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

<?php
/* For licensing terms, see /license.txt */

/**
 * This file contains class used like library, provides functions for attendance tool.
 * It's also used like model to attendance_controller (MVC pattern)
 * @author Christian Fasanando <christian1827@gmail.com>
 * @author Julio Montoya <gugli100@gmail.com> improvements
 * @package chamilo.attendance
 *
 */
class Attendance
{
	private $session_id;
	private $course_id;
	private $date_time;
	private $name;
	private $description;
	private $attendance_qualify_title;
	private $attendance_weight;
	private $course_int_id;
	public $category_id;

	// constants
	const DONE_ATTENDANCE_LOG_TYPE = 'done_attendance_sheet';
	const UPDATED_ATTENDANCE_LOG_TYPE = 'updated_attendance_sheet';
	const LOCKED_ATTENDANCE_LOG_TYPE = 'locked_attendance_sheet';

	/**
	 * Constructor
	 */
	public function __construct()
	{
		//$this->course_int_id = api_get_course_int_id();
	}

	/**
	 * Get the total number of attendance inside current course and current session
	 * @see SortableTable#get_total_number_of_items()
	 */
	public static function get_number_of_attendances($active = -1)
	{
		$tbl_attendance = Database :: get_course_table(TABLE_ATTENDANCE);
		$session_id = api_get_session_id();
		$condition_session = api_get_session_condition($session_id);
		$course_id = api_get_course_int_id();
		$sql = "SELECT COUNT(att.id) AS total_number_of_items
				FROM $tbl_attendance att
		        WHERE c_id = $course_id $condition_session ";
		if ($active == 1 || $active == 0) {
			$sql .= "AND att.active = $active";
		}
		$res = Database::query($sql);
		$obj = Database::fetch_object($res);

		return $obj->total_number_of_items;
	}

	/**
	 * Get attendance list only the id, name and attendance_qualify_max fields
	 * @param   string  course db name (optional)
	 * @param   int     session id (optional)
	 * @return  array	attendances list
	 */
	public function get_attendances_list($course_id = '', $session_id = null)
	{
		// Initializing database table and variables
		$tbl_attendance = Database :: get_course_table(TABLE_ATTENDANCE);
		$data = array();

		if (empty($course_id)) {
			$course_id = api_get_course_int_id();
		} else {
			$course_id = intval($course_id);
		}

		$session_id = isset($session_id)?intval($session_id):api_get_session_id();
		$condition_session = api_get_session_condition($session_id);

		// Get attendance data
		$sql = "SELECT id, name, attendance_qualify_max
				FROM $tbl_attendance
				WHERE c_id = $course_id AND active = 1 $condition_session ";
		$rs  = Database::query($sql);
		if (Database::num_rows($rs) > 0) {
			while ($row = Database::fetch_array($rs,'ASSOC')) {
				$data[$row['id']] = $row;
			}
		}

		return $data;
	}

	/**
	 * Get the attendaces to display on the current page (fill the sortable-table)
	 * @param   int     offset of first user to recover
	 * @param   int     Number of users to get
	 * @param   int     Column to sort on
	 * @param   string  Order (ASC,DESC)
	 * @see SortableTable#get_table_data($from)
	 */
	public static function get_attendance_data($from, $number_of_items, $column, $direction)
	{
		$tbl_attendance = Database::get_course_table(TABLE_ATTENDANCE);
		$course_id = api_get_course_int_id();
		$session_id = api_get_session_id();
		$condition_session = api_get_session_condition($session_id);
		$column = intval($column);
		$from = intval($from);
		$number_of_items = intval($number_of_items);

		if (!in_array($direction, array('ASC','DESC'))) {
			$direction = 'ASC';
		}

		$active_plus = '';
		if ((isset($_GET['isStudentView']) && $_GET['isStudentView'] == 'true') ||
			!api_is_allowed_to_edit(null, true)
		) {
			$active_plus = ' AND att.active = 1';
		}

		$sql = "SELECT
                    att.id AS col0,
                    att.name AS col1,
                    att.description AS col2,
                    att.attendance_qualify_max AS col3,
                    att.locked AS col4,
                    att.active AS col5,
                    att.session_id
				FROM $tbl_attendance att
				WHERE
					att.active <> 2 AND
					c_id = $course_id $active_plus $condition_session
				ORDER BY col$column $direction
				LIMIT $from,$number_of_items ";

		$res = Database::query($sql);
		$attendances = array ();

		$param_gradebook = '';
		if (isset($_SESSION['gradebook'])) {
			$param_gradebook = '&gradebook='.$_SESSION['gradebook'];
		}
		$user_info = api_get_user_info();
		$allowDelete = api_get_configuration_value('allow_delete_attendance');

		while ($attendance = Database::fetch_row($res)) {

			$student_param = '';
			if (api_is_drh() && $_GET['student_id']) {
				$student_param = '&student_id='.intval($_GET['student_id']);
			}

			$session_star = '';

			if (api_get_session_id() == $attendance[6]) {
				$session_star = api_get_session_image(api_get_session_id(), $user_info['status']);
			}

			if ($attendance[5] == 1) {
				$isDrhOfCourse = CourseManager::isUserSubscribedInCourseAsDrh(
					api_get_user_id(),
					api_get_course_info()
				);

				if (api_is_allowed_to_edit(null, true) || $isDrhOfCourse) {
					// Link to edit
					$attendance[1] = '<a href="index.php?'.api_get_cidreq().'&action=attendance_sheet_list&attendance_id='.$attendance[0].$param_gradebook.$student_param.'">'.$attendance[1].'</a>'.$session_star;
				} else {
					// Link to view
					$attendance[1] = '<a href="index.php?'.api_get_cidreq().'&action=attendance_sheet_list_no_edit&attendance_id='.$attendance[0].$param_gradebook.$student_param.'">'.$attendance[1].'</a>'.$session_star;
				}
			} else {
				$attendance[1] = '<a class="muted" href="index.php?'.api_get_cidreq().'&action=attendance_sheet_list&attendance_id='.$attendance[0].$param_gradebook.$student_param.'">'.$attendance[1].'</a>'.$session_star;
			}

			if ($attendance[5] == 1) {
				$attendance[3] = '<center>'.$attendance[3].'</center>';
			} else {
				$attendance[3] = '<center><span class="muted">'.$attendance[3].'</span></center>';
			}

			$attendance[3] = '<center>'.$attendance[3].'</center>';

			if (api_is_allowed_to_edit(null, true)) {
				$actions  = '';
				$actions .= '<center>';

				if (api_is_platform_admin()) {
					$actions .= '<a href="index.php?'.api_get_cidreq().'&action=attendance_edit&attendance_id='.$attendance[0].$param_gradebook.'">'.
						Display::return_icon('edit.png', get_lang('Edit'), array(), ICON_SIZE_SMALL).'</a>&nbsp;';
					// Visible
					if ($attendance[5] == 1) {
						$actions .= '<a href="index.php?'.api_get_cidreq().'&action=attendance_set_invisible&attendance_id='.$attendance[0].$param_gradebook.'">'.
							Display::return_icon('visible.png', get_lang('Hide'), array(), ICON_SIZE_SMALL).'</a>';
					} else {
						$actions .= '<a href="index.php?'.api_get_cidreq().'&action=attendance_set_visible&attendance_id='.$attendance[0].$param_gradebook.'">'.
							Display::return_icon('invisible.png', get_lang('Show'), array(), ICON_SIZE_SMALL).'</a>';
						$attendance[2] = '<span class="muted">'.$attendance[2].'</span>';
					}
					if ($allowDelete) {
						$actions .= '<a href="index.php?' . api_get_cidreq() . '&action=attendance_delete&attendance_id=' . $attendance[0] . $param_gradebook . '">' .
							Display::return_icon('delete.png', get_lang('Delete'), array(), ICON_SIZE_SMALL) . '</a>';
					}
				} else {
					$is_locked_attendance = self::is_locked_attendance($attendance[0]);
					if ($is_locked_attendance) {
						$actions .= Display::return_icon('edit_na.png', get_lang('Edit')).'&nbsp;';
						$actions .= Display::return_icon('visible.png', get_lang('Hide'));
					} else {
						$actions .= '<a href="index.php?'.api_get_cidreq().'&action=attendance_edit&attendance_id='.$attendance[0].$param_gradebook.'">'.
							Display::return_icon('edit.png', get_lang('Edit'), array(), ICON_SIZE_SMALL).'</a>&nbsp;';

						if ($attendance[5] == 1) {
							$actions .= ' <a href="index.php?'.api_get_cidreq().'&action=attendance_set_invisible&attendance_id='.$attendance[0].$param_gradebook.'">'.
								Display::return_icon('visible.png', get_lang('Hide'), array(), ICON_SIZE_SMALL).'</a>';
						} else {
							$actions .= ' <a href="index.php?'.api_get_cidreq().'&action=attendance_set_visible&attendance_id='.$attendance[0].$param_gradebook.'">'.
								Display::return_icon('invisible.png', get_lang('Show'), array(), ICON_SIZE_SMALL).'</a>';
							$attendance[2] = '<span class="muted">'.$attendance[2].'</span>';
						}
						if ($allowDelete) {
							$actions .= ' <a href="index.php?' . api_get_cidreq() . '&action=attendance_delete&attendance_id=' . $attendance[0] . $param_gradebook . '">' .
								Display::return_icon('delete.png', get_lang('Delete'), array(), ICON_SIZE_SMALL) . '</a>';
						}
					}
				}

				// display lock/unlock icon
				$is_done_all_calendar = self::is_all_attendance_calendar_done($attendance[0]);

				if ($is_done_all_calendar) {
					$locked   = $attendance[4];
					if ($locked == 0) {
						if (api_is_platform_admin()) {
							$message_alert = get_lang('AreYouSureToLockTheAttendance');
						} else {
							$message_alert = get_lang('UnlockMessageInformation');
						}
						$actions .= '&nbsp;<a onclick="javascript:if(!confirm(\''.$message_alert.'\')) return false;" href="index.php?'.api_get_cidreq().'&action=lock_attendance&attendance_id='.$attendance[0].$param_gradebook.'">'.Display::return_icon('unlock.png', get_lang('LockAttendance')).'</a>';
					} else {
						if (api_is_platform_admin()) {
							$actions .= '&nbsp;<a onclick="javascript:if(!confirm(\''.get_lang('AreYouSureToUnlockTheAttendance').'\')) return false;" href="index.php?'.api_get_cidreq().'&action=unlock_attendance&attendance_id='.$attendance[0].$param_gradebook.'">'.Display::return_icon('locked.png', get_lang('UnlockAttendance')).'</a>';
						} else {
							$actions .= '&nbsp;'.Display::return_icon('locked_na.png', get_lang('LockedAttendance'));
						}
					}
				}
				$actions .= '</center>';

				$attendances[] = array($attendance[0], $attendance[1], $attendance[2], $attendance[3],$actions);
			} else {
				$attendance[0] = '&nbsp;';
				$attendances[] = array($attendance[0], $attendance[1], $attendance[2], $attendance[3]);
			}
		}
		return $attendances;
	}

	/**
	 * Get the attendances by id to display on the current page
	 * @param  int     $attendance_id
	 * @return array   attendance data
	 */
	public function get_attendance_by_id($attendance_id)
	{
		$tbl_attendance = Database :: get_course_table(TABLE_ATTENDANCE);
		$attendance_id = intval($attendance_id);
		$course_id = api_get_course_int_id();
		$attendance_data = array();
		$sql = "SELECT * FROM $tbl_attendance
				WHERE c_id = $course_id AND id = '$attendance_id'";
		$res = Database::query($sql);
		if (Database::num_rows($res) > 0) {
			while ($row = Database::fetch_array($res)) {
				$attendance_data = $row;
			}
		}
		return $attendance_data;
	}

	/**
	 * Add attendances sheet inside table. This is the *list of* dates, not
	 * a specific date in itself.
	 * @param  bool   true for adding link in gradebook or false otherwise (optional)
	 * @return int    last attendance id
	 */
	public function attendance_add($link_to_gradebook = false)
	{
		global $_course;
		$tbl_attendance	= Database :: get_course_table(TABLE_ATTENDANCE);
		$table_link 	= Database :: get_main_table(TABLE_MAIN_GRADEBOOK_LINK);
		$session_id 	= api_get_session_id();
		$user_id 		= api_get_user_id();
		$course_code	= api_get_course_id();
		$course_id      = api_get_course_int_id();
		$title_gradebook= Database::escape_string($this->attendance_qualify_title);
		$value_calification  = 0;
		$weight_calification =	floatval($this->attendance_weight);
		$sql = "INSERT INTO $tbl_attendance SET
				c_id =  $course_id,
				name ='".Database::escape_string($this->name)."',
				description = '".Database::escape_string($this->description)."',
				attendance_qualify_title = '$title_gradebook',
				attendance_weight = '$weight_calification',
				session_id = '$session_id'";
		Database::query($sql);
		$affected_rows = Database::affected_rows();
		$last_id = 0;
		if (!empty($affected_rows)) {
			// save inside item property table
			$last_id = Database::insert_id();
			api_item_property_update($_course, TOOL_ATTENDANCE, $last_id,"AttendanceAdded", $user_id);
		}
		// add link to gradebook
		if ($link_to_gradebook && !empty($this->category_id)) {
			$description = '';
			$link_info = is_resource_in_course_gradebook($course_code,7,$last_id,$session_id);
			$link_id = $link_info['id'];
			if (!$link_info) {
				add_resource_to_course_gradebook(
					$this->category_id,
					$course_code,
					7,
					$last_id,
					$title_gradebook,
					$weight_calification,
					$value_calification,
					$description,
					1,
					$session_id
				);
			} else {
				Database::query('UPDATE '.$table_link.' SET weight='.$weight_calification.' WHERE id='.$link_id.'');
			}
		}
		return $last_id;
	}

	/**
	 * edit attendances inside table
	 * @param 	int	   attendance id
	 * @param  	bool   true for adding link in gradebook or false otherwise (optional)
	 * @return 	int    last id
	 */
	public function attendance_edit($attendance_id, $link_to_gradebook = false)
	{
		$_course = api_get_course_info();
		$tbl_attendance     = Database :: get_course_table(TABLE_ATTENDANCE);
		$table_link         = Database :: get_main_table(TABLE_MAIN_GRADEBOOK_LINK);
		$session_id         = api_get_session_id();
		$user_id            = api_get_user_id();
		$attendance_id      = intval($attendance_id);
		$course_code        = api_get_course_id();
		$course_id          = api_get_course_int_id();
		$title_gradebook	= Database::escape_string($this->attendance_qualify_title);
		$value_calification = 0;
		$weight_calification= floatval($this->attendance_weight);

		if (!empty($attendance_id)) {

			$sql = "UPDATE $tbl_attendance
                    SET name ='".Database::escape_string($this->name)."',
                        description = '".Database::escape_string($this->description)."',
                        attendance_qualify_title = '".$title_gradebook."',
                        attendance_weight = '".$weight_calification."'
                    WHERE c_id = $course_id AND id = '$attendance_id'";
			Database::query($sql);

			api_item_property_update($_course, TOOL_ATTENDANCE, $attendance_id,"AttendanceUpdated", $user_id);

			// add link to gradebook
			if ($link_to_gradebook && !empty($this->category_id)) {
				$description = '';
				$link_id = is_resource_in_course_gradebook($course_code, 7, $attendance_id, $session_id);
				if (!$link_id) {
					add_resource_to_course_gradebook(
						$this->category_id,
						$course_code,
						7,
						$attendance_id,
						$title_gradebook,
						$weight_calification,
						$value_calification,
						$description,
						1,
						$session_id
					);
				} else {
					Database::query('UPDATE '.$table_link.' SET weight='.$weight_calification.' WHERE id='.$link_id.'');
				}
			}
			return $attendance_id;
		}
		return null;
	}

	/**
	 * Restore attendance
	 * @param 	int|array	   one or many attendances id
	 * @return 	int    		   affected rows
	 */
	public function attendance_restore($attendance_id)
	{
		$_course = api_get_course_info();
		$tbl_attendance	= Database :: get_course_table(TABLE_ATTENDANCE);
		$user_id = api_get_user_id();
		$course_id = api_get_course_int_id();
		if (is_array($attendance_id)) {
			foreach ($attendance_id as $id) {
				$id	= intval($id);
				$sql = "UPDATE $tbl_attendance SET active = 1
						WHERE c_id = $course_id AND id = '$id'";
				Database::query($sql);
				$affected_rows = Database::affected_rows();
				if (!empty($affected_rows)) {
					// update row item property table
					api_item_property_update($_course, TOOL_ATTENDANCE, $id,"restore", $user_id);
				}
			}
		} else  {
			$attendance_id	= intval($attendance_id);
			$sql = "UPDATE $tbl_attendance SET active = 1
					WHERE c_id = $course_id AND id = '$attendance_id'";
			Database::query($sql);
			$affected_rows = Database::affected_rows();
			if (!empty($affected_rows)) {
				// update row item property table
				api_item_property_update($_course, TOOL_ATTENDANCE, $attendance_id,"restore", $user_id);
			}
		}

		return $affected_rows;
	}

	/**
	 * Delete attendances
	 * @param 	int|array	$attendance_id   one or many attendances id
	 * @return 	int    		   affected rows
	 */
	public function attendance_delete($attendance_id)
	{
		$_course = api_get_course_info();
		$tbl_attendance	= Database :: get_course_table(TABLE_ATTENDANCE);
		$user_id 		= api_get_user_id();
		$course_id      = api_get_course_int_id();
		if (is_array($attendance_id)) {
			foreach ($attendance_id as $id) {
				$id	= intval($id);
				$sql = "UPDATE $tbl_attendance SET active = 2
						WHERE c_id = $course_id AND id = '$id'";
				Database::query($sql);
				$affected_rows = Database::affected_rows();
				if (!empty($affected_rows)) {
					// update row item property table
					api_item_property_update($_course, TOOL_ATTENDANCE, $id, "delete", $user_id);
				}
			}
		} else  {
			$attendance_id	= intval($attendance_id);
			$sql = "UPDATE $tbl_attendance SET active = 2
					WHERE c_id = $course_id AND id = '$attendance_id'";

			Database::query($sql);
			$affected_rows = Database::affected_rows();
			if (!empty($affected_rows)) {
				// update row item property table
				api_item_property_update(
					$_course,
					TOOL_ATTENDANCE,
					$attendance_id,
					"delete",
					$user_id
				);
			}
		}
		return $affected_rows;
	}

	/**
	 * Changes visibility
	 * @param 	int|array	$attendanceId   one or many attendances id
	 * @param status
	 * @return 	int affected rows
	 */
	public function changeVisibility($attendanceId, $status = 1)
	{
		$_course = api_get_course_info();
		$tbl_attendance	= Database :: get_course_table(TABLE_ATTENDANCE);
		$user_id = api_get_user_id();
		$course_id = api_get_course_int_id();
		$status = intval($status);

		$action = 'visible';
		if ($status == 0) {
			$action = 'invisible';
		}

		if (is_array($attendanceId)) {
			foreach ($attendanceId as $id) {
				$id	= intval($id);
				$sql = "UPDATE $tbl_attendance SET active = $status
						WHERE c_id = $course_id AND id = '$id'";
				Database::query($sql);
				$affected_rows = Database::affected_rows();
				if (!empty($affected_rows)) {
					// update row item property table
					api_item_property_update($_course, TOOL_ATTENDANCE, $id, $action, $user_id);
				}
			}
		} else  {
			$attendanceId	= intval($attendanceId);
			$sql = "UPDATE $tbl_attendance SET active = $status
					WHERE c_id = $course_id AND id = '$attendanceId'";
			Database::query($sql);
			$affected_rows = Database::affected_rows();
			if (!empty($affected_rows)) {
				// update row item property table
				api_item_property_update(
					$_course,
					TOOL_ATTENDANCE,
					$attendanceId,
					$action,
					$user_id
				);
			}
		}

		return $affected_rows;
	}

	/**
	 * Lock or unlock an attendance
	 * @param   int     attendance id
	 * @param   bool    True to lock or false otherwise
	 */
	public function lock_attendance($attendance_id, $lock = true)
	{
		$tbl_attendance = Database::get_course_table(TABLE_ATTENDANCE);
		$course_id = api_get_course_int_id();
		$attendance_id = intval($attendance_id);
		$locked = ($lock)?1:0;
		$upd = "UPDATE $tbl_attendance SET locked = $locked
				WHERE c_id = $course_id AND id = $attendance_id";
		Database::query($upd);
		$affected_rows = Database::affected_rows();
		if ($affected_rows && $lock) {
			//save attendance sheet log
			$lastedit_date = Date('Y-m-d H:i:s');
			$lastedit_type = self::LOCKED_ATTENDANCE_LOG_TYPE;
			$lastedit_user_id = api_get_user_id();
			$this->save_attendance_sheet_log(
				$attendance_id,
				$lastedit_date,
				$lastedit_type,
				$lastedit_user_id
			);
		}
		return $affected_rows;
	}

	/**
	 * Get registered users inside current course
	 * @param 	int	   $attendance_id attendance id for showing attendance result field (optional)
	 * @return 	array  users data
	 */
	public function get_users_rel_course($attendance_id = 0)
	{
		$current_session_id = api_get_session_id();
		$current_course_id  = api_get_course_id();
		if (!empty($current_session_id)) {
			$a_course_users = CourseManager:: get_user_list_from_course_code(
				$current_course_id,
				$current_session_id,
				'',
				'lastname'
			);
		} else {
			$a_course_users = CourseManager:: get_user_list_from_course_code(
				$current_course_id,
				0,
				'',
				'lastname'
			);
		}
		// get registered users inside current course
		$a_users = array();
		foreach ($a_course_users as $key =>$user_data) {
			$value	= array();
			$uid 	= $user_data['user_id'];
			$status = $user_data['status'];

			$user_status_in_session = null;
			$user_status_in_course  = null;

			if (api_get_session_id()) {
				$user_status_in_session = SessionManager::get_user_status_in_course_session(
					$uid,
					$current_course_id,
					$current_session_id
				);
			} else {
				$user_status_in_course = CourseManager::get_user_in_course_status(
					$uid,
					$current_course_id
				);
			}

			//Not taking into account DRH or COURSEMANAGER
			if ($uid <= 1 || $status == DRH || $user_status_in_course == COURSEMANAGER || $user_status_in_session == 2) continue;

			if (!empty($attendance_id)) {
				$user_faults = $this->get_faults_of_user($uid, $attendance_id);
				$value['attendance_result'] = $user_faults['faults'].'/'.$user_faults['total'].' ('.$user_faults['faults_porcent'].'%)';
				$value['result_color_bar'] 	= $user_faults['color_bar'];
			}

			// user's picture
			$image_path 	= UserManager::get_user_picture_path_by_id($uid, 'web', false);
			$user_profile 	= UserManager::get_picture_user($uid, $image_path['file'], 22, USER_IMAGE_SIZE_SMALL, ' width="22" height="22" ');

			if (!empty($image_path['file'])) {
				$photo = '<center><a class="thickbox" href="'.$image_path['dir'].$image_path['file'].'"  ><img src="'.$user_profile['file'].'" '.$user_profile['style'].' alt="'.api_get_person_name($user_data['firstname'], $user_data['lastname']).'"  title="'.api_get_person_name($user_data['firstname'], $user_data['lastname']).'" /></a></center>';
			} else {
				$photo = '<center><img src="'.$user_profile['file'].'" '.$user_profile['style'].' alt="'.api_get_person_name($user_data['firstname'], $user_data['lastname']).'"  title="'.api_get_person_name($user_data['firstname'], $user_data['lastname']).'" /></center>';
			}

			$value['photo']      = $photo;
			$value['firstname']  = $user_data['firstname'];
			$value['lastname']	 = $user_data['lastname'];
			$value['username']   = $user_data['username'];
			$value['user_id']    = $uid;

			//Sending only 5 items in the array instead of 60
			$a_users[$key] = $value;
		}
		return $a_users;
	}

	/**
	 * add attendances sheet inside table
	 * @param 	int	   $calendar_id attendance calendar id
	 * @param  	array  $users_present present users during current class
	 * @param	int	   $attendance_id
	 * @return 	int    affected rows
	 */
	public function attendance_sheet_add($calendar_id, $users_present, $attendance_id)
	{
		$tbl_attendance_sheet 	= Database::get_course_table(TABLE_ATTENDANCE_SHEET);
		$tbl_attendance_calendar= Database::get_course_table(TABLE_ATTENDANCE_CALENDAR);
		$tbl_attendance_result 	= Database::get_course_table(TABLE_ATTENDANCE_RESULT);
		$tbl_attendance			= Database::get_course_table(TABLE_ATTENDANCE);

		$calendar_id = intval($calendar_id);
		$attendance_id = intval($attendance_id);
		$users = $this->get_users_rel_course();
		$course_id = api_get_course_int_id();

		$user_ids = array_keys($users);
		$users_absent = array_diff($user_ids,$users_present);
		$affected_rows = 0;

		// get last edit type
		$calendar_data = $this->get_attendance_calendar_by_id($calendar_id);
		$lastedit_type = self::DONE_ATTENDANCE_LOG_TYPE;
		if ($calendar_data['done_attendance']) {
			$lastedit_type = self::UPDATED_ATTENDANCE_LOG_TYPE;
		}

		// save users present in class
		foreach ($users_present as $user_present) {
			$uid = intval($user_present);
			// check if user already was registered with the $calendar_id
			$sql = "SELECT user_id FROM $tbl_attendance_sheet
					WHERE c_id = $course_id AND user_id='$uid' AND attendance_calendar_id = '$calendar_id'";
			$rs  = Database::query($sql);
			if (Database::num_rows($rs) == 0) {
				$sql = "INSERT INTO $tbl_attendance_sheet SET
						c_id					= $course_id,
						user_id 				= '$uid',
						attendance_calendar_id 	= '$calendar_id',
						presence 				= 1";
				Database::query($sql);
				$affected_rows += Database::affected_rows();
			} else {
				$sql = "UPDATE $tbl_attendance_sheet SET presence = 1
						WHERE c_id = $course_id AND user_id ='$uid' AND attendance_calendar_id = '$calendar_id'";
				Database::query($sql);
				$affected_rows += Database::affected_rows();
			}
		}

		// save users absent in class
		foreach ($users_absent as $user_absent) {
			$uid = intval($user_absent);
			// check if user already was registered with the $calendar_id
			$sql = "SELECT user_id FROM $tbl_attendance_sheet
					WHERE c_id = $course_id AND user_id='$uid' AND attendance_calendar_id = '$calendar_id'";
			$rs  = Database::query($sql);
			if (Database::num_rows($rs) == 0) {
				$sql = "INSERT INTO $tbl_attendance_sheet SET
						c_id = $course_id,
						user_id ='$uid',
						attendance_calendar_id = '$calendar_id',
						presence = 0";
				Database::query($sql);
				$affected_rows += Database::affected_rows();
			} else {
				$sql = "UPDATE $tbl_attendance_sheet SET presence = 0
						WHERE c_id = $course_id AND user_id ='$uid' AND attendance_calendar_id = '$calendar_id'";
				Database::query($sql);
				$affected_rows += Database::affected_rows();
			}
		}

		// update done_attendance inside attendance calendar table
		$sql = "UPDATE $tbl_attendance_calendar SET done_attendance = 1
				WHERE  c_id = $course_id AND id = '$calendar_id'";
		Database::query($sql);

		// save users' results
		$this->update_users_results($user_ids, $attendance_id);

		if ($affected_rows) {
			//save attendance sheet log
			$lastedit_date = Date('Y-m-d H:i:s');
			$lastedit_user_id = api_get_user_id();
			$calendar_date_value = $calendar_data['date_time'];
			$this->save_attendance_sheet_log(
				$attendance_id,
				$lastedit_date,
				$lastedit_type,
				$lastedit_user_id,
				$calendar_date_value
			);
		}

		return $affected_rows;
	}

	/**
	 * update users' attendance results
	 * @param 	array  $user_ids registered users inside current course
	 * @param	int	   $attendance_id
	 * @return 	void
	 */
	public function update_users_results($user_ids, $attendance_id)
	{
		$tbl_attendance_sheet 	= Database::get_course_table(TABLE_ATTENDANCE_SHEET);
		$tbl_attendance_calendar= Database::get_course_table(TABLE_ATTENDANCE_CALENDAR);
		$tbl_attendance_result  = Database::get_course_table(TABLE_ATTENDANCE_RESULT);
		$tbl_attendance			= Database::get_course_table(TABLE_ATTENDANCE);
		$course_id              = api_get_course_int_id();

		$attendance_id = intval($attendance_id);
		// fill results about presence of students
		$attendance_calendar = $this->get_attendance_calendar($attendance_id);
		$calendar_ids = array();
		// get all dates from calendar by current attendance
		foreach ($attendance_calendar as $cal) {
			$calendar_ids[] = $cal['id'];
		}
		// get count of presences by users inside current attendance and save like results
		$count_presences = 0;
		if (count($user_ids) > 0) {
			foreach ($user_ids as $uid) {
				$count_presences = 0;
				if (count($calendar_ids) > 0) {
					$sql = "SELECT count(presence) as count_presences
							FROM $tbl_attendance_sheet
					        WHERE
					        	c_id = $course_id AND
					        	user_id = '$uid' AND
					        	attendance_calendar_id IN(".implode(',',$calendar_ids).") AND
					        	presence = 1";
					$rs_count  = Database::query($sql);
					$row_count = Database::fetch_array($rs_count);
					$count_presences = $row_count['count_presences'];
				}
				// save results
				$sql = "SELECT id FROM $tbl_attendance_result
						WHERE c_id = $course_id AND user_id='$uid' AND attendance_id='$attendance_id'";
				$rs_check_result = Database::query($sql);
				if (Database::num_rows($rs_check_result) > 0) {
					// update result
					$sql = "UPDATE $tbl_attendance_result SET
							score='$count_presences'
							WHERE c_id = $course_id AND user_id='$uid' AND attendance_id='$attendance_id'";
					Database::query($sql);
				} else {
					// insert new result
					$sql = "INSERT INTO $tbl_attendance_result SET
							c_id = $course_id ,
							user_id			= '$uid',
							attendance_id 	= '$attendance_id',
							score			= '$count_presences'";
					Database::query($sql);
				}
			}
		}
		// update attendance qualify max
		$count_done_calendar = self::get_done_attendance_calendar($attendance_id);
		$sql = "UPDATE $tbl_attendance SET attendance_qualify_max='$count_done_calendar'
				WHERE c_id = $course_id AND id = '$attendance_id'";
		Database::query($sql);
	}

	/**
	 * update attendance_sheet_log table, is used as history of an attendance sheet
	 * @param   int     Attendance id
	 * @param   string  Last edit datetime
	 * @param   string  Event type ('locked_attendance', 'done_attendance_sheet' ...)
	 * @param   int     Last edit user id
	 * @param   string  Calendar datetime value (optional, when event type is 'done_attendance_sheet')
	 * @return  int     Affected rows
	 */
	public function save_attendance_sheet_log($attendance_id, $lastedit_date, $lastedit_type, $lastedit_user_id, $calendar_date_value = null)
	{
		$course_id = api_get_course_int_id();

		// define table
		$tbl_attendance_sheet_log = Database::get_course_table(TABLE_ATTENDANCE_SHEET_LOG);

		// protect data
		$attendance_id = intval($attendance_id);
		$lastedit_date = Database::escape_string($lastedit_date);
		$lastedit_type = Database::escape_string($lastedit_type);
		$lastedit_user_id = intval($lastedit_user_id);

		if (isset($calendar_date_value)) {
			$calendar_date_value = Database::escape_string($calendar_date_value);
		} else {
			$calendar_date_value = '';
		}

		// save data
		$ins = "INSERT INTO $tbl_attendance_sheet_log (c_id, attendance_id, lastedit_date, lastedit_type, lastedit_user_id, calendar_date_value)
                VALUES ($course_id, $attendance_id, '$lastedit_date', '$lastedit_type', $lastedit_user_id, '$calendar_date_value')";

		Database::query($ins);

		return Database::affected_rows();
	}

	/**
	 * Get number of done attendances inside current sheet
	 * @param	int	   attendance id
	 * @return 	int	   number of done attendances
	 */
	public static function get_done_attendance_calendar($attendance_id)
	{
		$tbl_attendance_calendar = Database::get_course_table(TABLE_ATTENDANCE_CALENDAR);
		$attendance_id = intval($attendance_id);
		$course_id = api_get_course_int_id();
		$sql = "SELECT count(done_attendance) as count
                FROM $tbl_attendance_calendar
                WHERE c_id = $course_id AND attendance_id = '$attendance_id' AND done_attendance=1";
		$rs  = Database::query($sql);
		$row = Database::fetch_array($rs);
		$count = $row['count'];
		return $count;
	}

	/**
	 * Get results of faults (absents) by user
	 * @param	int	   user id
	 * @param	int	   attendance id
	 * @return 	array  results containing number of faults, total done attendance,
	 * percent of faults and color depend on result (red, orange)
	 */
	public function get_faults_of_user($user_id, $attendance_id)
	{
		// initializing database table and variables
		$user_id 		= intval($user_id);
		$attendance_id 	= intval($attendance_id);
		$results = array();
		$attendance_data = $this->get_attendance_by_id($attendance_id);
		$calendar_count = self::get_number_of_attendance_calendar($attendance_id);
		$total_done_attendance 	= $attendance_data['attendance_qualify_max'];
		$attendance_user_score  = $this->get_user_score($user_id, $attendance_id);

		//This is the main change of the BT#1381
		//$total_done_attendance = $calendar_count;

		// calculate results
		$faults = $total_done_attendance - $attendance_user_score;

		$faults = $faults > 0 ? $faults:0;
		$faults_porcent = $calendar_count > 0 ?round(($faults*100)/$calendar_count,0):0;
		$results['faults'] 			= $faults;
		$results['total']			= $calendar_count;
		$results['faults_porcent'] 	= $faults_porcent;
		$color_bar = '';

		if ($faults_porcent > 25  ) {
			$color_bar = '#f28989';
		} else if ($faults_porcent > 10) {
			$color_bar = '#F90';
		}
		$results['color_bar'] = $color_bar;

		return $results;
	}

	/**
	 * Get results of faults average for all courses by user
	 * @param	int	   $user_id
	 * @return 	array  results containing number of faults, total done attendance,
	 * percentage of faults and color depend on result (red, orange)
	 */
	public function get_faults_average_inside_courses($user_id)
	{
		// get all courses of current user
		$courses = CourseManager::get_courses_list_by_user_id($user_id, true);

		$user_id = intval($user_id);
		$results = array();
		$total_faults = $total_weight = $porcent = 0;
		foreach ($courses as $course) {
			//$course_code = $course['code'];
			//$course_info = api_get_course_info($course_code);
			$course_id = $course['real_id'];
			$tbl_attendance_result 	= Database::get_course_table(TABLE_ATTENDANCE_RESULT);

			$attendances_by_course = $this->get_attendances_list($course_id);

			foreach ($attendances_by_course as $attendance) {
				// get total faults and total weight
				$total_done_attendance 	= $attendance['attendance_qualify_max'];
				$sql = "SELECT score
						FROM $tbl_attendance_result
                        WHERE
                        	c_id = $course_id AND
                        	user_id = $user_id AND
                        	attendance_id = ".$attendance['id'];
				$rs = Database::query($sql);
				$score = 0;
				if (Database::num_rows($rs) > 0) {
					$row = Database::fetch_array($rs);
					$score = $row['score'];
				}
				$faults = $total_done_attendance-$score;
				$faults = $faults > 0 ? $faults:0;
				$total_faults += $faults;
				$total_weight += $total_done_attendance;
			}
		}

		$porcent = $total_weight > 0 ?round(($total_faults*100)/$total_weight,0):0;
		$results['faults'] 	= $total_faults;
		$results['total']	= $total_weight;
		$results['porcent'] = $porcent;

		return $results;
	}

	/**
	 * Get results of faults average by course
	 * @param	int	   $user_id
	 * @param 	string	$course_code
	 * @param	int	   Session id (optional)
	 * @return 	array  results containing number of faults,
	 * total done attendance, porcent of faults and color depend on result (red, orange)
	 */
	public function get_faults_average_by_course($user_id, $course_code, $session_id = null)
	{
		// Database tables and variables
		$course_info = api_get_course_info($course_code);
		$tbl_attendance_result 	= Database::get_course_table(TABLE_ATTENDANCE_RESULT);
		$user_id = intval($user_id);
		$results = array();
		$total_faults = $total_weight = $porcent = 0;
		$attendances_by_course = $this->get_attendances_list($course_info['real_id'], $session_id);

		foreach ($attendances_by_course as $attendance) {
			// Get total faults and total weight
			$total_done_attendance 	= $attendance['attendance_qualify_max'];
			$sql = "SELECT score FROM $tbl_attendance_result
					WHERE
						c_id = {$course_info['real_id']} AND
						user_id = $user_id AND
						attendance_id=".$attendance['id'];
			$rs = Database::query($sql);
			$score = 0;
			if (Database::num_rows($rs) > 0) {
				$row = Database::fetch_array($rs);
				$score = $row['score'];
			}
			$faults = $total_done_attendance-$score;
			$faults = $faults > 0 ? $faults:0;
			$total_faults += $faults;
			$total_weight += $total_done_attendance;
		}

		$porcent = $total_weight > 0 ?round(($total_faults*100)/$total_weight,0):0;
		$results['faults'] 	= $total_faults;
		$results['total']	= $total_weight;
		$results['porcent'] = $porcent;
		return $results;
	}

	/**
	 * Get registered users' attendance sheet inside current course
	 * @param	int	   $attendance_id
	 * @param	int	   $user_id for showing data for only one user (optional)
	 * @return 	array  users attendance sheet data
	 */
	public function get_users_attendance_sheet($attendance_id, $user_id = 0)
	{
		$tbl_attendance_sheet 	= Database::get_course_table(TABLE_ATTENDANCE_SHEET);
		$tbl_attendance_calendar= Database::get_course_table(TABLE_ATTENDANCE_CALENDAR);

		$attendance_calendar = $this->get_attendance_calendar($attendance_id);
		$calendar_ids = array();
		// get all dates from calendar by current attendance
		foreach ($attendance_calendar as $cal) {
			$calendar_ids[] = $cal['id'];
		}

		$course_id = api_get_course_int_id();

		$data = array();
		if (empty($user_id)) {
			// get all registered users inside current course
			$users = $this->get_users_rel_course();
			$user_ids = array_keys($users);
			if (count($calendar_ids) > 0 && count($user_ids) > 0) {
				foreach ($user_ids as $uid) {
					$sql = "SELECT * FROM $tbl_attendance_sheet
					        WHERE
					        	c_id = $course_id AND
					        	user_id = '$uid' AND
					        	attendance_calendar_id IN(".implode(',',$calendar_ids).")
							";
					$res = Database::query($sql);
					if (Database::num_rows($res) > 0) {
						while ($row = Database::fetch_array($res)) {
							$data[$uid][$row['attendance_calendar_id']]['presence'] = $row['presence'];
						}
					}
				}
			}
		} else {
			// Get attendance for current user
			$user_id = intval($user_id);
			if (count($calendar_ids) > 0) {
				$sql = "SELECT cal.date_time, att.presence
                        FROM $tbl_attendance_sheet att
						INNER JOIN  $tbl_attendance_calendar cal
						ON cal.id = att.attendance_calendar_id
						WHERE
							att.c_id = $course_id AND
							cal.c_id =  $course_id AND
							att.user_id = '$user_id' AND
							att.attendance_calendar_id IN (".implode(',',$calendar_ids).")
                        ORDER BY date_time";
				$res = Database::query($sql);
				if (Database::num_rows($res) > 0) {
					while ($row = Database::fetch_array($res)) {
						$row['date_time'] = api_convert_and_format_date($row['date_time'], null, date_default_timezone_get());
						$data[$user_id][] = $row;
					}
				}
			}
		}
		return $data;
	}

	/**
	 * Get next attendance calendar without presences (done attendances)
	 * @param	int	attendance id
	 * @return 	int attendance calendar id
	 */
	public function get_next_attendance_calendar_id($attendance_id)
	{
		$tbl_attendance_calendar = Database::get_course_table(TABLE_ATTENDANCE_CALENDAR);
		$attendance_id = intval($attendance_id);
		$course_id = api_get_course_int_id();

		$sql = "SELECT id FROM $tbl_attendance_calendar
		        WHERE
		        	c_id = $course_id AND
		        	attendance_id = '$attendance_id' AND
		        	done_attendance = 0
		        ORDER BY date_time
		        LIMIT 1";
		$rs = Database::query($sql);
		$next_calendar_id = 0;
		if (Database::num_rows($rs) > 0) {
			$row = Database::fetch_array($rs);
			$next_calendar_id = $row['id'];
		}
		return $next_calendar_id;
	}

	/**
	 * Get next attendance calendar datetime without presences (done attendances)
	 * @param	int	attendance id
	 * @return 	int UNIX time format datetime
	 */
	public function get_next_attendance_calendar_datetime($attendance_id)
	{
		$tbl_attendance_calendar = Database::get_course_table(TABLE_ATTENDANCE_CALENDAR);
		$course_id = api_get_course_int_id();
		$attendance_id = intval($attendance_id);
		$sql = "SELECT id, date_time FROM $tbl_attendance_calendar
				WHERE
					c_id = $course_id AND
					attendance_id = '$attendance_id' AND
					done_attendance = 0
				ORDER BY date_time
				LIMIT 1";
		$rs = Database::query($sql);
		$next_calendar_datetime = 0;
		if (Database::num_rows($rs) > 0) {
			$row = Database::fetch_array($rs);
			$next_calendar_datetime = api_get_local_time($row['date_time']);
		}
		return $next_calendar_datetime;
	}

	/**
	 * Get user' score from current attendance
	 * @param	int	$user_id
	 * @param	int $attendance_id
	 * @return	int score
	 */
	public function get_user_score($user_id, $attendance_id)
	{
		$tbl_attendance_result 	= Database::get_course_table(TABLE_ATTENDANCE_RESULT);
		$user_id = intval($user_id);
		$attendance_id = intval($attendance_id);
		$course_id = api_get_course_int_id();
		$sql = "SELECT score FROM $tbl_attendance_result
				WHERE
					c_id = $course_id AND
					user_id='$user_id' AND
					attendance_id='$attendance_id'";
		$rs = Database::query($sql);
		$score = 0;
		if (Database::num_rows($rs) > 0) {
			$row = Database::fetch_array($rs);
			$score = $row['score'];
		}
		return $score;
	}

	/**
	 * Get attendance calendar data by id
	 * @param	int	attendance calendar id
	 * @return	array attendance calendar data
	 */
	public function get_attendance_calendar_by_id($calendar_id)
	{
		$tbl_attendance_calendar = Database::get_course_table(TABLE_ATTENDANCE_CALENDAR);
		$calendar_id = intval($calendar_id);
		$course_id = api_get_course_int_id();
		$sql = "SELECT * FROM $tbl_attendance_calendar
				WHERE c_id = $course_id AND id = '$calendar_id' ";
		$rs = Database::query($sql);
		$data = array();
		if (Database::num_rows($rs) > 0) {
			while ($row = Database::fetch_array($rs)) {
				$row['date_time'] = api_get_local_time($row['date_time']);
				$data = $row;
			}
		}
		return $data;
	}

	/**
	 * Get all attendance calendar data inside current attendance
	 * @param	int	attendance id
	 * @return	array attendance calendar data
	 */
	public function get_attendance_calendar($attendance_id, $type = 'all', $calendar_id = null)
	{
		global $dateFormatShort, $timeNoSecFormat;
		$tbl_attendance_calendar = Database::get_course_table(TABLE_ATTENDANCE_CALENDAR);
		$attendance_id = intval($attendance_id);
		$course_id = api_get_course_int_id();
		$sql = "SELECT * FROM $tbl_attendance_calendar
				WHERE c_id = $course_id AND attendance_id = '$attendance_id' ";
		if (!in_array($type, array('today', 'all', 'all_done', 'all_not_done','calendar_id'))) {
			$type = 'all';
		}
		switch ($type) {
			case 'calendar_id':
				$calendar_id = intval($calendar_id);
				if (!empty($calendar_id)) {
					$sql.= " AND id = $calendar_id";
				}
				break;
			case 'today':
				//$sql .= ' AND DATE_FORMAT(date_time,"%d-%m-%Y") = DATE_FORMAT("'.api_get_utc_datetime().'", "%d-%m-%Y" )';
				break;
			case 'all_done':
				$sql .= " AND done_attendance = 1 ";
				break;
			case 'all_not_done':
				$sql .= " AND done_attendance = 0 ";
				break;
			case 'all':
			default:
				break;
		}
		$sql .= " ORDER BY date_time ";

		$rs = Database::query($sql);
		$data = array();
		if (Database::num_rows($rs) > 0) {
			while ($row = Database::fetch_array($rs,'ASSOC')) {
				$row['db_date_time']    = $row['date_time'];
				$row['date_time']       = api_get_local_time($row['date_time']);
				$row['date']            = api_format_date($row['date_time'], DATE_FORMAT_SHORT);
				$row['time']            = api_format_date($row['date_time'], TIME_NO_SEC_FORMAT);
				if ($type == 'today') {
					if (date('d-m-Y', api_strtotime($row['date_time'], 'UTC')) == date('d-m-Y', time())) {
						$data[] = $row;
					}
				} else {
					$data[] = $row;
				}
			}
		}
		return $data;
	}

	/**
	 * Get number of attendance calendar inside current attendance
	 * @param	int	$attendance_id
	 * @return	int     number of dates in attendance calendar
	 */
	public static function get_number_of_attendance_calendar($attendance_id)
	{
		$tbl_attendance_calendar = Database::get_course_table(TABLE_ATTENDANCE_CALENDAR);
		$attendance_id = intval($attendance_id);
		$course_id = api_get_course_int_id();
		$sql = "SELECT count(id) FROM $tbl_attendance_calendar
                WHERE c_id = $course_id AND attendance_id = '$attendance_id'";
		$rs = Database::query($sql);
		$row = Database::fetch_row($rs);
		$count = $row[0];

		return $count;
	}

	/**
	 * Get count dates inside attendance calendar by attendance id
	 * @param	int	$attendance_id
	 * @return	int     count of dates
	 */
	public static function get_count_dates_inside_attendance_calendar($attendance_id)
	{
		$tbl_attendance_calendar = Database::get_course_table(TABLE_ATTENDANCE_CALENDAR);
		$attendance_id = intval($attendance_id);
		$course_id = api_get_course_int_id();
		$sql = "SELECT count(id) FROM $tbl_attendance_calendar
                WHERE
                	c_id = $course_id AND
                	attendance_id = '$attendance_id'";
		$rs = Database::query($sql);
		$count = 0;
		if (Database::num_rows($rs) > 0) {
			$row = Database::fetch_row($rs);
			$count = $row[0];
		}
		return $count;
	}

	/**
	 * check if all calendar of an attendance is done
	 * @param   int     $attendance_id
	 * @return  bool    True if all calendar is done, otherwise false
	 */
	public static function is_all_attendance_calendar_done($attendance_id)
	{
		$attendance_id = intval($attendance_id);
		$done_calendar = self::get_done_attendance_calendar($attendance_id);
		$count_dates_in_calendar = self::get_count_dates_inside_attendance_calendar($attendance_id);
		$number_of_dates = self::get_number_of_attendance_calendar($attendance_id);

		$result = false;
		if ($number_of_dates && (intval($count_dates_in_calendar) == intval($done_calendar))) {
			$result = true;
		}
		return $result;
	}

	/**
	 * check if an attendance is locked
	 * @param   int $attendance_id
	 * @param   bool
	 */
	public static function is_locked_attendance($attendance_id)
	{
		//use gradebook lock
		$result = api_resource_is_locked_by_gradebook($attendance_id, LINK_ATTENDANCE);
		return $result;
	}

	/**
	 * Add new datetime inside attendance calendar table
	 * @param	int	attendance id
	 * @return	int affected rows
	 */
	public function attendance_calendar_add($attendance_id)
	{
		$tbl_attendance_calendar = Database::get_course_table(TABLE_ATTENDANCE_CALENDAR);
		$affected_rows = 0;
		$attendance_id = intval($attendance_id);
		$course_id = api_get_course_int_id();
		// check if datetime already exists inside the table
		$sql = "SELECT id FROM $tbl_attendance_calendar
		        WHERE
		        	c_id = $course_id AND
		        	date_time='".Database::escape_string($this->date_time)."' AND
		        	attendance_id = '$attendance_id'";
		$rs = Database::query($sql);
		if (Database::num_rows($rs) == 0) {
			$sql = "INSERT INTO $tbl_attendance_calendar SET
					c_id			= $course_id,
					date_time		= '".Database::escape_string($this->date_time)."',
					attendance_id 	= '$attendance_id'";
			Database::query($sql);
			$affected_rows = Database::affected_rows();
		}

		// update locked attendance
		$is_all_calendar_done = self::is_all_attendance_calendar_done($attendance_id);
		if (!$is_all_calendar_done) {
			self::lock_attendance($attendance_id, false);
		} else {
			self::lock_attendance($attendance_id);
		}
		return $affected_rows;
	}

	/**
	 * save repeated date inside attendance calendar table
	 * @param   int $attendance_id
	 * @param   int $start_date start date in tms
	 * @param   int $end_date end date in tms
	 * @param   string $repeat_type daily, weekly, monthlyByDate
	 */
	public function attendance_repeat_calendar_add($attendance_id, $start_date, $end_date, $repeat_type)
	{
		$attendance_id = intval($attendance_id);
		// save start date
		$datetimezone = api_get_utc_datetime($start_date);
		$this->set_date_time($datetimezone);
		$res = $this->attendance_calendar_add($attendance_id);

		//86400 = 24 hours in seconds
		//604800 = 1 week in seconds
		// Saves repeated dates
		switch($repeat_type) {
			case 'daily':
				$j = 1;
				for ($i = $start_date + 86400; ($i <= $end_date); $i += 86400) {
					$datetimezone = api_get_utc_datetime($i);
					$this->set_date_time($datetimezone);
					$this->attendance_calendar_add($attendance_id);
					$j++;
				}
				break;
			case 'weekly':
				$j = 1;
				for ($i = $start_date + 604800; ($i <= $end_date); $i += 604800) {
					$datetimezone = api_get_utc_datetime($i);
					$this->set_date_time($datetimezone);
					$this->attendance_calendar_add($attendance_id);
					$j++;
				}
				break;
			case 'monthlyByDate':
				$j = 1;
				//@todo fix bug with february
				for ($i = $start_date + 2419200; ($i <= $end_date); $i += 2419200) {
					$datetimezone = api_get_utc_datetime($i);
					$this->set_date_time($datetimezone);
					$this->attendance_calendar_add($attendance_id);
					$j++;
				}
				break;
		}
	}

	/**
	 * Adds x months to a UNIX timestamp
	 * @param   int     The timestamp
	 * @param   int     The number of years to add
	 * @return  int     The new timestamp
	 */
	private function add_month($timestamp, $num=1)
	{
		$values = api_get_utc_datetime($timestamp);
		$values = str_replace(array(':','-',' '), '/', $values);
		list($y, $m, $d, $h, $n, $s) = split('/',$values);
		if($m+$num>12) {
			$y += floor($num/12);
			$m += $num%12;
		} else {
			$m += $num;
		}
		//date_default_timezone_set('UTC');
		// return mktime($h, $n, $s, $m, $d, $y);
		$result = api_strtotime($y.'-'.$m.'-'.$d.' '.$h.':'.$n.':'.$s, 'UTC');
		if (!empty($result)) {
			return $result;
		}
		return false;
	}

	/**
	 * edit a datetime inside attendance calendar table
	 * @param	int	attendance calendar id
	 * @param	int	attendance id
	 * @return	int affected rows
	 */
	public function attendance_calendar_edit($calendar_id, $attendance_id)
	{
		$tbl_attendance_calendar = Database::get_course_table(TABLE_ATTENDANCE_CALENDAR);
		$affected_rows = 0;
		$attendance_id = intval($attendance_id);
		$course_id = api_get_course_int_id();
		// check if datetime already exists inside the table
		$sql = "SELECT id FROM $tbl_attendance_calendar
		        WHERE
		        	c_id = $course_id AND
		        	date_time = '".Database::escape_string($this->date_time)."' AND
		        	attendance_id = '$attendance_id'";
		$rs = Database::query($sql);
		if (Database::num_rows($rs) == 0) {
			$sql = "UPDATE $tbl_attendance_calendar
					SET date_time='".Database::escape_string($this->date_time)."'
					WHERE c_id = $course_id AND id = '".intval($calendar_id)."'";
			Database::query($sql);
			$affected_rows = Database::affected_rows();
		}

		// update locked attendance
		$is_all_calendar_done = self::is_all_attendance_calendar_done($attendance_id);
		if (!$is_all_calendar_done) {
			self::lock_attendance($attendance_id, false);
		} else {
			self::lock_attendance($attendance_id);
		}
		return $affected_rows;
	}

	/**
	 * delete a datetime from attendance calendar table
	 * @param	int		attendance calendar id
	 * @param	int		attendance id
	 * @param	bool	true for removing all calendar inside current attendance, false for removing by calendar id
	 * @return	int affected rows
	 */
	public function attendance_calendar_delete($calendar_id, $attendance_id , $all_delete = false)
	{
		$tbl_attendance_calendar = Database::get_course_table(TABLE_ATTENDANCE_CALENDAR);
		$tbl_attendance_sheet 	 = Database::get_course_table(TABLE_ATTENDANCE_SHEET);

		$attendance_id = intval($attendance_id);
		// get all registered users inside current course
		$users = $this->get_users_rel_course();
		$user_ids = array_keys($users);
		$course_id = api_get_course_int_id();

		if ($all_delete) {
			$attendance_calendar = $this->get_attendance_calendar($attendance_id);
			// get all dates from calendar by current attendance
			if (!empty($attendance_calendar)) {
				foreach ($attendance_calendar as $cal) {
					// delete all data from attendance sheet
					$sql = "DELETE FROM $tbl_attendance_sheet
							WHERE c_id = $course_id AND attendance_calendar_id = '".intval($cal['id'])."'";
					Database::query($sql);
					// delete data from attendance calendar
					$sql = "DELETE FROM $tbl_attendance_calendar
							WHERE c_id = $course_id AND id = '".intval($cal['id'])."'";
					Database::query($sql);
				}
			}
		} else {
			// delete just one row from attendance sheet by the calendar id
			$sql = "DELETE FROM $tbl_attendance_sheet
					WHERE c_id = $course_id AND attendance_calendar_id = '".intval($calendar_id)."'";
			Database::query($sql);
			// delete data from attendance calendar
			$sql = "DELETE FROM $tbl_attendance_calendar
					WHERE c_id = $course_id AND id = '".intval($calendar_id)."'";
			Database::query($sql);
		}

		$affected_rows = Database::affected_rows();
		// update users' results
		$this->update_users_results($user_ids, $attendance_id);

		return $affected_rows;
	}

	/**
	 * buid a string datetime from array
	 * @param	array	array containing data e.g:
	 * $array('Y'=>'2010',  'F' => '02', 'd' => '10', 'H' => '12', 'i' => '30')
	 * @return	string	date and time e.g: '2010-02-10 12:30:00'
	 */
	public function build_datetime_from_array($array)
	{
		return return_datetime_from_array($array);
	}

	/** Setters for fields of attendances tables **/
	public function set_session_id($session_id)
	{
		$this->session_id = $session_id;
	}

	public function set_course_id($course_id)
	{
		$this->course_id = $course_id;
	}

	public function set_date_time($datetime)
	{
		$this->date_time = $datetime;
	}

	public function set_name($name)
	{
		$this->name = $name;
	}

	public function set_description($description)
	{
		$this->description = $description;
	}

	public function set_attendance_qualify_title($attendance_qualify_title)
	{
		$this->attendance_qualify_title = $attendance_qualify_title;
	}

	public function set_attendance_weight($attendance_weight)
	{
		$this->attendance_weight = $attendance_weight;
	}

	/** Getters for fields of attendances tables **/
	public function get_session_id()
	{
		return $this->session_id;
	}

	public function get_course_id()
	{
		return $this->course_id;
	}

	public function get_date_time()
	{
		return $this->date_time;
	}

	public function get_name()
	{
		return $this->name;
	}

	public function get_description()
	{
		return $this->description;
	}

	public function get_attendance_qualify_title()
	{
		return $this->attendance_qualify_title;
	}

	public function get_attendance_weight()
	{
		return $this->attendance_weight;
	}

	/**
	 * @param string $startDate in UTC time
	 * @param string $endDate in UTC time
	 *
	 * @return array
	 */
	public function getAttendanceLogin($startDate, $endDate)
	{
		if (empty($startDate) || $startDate == '0000-00-00' ||
			empty($endDate) || $endDate == '0000-00-00'
		) {
			return false;
		}

		$sessionId = api_get_session_id();
		$courseCode  = api_get_course_id();
		if (!empty($sessionId)) {
			$users = CourseManager:: get_user_list_from_course_code(
				$courseCode,
				$sessionId,
				'',
				'lastname',
				0
			);
		} else {
			$users = CourseManager:: get_user_list_from_course_code(
				$courseCode,
				0,
				'',
				'lastname',
				STUDENT
			);
		}

		$dateTimeStartOriginal = new DateTime($startDate);
		$dateTimeStart = new DateTime($startDate);
		$dateTimeEnd= new DateTime($endDate);
		$interval = $dateTimeStart->diff($dateTimeEnd);
		$days = intval($interval->format('%a'));

		$dateList = array($dateTimeStart->format('Y-m-d'));
		$headers = array(
			get_lang('User'),
			$dateTimeStart->format('Y-m-d')
		);

		for ($i = 0; $i < $days; $i++) {
			$dateTimeStart = $dateTimeStart->add(new DateInterval('P1D'));
			$date = $dateTimeStart->format('Y-m-d');
			$dateList[] = $date;
			$headers[] = $date;
		}

		$accessData = CourseManager::getCourseAccessPerCourseAndSession(
			$courseCode,
			$sessionId,
			$dateTimeStartOriginal->format('Y-m-d H:i:s'),
			$dateTimeEnd->format('Y-m-d H:i:s')
		);

		$results = array();
		if (!empty($accessData)) {
			foreach ($accessData as $data) {
				$onlyDate = substr($data['login_course_date'], 0, 10);
				$results[$data['user_id']][$onlyDate] = true;
			}
		}

		return array(
			'users' => $users,
			'dateList' => $dateList,
			'headers' => $headers,
			'results' => $results
		);
	}

	/**
	 * @param string $startDate in UTC time
	 * @param string $endDate in UTC time
	 *
	 * @return string
	 */
	public function getAttendanceLoginTable($startDate, $endDate)
	{
		$data = $this->getAttendanceLogin($startDate, $endDate);

		if (!$data) {
			return null;
		}

		$headers = $data['headers'];
		$dateList = $data['dateList'];
		$users = $data['users'];
		$results = $data['results'];

		$table = new HTML_Table(array('class' => 'data_table'));
		$row = 0;
		$column = 0;
		foreach ($headers as $header) {
			$table->setHeaderContents($row, $column, $header);
			$column++;
		}
		$row = 1;
		foreach ($users as $user) {
			$table->setCellContents(
				$row,
				0,
				$user['lastname'].' '.$user['firstname'].' ('.$user['username'].')'
			);
			$row ++;
		}

		$column = 1;
		$row = 1;
		foreach ($users as $user) {
			foreach ($dateList as $date) {
				$status = null;
				if (isset($results[$user['user_id']]) &&
					isset($results[$user['user_id']][$date])
				) {
					$status = 'X';
				}
				$table->setCellContents($row, $column, $status);
				$column++;
			}
			$row++;
			$column = 1;
		}

		return $table->toHtml();
	}

	/**
	 * @param string $startDate in UTC time
	 * @param string $endDate in UTC time
	 *
	 * @return string
	 */
	public function exportAttendanceLogin($startDate, $endDate)
	{
		$data = $this->getAttendanceLogin($startDate, $endDate);

		if (!$data) {
			return null;
		}
		$users = $data['users'];
		$results = $data['results'];

		$table = new HTML_Table(array('class' => 'data_table'));

		$table->setHeaderContents(0, 0, get_lang('User'));
		$table->setHeaderContents(0, 1, get_lang('Date'));

		$row = 1;
		foreach ($users as $user) {
			$table->setCellContents(
				$row,
				0,
				$user['lastname'].' '.$user['firstname'].' ('.$user['username'].')'
			);
			$row++;
		}
		$table->setColAttributes(0, array('style' => 'width:28%'));

		$row = 1;
		foreach ($users as $user) {
			if (isset($results[$user['user_id']]) &&
				!empty($results[$user['user_id']])
			) {
				$dates = implode(', ', array_keys($results[$user['user_id']]));
				$table->setCellContents($row, 1, $dates);
			}
			$row++;
		}

		//$tableToString = null;

		//$sessionInfo = api_get_session_info(api_get_session_id());
		//if (!empty($sessionInfo)) {
		/*$tableToString .= '<strong>'.get_lang('PeriodToDisplay').'</strong>: '.
			sprintf(get_lang('FromDateXToDateY'), $startDate, $endDate);*/
		//}

		$tableToString = $table->toHtml();

		$params = array(
			'filename' => get_lang('Attendance') . '_' . api_get_utc_datetime(),
			'pdf_title' => get_lang('Attendance'),
			'course_code' => api_get_course_id(),
			'show_real_course_teachers' => true
		);
		$pdf = new PDF('A4', null, $params);
		$pdf->html_to_pdf_with_template($tableToString);
	}
}