang('SessionCategoryNameIsRequired');
			return $msg;
		} elseif (!$month_start || !$day_start || !$year_start || !checkdate($month_start,$day_start,$year_start)) {
			$msg=get_lang('InvalidStartDate');
			return $msg;
        } elseif (!$month_end && !$day_end && !$year_end) {
            $date_end = "null";
		} elseif (!$month_end || !$day_end || !$year_end || !checkdate($month_end,$day_end,$year_end)) {
			$msg=get_lang('InvalidEndDate');
			return $msg;
		} elseif($date_start >= $date_end) {
			$msg=get_lang('StartDateShouldBeBeforeEndDate');
			return $msg;
		}
		$access_url_id = api_get_current_access_url_id();
        $sql = "INSERT INTO $tbl_session_category (name, date_start, date_end, access_url_id)
        		VALUES('".Database::escape_string($name)."','$date_start','$date_end', '$access_url_id')";
        Database::query($sql);
        $id_session = Database::insert_id();
        // Add event to system log
        $user_id = api_get_user_id();
        event_system(LOG_SESSION_CATEGORY_CREATE, LOG_SESSION_CATEGORY_ID, $id_session, api_get_utc_datetime(), $user_id);
        return $id_session;
	}

	/**
	 * Edit a sessions categories
	 * @author Jhon Hinojosa <jhon.hinojosa@dokeos.com>,from existing code
	 * @param	integer		id
	 * @param	string 		name
	 * @param 	integer		year_start
	 * @param 	integer		month_start
	 * @param 	integer		day_start
	 * @param 	integer		year_end
	 * @param 	integer		month_end
	 * @param 	integer		day_end
	 * @return $id;
	 * The parameter id is a primary key
	**/
	public static function edit_category_session($id, $sname,$syear_start,$smonth_start,$sday_start,$syear_end,$smonth_end, $sday_end)
    {
		$tbl_session_category = Database::get_main_table(TABLE_MAIN_SESSION_CATEGORY);
		$name= trim($sname);
		$year_start= intval($syear_start);
		$month_start=intval($smonth_start);
		$day_start=intval($sday_start);
		$year_end=intval($syear_end);
		$month_end=intval($smonth_end);
		$day_end=intval($sday_end);
		$id=intval($id);
		$date_start = "$year_start-".(($month_start < 10)?"0$month_start":$month_start)."-".(($day_start < 10)?"0$day_start":$day_start);
		$date_end = "$year_end-".(($month_end < 10)?"0$month_end":$month_end)."-".(($day_end < 10)?"0$day_end":$day_end);

		if (empty($name)) {
			$msg=get_lang('SessionCategoryNameIsRequired');
			return $msg;
		} elseif (!$month_start || !$day_start || !$year_start || !checkdate($month_start,$day_start,$year_start)) {
			$msg=get_lang('InvalidStartDate');
			return $msg;
		} elseif (!$month_end && !$day_end && !$year_end) {
            $date_end = null;
		} elseif (!$month_end || !$day_end || !$year_end || !checkdate($month_end,$day_end,$year_end)) {
			$msg=get_lang('InvalidEndDate');
			return $msg;
		} elseif($date_start >= $date_end) {
			$msg=get_lang('StartDateShouldBeBeforeEndDate');
			return $msg;
		}
        if ( $date_end <> null ) {
	        $sql = "UPDATE $tbl_session_category SET name = '".Database::escape_string($name)."', date_start = '$date_start' ".
                ", date_end = '$date_end' WHERE id= '".$id."' ";
        } else {
            $sql = "UPDATE $tbl_session_category SET name = '".Database::escape_string($name)."', date_start = '$date_start' ".
                ", date_end = NULL WHERE id= '".$id."' ";
        }
		$result = Database::query($sql);
		return ($result? true:false);
	}

	/**
	 * Delete sessions categories
	 * @author Jhon Hinojosa <jhon.hinojosa@dokeos.com>, from existing code
	 * @param	array	id_checked
	 * @param	bool	include delete session
	 * @param	bool	optional, true if the function is called by a webservice, false otherwise.
     * @return	void	Nothing, or false on error
	 * The parameters is a array to delete sessions
	 **/
	public static function delete_session_category($id_checked, $delete_session = false,$from_ws = false)
    {
		$tbl_session_category = Database::get_main_table(TABLE_MAIN_SESSION_CATEGORY);
		$tbl_session = Database::get_main_table(TABLE_MAIN_SESSION);
		if (is_array($id_checked)) {
			$id_checked = Database::escape_string(implode(',',$id_checked));
		} else {
			$id_checked = intval($id_checked);
		}

		//Setting session_category_id to 0
		$sql = "UPDATE $tbl_session SET session_category_id = 0 WHERE session_category_id IN (".$id_checked.")";
        Database::query($sql);

		$sql = "SELECT id FROM $tbl_session WHERE session_category_id IN (".$id_checked.")";
		$result = Database::query($sql);
		while ($rows = Database::fetch_array($result)) {
			$session_id = $rows['id'];
			if ($delete_session) {
				if ($from_ws) {
					SessionManager::delete_session($session_id,true);
				} else {
					SessionManager::delete_session($session_id);
				}
			}
		}
		$sql = "DELETE FROM $tbl_session_category WHERE id IN (".$id_checked.")";
		Database::query($sql);

		// Add event to system log
		$user_id = api_get_user_id();
		event_system(LOG_SESSION_CATEGORY_DELETE, LOG_SESSION_CATEGORY_ID, $id_checked, api_get_utc_datetime(), $user_id);

		// delete extra session fields where field variable is "PERIODO"
		$t_sf 		= Database::get_main_table(TABLE_MAIN_SESSION_FIELD);
		$t_sfv 		= Database::get_main_table(TABLE_MAIN_SESSION_FIELD_VALUES);

		$sql = "SELECT t_sfv.field_id FROM $t_sfv t_sfv, $t_sf t_sf  WHERE t_sfv.session_id = '$id_checked' AND t_sf.field_variable = 'PERIODO' ";
		$rs_field = Database::query($sql);

		$field_id = 0;
		if (Database::num_rows($rs_field) > 0) {
			$row_field = Database::fetch_row($rs_field);
			$field_id = $row_field[0];
			$sql_delete_sfv = "DELETE FROM $t_sfv WHERE session_id = '$id_checked' AND field_id = '$field_id'";
			Database::query($sql_delete_sfv);
		}

		$sql = "SELECT * FROM $t_sfv WHERE field_id = '$field_id' ";
		$rs_field_id = Database::query($sql);

		if (Database::num_rows($rs_field_id) == 0) {
			$sql_delete_sf = "DELETE FROM $t_sf WHERE id = '$field_id'";
			Database::query($sql_delete_sf);
		}

		return true;
	}

	/**
     * Get a list of sessions of which the given conditions match with an = 'cond'
	 * @param  array $conditions a list of condition (example : array('status =' =>STUDENT) or array('s.name LIKE' => "%$needle%")
	 * @param  array $order_by a list of fields on which sort
	 * @return array An array with all sessions of the platform.
	 * @todo   optional course code parameter, optional sorting parameters...
	*/
	public static function get_sessions_list($conditions = array(), $order_by = array())
    {

		$session_table                = Database::get_main_table(TABLE_MAIN_SESSION);
		$session_category_table       = Database::get_main_table(TABLE_MAIN_SESSION_CATEGORY);
		$user_table                   = Database::get_main_table(TABLE_MAIN_USER);
		$table_access_url_rel_session = Database::get_main_table(TABLE_MAIN_ACCESS_URL_REL_SESSION);

		$access_url_id = api_get_current_access_url_id();

        $return_array = array();

		$sql_query = " SELECT s.id, s.name, s.nbr_courses, s.date_start, s.date_end, u.firstname, u.lastname, sc.name as category_name, s.promotion_id
				FROM $session_table s
				INNER JOIN $user_table u ON s.id_coach = u.user_id
				INNER JOIN $table_access_url_rel_session ar ON ar.session_id = s.id
				LEFT JOIN  $session_category_table sc ON s.session_category_id = sc.id
				WHERE ar.access_url_id = $access_url_id ";

		if (count($conditions)>0) {
			$sql_query .= ' AND ';
			foreach ($conditions as $field=>$value) {
                $field = Database::escape_string($field);
                $value = Database::escape_string($value);
				$sql_query .= $field." '".$value."'";
			}
		}
		if (count($order_by)>0) {
			$sql_query .= ' ORDER BY '.Database::escape_string(implode(',',$order_by));
		}
        //echo $sql_query;
		$sql_result = Database::query($sql_query);
        if (Database::num_rows($sql_result)>0) {
    		while ($result = Database::fetch_array($sql_result)) {
    			$return_array[$result['id']] = $result;
    		}
        }
		return $return_array;
	}

	/**
	 * Get the session category information by id
	 * @param string session category ID
	 * @return mixed false if the session category does not exist, array if the session category exists
	 */
	public static function get_session_category ($id)
    {
		$id = intval($id);
		$tbl_session_category = Database::get_main_table(TABLE_MAIN_SESSION_CATEGORY);
		$sql = "SELECT id, name, date_start, date_end FROM $tbl_session_category WHERE id= $id";
		$result = Database::query($sql);
		$num = Database::num_rows($result);
		if ($num>0){
			return Database::fetch_array($result);
		} else {
			return false;
		}
	}

	/**
	 * Get all session categories (filter by access_url_id)
	 * @return mixed false if the session category does not exist, array if the session category exists
	 */
	public static function get_all_session_category()
    {
		$tbl_session_category = Database::get_main_table(TABLE_MAIN_SESSION_CATEGORY);
		$id = api_get_current_access_url_id();
		$sql = 'SELECT * FROM '.$tbl_session_category.' WHERE access_url_id ="'.$id.'" ORDER BY name ASC';
		$result = Database::query($sql);
		if (Database::num_rows($result) > 0 ){
		    $data = Database::store_result($result,'ASSOC');
		    return $data;
		} else {
			return false;
		}
	}

	/**
	 * Assign a coach to course in session with status = 2
	 * @param int  		- user id
	 * @param int  		- session id
	 * @param string  	- course code
	 * @param bool  	- optional, if is true the user don't be a coach now, otherwise it'll assign a coach
	 * @return bool true if there are affected rows, otherwise false
	 */
	public static function set_coach_to_course_session($user_id, $session_id = 0, $course_code = '', $nocoach = false)
    {
		// Definition of variables
		$user_id = intval($user_id);

		if (!empty($session_id)) {
			$session_id = intval($session_id);
		} else {
			$session_id = api_get_session_id();
		}

		if (!empty($course_code)) {
			$course_code = Database::escape_string($course_code);
		} else {
			$course_code = api_get_course_id();
		}

		// Table definition
		$tbl_session_rel_course_rel_user = Database::get_main_table(TABLE_MAIN_SESSION_COURSE_USER);
		$tbl_session_rel_user = Database::get_main_table(TABLE_MAIN_SESSION_USER);
		$tbl_user	= Database::get_main_table(TABLE_MAIN_USER);

		// check if user is a teacher
		$sql= "SELECT * FROM $tbl_user WHERE status='1' AND user_id = '$user_id'";

		$rs_check_user = Database::query($sql);

		if (Database::num_rows($rs_check_user) > 0) {
			if ($nocoach) {
				// check if user_id exits int session_rel_user
				$sql = "SELECT id_user FROM $tbl_session_rel_user WHERE id_session = '$session_id' AND id_user = '$user_id'";
				$res = Database::query($sql);

				if (Database::num_rows($res) > 0) {
					// The user don't be a coach now
					$sql = "UPDATE $tbl_session_rel_course_rel_user SET status = 0 WHERE id_session = '$session_id' AND course_code = '$course_code' AND id_user = '$user_id' ";
					Database::query($sql);
					if (Database::affected_rows() > 0) return true;
					else return false;
				} else {
					// The user don't be a coach now
					$sql = "DELETE FROM $tbl_session_rel_course_rel_user WHERE id_session = '$session_id' AND course_code = '$course_code' AND id_user = '$user_id' ";
					Database::query($sql);
					if (Database::affected_rows() > 0) return true;
					else return false;
				}
			} else {
				// Assign user like a coach to course
				// First check if the user is registered in the course
				$sql = "SELECT id_user FROM $tbl_session_rel_course_rel_user WHERE id_session = '$session_id' AND course_code = '$course_code' AND id_user = '$user_id'";
				$rs_check = Database::query($sql);

				// Then update or insert.
				if (Database::num_rows($rs_check) > 0) {
					$sql = "UPDATE $tbl_session_rel_course_rel_user SET status = 2
					        WHERE id_session = '$session_id' AND course_code = '$course_code' AND id_user = '$user_id' ";
					Database::query($sql);
					if (Database::affected_rows() > 0) {
                        return true;
                    } else {
                        return false;
                    }
				} else {
					$sql = "INSERT INTO $tbl_session_rel_course_rel_user(id_session, course_code, id_user, status) VALUES('$session_id', '$course_code', '$user_id', 2)";
					Database::query($sql);
					if (Database::affected_rows() > 0) {
                        return true;
                    } else {
                        return false;
                    }
				}
			}
		} else {
			return false;
		}
	}

    /**
    * Subscribes sessions to human resource manager (Dashboard feature)
    * @param	int 		Human Resource Manager id
    * @param	array 		Sessions id
    * @return int
    **/
	public static function suscribe_sessions_to_hr_manager($userInfo, $sessions_list, $sendEmail = false, $removeOldConnections = true)
    {
        // Database Table Definitions
        $tbl_session_rel_user = Database::get_main_table(TABLE_MAIN_SESSION_USER);
        $tbl_session_rel_access_url = Database::get_main_table(TABLE_MAIN_ACCESS_URL_REL_SESSION);

        if (empty($userInfo)) {
            return 0;
        }

        $userId = $userInfo['user_id'];
        // Only subscribe DRH users.
        if ($userInfo['status'] != DRH) {
            return 0;
        }

        $affected_rows = 0;

        // Deleting assigned sessions to hrm_id.
        if ($removeOldConnections) {
            if (api_is_multiple_url_enabled()) {
                $sql = "SELECT id_session
                        FROM $tbl_session_rel_user s
                        INNER JOIN $tbl_session_rel_access_url a ON (a.session_id = s.id_session)
                        WHERE
                            id_user = $userId AND
                            relation_type=".SESSION_RELATION_TYPE_RRHH." AND
                            access_url_id = ".api_get_current_access_url_id()."";
            } else {
                $sql = "SELECT id_session FROM $tbl_session_rel_user s
                        WHERE id_user = $userId AND relation_type=".SESSION_RELATION_TYPE_RRHH."";
            }
            $result = Database::query($sql);

            if (Database::num_rows($result) > 0) {
                while ($row = Database::fetch_array($result))   {
                     $sql = "DELETE FROM $tbl_session_rel_user
                            WHERE
                                id_session = {$row['id_session']} AND
                                id_user = $userId AND
                                relation_type=".SESSION_RELATION_TYPE_RRHH." ";
                     Database::query($sql);
                }
            }
        }

		// Inserting new sessions list.
		if (!empty($sessions_list) && is_array($sessions_list)) {
			foreach ($sessions_list as $session_id) {
				$session_id = intval($session_id);
				$sql = "INSERT IGNORE INTO $tbl_session_rel_user (id_session, id_user, relation_type)
				        VALUES ($session_id, $userId, '".SESSION_RELATION_TYPE_RRHH."')";
				Database::query($sql);
                $affected_rows++;
			}
		}
		return $affected_rows;
	}

    /**
     * @param int $userId
     * @param int $sessionId
     * @return array
     */
    public static function getSessionFollowedByDrh($userId, $sessionId)
    {
        $tbl_session 			= 	Database::get_main_table(TABLE_MAIN_SESSION);
        $tbl_session_rel_user 	= 	Database::get_main_table(TABLE_MAIN_SESSION_USER);
        $tbl_session_rel_access_url =   Database::get_main_table(TABLE_MAIN_ACCESS_URL_REL_SESSION);

        $userId = intval($userId);
        $sessionId = intval($sessionId);

        $select = " SELECT * ";
        if (api_is_multiple_url_enabled()) {
            $sql = " $select FROM $tbl_session s
                    INNER JOIN $tbl_session_rel_user sru ON (sru.id_session = s.id)
                    LEFT JOIN $tbl_session_rel_access_url a ON (s.id = a.session_id)
                    WHERE
                        sru.id_user = '$userId' AND
                        sru.id_session = '$sessionId' AND
                        sru.relation_type = '".SESSION_RELATION_TYPE_RRHH."' AND
                        access_url_id = ".api_get_current_access_url_id()."
                        ";
        } else {
            $sql = "$select FROM $tbl_session s
                     INNER JOIN $tbl_session_rel_user sru
                     ON
                        sru.id_session = s.id AND
                        sru.id_user = '$userId' AND
                        sru.id_session = '$sessionId' AND
                        sru.relation_type = '".SESSION_RELATION_TYPE_RRHH."'
                        ";
        }
        $result = Database::query($sql);
        if (Database::num_rows($result)) {
            $row = Database::fetch_array($result, 'ASSOC');
            $row['course_list'] = self::get_course_list_by_session_id($sessionId);
            return $row;
        }
        return array();
    }

	/**
	 * Get sessions followed by human resources manager
	 * @param int $userId
     * @param int $start
     * @param int $limit
     * @param bool $getCount
     * @param bool $getOnlySessionId
     * @param bool $getSql
     * @param string $orderCondition
	 * @return array sessions
	 */
	public static function get_sessions_followed_by_drh(
        $userId,
        $start = null,
        $limit = null,
        $getCount = false,
        $getOnlySessionId = false,
        $getSql = false,
        $orderCondition = null
    ) {
        return self::getSessionsFollowedByUser(
            $userId,
            DRH,
            $start,
            $limit,
            $getCount,
            $getOnlySessionId,
            $getSql,
            $orderCondition
        );
	}

    /**
     * Get sessions followed by human resources manager
     * @param int $userId
     * @param int $start
     * @param int $limit
     * @param bool $getCount
     * @param bool $getOnlySessionId
     * @param bool $getSql
     * @param string $orderCondition
     * @return array sessions
     */
    public static function getSessionsFollowedByUser(
        $userId,
        $status = null,
        $start = null,
        $limit = null,
        $getCount = false,
        $getOnlySessionId = false,
        $getSql = false,
        $orderCondition = null
    ) {
        // Database Table Definitions
        $tbl_session 			= Database::get_main_table(TABLE_MAIN_SESSION);
        $tbl_session_rel_user 	= Database::get_main_table(TABLE_MAIN_SESSION_USER);
        $tbl_session_rel_course_rel_user = Database::get_main_table(TABLE_MAIN_SESSION_COURSE_USER);
        $tbl_session_rel_access_url = Database::get_main_table(TABLE_MAIN_ACCESS_URL_REL_SESSION);

        $userId = intval($userId);

        $select = " SELECT DISTINCT * ";

        if ($getCount) {
            $select = " SELECT count(DISTINCT(s.id)) as count ";
        }

        if ($getOnlySessionId) {
            $select = " SELECT DISTINCT(s.id) ";
        }

        $limitCondition = null;
        if (!empty($start) && !empty($limit)) {
            $limitCondition = " LIMIT ".intval($start). ", ".intval($limit);
        }

        if (empty($orderCondition)) {
            $orderCondition = " ORDER BY s.name ";
        }

        $whereConditions = null;
        $sessionCourseConditions = null;
        $sessionConditions = null;
        $sessionQuery = null;
        $courseSessionQuery = null;

        switch($status) {
            case DRH:
                $sessionQuery = "SELECT sru.id_session
                                 FROM
                                 $tbl_session_rel_user sru
                                 WHERE
                                    sru.relation_type = '".SESSION_RELATION_TYPE_RRHH."' AND
                                    sru.id_user = $userId";
                break;
            case COURSEMANAGER:
                $courseSessionQuery = "
                    SELECT scu.id_session as id
                    FROM $tbl_session_rel_course_rel_user scu
                    WHERE (scu.status = 2 AND scu.id_user = $userId)";

                $whereConditions = " OR (s.id_coach = $userId) ";

                break;
        }
        $subQuery = $sessionQuery.$courseSessionQuery;

        $sql = " $select FROM $tbl_session s
                INNER JOIN $tbl_session_rel_access_url a ON (s.id = a.session_id)
                WHERE
                    access_url_id = ".api_get_current_access_url_id()." AND
                    s.id IN (
                        $subQuery
                    )
                    $whereConditions
                    $orderCondition
                    $limitCondition";


        if ($getSql) {
            return $sql;
        }

        $result = Database::query($sql);

        if ($getCount) {
            $row = Database::fetch_array($result);
            return $row['count'];
        }

        $sessions = array();
        if (Database::num_rows($result) > 0) {
            while ($row = Database::fetch_array($result)) {
                $sessions[$row['id']] = $row;
            }
        }
        return $sessions;
    }

	/**
	 * Gets the list of courses by session filtered by access_url
	 * @param int session id
     * @param string course_name
	 * @return array list of courses
	 */
	public static function get_course_list_by_session_id($session_id, $course_name = '')
    {
		$tbl_course				= Database::get_main_table(TABLE_MAIN_COURSE);
		$tbl_session_rel_course	= Database::get_main_table(TABLE_MAIN_SESSION_COURSE);

		// select the courses
		$sql = "SELECT * FROM $tbl_course c
                INNER JOIN $tbl_session_rel_course src ON c.code = src.course_code
		        WHERE src.id_session = '$session_id'";
        if (!empty($course_name)) {
            $course_name = Database::escape_string($course_name);
            $sql .= " AND c.title LIKE '%$course_name%' ";
        }

        $sql .= "ORDER BY title;";
		$result 	= Database::query($sql);
		$num_rows 	= Database::num_rows($result);
		$courses = array();
		if ($num_rows > 0) {
			while ($row = Database::fetch_array($result,'ASSOC'))	{
				$courses[$row['id']] = $row;
			}
		}
		return $courses;
	}

    /**
     * Gets the list of courses by session filtered by access_url
     * @param int session id
     * @return array list of courses
     */
    public static function getAllCoursesFollowedByUser(
        $userId,
        $sessionId,
        $from,
        $limit,
        $column,
        $direction,
        $getCount = false
    ) {
        if (empty($sessionId)) {
            $sessionsSQL = SessionManager::get_sessions_followed_by_drh(
                $userId,
                null,
                null,
                null,
                true,
                true
            );
        } else {
            $sessionsSQL = intval($sessionId);
        }

        $tbl_course = Database::get_main_table(TABLE_MAIN_COURSE);
        $tbl_session_rel_course	= Database::get_main_table(TABLE_MAIN_SESSION_COURSE);

        if ($getCount) {
            $select = "SELECT COUNT(DISTINCT(c.code)) as count ";
        } else {
            $select = "SELECT DISTINCT c.* ";
        }

        // Select the courses
        $sql = "$select
                FROM $tbl_course c
                INNER JOIN $tbl_session_rel_course src
                ON c.code = src.course_code
		        WHERE src.id_session IN ($sessionsSQL)
		        ";
        if ($getCount) {
            $result = Database::query($sql);
            $row = Database::fetch_array($result,'ASSOC');
            return $row['count'];
        }

        if (isset($from) && isset($limit)) {
            $from = intval($from);
            $limit = intval($limit);
            $sql .= " LIMIT $from, $limit";
        }

        $result = Database::query($sql);
        $num_rows = Database::num_rows($result);
        $courses = array();

        if ($num_rows > 0) {
            while ($row = Database::fetch_array($result,'ASSOC'))	{
                $courses[$row['id']] = $row;
            }
        }
        return $courses;
    }


    /**
     * Gets the count of courses by session filtered by access_url
     * @param int session id
     * @return array list of courses
     */
    public static function getCourseCountBySessionId($session_id)
    {
        $tbl_course				= Database::get_main_table(TABLE_MAIN_COURSE);
        $tbl_session_rel_course	= Database::get_main_table(TABLE_MAIN_SESSION_COURSE);

        // select the courses
        $sql = "SELECT COUNT(c.code) count FROM $tbl_course c
                INNER JOIN $tbl_session_rel_course src
                ON c.code = src.course_code
		        WHERE src.id_session = '$session_id'";

        $result = Database::query($sql);
        $num_rows = Database::num_rows($result);
        if ($num_rows > 0) {
            $row = Database::fetch_array($result,'ASSOC');
            return $row['count'];
        }
        return null;
    }

	/**
	 * Get the session id based on the original id and field name in the extra fields. Returns 0 if session was not found
	 *
	 * @param string Original session id
	 * @param string Original field name
	 * @return int Session id
	 */
	public static function get_session_id_from_original_id($original_session_id_value, $original_session_id_name)
    {
		$t_sfv = Database::get_main_table(TABLE_MAIN_SESSION_FIELD_VALUES);
		$table_field = Database::get_main_table(TABLE_MAIN_SESSION_FIELD);
		$sql = "SELECT session_id
                FROM $table_field sf INNER JOIN $t_sfv sfv ON sfv.field_id=sf.id
                WHERE field_variable='$original_session_id_name' AND field_value='$original_session_id_value'";
		$res_session = Database::query($sql);
		$row = Database::fetch_object($res_session);
		if ($row) {
			return $row->session_id;
		} else {
			return 0;
		}
	}

    /**
     * Get users by session
     * @param  int session id
     * @param	int	filter by status coach = 2
     * @return  array a list with an user list
     */
    public static function get_users_by_session($id, $status = null)
    {
        if (empty($id)) {
            return array();
        }
        $id = intval($id);
        $tbl_user               = Database::get_main_table(TABLE_MAIN_USER);
        $tbl_session_rel_user   = Database::get_main_table(TABLE_MAIN_SESSION_USER);

        $sql = "SELECT $tbl_user.user_id, lastname, firstname, username
                FROM $tbl_user INNER JOIN $tbl_session_rel_user
                    ON $tbl_user.user_id = $tbl_session_rel_user.id_user
                    AND $tbl_session_rel_user.id_session = $id";

        if (isset($status) && $status != '') {
            $status = intval($status);
        	$sql .= " WHERE relation_type = $status ";
        }

        $result = Database::query($sql);
        while ($row = Database::fetch_array($result,'ASSOC')) {
            $return_array[] = $row;
        }
        return $return_array;
    }

    /**
    * The general coach (field: session.id_coach)
    * @param int user id
    * @return array
    */
    public static function get_sessions_by_general_coach($user_id) {
        $session_table = Database::get_main_table(TABLE_MAIN_SESSION);
        $user_id = intval($user_id);

        // session where we are general coach
        $sql = "SELECT DISTINCT *
                FROM $session_table
                WHERE id_coach = $user_id";

        if (api_is_multiple_url_enabled()) {
            $tbl_session_rel_access_url = Database::get_main_table(TABLE_MAIN_ACCESS_URL_REL_SESSION);
            $access_url_id = api_get_current_access_url_id();
            if ($access_url_id != -1) {
                $sql = 'SELECT DISTINCT session.*
                    FROM '.$session_table.' session INNER JOIN '.$tbl_session_rel_access_url.' session_rel_url
                    ON (session.id = session_rel_url.session_id)
                    WHERE id_coach = '.$user_id.' AND access_url_id = '.$access_url_id;
            }
        }
        $sql .= ' ORDER by name';
        $result = Database::query($sql);
        return Database::store_result($result, 'ASSOC');
    }

    /**
     * @param int $user_id
     * @return array
     */
    public static function get_sessions_by_coach($user_id)
    {
        $session_table = Database::get_main_table(TABLE_MAIN_SESSION);
        return Database::select('*', $session_table, array('where'=>array('id_coach = ?'=>$user_id)));
    }

    /**
     * @param int $user_id
     * @param string $course_code
     * @param int $session_id
     * @return array|bool
     */
    public static function get_user_status_in_course_session($user_id, $course_code, $session_id)
    {
        $tbl_session_rel_course_rel_user    = Database::get_main_table(TABLE_MAIN_SESSION_COURSE_USER);
        $tbl_user                           = Database::get_main_table(TABLE_MAIN_USER);
        $sql = "SELECT session_rcru.status
                FROM $tbl_session_rel_course_rel_user session_rcru, $tbl_user user
                WHERE session_rcru.id_user = user.user_id AND
                session_rcru.id_session = '".intval($session_id)."' AND
                session_rcru.course_code ='".Database::escape_string($course_code)."' AND
                user.user_id = ".intval($user_id);

        $result = Database::query($sql);
        $status = false;
        if (Database::num_rows($result)) {
            $status = Database::fetch_row($result);
            $status = $status['0'];
        }
        return $status;
    }

    /**
     * Gets user status within a session
     * @param $user_id
     * @param $course_code
     * @param $session_id
     * @return int
     * @assert (null,null,null) === false
     */
    public static function get_user_status_in_session($user_id, $course_code, $session_id)
    {
        if (empty($user_id) or empty($course_code) or empty($session_id)) {
            return false;
        }
        $tbl_session_rel_course_rel_user    = Database::get_main_table(TABLE_MAIN_SESSION_COURSE_USER);
        $tbl_user                           = Database::get_main_table(TABLE_MAIN_USER);
        $sql = "SELECT session_rcru.status
                FROM $tbl_session_rel_course_rel_user session_rcru, $tbl_user user
                WHERE session_rcru.id_user = user.user_id AND
                session_rcru.id_session = '".intval($session_id)."' AND
                session_rcru.course_code ='".Database::escape_string($course_code)."' AND
                user.user_id = ".intval($user_id);
        $result = Database::query($sql);
        $status = false;
        if (Database::num_rows($result)) {
            $status = Database::fetch_row($result);
            $status = $status['0'];
        }
        return $status;
    }

    /**
     * @param int $id
     * @return array
     */
    public static function get_all_sessions_by_promotion($id)
    {
        $t = Database::get_main_table(TABLE_MAIN_SESSION);
        return Database::select('*', $t, array('where'=>array('promotion_id = ?'=>$id)));
    }

    /**
     * @param int $promotion_id
     * @param array $list
     */
    public static function suscribe_sessions_to_promotion($promotion_id, $list)
    {
        $t = Database::get_main_table(TABLE_MAIN_SESSION);
        $params = array();
        $params['promotion_id'] = 0;
        Database::update($t, $params, array('promotion_id = ?'=>$promotion_id));

        $params['promotion_id'] = $promotion_id;
        if (!empty($list)) {
            foreach ($list as $session_id) {
                $session_id= intval($session_id);
                Database::update($t, $params, array('id = ?'=>$session_id));
            }
        }
    }

    /**
    * Updates a session status
    * @param	int 	session id
    * @param	int 	status
    */
    public static function set_session_status($session_id, $status)
    {
        $t = Database::get_main_table(TABLE_MAIN_SESSION);
        $params['visibility'] = $status;
    	Database::update($t, $params, array('id = ?'=>$session_id));
    }

    /**
     * Copies a session with the same data to a new session.
     * The new copy is not assigned to the same promotion. @see suscribe_sessions_to_promotions() for that
     * @param   int     Session ID
     * @param   bool    Whether to copy the relationship with courses
     * @param   bool    Whether to copy the relationship with users
     * @param	bool	New courses will be created
     * @return  int     The new session ID on success, 0 otherwise
     * @todo make sure the extra session fields are copied too
     */
    public static function copy_session($id, $copy_courses = true, $copy_users = true, $create_new_courses = false, $set_exercises_lp_invisible = false)
    {
        $id = intval($id);
        $s = self::fetch($id);
        $s['year_start']    = substr($s['date_start'],0,4);
        $s['month_start']   = substr($s['date_start'],5,2);
        $s['day_start']     = substr($s['date_start'],8,2);
        $s['year_end']      = substr($s['date_end'],0,4);
        $s['month_end']     = substr($s['date_end'],5,2);
        $s['day_end']       = substr($s['date_end'],8,2);
        $consider_start = true;
        if ($s['year_start'].'-'.$s['month_start'].'-'.$s['day_start'] == '0000-00-00') {
            $consider_start = false;
        }
        $consider_end = true;
        if ($s['year_end'].'-'.$s['month_end'].'-'.$s['day_end'] == '0000-00-00') {
            $consider_end = false;
        }

        $sid = self::create_session($s['name'].' '.get_lang('CopyLabelSuffix'),
             $s['year_start'], $s['month_start'], $s['day_start'],
             $s['year_end'],$s['month_end'],$s['day_end'],
             $s['nb_days_acess_before_beginning'],$s['nb_days_acess_after_end'],
             false,(int)$s['id_coach'], $s['session_category_id'],
             (int)$s['visibility'],$consider_start, $consider_end, true);

        if (!is_numeric($sid) || empty($sid)) {
        	return false;
        }

        if ($copy_courses) {
            // Register courses from the original session to the new session
            $courses = self::get_course_list_by_session_id($id);

            $short_courses = $new_short_courses = array();
            if (is_array($courses) && count($courses)>0) {
            	foreach ($courses as $course) {
            		$short_courses[] = $course;
            	}
            }

            $courses = null;

            //We will copy the current courses of the session to new courses
            if (!empty($short_courses)) {
                if ($create_new_courses) {
                    //Just in case
                    if (function_exists('ini_set')) {
                    	api_set_memory_limit('256M');
                    	ini_set('max_execution_time',0);
                    }
                    $params = array();
                    $params['skip_lp_dates'] = true;

                    foreach ($short_courses as $course_data) {
                        $course_info = CourseManager::copy_course_simple($course_data['title'].' '.get_lang('CopyLabelSuffix'), $course_data['course_code'], $id, $sid, $params);
                        if ($course_info) {
                            //By default new elements are invisible
                            if ($set_exercises_lp_invisible) {
                                require_once api_get_path(SYS_CODE_PATH).'newscorm/learnpathList.class.php';
                                $list       = new LearnpathList('', $course_info['code'], $sid);
                                $flat_list  = $list->get_flat_list();
                                if (!empty($flat_list)) {
                                    foreach($flat_list as $lp_id => $data) {
                                        api_item_property_update($course_info, TOOL_LEARNPATH, $lp_id, 'invisible', api_get_user_id(), 0 ,0, 0, 0, $sid);
                                        api_item_property_update($course_info, TOOL_LEARNPATH, $lp_id, 'invisible', api_get_user_id(), 0 ,0, 0, 0);
                                    }
                                }
                                $quiz_table   = Database::get_course_table(TABLE_QUIZ_TEST);
                                $course_id	 = $course_info['real_id'];
                                //@todo check this query
                                $sql = "UPDATE $quiz_table SET active = 0 WHERE c_id = $course_id ";
                                $result=Database::query($sql);
                            }
                            $new_short_courses[] = $course_info['code'];
                        }
                    }
                } else {
                    foreach($short_courses as $course_data) {
                        $new_short_courses[] = $course_data['code'];
                    }
                }

                $short_courses = $new_short_courses;
                self::add_courses_to_session($sid, $short_courses, true);
                $short_courses = null;
            }
        }
        if ($copy_users) {
            // Register users from the original session to the new session
            $users = self::get_users_by_session($id);
            $short_users = array();
            if (is_array($users) && count($users)>0) {
                foreach ($users as $user) {
                    $short_users[] = $user['user_id'];
                }
            }
            $users = null;
            //Subscribing in read only mode
            self::suscribe_users_to_session($sid, $short_users, SESSION_VISIBLE_READ_ONLY, true, false);
            $short_users = null;
        }
    	return $sid;
    }

    /**
     * @param int $user_id
     * @param int $session_id
     * @return bool
     */
    static function user_is_general_coach($user_id, $session_id) {
    	$session_id = intval($session_id);
    	$user_id = intval($user_id);
    	$session_table = Database::get_main_table(TABLE_MAIN_SESSION);
    	$sql = "SELECT DISTINCT id
	         	FROM $session_table
	         	WHERE session.id_coach =  '".$user_id."' AND id = '$session_id'";
    	$result = Database::query($sql);
    	if ($result && Database::num_rows($result)) {
    		return true;
    	}
    	return false;
    }

    /**
     * Get the number of sessions
     * @param  int ID of the URL we want to filter on (optional)
     * @return int Number of sessions
     */
    public static function count_sessions($access_url_id = null)
    {
        $session_table = Database::get_main_table(TABLE_MAIN_SESSION);
        $access_url_rel_session_table = Database::get_main_table(TABLE_MAIN_ACCESS_URL_REL_SESSION);
        $sql = "SELECT count(id) FROM $session_table s";
        if (!empty($access_url_id) && $access_url_id == intval($access_url_id)) {
            $sql .= ", $access_url_rel_session_table u ".
                    " WHERE s.id = u.session_id AND u.access_url_id = $access_url_id";
        }
        $res = Database::query($sql);
        $row = Database::fetch_row($res);
        return $row[0];
    }

    /**
     * @param int $id
     */
    static function protect_session_edit($id)
    {
        api_protect_admin_script(true);
        $session_info = self::fetch($id);
        if (!api_is_platform_admin() && api_get_setting('allow_session_admins_to_manage_all_sessions') != 'true') {
            if ($session_info['session_admin_id'] != api_get_user_id()) {
                api_not_allowed(true);
            }
        }
    }

    /**
     * @param string $course_code
     * @return array
     */
    public static function get_session_by_course($course_code)
    {
        $table_session_course = Database::get_main_table(TABLE_MAIN_SESSION_COURSE);
        $table_session = Database::get_main_table(TABLE_MAIN_SESSION);
        $course_code = Database::escape_string($course_code);
        $sql = "SELECT name, s.id
                FROM $table_session_course sc INNER JOIN $table_session s ON (sc.id_session = s.id)
                WHERE sc.course_code = '$course_code' ";
        $result = Database::query($sql);
        return Database::store_result($result);
    }

    /**
     * @param int $user_id
     * @param bool $ignore_visibility_for_admins
     * @return array
     */
    public static function get_sessions_by_user($user_id, $ignore_visibility_for_admins = false)
    {
       $session_categories = UserManager::get_sessions_by_category($user_id, false, $ignore_visibility_for_admins);
       $session_array = array();
       if (!empty($session_categories)) {
           foreach ($session_categories as $category) {
               if (isset($category['sessions'])) {
                   foreach ($category['sessions'] as $session) {
                       $session_array[] = $session;
                   }
               }
           }
       }
       return $session_array;
    }

    /**
     * @param string $file
     * @param bool $updateSession options:
     *  true: if the session exists it will be updated.
     *  false: if session exists a new session will be created adding a counter session1, session2, etc
     * @param int $defaultUserId
     * @param mixed $logger
     * @param array $extraFields convert a file row to an extra field. Example in CSV file there's a SessionID then it will
     * converted to extra_external_session_id if you set this: array('SessionId' => 'extra_external_session_id')
     * @param string $extraFieldId
     * @param int $daysCoachAccessBeforeBeginning
     * @param int $daysCoachAccessAfterBeginning
     * @param int $sessionVisibility
     * @param array $fieldsToAvoidUpdate
     * @param bool $deleteUsersNotInList
     * @param bool $updateCourseCoaches
     * @param bool $sessionWithCoursesModifier
     * @return array
     */
    static function importCSV(
        $file,
        $updateSession,
        $defaultUserId = null,
        $logger = null,
        $extraFields = array(),
        $extraFieldId = null,
        $daysCoachAccessBeforeBeginning = null,
        $daysCoachAccessAfterBeginning = null,
        $sessionVisibility = 1,
        $fieldsToAvoidUpdate = array(),
        $deleteUsersNotInList = false,
        $updateCourseCoaches = false,
        $sessionWithCoursesModifier = false
    ) {
        $content = file($file);

        $error_message = null;
        $session_counter = 0;

        if (empty($defaultUserId)) {
            $defaultUserId = api_get_user_id();
        }

        $eol = PHP_EOL;
        if (PHP_SAPI !='cli') {
            $eol = '<br />';
        }

        $debug = false;
        if (isset($logger)) {
            $debug = true;
        }

        $extraParameters = null;

        if (!empty($daysCoachAccessBeforeBeginning) && !empty($daysCoachAccessAfterBeginning)) {
            $extraParameters .= ' , nb_days_access_before_beginning = '.intval($daysCoachAccessBeforeBeginning);
            $extraParameters .= ' , nb_days_access_after_end = '.intval($daysCoachAccessAfterBeginning);
        }

        $tbl_session = Database::get_main_table(TABLE_MAIN_SESSION);
        $tbl_session_user = Database::get_main_table(TABLE_MAIN_SESSION_USER);
        $tbl_session_course  = Database::get_main_table(TABLE_MAIN_SESSION_COURSE);
        $tbl_session_course_user = Database::get_main_table(TABLE_MAIN_SESSION_COURSE_USER);

        $sessions = array();

        if (!api_strstr($content[0], ';')) {
            $error_message = get_lang('NotCSV');
        } else {
            $tag_names = array();

            foreach ($content as $key => $enreg) {
                $enreg = explode(';', trim($enreg));
                if ($key) {
                    foreach ($tag_names as $tag_key => $tag_name) {
                        $sessions[$key - 1][$tag_name] = $enreg[$tag_key];
                    }
                } else {
                    foreach ($enreg as $tag_name) {
                        $tag_names[] = api_preg_replace('/[^a-zA-Z0-9_\-]/', '', $tag_name);
                    }
                    if (!in_array('SessionName', $tag_names) || !in_array('DateStart', $tag_names) || !in_array('DateEnd', $tag_names)) {
                        $error_message = get_lang('NoNeededData');
                        break;
                    }
                }
            }

            $sessionList = array();
            // Looping the sessions.
            foreach ($sessions as $enreg) {
                $user_counter = 0;
                $course_counter = 0;

                if (isset($extraFields) && !empty($extraFields)) {
                    foreach ($extraFields as $original => $to) {
                        $enreg[$to] = isset($enreg[$original]) ? $enreg[$original] : null;
                    }
                }

                $session_name = Database::escape_string($enreg['SessionName']);

                if (empty($session_name)) {
                    continue;
                }

                $date_start             = $enreg['DateStart'];
                $date_end               = $enreg['DateEnd'];
                $visibility             = isset($enreg['Visibility']) ? $enreg['Visibility'] : $sessionVisibility;
                $session_category_id    = isset($enreg['SessionCategory']) ? $enreg['SessionCategory'] : null;
                $sessionDescription     = isset($enreg['SessionDescription']) ? $enreg['SessionDescription'] : null;

                $extraSessionParameters = null;
                if (!empty($sessionDescription)) {
                    $extraSessionParameters = " , description = '".Database::escape_string($sessionDescription)."'";
                }

                // Searching a general coach.
                if (!empty($enreg['Coach'])) {
                    $coach_id = UserManager::get_user_id_from_username($enreg['Coach']);
                    if ($coach_id === false) {
                        // If the coach-user does not exist - I'm the coach.
                        $coach_id = $defaultUserId;
                    }
                } else {
                    $coach_id = $defaultUserId;
                }

                if (!$updateSession) {
                    // Always create a session.
                    $unique_name = false;
                    $i = 0;
                    // Change session name, verify that session doesn't exist.
                    $suffix = null;
                    while (!$unique_name) {
                        if ($i > 1) {
                            $suffix = ' - '.$i;
                        }
                        $sql = 'SELECT 1 FROM '.$tbl_session.' WHERE name="'.$session_name.$suffix.'"';
                        $rs = Database::query($sql);

                        if (Database::result($rs, 0, 0)) {
                            $i++;
                        } else {
                            $unique_name = true;
                            $session_name .= $suffix;
                        }
                    }

                    // Creating the session.
                    $sql = "INSERT IGNORE INTO $tbl_session SET
                            name = '".$session_name."',
                            id_coach = '$coach_id',
                            date_start = '$date_start',
                            date_end = '$date_end',
                            visibility = '$visibility',
                            session_category_id = '$session_category_id',
                            session_admin_id = ".intval($defaultUserId).$extraParameters.$extraSessionParameters;
                    Database::query($sql);

                    $session_id = Database::insert_id();
                    if ($debug) {
                        if ($session_id) {
                            foreach ($enreg as $key => $value) {
                                if (substr($key, 0, 6) == 'extra_') { //an extra field
                                    self::update_session_extra_field_value($session_id, substr($key, 6), $value);
                                }
                            }

                            $logger->addInfo("Sessions - Session created: #$session_id - $session_name");
                        } else {
                            $logger->addError("Sessions - Session NOT created: $session_name");
                        }
                    }
                    $session_counter++;
                } else {
                    $sessionId = null;
                    if (isset($extraFields) && !empty($extraFields) && !empty($enreg['extra_'.$extraFieldId])) {
                        $sessionId = self::get_session_id_from_original_id($enreg['extra_'.$extraFieldId], $extraFieldId);
                        if (empty($sessionId)) {
                            $my_session_result = false;
                        } else {
                            $my_session_result = true;
                        }
                    } else {
                        $my_session_result = self::get_session_by_name($enreg['SessionName']);
                    }

                    if ($my_session_result === false) {

                        // Creating a session.
                        $sql_session = "INSERT IGNORE INTO $tbl_session SET
                                name = '$session_name',
                                id_coach = '$coach_id',
                                date_start = '$date_start',
                                date_end = '$date_end',
                                visibility = '$visibility',
                                session_category_id = '$session_category_id' ".$extraParameters.$extraSessionParameters;

                        Database::query($sql_session);

                        // We get the last insert id.
                        $my_session_result = SessionManager::get_session_by_name($enreg['SessionName']);
                        $session_id = $my_session_result['id'];

                        if ($session_id) {

                            if ($session_id) {
                                foreach ($enreg as $key => $value) {
                                    if (substr($key, 0, 6) == 'extra_') { //an extra field
                                        self::update_session_extra_field_value($session_id, substr($key, 6), $value);
                                    }
                                }
                                if ($debug) {
                                    $logger->addInfo("Sessions - #$session_id created: $session_name");
                                }
                            } else {
                                if ($debug) {
                                    $logger->addError("Sessions - Session NOT created: $session_name");
                                }
                            }

                            // Delete session-user relation only for students
                            $sql = "DELETE FROM $tbl_session_user
                                    WHERE id_session = '$session_id' AND relation_type <> ".SESSION_RELATION_TYPE_RRHH;
                            Database::query($sql);

                            $sql = "DELETE FROM $tbl_session_course WHERE id_session = '$session_id'";
                            Database::query($sql);

                            // Delete session-course-user relationships students and coaches.
                            if ($updateCourseCoaches) {
                                $sql = "DELETE FROM $tbl_session_course_user WHERE id_session = '$session_id' AND status in ('0', '2')";
                                Database::query($sql);
                            } else {
                                // Delete session-course-user relation ships *only* for students.
                                $sql = "DELETE FROM $tbl_session_course_user WHERE id_session = '$session_id' AND status <> 2";
                                Database::query($sql);
                            }
                        }
                    } else {

                        // Updating the session.
                        $params = array(
                            'id_coach' => $coach_id,
                            'date_start' => $date_start,
                            'date_end' => $date_end,
                            'visibility' => $visibility,
                            'session_category_id' => $session_category_id
                        );

                        if (!empty($sessionDescription)) {
                            $params['description'] = $sessionDescription;
                        }

                        if (!empty($fieldsToAvoidUpdate)) {
                            foreach ($fieldsToAvoidUpdate as $field) {
                                unset($params[$field]);
                            }
                        }

                        if (isset($sessionId) && !empty($sessionId)) {
                            Database::update($tbl_session, $params, array('id = ?' => $sessionId));
                            $session_id = $sessionId;
                        } else {
                            Database::update($tbl_session, $params, array("name = '?' " => $enreg['SessionName']));

                            $row = Database::query("SELECT id FROM $tbl_session WHERE name = '$session_name'");
                            list($session_id) = Database::fetch_array($row);
                        }

                        if ($session_id) {

                            foreach ($enreg as $key => $value) {
                                if (substr($key, 0, 6) == 'extra_') { //an extra field
                                    self::update_session_extra_field_value($session_id, substr($key, 6), $value);
                                }
                            }

                            // Delete session-user relation only for students
                            $sql = "DELETE FROM $tbl_session_user
                                    WHERE id_session = '$session_id' AND relation_type <> ".SESSION_RELATION_TYPE_RRHH;
                            Database::query($sql);

                            $sql = "DELETE FROM $tbl_session_course WHERE id_session = '$session_id'";
                            Database::query($sql);

                            // Delete session-course-user relationships students and coaches.
                            if ($updateCourseCoaches) {
                                $sql = "DELETE FROM $tbl_session_course_user WHERE id_session = '$session_id' AND status in ('0', '2')";
                                Database::query($sql);
                            } else {
                                // Delete session-course-user relation ships *only* for students.
                                $sql = "DELETE FROM $tbl_session_course_user WHERE id_session = '$session_id' AND status <> 2";
                                Database::query($sql);
                            }
                        }
                    }
                    $session_counter++;
                }

                $sessionList[] = $session_id;

                $users = explode('|', $enreg['Users']);

                // Adding the relationship "Session - User" for students
                $userList = array();
                if (is_array($users)) {
                    foreach ($users as $user) {
                        $user_id = UserManager::get_user_id_from_username($user);
                        if ($user_id !== false) {
                            $userList[] = $user_id;
                            // Insert new users.
                            $sql = "INSERT IGNORE INTO $tbl_session_user SET
                                    id_user = '$user_id',
                                    id_session = '$session_id'";
                            Database::query($sql);
                            if ($debug) {
                                $logger->addInfo("Sessions - Adding User #$user_id ($user) to session #$session_id");
                            }
                            $user_counter++;
                        }
                    }
                }

                if ($deleteUsersNotInList) {
                    // Getting user in DB in order to compare to the new list.
                    $usersListInDatabase = self::get_users_by_session($session_id, 0);

                    if (!empty($usersListInDatabase)) {
                        if (empty($userList)) {
                            foreach ($usersListInDatabase as $userInfo) {
                                self::unsubscribe_user_from_session($session_id, $userInfo['user_id']);
                            }
                        } else {
                            foreach ($usersListInDatabase as $userInfo) {
                                if (!in_array($userInfo['user_id'], $userList)) {
                                    self::unsubscribe_user_from_session($session_id, $userInfo['user_id']);
                                }
                            }
                        }
                    }
                }

                $courses = explode('|', $enreg['Courses']);

                // See BT#6449
                $onlyAddFirstCoachOrTeacher = false;
                $removeAllTeachersFromCourse = false;

                if ($sessionWithCoursesModifier) {

                    if (count($courses) >= 2) {
                        // Only first teacher in course session;
                        $onlyAddFirstCoachOrTeacher = true;

                        // Remove all teachers from course.
                        $removeAllTeachersFromCourse = true;
                    }
                }

                foreach ($courses as $course) {
                    $courseArray = bracketsToArray($course);
                    $course_code = $courseArray[0];

                    if (CourseManager::course_exists($course_code)) {

                        $courseInfo = api_get_course_info($course_code);

                        // Adding the course to a session.
                        $sql_course = "INSERT IGNORE INTO $tbl_session_course
                                       SET course_code = '$course_code', id_session='$session_id'";
                        Database::query($sql_course);
                        $course_info = api_get_course_info($course_code);
                        SessionManager::installCourse($session_id, $course_info['real_id']);

                        if ($debug) {
                            $logger->addInfo("Sessions - Adding course '$course_code' to session #$session_id");
                        }

                        $course_counter++;

                        $course_coaches = isset($courseArray[1]) ? $courseArray[1] : null;
                        $course_users   = isset($courseArray[2]) ? $courseArray[2] : null;

                        $course_users   = explode(',', $course_users);
                        $course_coaches = explode(',', $course_coaches);

                        // Checking if the flag is set TeachersWillBeAddedAsCoachInAllCourseSessions (course_edit.php)
                        $addTeachersToSession = true;

                        if (array_key_exists('add_teachers_to_sessions_courses', $courseInfo)) {
                            $addTeachersToSession = $courseInfo['add_teachers_to_sessions_courses'];
                        }

                        // If any user provided for a course, use the users array.
                        if (empty($course_users)) {
                            if (!empty($userList)) {
                                SessionManager::subscribe_users_to_session_course($userList, $session_id, $course_code);
                                if ($debug) {
                                    $msg = "Sessions - Adding student list ".implode(', #', $userList)." to course: '$course_code' and session #$session_id";
                                    $logger->addInfo($msg);
                                }
                            }
                        }

                        // Adding coaches to session course user.
                        if (!empty($course_coaches)) {
                            $savedCoaches = array();
                            // only edit if add_teachers_to_sessions_courses is set.
                            if ($addTeachersToSession) {
                                // Adding course teachers as course session teachers.
                                $alreadyAddedTeachers = CourseManager::get_teacher_list_from_course_code($course_code);

                                if (!empty($alreadyAddedTeachers)) {
                                    $teachersToAdd = array();
                                    foreach ($alreadyAddedTeachers as $user) {
                                        $teachersToAdd[] = $user['username'];
                                    }
                                    $course_coaches = array_merge($course_coaches, $teachersToAdd);
                                }
                                foreach ($course_coaches as $course_coach) {
                                    $coach_id = UserManager::get_user_id_from_username($course_coach);
                                    if ($coach_id !== false) {
                                        // Just insert new coaches
                                        SessionManager::updateCoaches($session_id, $course_code, array($coach_id), false);

                                        if ($debug) {
                                            $logger->addInfo("Sessions - Adding course coach: user #$coach_id ($course_coach) to course: '$course_code' and session #$session_id");
                                        }
                                        $savedCoaches[] = $coach_id;
                                    } else {
                                        $error_message .= get_lang('UserDoesNotExist').' : '.$course_coach.$eol;
                                    }
                                }
                            }

                            // Custom courses/session coaches
                            $teacherToAdd = null;
                            if ($onlyAddFirstCoachOrTeacher == true) {
                                foreach ($course_coaches as $course_coach) {
                                    $coach_id = UserManager::get_user_id_from_username($course_coach);
                                    if ($coach_id !== false) {
                                        $teacherToAdd = $coach_id;
                                        break;
                                    }
                                }
                                if (!empty($teacherToAdd)) {
                                    SessionManager::updateCoaches($session_id, $course_code, array($teacherToAdd), true);
                                }
                            }

                            if ($removeAllTeachersFromCourse && !empty($teacherToAdd)) {
                                // Deleting all course teachers and adding the only coach as teacher.
                                $teacherList = CourseManager::get_teacher_list_from_course_code($course_code);
                                if (!empty($teacherList)) {
                                    foreach ($teacherList as $teacher) {
                                        CourseManager::unsubscribe_user($teacher['user_id'], $course_code);
                                    }
                                }
                                CourseManager::subscribe_user($teacherToAdd, $course_code, COURSEMANAGER);
                            }

                            // Continue default behaviour.
                            if ($onlyAddFirstCoachOrTeacher == false) {
                                // Checking one more time see BT#6449#note-149
                                $coaches = SessionManager::getCoachesByCourseSession($session_id, $course_code);

                                if (empty($coaches)) {
                                    foreach ($course_coaches as $course_coach) {
                                        $course_coach = trim($course_coach);
                                        $coach_id = UserManager::get_user_id_from_username($course_coach);
                                        if ($coach_id !== false) {
                                            // Just insert new coaches
                                            SessionManager::updateCoaches($session_id, $course_code, array($coach_id), false);

                                            if ($debug) {
                                                $logger->addInfo("Sessions - Adding course coach: user #$coach_id ($course_coach) to course: '$course_code' and session #$session_id");
                                            }
                                            $savedCoaches[] = $coach_id;
                                        } else {
                                            $error_message .= get_lang('UserDoesNotExist').' : '.$course_coach.$eol;
                                        }
                                    }
                                }
                            }
                        }

                        // Adding Students, updating relationship "Session - Course - User".
                        if (!empty($course_users)) {
                            foreach ($course_users as $user) {
                                $user_id = UserManager::get_user_id_from_username($user);

                                if ($user_id !== false) {
                                    SessionManager::subscribe_users_to_session_course(array($user_id), $session_id, $course_code);
                                    if ($debug) {
                                        $logger->addInfo("Sessions - Adding student: user #$user_id ($user) to course: '$course_code' and session #$session_id");
                                    }
                                } else {
                                    $error_message .= get_lang('UserDoesNotExist').': '.$user.$eol;
                                }
                            }
                        }

                        $course_info = CourseManager::get_course_information($course_code);
                        $inserted_in_course[$course_code] = $course_info['title'];
                    }
                }
                $access_url_id = api_get_current_access_url_id();
                UrlManager::add_session_to_url($session_id, $access_url_id);
                $sql_update_users = "UPDATE $tbl_session SET nbr_users = '$user_counter', nbr_courses = '$course_counter' WHERE id = '$session_id'";
                Database::query($sql_update_users);
            }
        }
        return array(
            'error_message' => $error_message,
            'session_counter' =>  $session_counter,
            'session_list' => $sessionList
        );

    }

    /**
     * @param int $sessionId
     * @param string $courseCode
     * @return array
     */
    public static function getCoachesByCourseSession($sessionId, $courseCode)
    {
        $tbl_session_rel_course_rel_user	= Database::get_main_table(TABLE_MAIN_SESSION_COURSE_USER);
        $sessionId = intval($sessionId);
        $courseCode = Database::escape_string($courseCode);

        $sql = "SELECT id_user FROM $tbl_session_rel_course_rel_user WHERE id_session = '$sessionId' AND course_code = '$courseCode' AND status = 2";
        $result = Database::query($sql);

        $coaches = array();
        if (Database::num_rows($result) > 0) {
            while ($row = Database::fetch_row($result)) {
                $coaches[] = $row[0];
            }
        }
        return $coaches;
    }

    /**
     * Get all coaches added in the session - course relationship
     * @param int $sessionId
     * @return array
     */
    public static function getCoachesBySession($sessionId)
    {
        $table = Database::get_main_table(TABLE_MAIN_SESSION_COURSE_USER);
        $sessionId = intval($sessionId);

        $sql = "SELECT DISTINCT id_user FROM $table
                WHERE id_session = '$sessionId' AND status = 2";
        $result = Database::query($sql);

        $coaches = array();
        if (Database::num_rows($result) > 0) {
            while ($row = Database::fetch_array($result)) {
                $coaches[] = $row['id_user'];
            }
        }
        return $coaches;
    }

    /**
     * @param string $status
     * @param int $userId
     * @param bool $getCount
     * @param int  $from
     * @param int  $numberItems
     * @param int $column
     * @param string $direction
     * @param string $keyword
     * @param string $active
     * @param string $lastConnectionDate
     * @param array $sessionIdList
     * @param array $studentIdList
     * @param int $filterByStatus
     * @return array|int
     */
    public static function getAllUsersFromCoursesFromAllSessionFromStatus(
        $status,
        $userId,
        $getCount = false,
        $from = null,
        $numberItems = null,
        $column = 1,
        $direction = 'asc',
        $keyword = null,
        $active = null,
        $lastConnectionDate = null,
        $sessionIdList = array(),
        $studentIdList = array(),
        $filterByStatus = null
    ) {
        $filterByStatus = intval($filterByStatus);

        $tbl_user = Database::get_main_table(TABLE_MAIN_USER);
        $tbl_session = Database::get_main_table(TABLE_MAIN_SESSION);
        $tbl_course = Database::get_main_table(TABLE_MAIN_COURSE);
        $tbl_course_user = Database::get_main_table(TABLE_MAIN_COURSE_USER);
        $tbl_course_rel_access_url = Database::get_main_table(TABLE_MAIN_ACCESS_URL_REL_COURSE);
        $tbl_session_rel_course_rel_user = Database::get_main_table(TABLE_MAIN_SESSION_COURSE_USER);
        $tbl_session_rel_access_url = Database::get_main_table(TABLE_MAIN_ACCESS_URL_REL_SESSION);

        $direction = in_array(strtolower($direction), array('asc', 'desc')) ? $direction : 'asc';
        $column = Database::escape_string($column);
        $userId = intval($userId);

        $limitCondition = null;

        if (isset($from) && isset($numberItems)) {
            $from = intval($from);
            $numberItems = intval($numberItems);
            $limitCondition = "LIMIT $from, $numberItems";
        }

        $urlId = api_get_current_access_url_id();

        $sessionConditions = null;
        $courseConditions = null;
        $userConditions = null;

        if (isset($active)) {
            $active = intval($active);
            $userConditions .= " AND active = $active";
        }

        switch ($status) {
            case 'drh':
                // Classic DRH
                if (empty($studentIdList)) {
                    $studentListSql = UserManager::get_users_followed_by_drh(
                        $userId,
                        $filterByStatus,
                        true,
                        false
                    );
                    $studentIdList = array_keys($studentListSql);
                    $studentListSql = "'".implode("','", $studentIdList)."'";
                } else {
                    $studentIdList = array_map('intval', $studentIdList);
                    $studentListSql = "'".implode("','", $studentIdList)."'";
                }
                if (!empty($studentListSql)) {
                    $userConditions = " AND u.user_id IN (".$studentListSql.") ";
                }
                break;
            case 'drh_all':
                // Show all by DRH
                if (empty($sessionIdList)) {
                    $sessionsListSql = SessionManager::get_sessions_followed_by_drh(
                        $userId,
                        null,
                        null,
                        false,
                        true,
                        true
                    );
                } else {
                    $sessionIdList = array_map('intval', $sessionIdList);
                    $sessionsListSql = "'".implode("','", $sessionIdList)."'";
                }
                if (!empty($sessionsListSql)) {
                    $sessionConditions = " AND s.id IN (".$sessionsListSql.") ";
                }
                break;
            case 'session_admin';
                $sessionConditions = " AND s.id_coach = $userId ";
                break;
            case 'admin':
                break;
            case 'teacher':
                $sessionConditions = " AND s.id_coach = $userId ";

                // $statusConditions = " AND s.id_coach = $userId";
                break;
        }

        $select = "SELECT DISTINCT u.* ";
        $masterSelect = "SELECT DISTINCT * FROM ";

        if ($getCount) {
            $select = "SELECT DISTINCT u.user_id ";
            $masterSelect = "SELECT COUNT(DISTINCT(user_id)) as count FROM ";
        }

        if (!empty($filterByStatus)) {
            $userConditions .= " AND u.status = ".$filterByStatus;
        }

        if (!empty($lastConnectionDate)) {
            $lastConnectionDate = Database::escape_string($lastConnectionDate);
            $userConditions .=  " AND u.last_login <= '$lastConnectionDate' ";
        }

        if (!empty($keyword)) {
            $keyword = Database::escape_string($keyword);
            $userConditions .= " AND (
                u.username LIKE '%$keyword%' OR
                u.firstname LIKE '%$keyword%' OR
                u.lastname LIKE '%$keyword%' OR
                u.official_code LIKE '%$keyword%' OR
                u.email LIKE '%$keyword%'
            )";
        }

        $where = " WHERE
                   access_url_id = $urlId
                   $userConditions
        ";

        $sql = "$masterSelect (
                ($select
                FROM $tbl_session s
                    INNER JOIN $tbl_session_rel_course_rel_user su ON (s.id = su.id_session)
                    INNER JOIN $tbl_user u ON (u.user_id = su.id_user AND s.id = id_session)
                    INNER JOIN $tbl_session_rel_access_url url ON (url.session_id = s.id)
                    $where
                    $sessionConditions
                )
                UNION (
                    $select
                    FROM $tbl_course c
                    INNER JOIN $tbl_course_user cu ON (cu.course_code = c.code)
                    INNER JOIN $tbl_user u ON (u.user_id = cu.user_id)
                    INNER JOIN $tbl_course_rel_access_url url ON (url.course_code = c.code)
                    $where
                    $courseConditions
                )
                ) as t1
                ";

        if ($getCount) {
            ///var_dump($sql);
            $result = Database::query($sql);
            $count = 0;
            if (Database::num_rows($result)) {
                $rows = Database::fetch_array($result);
                $count = $rows['count'];
            }
            return $count;
        }

        if (!empty($column) && !empty($direction)) {
            $column = str_replace('u.', '', $column);
            $sql .= " ORDER BY $column $direction ";
        }

        $sql .= $limitCondition;

        $result = Database::query($sql);
        $result = Database::store_result($result);

        return $result ;
    }

    /**
     * @param int $sessionId
     * @param string $courseCode
     * @param array $coachList
     * @param bool $deleteCoachesNotInList
     */
    public static function updateCoaches($sessionId, $courseCode, $coachList, $deleteCoachesNotInList = false)
    {
        $currentCoaches = self::getCoachesByCourseSession($sessionId, $courseCode);

        if (!empty($coachList)) {
            foreach ($coachList as $userId) {
                self::set_coach_to_course_session($userId, $sessionId, $courseCode);
            }
        }

        if ($deleteCoachesNotInList) {
            if (!empty($coachList)) {
                $coachesToDelete = array_diff($currentCoaches, $coachList);
            } else {
                $coachesToDelete = $currentCoaches;
            }

            if (!empty($coachesToDelete)) {
                foreach ($coachesToDelete as $userId) {
                    self::set_coach_to_course_session($userId, $sessionId, $courseCode, true);
                }
            }
        }
    }

    /**
     * @param array $sessions
     * @param array $sessionsDestination
     * @return string
     */
    public static function copyStudentsFromSession($sessions, $sessionsDestination)
    {
        $messages = array();
        if (!empty($sessions)) {
            foreach ($sessions as $sessionId) {
                $sessionInfo = self::fetch($sessionId);
                $userList = self::get_users_by_session($sessionId, 0);
                if (!empty($userList)) {
                    $newUserList = array();
                    $userToString = null;
                    foreach ($userList as $userInfo) {
                        $newUserList[] = $userInfo['user_id'];
                        $userToString .= $userInfo['firstname'].' '.$userInfo['lastname'].'<br />';
                    }

                    if (!empty($sessionsDestination)) {
                        foreach ($sessionsDestination  as $sessionDestinationId) {
                            $sessionDestinationInfo = self::fetch($sessionDestinationId);
                            $messages[] = Display::return_message(
                                sprintf(get_lang('AddingStudentsFromSessionXToSessionY'), $sessionInfo['name'], $sessionDestinationInfo['name']),
                                'info',
                                false
                            );
                            if ($sessionId == $sessionDestinationId) {
                                $messages[] = Display::return_message(get_lang('SkipSession'), 'warning', false);
                                continue;
                            }
                            $messages[] = Display::return_message(get_lang('StudentList').'<br />'.$userToString, 'info', false);
                            SessionManager::suscribe_users_to_session($sessionDestinationId, $newUserList, SESSION_VISIBLE_READ_ONLY, false);
                        }
                    } else {
                        $messages[] = Display::return_message(get_lang('NoDestinationSessionProvided'), 'warning');
                    }
                } else {
                    $messages[] = Display::return_message(get_lang('NoStudentsFoundForSession').' #'.$sessionInfo['name'], 'warning');
                }
            }
        } else {
            $messages[]= Display::return_message(get_lang('NoData'), 'warning');
        }
        return $messages;
    }

    /**
     * Assign coaches of a session(s) as teachers to a given course (or courses)
     * @param array A list of session IDs
     * @param array A list of course IDs
     * @return string
     */
    public static function copyCoachesFromSessionToCourse($sessions, $courses)
    {
        $coachesPerSession = array();
        foreach ($sessions as $sessionId) {
            $coaches = self::getCoachesBySession($sessionId);
            $coachesPerSession[$sessionId] = $coaches;
        }

        $result = array();

        if (!empty($courses)) {
            foreach ($courses as $courseId) {
                $courseInfo = api_get_course_info_by_id($courseId);
                foreach ($coachesPerSession as $sessionId => $coachList) {
                    CourseManager::updateTeachers(
                        $courseInfo['code'],
                        $coachList,
                        false,
                        false,
                        false
                    );
                    $result[$courseInfo['code']][$sessionId] = $coachList;
                }
            }
        }
        $sessionUrl = api_get_path(WEB_CODE_PATH).'admin/resume_session.php?id_session=';

        $htmlResult = null;

        if (!empty($result)) {
            foreach ($result as $courseCode => $data) {
                $url = api_get_course_url($courseCode);
                $htmlResult .= sprintf(get_lang('CoachesSubscribedAsATeacherInCourseX'), Display::url($courseCode, $url, array('target' => '_blank')));
                foreach ($data as $sessionId => $coachList) {
                    $sessionInfo = self::fetch($sessionId);
                    $htmlResult .= '<br />';
                    $htmlResult .= Display::url(
                        get_lang('Session').': '.$sessionInfo['name'].' <br />',
                        $sessionUrl.$sessionId,
                        array('target' => '_blank')
                    );
                    $teacherList = array();
                    foreach ($coachList as $coachId) {
                        $userInfo = api_get_user_info($coachId);
                        $teacherList[] = $userInfo['complete_name'];
                    }
                    if (!empty($teacherList)) {
                        $htmlResult .= implode(', ', $teacherList);
                    } else {
                        $htmlResult .= get_lang('NothingToAdd');
                    }
                }
                $htmlResult .= '<br />';
            }
            $htmlResult = Display::return_message($htmlResult, 'normal', false);
        }
        return $htmlResult;
    }

    /**
     * @param string $keyword
     * @param string $active
     * @param string $lastConnectionDate
     * @param array $sessionIdList
     * @param array $studentIdList
     * @param int $userStatus STUDENT|COURSEMANAGER constants

     * @return array|int
     */
    public static function getCountUserTracking(
        $keyword = null,
        $active = null,
        $lastConnectionDate = null,
        $sessionIdList = array(),
        $studentIdList = array(),
        $filterUserStatus = null
    ) {
        $userId = api_get_user_id();
        $drhLoaded = false;

        if (api_is_drh()) {
            if (api_drh_can_access_all_session_content()) {
                $count = self::getAllUsersFromCoursesFromAllSessionFromStatus(
                    'drh_all',
                    $userId,
                    true,
                    null,
                    null,
                    null,
                    null,
                    $keyword,
                    $active,
                    $lastConnectionDate,
                    $sessionIdList,
                    $studentIdList,
                    $filterUserStatus
                );
                $drhLoaded = true;
            }
        }

        if ($drhLoaded == false) {
            $count = UserManager::getUsersFollowedByUser(
                $userId,
                $filterUserStatus,
                false,
                false,
                true,
                null,
                null,
                null,
                null,
                $active,
                $lastConnectionDate,
                COURSEMANAGER
            );
        }

        return $count;
    }

    /**
     * Get teachers followed by a user
     * @param int $userId
     * @param int $active
     * @param string $lastConnectionDate
     * @param bool $getCount
     * @param array $sessionIdList
     * @return array|int
     */
    public static function getTeacherTracking(
        $userId,
        $active = 1,
        $lastConnectionDate = null,
        $getCount = false,
        $sessionIdList = array()
    ) {
        $teacherResult = array();

        if (api_is_drh() || api_is_platform_admin()) {
            // Followed teachers by drh
            if (api_drh_can_access_all_session_content()) {
                if (empty($sessionIdList)) {
                    $sessions = SessionManager::get_sessions_followed_by_drh($userId);
                    $sessionIdList = array();
                    foreach ($sessions as $session) {
                        $sessionIdList[] = $session['id'];
                    }
                }

                $sessionIdList = array_map('intval', $sessionIdList);
                $sessionToString = implode("', '",  $sessionIdList);

                $course = Database::get_main_table(TABLE_MAIN_COURSE);
                $sessionCourse = Database::get_main_table(TABLE_MAIN_SESSION_COURSE);
                $courseUser = Database::get_main_table(TABLE_MAIN_COURSE_USER);

                // Select the teachers.
                $sql = "SELECT DISTINCT(cu.user_id) FROM $course c
                        INNER JOIN $sessionCourse src ON c.code = src.course_code
                        INNER JOIN $courseUser cu ON (cu.course_code = c.code)
		                WHERE src.id_session IN ('$sessionToString') AND cu.status = 1";
                $result = Database::query($sql);
                $teacherListId = array();
                while($row = Database::fetch_array($result, 'ASSOC')) {
                    $teacherListId[$row['user_id']] = $row['user_id'];
                }
            } else {
                $teacherResult = UserManager::get_users_followed_by_drh($userId, COURSEMANAGER);
                $teacherListId = array();
                foreach ($teacherResult as $userInfo) {
                    $teacherListId[] = $userInfo['user_id'];
                }
            }
        }

        if (!empty($teacherListId)) {
            $tableUser = Database::get_main_table(TABLE_MAIN_USER);

            $select = "SELECT DISTINCT u.* ";
            if ($getCount) {
                $select = "SELECT count(DISTINCT(u.user_id)) as count";
            }

            $sql = "$select FROM $tableUser u";

            if (!empty($lastConnectionDate)) {
                $tableLogin = Database::get_main_table(TABLE_STATISTIC_TRACK_E_LOGIN);
                //$sql .= " INNER JOIN $tableLogin l ON (l.login_user_id = u.user_id) ";
            }
            $active = intval($active);
            $teacherListId = implode("','", $teacherListId);
            $where = " WHERE u.active = $active AND u.user_id IN ('$teacherListId') ";

            if (!empty($lastConnectionDate)) {
                $lastConnectionDate = Database::escape_string($lastConnectionDate);
                //$where .= " AND l.login_date <= '$lastConnectionDate' ";
            }

            $sql .= $where;
            $result = Database::query($sql);
            if (Database::num_rows($result)) {
                if ($getCount) {
                    $row = Database::fetch_array($result);
                    return $row['count'];
                } else {

                    return Database::store_result($result, 'ASSOC');
                }
            }
        }

        return 0;
    }

    /**
     * Get the list of course tools that have to be dealt with in case of
     * registering any course to a session
     * @return array The list of tools to be dealt with (literal names)
     */
    public static function getCourseToolToBeManaged()
    {
        return array(
            'courseDescription',
            'courseIntroduction'
        );
    }

    /**
     * Calls the methods bound to each tool when a course is registered into a session
     * @param int $sessionId
     * @param int $courseId
     * @return void
     */
    public static function installCourse($sessionId, $courseId)
    {
        return true;
        $toolList = self::getCourseToolToBeManaged();

        foreach($toolList as $tool) {
            $method = 'add'.$tool;
            if (method_exists(get_class(), $method)) {
                self::$method($sessionId, $courseId);
            }
        }
    }

    /**
     * Calls the methods bound to each tool when a course is unregistered from
     * a session
     * @param int $sessionId
     * @param int $courseId
     */
    public static function unInstallCourse($sessionId, $courseId)
    {
        return true;
        $toolList = self::getCourseToolToBeManaged();

        foreach($toolList as $tool) {
            $method = 'remove'.$tool;
            if (method_exists(get_class(), $method)) {
                self::$method($sessionId, $courseId);
            }
        }
    }

    /**
     * @param int $sessionId
     * @param int $courseId
     */
    public static function addCourseIntroduction($sessionId, $courseId)
    {
        // @todo create a tool intro lib
        $sessionId = intval($sessionId);
        $courseId = intval($courseId);

        $TBL_INTRODUCTION = Database::get_course_table(TABLE_TOOL_INTRO);
        $sql = "SELECT * FROM $TBL_INTRODUCTION WHERE c_id = $courseId";
        $result = Database::query($sql);
        $result = Database::store_result($result, 'ASSOC');

        if (!empty($result)) {
            foreach ($result as $result) {
                // @todo check if relation exits.
                $result['session_id'] = $sessionId;
                Database::insert($TBL_INTRODUCTION, $result);
            }
        }
    }

    /**
     * @param int $sessionId
     * @param int $courseId
     */
    public static function removeCourseIntroduction($sessionId, $courseId)
    {
        $sessionId = intval($sessionId);
        $courseId = intval($courseId);
        $TBL_INTRODUCTION = Database::get_course_table(TABLE_TOOL_INTRO);
        $sql = "DELETE FROM $TBL_INTRODUCTION WHERE c_id = $courseId AND session_id = $sessionId";
        Database::query($sql);
    }

    /**
     * @param int $sessionId
     * @param int $courseId
     */
    public static function addCourseDescription($sessionId, $courseId)
    {
        /*$description = new CourseDescription();
        $descriptions = $description->get_descriptions($courseId);
        foreach ($descriptions as $description) {
        }*/
    }

    /**
     * @param int $sessionId
     * @param int $courseId
     */
    public static function removeCourseDescription($sessionId, $courseId)
    {

    }

    /**
     * @param array $list  format see self::importSessionDrhCSV()
     * @param bool $sendEmail
     * @param bool $removeOldRelationShips
     * @return string
     */
    public static function subscribeDrhToSessionList($userSessionList, $sendEmail, $removeOldRelationShips)
    {
        if (!empty($userSessionList)) {
            foreach ($userSessionList as $userId => $data) {
                $sessionList = array();
                foreach ($data['session_list'] as $sessionInfo) {
                    $sessionList[] = $sessionInfo['session_id'];
                }
                $userInfo = $data['user_info'];
                self::suscribe_sessions_to_hr_manager($userInfo, $sessionList, $sendEmail, $removeOldRelationShips);
            }
        }
    }

    /**
     * @param array $userSessionList format see self::importSessionDrhCSV()
     */
    public static function checkSubscribeDrhToSessionList($userSessionList)
    {
        $message = null;
        if (!empty($userSessionList)) {
            if (!empty($userSessionList)) {
                foreach ($userSessionList as $userId => $data) {
                    $userInfo = $data['user_info'];

                    $sessionListSubscribed = self::get_sessions_followed_by_drh($userId);
                    if (!empty($sessionListSubscribed)) {
                        $sessionListSubscribed = array_keys($sessionListSubscribed);
                    }

                    $sessionList = array();
                    if (!empty($data['session_list'])) {
                        foreach ($data['session_list'] as $sessionInfo) {
                            if (in_array($sessionInfo['session_id'], $sessionListSubscribed)) {
                                $sessionList[] = $sessionInfo['session_info']['name'];
                            }
                        }
                    }

                    $message .= '<strong>'.get_lang('User').'</strong> '.$userInfo['complete_name'].' <br />';

                    if (!in_array($userInfo['status'], array(DRH)) && !api_is_platform_admin_by_id($userInfo['user_id'])) {
                        $message .= get_lang('UserMustHaveTheDrhRole').'<br />';
                        continue;
                    }

                    if (!empty($sessionList)) {
                        $message .= '<strong>'.get_lang('Sessions').':</strong> <br />';
                        $message .= implode(', ', $sessionList).'<br /><br />';
                    } else {
                        $message .= get_lang('NoSessions').' <br /><br />';
                    }
                }
            }
        }
        return $message;
    }

    /**
     * @param string $file
     * @param bool $sendEmail
     * @param bool $removeOldRelationShips
     */
    public static function importSessionDrhCSV($file, $sendEmail, $removeOldRelationShips)
    {
        $list = Import::csv_reader($file);

        if (!empty($list)) {
            $userSessionList = array();
            foreach ($list as $data) {
                $userInfo = api_get_user_info_from_username($data['Username']);
                $sessionInfo = self::get_session_by_name($data['SessionName']);

                if (!empty($userInfo) && !empty($sessionInfo)) {
                    $userSessionList[$userInfo['user_id']]['session_list'][] = array(
                        'session_id' => $sessionInfo['id'],
                        'session_info' => $sessionInfo
                    );
                    $userSessionList[$userInfo['user_id']]['user_info'] = $userInfo;
                }
            }

            self::subscribeDrhToSessionList($userSessionList, $sendEmail, $removeOldRelationShips);
            return self::checkSubscribeDrhToSessionList($userSessionList);
        }
    }
}