<?php
/* For licensing terms, see /license.txt */
/**
 * Defines a gradebook Category object
 * @package chamilo.gradebook
 */
/**
 * Init
 */
/**
 * Class
 * @package chamilo.gradebook
 */


class Category implements GradebookItem
{
    private $id;
    private $name;
    private $description;
    private $user_id;
    private $course_code;
    private $parent;
    private $weight;
    private $visible;
    private $certificate_min_score;
    private $session_id;
    private $skills = array();
    private $grade_model_id;

    public function __construct()
    {
    }

    // GETTERS AND SETTERS

    public function get_id()
    {
        return $this->id;
    }

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

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

    public function get_user_id()
    {
        return $this->user_id;
    }

    public function get_certificate_min_score()
    {
        if (!empty($this->certificate_min_score)) {
            return $this->certificate_min_score;
        } else {
            return null;
        }
    }

    public function get_course_code()
    {
        return $this->course_code;
    }

    public function get_parent_id()
    {
        return $this->parent;
    }

    public function get_weight()
    {
        return $this->weight;
    }

    public function is_locked()
    {
        return isset($this->locked) && $this->locked == 1 ? true : false;
    }

    public function is_visible()
    {
        return $this->visible;
    }

    public function set_id($id)
    {
        $this->id = $id;
    }

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

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

    public function set_user_id($user_id)
    {
        $this->user_id = $user_id;
    }

    public function set_course_code($course_code)
    {
        $this->course_code = $course_code;
        $courseInfo        = api_get_course_info($course_code);
        $this->course_id   = $courseInfo['real_id'];
    }

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

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


    public function set_certificate_min_score($min_score = null)
    {
        $this->certificate_min_score = $min_score;
    }

    public function set_parent_id($parent)
    {
        $this->parent = intval($parent);
    }

    /**
     * Filters to int and sets the session ID
     * @param   int     The session ID from the Dokeos course session
     */
    public function set_session_id($session_id = 0)
    {
        $this->session_id = (int)$session_id;
    }

    public function set_weight($weight)
    {
        $this->weight = $weight;
    }

    public function set_visible($visible)
    {
        $this->visible = $visible;
    }

    public function set_grade_model_id($id)
    {
        $this->grade_model_id = $id;
    }

    public function set_locked($locked)
    {
        $this->locked = $locked;
    }

    public function get_grade_model_id()
    {
        return $this->grade_model_id;
    }

    public function get_type()
    {
        return 'category';
    }

    public function get_skills($from_db = true)
    {
        if ($from_db) {
            $cat_id = $this->get_id();

            $gradebook = new Gradebook();
            $skills    = $gradebook->get_skills_by_gradebook($cat_id);
        } else {
            $skills = $this->skills;
        }

        return $skills;
    }

    public function get_skills_for_select()
    {
        $skills       = $this->get_skills();
        $skill_select = array();
        if (!empty($skills)) {
            foreach ($skills as $skill) {
                $skill_select[$skill['id']] = $skill['name'];
            }
        }

        return $skill_select;
    }

    // CRUD FUNCTIONS

    /**
     * Retrieve categories and return them as an array of Category objects
     * @param int      category id
     * @param int      user id (category owner)
     * @param string   course code
     * @param int      parent category
     * @param bool     visible
     * @param int      session id (in case we are in a session)
     * @param bool     Whether to show all "session" categories (true) or hide them (false) in case there is no session id
     */


    public static function load(
        $id = null,
        $user_id = null,
        $course_code = null,
        $parent_id = null,
        $visible = null,
        $session_id = null,
        $order_by = null
    ) {
        //if the category given is explicitly 0 (not null), then create
        // a root category object (in memory)
        if (isset($id) && (int)$id === 0) {
            $cats   = array();
            $cats[] = Category::create_root_category();

            return $cats;
        }

        $tbl_grade_categories = Database :: get_main_table(TABLE_MAIN_GRADEBOOK_CATEGORY);
        $sql                  = 'SELECT * FROM '.$tbl_grade_categories;
        $paramcount           = 0;
        if (isset($id)) {
            $id = Database::escape_string($id);
            $sql .= ' WHERE id = '.intval($id);
            $paramcount++;
        }
        if (isset($user_id)) {
            $user_id = intval($user_id);
            if ($paramcount != 0) {
                $sql .= ' AND';
            } else {
                $sql .= ' WHERE';
            }
            $sql .= ' user_id = '.intval($user_id);
            $paramcount++;
        }

        if (isset($course_code)) {
            $course_code = Database::escape_string($course_code);
            if ($paramcount != 0) {
                $sql .= ' AND';
            } else {
                $sql .= ' WHERE';
            }

            if ($course_code == '0') {
                $sql .= ' course_code is null ';
            } else {
                $sql .= " course_code = '".Database::escape_string($course_code)."'";
            }

            /*if ($show_session_categories !== true) {
                // a query on the course should show all
                // the categories inside sessions for this course
                // otherwise a special parameter is given to ask explicitely
                $sql .= " AND (session_id IS NULL OR session_id = 0) ";
            } else {*/

            if (empty($session_id)) {
                $sql .= ' AND (session_id IS NULL OR session_id = 0) ';
            } else {
                $sql .= ' AND session_id = '.(int)$session_id.' ';
            }
            //}
            $paramcount++;
        }

        if (isset($parent_id)) {
            $parent_id = Database::escape_string($parent_id);
            if ($paramcount != 0) {
                $sql .= ' AND ';
            } else {
                $sql .= ' WHERE ';
            }
            $sql .= ' parent_id = '.intval($parent_id);
            $paramcount++;
        }
        if (isset($visible)) {
            $visible = Database::escape_string($visible);
            if ($paramcount != 0) {
                $sql .= ' AND';
            } else {
                $sql .= ' WHERE';
            }
            $sql .= ' visible = '.intval($visible);
            $paramcount++;
        }

        if (!empty($order_by)) {
            if (!empty($order_by) && $order_by != '') {
                $sql .= ' '.$order_by;
            }
        }
        $result = Database::query($sql);
        $allcat = array();
        if (Database::num_rows($result) > 0) {
            $allcat = Category::create_category_objects_from_sql_result($result);
        }

        return $allcat;
    }

    private function create_root_category()
    {
        $cat = new Category();
        $cat->set_id(0);
        $cat->set_name(get_lang('RootCat'));
        $cat->set_description(null);
        $cat->set_user_id(0);
        $cat->set_course_code(null);
        $cat->set_parent_id(null);
        $cat->set_weight(0);
        $cat->set_visible(1);

        return $cat;
    }

    private static function create_category_objects_from_sql_result($result)
    {
        $allcat = array();
        while ($data = Database::fetch_array($result)) {
            $cat = new Category();
            $cat->set_id($data['id']);
            $cat->set_name($data['name']);
            $cat->set_description($data['description']);
            $cat->set_user_id($data['user_id']);
            $cat->set_course_code($data['course_code']);
            $cat->set_parent_id($data['parent_id']);
            $cat->set_weight($data['weight']);
            $cat->set_visible($data['visible']);
            $cat->set_session_id($data['session_id']);
            $cat->set_certificate_min_score($data['certif_min_score']);
            $cat->set_grade_model_id($data['grade_model_id']);
            $cat->set_locked($data['locked']);
            $allcat[] = $cat;
        }

        return $allcat;
    }

    /**
     * Insert this category into the database
     */
    public function add()
    {
        if (isset($this->name) && '-1' == $this->name) {
            return false;
        }

        if (isset($this->name) && isset($this->user_id)) {
            $tbl_grade_categories = Database :: get_main_table(TABLE_MAIN_GRADEBOOK_CATEGORY);
            $sql                  = 'INSERT INTO '.$tbl_grade_categories.' (name,user_id,weight,visible';
            if (isset($this->description)) {
                $sql .= ',description';
            }
            if (isset($this->course_code)) {
                $sql .= ',course_code';
            }
            if (isset($this->parent)) {
                $sql .= ',parent_id';
            }
            if (!empty($this->session_id)) {
                $sql .= ', session_id';
            }

            if (isset($this->grade_model_id)) {
                $sql .= ', grade_model_id ';
            }
            if (isset($this->certificate_min_score) && !empty($this->certificate_min_score)) {
                $sql .= ', certif_min_score ';
            }


            /*
            $setting = api_get_setting('tool_visible_by_default_at_creation');
            $visible = 1;
            if (isset($setting['gradebook'])) {
                if ($setting['gradebook'] == 'false') {
                    $visible = 0;
                }
            }*/

            $visible = intval($this->is_visible());

            $sql .= ") VALUES ('".Database::escape_string($this->get_name())."'"
                .','.intval($this->get_user_id())
                .','.Database::escape_string($this->get_weight())
                .','.$visible;
            if (isset($this->description)) {
                $sql .= ",'".Database::escape_string($this->get_description())."'";
            }
            if (isset($this->course_code)) {
                $sql .= ",'".Database::escape_string($this->get_course_code())."'";
            }
            if (isset($this->parent)) {
                $sql .= ','.intval($this->get_parent_id());
            }
            if (!empty($this->session_id)) {
                $sql .= ', '.intval($this->get_session_id());
            }
            if (isset($this->grade_model_id)) {
                $sql .= ', '.intval($this->get_grade_model_id());
            }
            if (isset($this->certificate_min_score) && !empty($this->certificate_min_score)) {
                $sql .= ', '.Database::escape_string($this->get_certificate_min_score());
            }
            $sql .= ')';
            Database::query($sql);
            $id = Database::insert_id();
            $this->set_id($id);

            if (!empty($id)) {

                $parent_id      = $this->get_parent_id();
                $grade_model_id = $this->get_grade_model_id();
                if ($parent_id == 0) {
                    //do something
                    if (isset($grade_model_id) && !empty($grade_model_id) && $grade_model_id != '-1') {
                        $obj                    = new GradeModel();
                        $components             = $obj->get_components($grade_model_id);
                        $default_weight_setting = api_get_setting('gradebook_default_weight');
                        $default_weight         = 100;
                        if (isset($default_weight_setting)) {
                            $default_weight = $default_weight_setting;
                        }
                        foreach ($components as $component) {
                            $gradebook = new Gradebook();
                            $params    = array();

                            $params['name']        = $component['acronym'];
                            $params['description'] = $component['title'];
                            $params['user_id']     = api_get_user_id();
                            $params['parent_id']   = $id;
                            $params['weight']      = $component['percentage'] / 100 * $default_weight;
                            $params['session_id']  = api_get_session_id();
                            $params['course_code'] = $this->get_course_code();

                            $gradebook->save($params);
                        }
                    }
                }
            }

            $gradebook = new Gradebook();
            $gradebook->update_skills_to_gradebook($this->id, $this->get_skills(false));

            return $id;
        }
    }

    /**
     * Update the properties of this category in the database
     * @todo fix me
     */
    public function save()
    {
        $tbl_grade_categories = Database :: get_main_table(TABLE_MAIN_GRADEBOOK_CATEGORY);

        $sql = 'UPDATE '.$tbl_grade_categories." SET name = '".Database::escape_string(
                $this->get_name()
            )."'".', description = ';
        if (isset($this->description)) {
            $sql .= "'".Database::escape_string($this->get_description())."'";
        } else {
            $sql .= 'null';
        }
        $sql .= ', user_id = '.intval($this->get_user_id())
            .', course_code = ';
        if (isset($this->course_code)) {
            $sql .= "'".Database::escape_string($this->get_course_code())."'";
        } else {
            $sql .= 'null';
        }
        $sql .= ', parent_id = ';
        if (isset($this->parent)) {
            $sql .= intval($this->get_parent_id());
        } else {
            $sql .= 'null';
        }
        $sql .= ', certif_min_score = ';
        if (isset($this->certificate_min_score) && !empty($this->certificate_min_score)) {
            $sql .= Database::escape_string($this->get_certificate_min_score());
        } else {
            $sql .= 'null';
        }
        if (isset($this->grade_model_id)) {
            $sql .= ', grade_model_id = '.intval($this->get_grade_model_id());
        }
        $sql .= ', weight = '.Database::escape_string($this->get_weight())
            .', visible = '.intval($this->is_visible())
            .' WHERE id = '.intval($this->id);

        Database::query($sql);

        if (!empty($this->id)) {
            $parent_id      = $this->get_parent_id();
            $grade_model_id = $this->get_grade_model_id();
            if ($parent_id == 0) {

                if (isset($grade_model_id) && !empty($grade_model_id) && $grade_model_id != '-1') {
                    $obj                    = new GradeModel();
                    $components             = $obj->get_components($grade_model_id);
                    $default_weight_setting = api_get_setting('gradebook_default_weight');
                    $default_weight         = 100;
                    if (isset($default_weight_setting)) {
                        $default_weight = $default_weight_setting;
                    }
                    $final_weight = $this->get_weight();
                    if (!empty($final_weight)) {
                        $default_weight = $this->get_weight();
                    }
                    foreach ($components as $component) {
                        $gradebook = new Gradebook();
                        $params    = array();

                        $params['name']        = $component['acronym'];
                        $params['description'] = $component['title'];
                        $params['user_id']     = api_get_user_id();
                        $params['parent_id']   = $this->id;
                        $params['weight']      = $component['percentage'] / 100 * $default_weight;
                        $params['session_id']  = api_get_session_id();
                        $params['course_code'] = $this->get_course_code();

                        $gradebook->save($params);
                    }
                }
            }
        }


        $gradebook = new Gradebook();
        $gradebook->update_skills_to_gradebook($this->id, $this->get_skills(false));

    }

    /**
     * Update link weights see #5168
     * @param type $new_weight
     */
    function update_children_weight($new_weight)
    {

        //$evals = $this->get_evaluations();
        $links      = $this->get_links();
        $old_weight = $this->get_weight();

        if (!empty($links)) {
            foreach ($links as $link_item) {
                if (isset($link_item)) {
                    $new_item_weight = $new_weight * $link_item->get_weight() / $old_weight;
                    $link_item->set_weight($new_item_weight);
                    $link_item->save();
                }
            }
        }
    }


    /**
     * Delete this evaluation from the database
     */
    public function delete()
    {
        $tbl_grade_categories = Database :: get_main_table(TABLE_MAIN_GRADEBOOK_CATEGORY);
        $sql                  = 'DELETE FROM '.$tbl_grade_categories.' WHERE id = '.intval($this->id);
        Database::query($sql);
    }

    /**
     * Not delete this category from the database,when visible=3 is category eliminated
     */
    public function update_category_delete($course_id)
    {
        $tbl_grade_categories = Database :: get_main_table(TABLE_MAIN_GRADEBOOK_CATEGORY);
        $sql                  = 'UPDATE '.$tbl_grade_categories.' SET visible=3 WHERE course_code ="'.Database::escape_string(
                $course_id
            ).'"';
        Database::query($sql);
    }

    /**
     * Show message resource delete
     */
    public function show_message_resource_delete($course_id)
    {
        $tbl_grade_categories = Database :: get_main_table(TABLE_MAIN_GRADEBOOK_CATEGORY);
        $sql                  = 'SELECT count(*) AS num from '.$tbl_grade_categories.' WHERE course_code ="'.Database::escape_string(
                $course_id
            ).'" AND visible=3';
        $res                  = Database::query($sql);
        $option               = Database::fetch_array($res, 'ASSOC');
        if ($option['num'] >= 1) {
            return '&nbsp;&nbsp;<span class="resource-deleted">(&nbsp;'.get_lang('ResourceDeleted').'&nbsp;)</span>';
        } else {
            return false;
        }
    }

    /**
     * Shows all information of an category
     */
    public function shows_all_information_an_category($selectcat = '')
    {
        if ($selectcat == '') {
            return null;
        } else {
            $tbl_category = Database :: get_main_table(TABLE_MAIN_GRADEBOOK_CATEGORY);
            $sql          = 'SELECT name,description,user_id,course_code,parent_id,weight,visible,certif_min_score,session_id
                    FROM '.$tbl_category.' c
                    WHERE c.id = '.intval($selectcat);
            $result       = Database::query($sql);
            $row          = Database::fetch_array($result, 'ASSOC');

            return $row;
        }
    }

// OTHER FUNCTIONS

    /**
     * Check if a category name (with the same parent category) already exists
     * @param $name name to check (if not given, the name property of this object will be checked)
     * @param $parent parent category
     */
    public function does_name_exist($name, $parent)
    {
        if (!isset ($name)) {
            $name   = $this->name;
            $parent = $this->parent;
        }
        $tbl_grade_categories = Database :: get_main_table(TABLE_MAIN_GRADEBOOK_CATEGORY);
        $sql                  = 'SELECT count(id) AS number'
            .' FROM '.$tbl_grade_categories
            ." WHERE name = '".Database::escape_string($name)."'";

        if (api_is_allowed_to_edit()) {
            $parent   = Category::load($parent);
            $courseId = $parent[0]->get_course_id();
            if (isset($courseId) && !empty($courseId)) {
                $main_course_user_table = Database :: get_main_table(TABLE_MAIN_COURSE_USER);
                $sql .= ' AND user_id IN ('
                    .' SELECT user_id FROM '.$main_course_user_table
                    ." WHERE c_id = '".Database::escape_string($courseId)."'"
                    .' AND status = '.COURSEMANAGER
                    .')';
            } else {
                $sql .= ' AND user_id = '.api_get_user_id();
            }

        } else {
            $sql .= ' AND user_id = '.api_get_user_id();
        }
        if (!isset ($parent)) {
            $sql .= ' AND parent_id is null';
        } else {
            $sql .= ' AND parent_id = '.intval($parent);
        }

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

        return ($number[0] != 0);
    }

    /**
     * Checks if the certificate is available for the given user in this category
     * @param    integer    User ID
     * @return    boolean    True if conditions match, false if fails
     */
    public function is_certificate_available($user_id)
    {
        $score = $this->calc_score($user_id, $this->course_code);
        if (isset($score)) {
            $certification_score = ($score[0] / $score[1]) * 100; //get a percentage score to compare to minimum certificate score
            if ($certification_score >= $this->certificate_min_score) {
                return true;
            }
        }

        return false;
    }

    /**
     * Is this category a course ?
     * A category is a course if it has a course code and no parent category.
     */
    public function is_course()
    {
        return (isset($this->course_code) && !empty($this->course_code)
            && (!isset($this->parent) || $this->parent == 0));
    }

    /**
     * Calculate the score of this category
     * @param $stud_id student id (default: all students - then the average is returned)
     * @return    array (score sum, weight sum)
     *            or null if no scores available
     */
    public function calc_score($stud_id = null, $course_code = '', $session_id = null)
    {
        // get appropriate subcategories, evaluations and links
        if (!empty($course_code)) {
            $cats  = $this->get_subcategories($stud_id, $course_code, $session_id);
            $evals = $this->get_evaluations($stud_id, false, $course_code);
            $links = $this->get_links($stud_id, false, $course_code);
        } else {
            $cats  = $this->get_subcategories($stud_id);
            $evals = $this->get_evaluations($stud_id);
            $links = $this->get_links($stud_id);
        }

        // calculate score
        $rescount  = 0;
        $ressum    = 0;
        $weightsum = 0;

        if (!empty($cats)) {
            foreach ($cats as $cat) {
                $catres = $cat->calc_score($stud_id, $course_code, $session_id); // recursive call
                if ($cat->get_weight() != 0) {
                    $catweight = $cat->get_weight();
                    $rescount++;
                    $weightsum += $catweight;
                }
                if (isset($catres)) {
                    $ressum += (($catres[0] / $catres[1]) * $catweight);
                }
            }
        }

        if (!empty($evals)) {
            foreach ($evals as $eval) {
                $evalres = $eval->calc_score($stud_id);
                if (isset($evalres) && $eval->get_weight() != 0) {
                    $evalweight = $eval->get_weight();
                    $rescount++;
                    $weightsum += $evalweight;
                    $ressum += (($evalres[0] / $evalres[1]) * $evalweight);
                } else {

                }
            }
        }

        if (!empty($links)) {
            foreach ($links as $link) {
                $linkres = $link->calc_score($stud_id);

                if (isset($linkres) && $link->get_weight() != 0) {
                    $linkweight     = $link->get_weight();
                    $link_res_denom = ($linkres[1] == 0) ? 1 : $linkres[1];
                    $rescount++;
                    $weightsum += $linkweight;
                    $ressum += (($linkres[0] / $link_res_denom) * $linkweight);
                } else {
                    //adding if result does not exists
                    if ($link->get_weight() != 0) {
                        $linkweight = $link->get_weight();
                        $weightsum += $linkweight;
                    }
                }
            }
        }

        if ($rescount == 0) {
            return null;
        } else {
            return array($ressum, $weightsum);
        }
    }

    /**
     * Delete this category and every subcategory, evaluation and result inside
     */
    public function delete_all()
    {
        $cats  = Category::load(null, null, $this->course_code, $this->id, null);
        $evals = Evaluation::load(null, null, $this->course_code, $this->id, null);
        $links = LinkFactory::load(null, null, null, null, $this->course_code, $this->id, null);
        if (!empty($cats)) {
            foreach ($cats as $cat) {
                $cat->delete_all();
                $cat->delete();
            }
        }
        if (!empty($evals)) {
            foreach ($evals as $eval) {
                $eval->delete_with_results();
            }
        }
        if (!empty($links)) {
            foreach ($links as $link) {
                $link->delete();
            }
        }
        $this->delete();
    }


    /**
     * Return array of Category objects where a student is subscribed to.
     * @param int       student id
     * @param string    Course code
     * @param int       Session id
     */
    public function get_root_categories_for_student($stud_id, $course_code = null, $session_id = null)
    {
        // courses

        $main_course_user_table = Database :: get_main_table(TABLE_MAIN_COURSE_USER);
        $course_table           = Database :: get_main_table(TABLE_MAIN_COURSE);
        $tbl_grade_categories   = Database :: get_main_table(TABLE_MAIN_GRADEBOOK_CATEGORY);

        $sql = 'SELECT * FROM '.$tbl_grade_categories.' WHERE parent_id = 0';
        if (!api_is_allowed_to_edit()) {
            $sql .= ' AND visible = 1';
            //proceed with checks on optional parameters course & session
            if (!empty($course_code)) {
                // TODO: considering it highly improbable that a user would get here
                // if he doesn't have the rights to view this course and this
                // session, we don't check his registration to these, but this
                // could be an improvement
                if (!empty($session_id)) {
                    $sql .= " AND course_code  = '".Database::escape_string($course_code)."'"
                        ." AND session_id = ".(int)$session_id;
                } else {
                    $sql .= " AND course_code  = '".Database::escape_string(
                            $course_code
                        )."' AND session_id is null OR session_id=0";
                }
            } else {
                //no optional parameter, proceed as usual
                $sql .= ' AND course_code IN
                         (
                            SELECT course.code
                            FROM '.$main_course_user_table.' course_user
                            INNER JOIN '.$course_table.' course ON (course.id AND course_user.c_id)
                            WHERE user_id = '.intval($stud_id).' AND status = '.STUDENT
                    .')';
            }
        } elseif (api_is_allowed_to_edit() && !api_is_platform_admin()) {
            //proceed with checks on optional parameters course & session
            if (!empty($course_code)) {
                // TODO: considering it highly improbable that a user would get here
                // if he doesn't have the rights to view this course and this
                // session, we don't check his registration to these, but this
                // could be an improvement
                $sql .= " AND course_code  = '".Database::escape_string($course_code)."'";
                if (!empty($session_id)) {
                    $sql .= " AND session_id = ".(int)$session_id;
                } else {
                    $sql .= "AND session_id IS NULL OR session_id=0";
                }
            } else {
                $sql .= ' AND course_code in'
                    .' (SELECT course_code FROM '.$main_course_user_table
                    .' WHERE user_id = '.api_get_user_id()
                    .' AND status = '.COURSEMANAGER
                    .')';
            }
        } elseif (api_is_platform_admin()) {
            if (isset($session_id) && $session_id != 0) {
                $sql .= ' AND session_id='.intval($session_id);
            } else {
                $sql .= ' AND coalesce(session_id,0)=0';
            }
        }
        $result = Database::query($sql);
        $cats   = Category::create_category_objects_from_sql_result($result);

        // Course independent categories
        if (empty($course_code)) {
            $cats = Category::get_independent_categories_with_result_for_student(0, $stud_id, $cats);
        }

        return $cats;

    }

    /**
     * Return array of Category objects where a teacher is admin for.
     * @param int user id (to return everything, use 'null' here)
     * @param string course code (optional)
     * @param int session id (optional)
     */
    public function get_root_categories_for_teacher($user_id, $course_code = null, $session_id = null)
    {
        if ($user_id == null) {
            return Category::load(null, null, $course_code, 0, null, $session_id);
        }

        // Courses
        $main_course_user_table = Database :: get_main_table(TABLE_MAIN_COURSE_USER);
        $tbl_grade_categories   = Database :: get_main_table(TABLE_MAIN_GRADEBOOK_CATEGORY);
        $course_table           = Database :: get_main_table(TABLE_MAIN_COURSE);

        $sql = 'SELECT * FROM '.$tbl_grade_categories.' WHERE parent_id = 0';
        if (!empty($course_code)) {
            $sql .= " AND course_code = '".Database::escape_string($course_code)."' ";
            if (!empty($session_id)) {
                $sql .= " AND session_id = ".(int)$session_id;
            }
        } else {
            $sql .= ' AND course_code IN
                         (
                            SELECT course.code
                            FROM '.$main_course_user_table.' course_user
                            INNER JOIN '.$course_table.' course ON (course.id AND course_user.c_id)
                            WHERE user_id = '.intval($stud_id).' AND status = '.STUDENT
                .')';
        }
        $result = Database::query($sql);
        $cats   = Category::create_category_objects_from_sql_result($result);
        // course independent categories
        if (isset($course_code)) {
            $indcats = Category::load(null, $user_id, $course_code, 0, null, $session_id);
            $cats    = array_merge($cats, $indcats);
        }

        return $cats;
    }


    /**
     * Can this category be moved to somewhere else ?
     * The root and courses cannot be moved.
     */
    public function is_movable()
    {
        return (!(!isset ($this->id) || $this->id == 0 || $this->is_course()));
    }

    /**
     * Generate an array of possible categories where this category can be moved to.
     * Notice: its own parent will be included in the list: it's up to the frontend
     * to disable this element.
     * @return array 2-dimensional array - every element contains 3 subelements (id, name, level)
     */
    public function get_target_categories()
    {
        // the root or a course -> not movable
        if (!$this->is_movable()) {
            return null;
        } // otherwise:
        // - course independent category
        //   -> movable to root or other independent categories
        // - category inside a course
        //   -> movable to root, independent categories or categories inside the course
        else {
            $user    = (api_is_platform_admin() ? null : api_get_user_id());
            $targets = array();
            $level   = 0;

            $root      = array(0, get_lang('RootCat'), $level);
            $targets[] = $root;

            if (isset($this->course_code) && !empty($this->course_code)) {
                $crscats = Category::load(null, null, $this->course_code, 0);
                foreach ($crscats as $cat) {
                    if ($this->can_be_moved_to_cat($cat)) {
                        $targets[] = array($cat->get_id(), $cat->get_name(), $level + 1);
                        $targets   = $this->add_target_subcategories($targets, $level + 1, $cat->get_id());
                    }
                }
            }

            $indcats = Category::load(null, $user, 0, 0);
            foreach ($indcats as $cat) {
                if ($this->can_be_moved_to_cat($cat)) {
                    $targets[] = array($cat->get_id(), $cat->get_name(), $level + 1);
                    $targets   = $this->add_target_subcategories($targets, $level + 1, $cat->get_id());
                }
            }

            return $targets;
        }
    }

    /**
     * Internal function used by get_target_categories()
     */
    private function add_target_subcategories($targets, $level, $catid)
    {
        $subcats = Category::load(null, null, null, $catid);
        foreach ($subcats as $cat) {
            if ($this->can_be_moved_to_cat($cat)) {
                $targets[] = array($cat->get_id(), $cat->get_name(), $level + 1);
                $targets   = $this->add_target_subcategories($targets, $level + 1, $cat->get_id());
            }
        }

        return $targets;
    }

    /**
     * Internal function used by get_target_categories() and add_target_subcategories()
     * Can this category be moved to the given category ?
     * Impossible when origin and target are the same... children won't be processed
     * either. (a category can't be moved to one of its own children)
     */
    private function can_be_moved_to_cat($cat)
    {
        return ($cat->get_id() != $this->get_id());
    }

    /**
     * Move this category to the given category.
     * If this category moves from inside a course to outside,
     * its course code must be changed, as well as the course code
     * of all underlying categories and evaluations. All links will
     * be deleted as well !
     */
    public function move_to_cat($cat)
    {
        $this->set_parent_id($cat->get_id());
        if ($this->get_course_code() != $cat->get_course_code()) {
            $this->set_course_code($cat->get_course_code());
            $this->apply_course_code_to_children();
        }
        $this->save();
    }

    /**
     * Internal function used by move_to_cat()
     */
    private function apply_course_code_to_children()
    {
        $cats  = Category::load(null, null, null, $this->id, null);
        $evals = Evaluation::load(null, null, null, $this->id, null);
        $links = LinkFactory::load(null, null, null, null, null, $this->id, null);

        foreach ($cats as $cat) {
            $cat->set_course_code($this->get_course_code());
            $cat->save();
            $cat->apply_course_code_to_children();
        }

        foreach ($evals as $eval) {
            $eval->set_course_code($this->get_course_code());
            $eval->save();
        }

        foreach ($links as $link) {
            $link->delete();
        }

    }


    /**
     * Generate an array of all categories the user can navigate to
     */
    public function get_tree()
    {
        $targets = array();
        $level   = 0;

        $root      = array(0, get_lang('RootCat'), $level);
        $targets[] = $root;

        // course or platform admin
        if (api_is_allowed_to_edit()) {
            $user = (api_is_platform_admin() ? null : api_get_user_id());

            $cats = Category::get_root_categories_for_teacher($user);
            foreach ($cats as $cat) {
                $targets[] = array($cat->get_id(), $cat->get_name(), $level + 1);
                $targets   = Category::add_subtree($targets, $level + 1, $cat->get_id(), null);
            }
        } else { // student
            $cats = Category::get_root_categories_for_student(api_get_user_id());
            foreach ($cats as $cat) {
                $targets[] = array($cat->get_id(), $cat->get_name(), $level + 1);
                $targets   = Category::add_subtree($targets, $level + 1, $cat->get_id(), 1);
            }
        }

        return $targets;
    }

    /**
     * Internal function used by get_tree()
     */
    private function add_subtree($targets, $level, $catid, $visible)
    {
        $subcats = Category::load(null, null, null, $catid, $visible);

        if (!empty($subcats)) {
            foreach ($subcats as $cat) {
                $targets[] = array($cat->get_id(), $cat->get_name(), $level + 1);
                $targets   = Category::add_subtree($targets, $level + 1, $cat->get_id(), $visible);
            }
        }

        return $targets;
    }

    /**
     * Generate an array of courses that a teacher hasn't created a category for.
     * @return array 2-dimensional array - every element contains 2 subelements (code, title)
     */
    public function get_not_created_course_categories($user_id)
    {
        $tbl_main_courses     = Database :: get_main_table(TABLE_MAIN_COURSE);
        $tbl_main_course_user = Database :: get_main_table(TABLE_MAIN_COURSE_USER);
        $tbl_grade_categories = Database :: get_main_table(TABLE_MAIN_GRADEBOOK_CATEGORY);

        $sql = 'SELECT DISTINCT(code), title
                FROM '.$tbl_main_courses.' cc, '.$tbl_main_course_user.' cu
                WHERE cc.c_id = cu.id AND cu.status = '.COURSEMANAGER;
        if (!api_is_platform_admin()) {
            $sql .= ' AND cu.user_id = '.$user_id;
        }
        $sql .= ' AND cc.code NOT IN
                (
                    SELECT course_code FROM '.$tbl_grade_categories.'
                    WHERE parent_id = 0 AND course_code IS NOT null
                )';
        $result = Database::query($sql);

        $cats = array();
        while ($data = Database::fetch_array($result)) {
            $cats[] = array($data['code'], $data['title']);
        }

        return $cats;

    }

    /**
     * Generate an array of all courses that a teacher is admin of.
     * @return array 2-dimensional array - every element contains 2 subelements (code, title)
     */
    public function get_all_courses($user_id)
    {
        $tbl_main_courses     = Database :: get_main_table(TABLE_MAIN_COURSE);
        $tbl_main_course_user = Database :: get_main_table(TABLE_MAIN_COURSE_USER);
        $tbl_grade_categories = Database :: get_main_table(TABLE_MAIN_GRADEBOOK_CATEGORY);

        $sql = 'SELECT DISTINCT(code), title FROM '.$tbl_main_courses.' cc, '.$tbl_main_course_user.' cu'
            .' WHERE cc.id = cu.c_id'
            .' AND cu.status = '.COURSEMANAGER;
        if (!api_is_platform_admin()) {
            $sql .= ' AND cu.user_id = '.intval($user_id);
        }

        $result = Database::query($sql);
        $cats   = array();
        while ($data = Database::fetch_array($result)) {
            $cats[] = array($data['code'], $data['title']);
        }

        return $cats;
    }

    /**
     * Apply the same visibility to every subcategory, evaluation and link
     */
    public function apply_visibility_to_children()
    {
        $cats  = Category::load(null, null, null, $this->id, null);
        $evals = Evaluation::load(null, null, null, $this->id, null);
        $links = LinkFactory::load(null, null, null, null, null, $this->id, null);
        if (!empty($cats)) {
            foreach ($cats as $cat) {
                $cat->set_visible($this->is_visible());
                $cat->save();
                $cat->apply_visibility_to_children();
            }
        }
        if (!empty($evals)) {
            foreach ($evals as $eval) {
                $eval->set_visible($this->is_visible());
                $eval->save();
            }
        }
        if (!empty($links)) {
            foreach ($links as $link) {
                $link->set_visible($this->is_visible());
                $link->save();
            }
        }
    }


    /**
     * Check if a category contains evaluations with a result for a given student
     */
    public function has_evaluations_with_results_for_student($stud_id)
    {
        $evals = Evaluation::get_evaluations_with_result_for_student($this->id, $stud_id);
        if (count($evals) != 0) {
            return true;
        } else {
            $cats = Category::load(
                null,
                null,
                null,
                $this->id,
                api_is_allowed_to_edit() ? null : 1
            );
            foreach ($cats as $cat) {
                if ($cat->has_evaluations_with_results_for_student($stud_id)) {
                    return true;
                }

            }

            return false;
        }
    }

    /**
     * Retrieve all categories inside a course independent category
     * that should be visible to a student.
     * @param $cat_id parent category
     * @param $stud_id student id
     * @param $cats optional: if defined, the categories will be added to this array
     */
    public function get_independent_categories_with_result_for_student($cat_id, $stud_id, $cats = array())
    {
        $creator = (api_is_allowed_to_edit() && !api_is_platform_admin()) ? api_get_user_id() : null;

        $crsindcats = Category::load(
            null,
            $creator,
            '0',
            $cat_id,
            api_is_allowed_to_edit() ? null : 1
        );

        if (!empty($crsindcats)) {
            foreach ($crsindcats as $crsindcat) {
                if ($crsindcat->has_evaluations_with_results_for_student($stud_id)) {
                    $cats[] = $crsindcat;
                }
            }
        }

        return $cats;
    }

    /**
     * Return the session id (in any case, even if it's null or 0)
     * @return  int Session id (can be null)
     */
    public function get_session_id()
    {
        return $this->session_id;
    }


    /**
     * Get appropriate subcategories visible for the user (and optionally the course and session)
     * @param int $stud_id student id (default: all students)
     * @param string   Course code (optional)
     * @param int      Session ID (optional)
     * @return  array   Array of subcategories
     */
    public function get_subcategories($stud_id = null, $course_code = null, $session_id = null, $order = null)
    {
        // 1 student
        if (isset($stud_id)) {
            // special case: this is the root
            if ($this->id == 0) {
                return Category::get_root_categories_for_student($stud_id, $course_code, $session_id);
            } else {
                return Category::load(
                    null,
                    null,
                    $course_code,
                    $this->id,
                    api_is_allowed_to_edit() ? null : 1,
                    $session_id,
                    $order
                );
            }
        } else { // all students
            // course admin
            if (api_is_allowed_to_edit() && !api_is_platform_admin()) {
                // root
                if ($this->id == 0) {
                    return $this->get_root_categories_for_teacher(api_get_user_id(), $course_code, $session_id, false);
                    // inside a course
                } elseif (!empty($this->course_code)) {
                    return Category::load(null, null, $this->course_code, $this->id, null, $session_id, $order);
                } elseif (!empty($course_code)) {
                    return Category::load(null, null, $course_code, $this->id, null, $session_id, $order);
                    // course independent
                } else {
                    return Category::load(null, api_get_user_id(), 0, $this->id, null);
                }
            } elseif (api_is_platform_admin()) {
                // platform admin
                //we explicitly avoid listing subcats from another session
                return Category::load(null, null, $course_code, $this->id, null, $session_id, $order);
            }
        }

        return array();
    }

    /**
     * Get appropriate evaluations visible for the user
     * @param int $stud_id student id (default: all students)
     * @param boolean $recursive process subcategories (default: no recursion)
     */
    public function get_evaluations($stud_id = null, $recursive = false, $course_code = '')
    {
        $evals = array();

        if (empty($course_code)) {
            $course_code = api_get_course_id();
        }

        // 1 student
        if (isset($stud_id) && !empty($stud_id)) {
            // special case: this is the root
            if ($this->id == 0) {
                $evals = Evaluation::get_evaluations_with_result_for_student(0, $stud_id);
            } else {
                $evals = Evaluation::load(null, null, $course_code, $this->id, api_is_allowed_to_edit() ? null : 1);
            }
        } else { // all students
            // course admin
            if ((api_is_allowed_to_edit() || api_is_drh() || api_is_session_admin()) && !api_is_platform_admin()) {
                // root
                if ($this->id == 0) {
                    $evals = Evaluation::load(null, api_get_user_id(), null, $this->id, null);
                } elseif (isset($this->course_code) && !empty($this->course_code)) {
                    // inside a course
                    $evals = Evaluation::load(null, null, $course_code, $this->id, null);
                } else {
                    // course independent
                    $evals = Evaluation::load(null, api_get_user_id(), null, $this->id, null);
                }
            } elseif (api_is_platform_admin()) {
                //platform admin
                $evals = Evaluation::load(null, null, $course_code, $this->id, null);
            }
        }

        if ($recursive) {
            $subcats = $this->get_subcategories($stud_id, $course_code);
            if (!empty($subcats)) {
                foreach ($subcats as $subcat) {
                    $subevals = $subcat->get_evaluations($stud_id, true, $course_code);
                    //$this->debugprint($subevals);
                    $evals = array_merge($evals, $subevals);
                }
            }
        }

        return $evals;

    }

    /**
     * Get appropriate links visible for the user
     * @param int $stud_id student id (default: all students)
     * @param boolean $recursive process subcategories (default: no recursion)
     */
    public function get_links($stud_id = null, $recursive = false, $course_code = '')
    {
        $links = array();

        if (empty($course_code)) {
            $course_code = api_get_course_id();
        }

        // no links in root or course independent categories
        if ($this->id == 0) {

        } elseif (isset($stud_id)) {
            // 1 student $stud_id
            $links = LinkFactory::load(
                null,
                null,
                null,
                null,
                empty($this->course_code) ? null : $course_code,
                $this->id,
                api_is_allowed_to_edit() ? null : 1
            );
        } elseif (api_is_allowed_to_edit() || api_is_drh() || api_is_session_admin()) {
            // all students -> only for course/platform admin
            $links = LinkFactory::load(
                null,
                null,
                null,
                null,
                empty($this->course_code) ? null : $this->course_code,
                $this->id,
                null
            );
        }


        if ($recursive) {
            $subcats = $this->get_subcategories($stud_id, $course_code);
            if (!empty($subcats)) {
                foreach ($subcats as $subcat) {
                    $sublinks = $subcat->get_links($stud_id, false, $course_code);
                    $links    = array_merge($links, $sublinks);
                }
            }
        }

        return $links;

    }


// Other methods implementing GradebookItem

    public function get_item_type()
    {
        return 'C';
    }

    public function set_skills($skills)
    {
        $this->skills = $skills;
    }

    public function get_date()
    {
        return null;
    }

    public function get_icon_name()
    {
        return 'cat';
    }

    /**
     * Find category by name
     * @param string $name_mask search string
     * @return array category objects matching the search criterium
     */
    public function find_category($name_mask, $allcat)
    {
        $foundcats = array();
        foreach ($allcat as $search_cat) {
            if (!(strpos(strtolower($search_cat->get_name()), strtolower($name_mask)) === false)) {
                $foundcats[] = $search_cat;
            }
        }

        return $foundcats;
    }

    /**
     * This function, locks a category , only one who can unlock it is the platform administrator.
     * @param int locked 1 or unlocked 0
     * @return bool
     *
     * */
    function lock($locked)
    {
        $table = Database::get_main_table(TABLE_MAIN_GRADEBOOK_CATEGORY);
        $sql   = "UPDATE $table SET locked = '".intval($locked)."' WHERE id='".intval($this->id)."'";
        Database::query($sql);
    }

    function lock_all_items($locked)
    {
        if (api_get_setting('gradebook_locking_enabled') == 'true') {
            $this->lock($locked);

            $evals_to_lock = $this->get_evaluations();

            if (!empty($evals_to_lock)) {
                foreach ($evals_to_lock as $item) {
                    $item->lock($locked);
                }
            }

            $link_to_lock = $this->get_links();
            if (!empty($link_to_lock)) {
                foreach ($link_to_lock as $item) {
                    $item->lock($locked);
                }
            }

            $event_type = LOG_GRADEBOOK_UNLOCKED;
            if ($locked == 1) {
                $event_type = LOG_GRADEBOOK_LOCKED;
            }
            event_system($event_type, LOG_GRADEBOOK_ID, $this->id);
        }
    }

    static function register_user_certificate($category_id, $user_id)
    {
        // generating the total score for a course
        $cats_course = Category :: load($category_id, null, null, null, null, null, false);

        $alleval_course = $cats_course[0]->get_evaluations($user_id, true);
        $alllink_course = $cats_course[0]->get_links($user_id, true);

        $evals_links = array_merge($alleval_course, $alllink_course);

        $item_total = 0;

        //@todo move these in a function
        $sum_categories_weight_array = array();
        if (isset($cats_course) && !empty($cats_course)) {
            $categories = Category::load(null, null, null, $category_id);
            if (!empty($categories)) {
                foreach ($categories as $category) {
                    $sum_categories_weight_array[$category->get_id()] = $category->get_weight();
                }
            } else {
                $sum_categories_weight_array[$category_id] = $cats_course[0]->get_weight();
            }
        }

        $main_weight = $cats_course[0]->get_weight();

        $item_total_value = 0;
        $item_value       = 0;

        for ($count = 0; $count < count($evals_links); $count++) {
            $item               = $evals_links[$count];
            $score              = $item->calc_score($user_id);
            $divide             = (($score[1]) == 0) ? 1 : $score[1];
            $sub_cat_percentage = $sum_categories_weight_array[$item->get_category_id()];
            $item_value         = $score[0] / $divide * $item->get_weight() * $sub_cat_percentage / $main_weight;
            $item_total_value += $item_value;
        }
        $item_total_value = (float)$item_total_value;

        $cattotal = Category :: load($category_id);

        $scoretotal = $cattotal[0]->calc_score($user_id);

        //Do not remove this the gradebook/lib/fe/gradebooktable.class.php file load this variable as a global
        $scoredisplay = ScoreDisplay :: instance();

        $my_score_in_gradebook = $scoredisplay->display_score($scoretotal, SCORE_SIMPLE);

        //Show certificate
        $certificate_min_score = $cats_course[0]->get_certificate_min_score();

        $scoretotal_display = $scoredisplay->display_score(
            $scoretotal,
            SCORE_DIV_PERCENT
        ); //a student always sees only the teacher's repartition

        if (isset($certificate_min_score) && $item_total_value >= $certificate_min_score) {
            $my_certificate = get_certificate_by_user_id($cats_course[0]->get_id(), $user_id);
            if (empty($my_certificate)) {
                register_user_info_about_certificate(
                    $category_id,
                    $user_id,
                    $my_score_in_gradebook,
                    api_get_utc_datetime()
                );
                $my_certificate = get_certificate_by_user_id($cats_course[0]->get_id(), $user_id);
            }

            if (!empty($my_certificate)) {
                $certificate_obj = new Certificate($my_certificate['id']);

                $url          = Certificate::getCertificatePublicURL($my_certificate['id']);
                $certificates = Display::url(
                    Display::return_icon('certificate.png', get_lang('Certificates'), array(), 32),
                    $url,
                    array('target' => '_blank')
                );
                $html         = '<div class="actions" align="right">';
                $html .= Display::url($url, $url, array('target' => '_blank'));
                $html .= $certificates;
                $html .= '</div>';

                return $html;
            }
        } else {
            return false;
        }
    }
}