Proyectos de Subversion Moodle

<?php

// This file is part of Moodle - http://moodle.org/

//

// Moodle is free software: you can redistribute it and/or modify

// it under the terms of the GNU General Public License as published by

// the Free Software Foundation, either version 3 of the License, or

// (at your option) any later version.

//

// Moodle is distributed in the hope that it will be useful,

// but WITHOUT ANY WARRANTY; without even the implied warranty of

// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

// GNU General Public License for more details.

//

// You should have received a copy of the GNU General Public License

// along with Moodle.  If not, see <http://www.gnu.org/licenses/>.

/**

 * Utility class for browsing of course files.

 *

 * @package    core_files

 * @copyright  2008 Petr Skoda (http://skodak.org)

 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later

 */

defined('MOODLE_INTERNAL') || die();

/**

 * Represents a course context in the tree navigated by {@link file_browser}.

 *

 * @package    core_files

 * @copyright  2008 Petr Skoda (http://skodak.org)

 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later

 */

class file_info_context_course extends file_info {

    /** @var stdClass course object */

    protected $course;

    /** @var file_info_context_module[] cached child modules. See {@link get_child_module()} */

    protected $childrenmodules = [];

    /**

     * Constructor

     *

     * @param file_browser $browser file browser instance

     * @param stdClass $context context object

     * @param stdClass $course course object

     */

    public function __construct($browser, $context, $course) {

        parent::__construct($browser, $context);

        $this->course   = $course;

    }

    /**

     * Return information about this specific context level

     *

     * @param string $component component

     * @param string $filearea file area

     * @param int $itemid item ID

     * @param string $filepath file path

     * @param string $filename file name

     * @return file_info|null file_info instance or null if not found or access not allowed

     */

    public function get_file_info($component, $filearea, $itemid, $filepath, $filename) {

        // try to emulate require_login() tests here

        if (!isloggedin()) {

            return null;

        }

        if (!$this->course->visible and !has_capability('moodle/course:viewhiddencourses', $this->context)) {

            return null;

        }

        if (!is_viewing($this->context) and !$this->browser->is_enrolled($this->course->id)) {

            // no peaking here if not enrolled or inspector

            return null;

        }

        if (empty($component)) {

            return $this;

        }

        $methodname = "get_area_{$component}_{$filearea}";

        if (method_exists($this, $methodname)) {

            return $this->$methodname($itemid, $filepath, $filename);

        }

        return null;

    }

    /**

     * Returns list of areas inside this course

     *

     * @param string $extensions Only return areas that have files with these extensions

     * @param bool $returnemptyfolders return all areas always, if true it will ignore the previous argument

     * @return array

     */

    protected function get_course_areas($extensions = '*', $returnemptyfolders = false) {

        global $DB;

        $allareas = [

            'course_summary',

            'course_overviewfiles',

            'course_section',

            'backup_section',

            'backup_course',

            'backup_automated',

            'course_legacy'

        ];

        if ($returnemptyfolders) {

            return $allareas;

        }

        $params1 = ['contextid' => $this->context->id, 'emptyfilename' => '.'];

        $sql1 = "SELECT " . $DB->sql_concat('f.component', "'_'", 'f.filearea') . "

            FROM {files} f

            WHERE f.filename <> :emptyfilename AND f.contextid = :contextid ";

        $sql3 = ' GROUP BY f.component, f.filearea';

        list($sql2, $params2) = $this->build_search_files_sql($extensions);

        $areaswithfiles = $DB->get_fieldset_sql($sql1 . $sql2 . $sql3, array_merge($params1, $params2));

        return array_intersect($allareas, $areaswithfiles);

    }

    /**

     * Gets a stored file for the course summary filearea directory

     *

     * @param int $itemid item ID

     * @param string $filepath file path

     * @param string $filename file name

     * @return file_info|null file_info instance or null if not found or access not allowed

     */

    protected function get_area_course_summary($itemid, $filepath, $filename) {

        global $CFG;

        if (!has_capability('moodle/course:update', $this->context)) {

            return null;

        }

        if (is_null($itemid)) {

            return $this;

        }

        $fs = get_file_storage();

        $filepath = is_null($filepath) ? '/' : $filepath;

        $filename = is_null($filename) ? '.' : $filename;

        if (!$storedfile = $fs->get_file($this->context->id, 'course', 'summary', 0, $filepath, $filename)) {

            if ($filepath === '/' and $filename === '.') {

                $storedfile = new virtual_root_file($this->context->id, 'course', 'summary', 0);

            } else {

                // not found

                return null;

            }

        }

        $urlbase = $CFG->wwwroot.'/pluginfile.php';

        return new file_info_stored($this->browser, $this->context, $storedfile, $urlbase, get_string('areacourseintro', 'repository'), false, true, true, false);

    }

    /**

     * Gets a stored file for the course images filearea directory

     *

     * @param int $itemid item ID

     * @param string $filepath file path

     * @param string $filename file name

     * @return file_info|null file_info instance or null if not found or access not allowed

     */

    protected function get_area_course_overviewfiles($itemid, $filepath, $filename) {

        global $CFG;

        if (!has_capability('moodle/course:update', $this->context)) {

            return null;

        }

        if (is_null($itemid)) {

            return $this;

        }

        $fs = get_file_storage();

        $filepath = is_null($filepath) ? '/' : $filepath;

        $filename = is_null($filename) ? '.' : $filename;

        if (!$storedfile = $fs->get_file($this->context->id, 'course', 'overviewfiles', 0, $filepath, $filename)) {

            if ($filepath === '/' and $filename === '.') {

                $storedfile = new virtual_root_file($this->context->id, 'course', 'overviewfiles', 0);

            } else {

                // not found

                return null;

            }

        }

        $urlbase = $CFG->wwwroot.'/pluginfile.php';

        return new file_info_stored($this->browser, $this->context, $storedfile, $urlbase, get_string('areacourseoverviewfiles', 'repository'), false, true, true, false);

    }

    /**

     * Gets a stored file for the course section filearea directory

     *

     * @param int $itemid item ID

     * @param string $filepath file path

     * @param string $filename file name

     * @return file_info|null file_info instance or null if not found or access not allowed

     */

    protected function get_area_course_section($itemid, $filepath, $filename) {

        global $CFG, $DB;

        if (!has_capability('moodle/course:update', $this->context)) {

            return null;

        }

        if (empty($itemid)) {

            // list all sections

            return new file_info_area_course_section($this->browser, $this->context, $this->course, $this);

        }

        if (!$section = $DB->get_record('course_sections', array('course'=>$this->course->id, 'id'=>$itemid))) {

            return null; // does not exist

        }

        $fs = get_file_storage();

        $filepath = is_null($filepath) ? '/' : $filepath;

        $filename = is_null($filename) ? '.' : $filename;

        if (!$storedfile = $fs->get_file($this->context->id, 'course', 'section', $itemid, $filepath, $filename)) {

            if ($filepath === '/' and $filename === '.') {

                $storedfile = new virtual_root_file($this->context->id, 'course', 'section', $itemid);

            } else {

                // not found

                return null;

            }

        }

        $urlbase = $CFG->wwwroot.'/pluginfile.php';

        require_once($CFG->dirroot.'/course/lib.php');

        $sectionname = get_section_name($this->course, $section);

        return new file_info_stored($this->browser, $this->context, $storedfile, $urlbase, $sectionname, true, true, true, false);

    }

    /**

     * Gets a stored file for the course legacy filearea directory

     *

     * @param int $itemid item ID

     * @param string $filepath file path

     * @param string $filename file name

     * @return file_info|null file_info instance or null if not found or access not allowed

     */

    protected function get_area_course_legacy($itemid, $filepath, $filename) {

        if (!has_capability('moodle/course:managefiles', $this->context)) {

            return null;

        }

        if ($this->course->id != SITEID and $this->course->legacyfiles != 2) {

            // bad luck, legacy course files not used any more

        }

        if (is_null($itemid)) {

            return $this;

        }

        $fs = get_file_storage();

        $filepath = is_null($filepath) ? '/' : $filepath;

        $filename = is_null($filename) ? '.' : $filename;

        if (!$storedfile = $fs->get_file($this->context->id, 'course', 'legacy', 0, $filepath, $filename)) {

            if ($filepath === '/' and $filename === '.') {

                $storedfile = new virtual_root_file($this->context->id, 'course', 'legacy', 0);

            } else {

                // not found

                return null;

            }

        }

        return new file_info_area_course_legacy($this->browser, $this->context, $storedfile);

    }

    /**

     * Gets a stored file for the backup course filearea directory

     *

     * @param int $itemid item ID

     * @param string $filepath file path

     * @param string $filename file name

     * @return file_info|null file_info instance or null if not found or access not allowed

     */

    protected function get_area_backup_course($itemid, $filepath, $filename) {

        global $CFG;

        if (!has_capability('moodle/backup:backupcourse', $this->context) and !has_capability('moodle/restore:restorecourse', $this->context)) {

            return null;

        }

        if (is_null($itemid)) {

            return $this;

        }

        $fs = get_file_storage();

        $filepath = is_null($filepath) ? '/' : $filepath;

        $filename = is_null($filename) ? '.' : $filename;

        if (!$storedfile = $fs->get_file($this->context->id, 'backup', 'course', 0, $filepath, $filename)) {

            if ($filepath === '/' and $filename === '.') {

                $storedfile = new virtual_root_file($this->context->id, 'backup', 'course', 0);

            } else {

                // not found

                return null;

            }

        }

        $downloadable = has_capability('moodle/backup:downloadfile', $this->context);

        $uploadable   = has_capability('moodle/restore:uploadfile', $this->context);

        $urlbase = $CFG->wwwroot.'/pluginfile.php';

        return new file_info_stored($this->browser, $this->context, $storedfile, $urlbase, get_string('coursebackup', 'repository'), false, $downloadable, $uploadable, false);

    }

    /**

     * Gets a stored file for the automated backup filearea directory

     *

     * @param int $itemid item ID

     * @param string $filepath file path

     * @param string $filename file name

     * @return file_info|null

     */

    protected function get_area_backup_automated($itemid, $filepath, $filename) {

        global $CFG;

        if (!has_capability('moodle/restore:viewautomatedfilearea', $this->context)) {

            return null;

        }

        if (is_null($itemid)) {

            return $this;

        }

        $fs = get_file_storage();

        $filepath = is_null($filepath) ? '/' : $filepath;

        $filename = is_null($filename) ? '.' : $filename;

        if (!$storedfile = $fs->get_file($this->context->id, 'backup', 'automated', 0, $filepath, $filename)) {

            if ($filepath === '/' and $filename === '.') {

                $storedfile = new virtual_root_file($this->context->id, 'backup', 'automated', 0);

            } else {

                // not found

                return null;

            }

        }

        // Automated backup files are only downloadable if the user has both 'backup:downloadfile and 'restore:userinfo'.

        $downloadable = has_capability('moodle/backup:downloadfile', $this->context) &&

                        has_capability('moodle/restore:userinfo', $this->context);

        $uploadable   = false;

        $urlbase = $CFG->wwwroot.'/pluginfile.php';

        return new file_info_stored($this->browser, $this->context, $storedfile, $urlbase, get_string('automatedbackup', 'repository'), true, $downloadable, $uploadable, false);

    }

    /**

     * Gets a stored file for the backup section filearea directory

     *

     * @param int $itemid item ID

     * @param string $filepath file path

     * @param string $filename file name

     * @return file_info|null file_info instance or null if not found or access not allowed

     */

    protected function get_area_backup_section($itemid, $filepath, $filename) {

        global $CFG, $DB;

        if (!has_capability('moodle/backup:backupcourse', $this->context) and !has_capability('moodle/restore:restorecourse', $this->context)) {

            return null;

        }

        if (empty($itemid)) {

            // list all sections

            return new file_info_area_backup_section($this->browser, $this->context, $this->course, $this);

        }

        if (!$section = $DB->get_record('course_sections', array('course'=>$this->course->id, 'id'=>$itemid))) {

            return null; // does not exist

        }

        $fs = get_file_storage();

        $filepath = is_null($filepath) ? '/' : $filepath;

        $filename = is_null($filename) ? '.' : $filename;

        if (!$storedfile = $fs->get_file($this->context->id, 'backup', 'section', $itemid, $filepath, $filename)) {

            if ($filepath === '/' and $filename === '.') {

                $storedfile = new virtual_root_file($this->context->id, 'backup', 'section', $itemid);

            } else {

                // not found

                return null;

            }

        }

        $downloadable = has_capability('moodle/backup:downloadfile', $this->context);

        $uploadable   = has_capability('moodle/restore:uploadfile', $this->context);

        $urlbase = $CFG->wwwroot.'/pluginfile.php';

        return new file_info_stored($this->browser, $this->context, $storedfile, $urlbase, $section->id, true, $downloadable, $uploadable, false);

    }

    /**

     * Returns localised visible name.

     *

     * @return string

     */

    public function get_visible_name() {

        return ($this->course->id == SITEID) ? get_string('frontpage', 'admin') : format_string(get_course_display_name_for_list($this->course), true, array('context'=>$this->context));

    }

    /**

     * Whether or not new files or directories can be added

     *

     * @return bool

     */

    public function is_writable() {

        return false;

    }

    /**

     * Whether or not this is a directory

     *

     * @return bool

     */

    public function is_directory() {

        return true;

    }

    /**

     * Returns list of children.

     *

     * @return array of file_info instances

     */

    public function get_children() {

        return $this->get_filtered_children('*', false, true);

    }

    /**

     * Returns the child module if it is accessible by the current user

     *

     * @param cm_info|int $cm

     * @return file_info_context_module|null

     */

    protected function get_child_module($cm) {

        $cmid = is_object($cm) ? $cm->id : $cm;

        if (!array_key_exists($cmid, $this->childrenmodules)) {

            $this->childrenmodules[$cmid] = null;

            if (!($cm instanceof cm_info)) {

                $cms = get_fast_modinfo($this->course)->cms;

                $cm = array_key_exists($cmid, $cms) ? $cms[$cmid] : null;

            }

            if ($cm && $cm->uservisible) {

                $this->childrenmodules[$cmid] = new file_info_context_module($this->browser,

                    $cm->context, $this->course, $cm, $cm->modname);

            }

        }

        return $this->childrenmodules[$cmid];

    }

    /**

     * Help function to return files matching extensions or their count

     *

     * @param string|array $extensions, either '*' or array of lowercase extensions, i.e. array('.gif','.jpg')

     * @param bool|int $countonly if false returns the children, if an int returns just the

     *    count of children but stops counting when $countonly number of children is reached

     * @param bool $returnemptyfolders if true returns items that don't have matching files inside

     * @return array|int array of file_info instances or the count

     */

    private function get_filtered_children($extensions = '*', $countonly = false, $returnemptyfolders = false) {

        $children = array();

        $courseareas = $this->get_course_areas($extensions, $returnemptyfolders);

        foreach ($courseareas as $areaname) {

            $area = explode('_', $areaname, 2);

            if ($child = $this->get_file_info($area[0], $area[1], 0, '/', '.')) {

                $children[] = $child;

                if (($countonly !== false) && count($children) >= $countonly) {

                    return $countonly;

                }

            }

        }

        $cnt = count($children);

        if (!has_capability('moodle/course:managefiles', $this->context)) {

            // 'managefiles' capability is checked in every activity module callback.

            // Don't even waste time on retrieving the modules if we can't browse the files anyway

        } else {

            if ($returnemptyfolders) {

                $modinfo = get_fast_modinfo($this->course);

                foreach ($modinfo->cms as $cminfo) {

                    if ($child = $this->get_child_module($cminfo)) {

                        $children[] = $child;

                        $cnt++;

                    }

                }

            } else if ($moduleareas = $this->get_module_areas_with_files($extensions)) {

                // We found files in some of the modules.

                // Create array of children modules ordered with the same way as cms in modinfo.

                $modulechildren = array_fill_keys(array_keys(get_fast_modinfo($this->course)->get_cms()), null);

                foreach ($moduleareas as $area) {

                    if ($modulechildren[$area->cmid]) {

                        // We already found non-empty area within the same module, do not analyse other areas.

                        continue;

                    }

                    if ($child = $this->get_child_module($area->cmid)) {

                        if ($child->get_file_info($area->component, $area->filearea, $area->itemid, null, null)) {

                            $modulechildren[$area->cmid] = $child;

                            $cnt++;

                            if (($countonly !== false) && $cnt >= $countonly) {

                                return $cnt;

                            }

                        }

                    }

                }

                $children = array_merge($children, array_values(array_filter($modulechildren)));

            }

        }

        if ($countonly !== false) {

            return count($children);

        }

        return $children;

    }

    /**

     * Returns list of areas inside the course modules that have files with the given extension

     *

     * @param string $extensions

     * @return array

     */

    protected function get_module_areas_with_files($extensions = '*') {

        global $DB;

        $params1 = ['contextid' => $this->context->id,

            'emptyfilename' => '.',

            'contextlevel' => CONTEXT_MODULE,

            'course' => $this->course->id];

        $ctxfieldsas = context_helper::get_preload_record_columns_sql('ctx');

        $ctxfields = implode(', ', array_keys(context_helper::get_preload_record_columns('ctx')));

        $sql1 = "SELECT

                    ctx.id AS contextid,

                    f.component,

                    f.filearea,

                    f.itemid,

                    ctx.instanceid AS cmid,

                    {$ctxfieldsas}

            FROM {files} f

            INNER JOIN {context} ctx ON ctx.id = f.contextid

            INNER JOIN {course_modules} cm ON cm.id = ctx.instanceid

            WHERE f.filename <> :emptyfilename

              AND cm.course = :course

              AND ctx.contextlevel = :contextlevel";

        $sql3 = "

            GROUP BY ctx.id, f.component, f.filearea, f.itemid, {$ctxfields}

            ORDER BY ctx.id, f.component, f.filearea, f.itemid";

        list($sql2, $params2) = $this->build_search_files_sql($extensions);

        $areas = [];

        if ($rs = $DB->get_recordset_sql($sql1. $sql2 . $sql3, array_merge($params1, $params2))) {

            foreach ($rs as $record) {

                context_helper::preload_from_record($record);

                $areas[] = $record;

            }

            $rs->close();

        }

        // Sort areas so 'backup' and 'intro' are in the beginning of the list, they are the easiest to check access to.

        usort($areas, function($a, $b) {

            $aeasy = ($a->filearea === 'intro' && substr($a->component, 0, 4) === 'mod_') ||

                ($a->filearea === 'activity' && $a->component === 'backup');

            $beasy = ($b->filearea === 'intro' && substr($b->component, 0, 4) === 'mod_') ||

                ($b->filearea === 'activity' && $b->component === 'backup');

            return $aeasy == $beasy ? 0 : ($aeasy ? -1 : 1);

        });

        return $areas;

    }

    /**

     * Returns list of children which are either files matching the specified extensions

     * or folders that contain at least one such file.

     *

     * @param string|array $extensions, either '*' or array of lowercase extensions, i.e. array('.gif','.jpg')

     * @return array of file_info instances

     */

    public function get_non_empty_children($extensions = '*') {

        return $this->get_filtered_children($extensions, false);

    }

    /**

     * Returns the number of children which are either files matching the specified extensions

     * or folders containing at least one such file.

     *

     * @param string|array $extensions, for example '*' or array('.gif','.jpg')

     * @param int $limit stop counting after at least $limit non-empty children are found

     * @return int

     */

    public function count_non_empty_children($extensions = '*', $limit = 1) {

        return $this->get_filtered_children($extensions, $limit);

    }

    /**

     * Returns parent file_info instance

     *

     * @return file_info or null for root

     */

    public function get_parent() {

        $parent = $this->context->get_parent_context();

        return $this->browser->get_file_info($parent);

    }

}

/**

 * Subclass of file_info_stored for files in the course files area.

 *

 * @package   core_files

 * @copyright 2008 Petr Skoda (http://skodak.org)

 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later

 */

class file_info_area_course_legacy extends file_info_stored {

    /**

     * Constructor

     *

     * @param file_browser $browser file browser instance

     * @param stdClass $context context object

     * @param stored_file $storedfile stored_file instance

     */

    public function __construct($browser, $context, $storedfile) {

        global $CFG;

        $urlbase = $CFG->wwwroot.'/file.php';

        parent::__construct($browser, $context, $storedfile, $urlbase, get_string('coursefiles'), false, true, true, false);

    }

    /**

     * Returns file download url

     *

     * @param bool $forcedownload whether or not force download

     * @param bool $https whether or not force https

     * @return string url

     */

    public function get_url($forcedownload=false, $https=false) {

        if (!$this->is_readable()) {

            return null;

        }

        if ($this->lf->is_directory()) {

            return null;

        }

        $filepath = $this->lf->get_filepath();

        $filename = $this->lf->get_filename();

        $courseid = $this->context->instanceid;

        $path = '/'.$courseid.$filepath.$filename;

        return file_encode_url($this->urlbase, $path, $forcedownload, $https);

    }

    /**

     * Returns list of children.

     *

     * @return array of file_info instances

     */

    public function get_children() {

        if (!$this->lf->is_directory()) {

            return array();

        }

        $result = array();

        $fs = get_file_storage();

        $storedfiles = $fs->get_directory_files($this->context->id, 'course', 'legacy', 0, $this->lf->get_filepath(), false, true, "filepath ASC, filename ASC");

        foreach ($storedfiles as $file) {

            $result[] = new file_info_area_course_legacy($this->browser, $this->context, $file);

        }

        return $result;

    }

    /**

     * Returns list of children which are either files matching the specified extensions

     * or folders that contain at least one such file.

     *

     * @param string|array $extensions, either '*' or array of lowercase extensions, i.e. array('.gif','.jpg')

     * @return array of file_info instances

     */

    public function get_non_empty_children($extensions = '*') {

        if (!$this->lf->is_directory()) {

            return array();

        }

        $result = array();

        $fs = get_file_storage();

        $storedfiles = $fs->get_directory_files($this->context->id, 'course', 'legacy', 0,

                                                $this->lf->get_filepath(), false, true, "filepath, filename");

        foreach ($storedfiles as $file) {

            $extension = core_text::strtolower(pathinfo($file->get_filename(), PATHINFO_EXTENSION));

            if ($file->is_directory() || $extensions === '*' || (!empty($extension) && in_array('.'.$extension, $extensions))) {

                $fileinfo = new file_info_area_course_legacy($this->browser, $this->context, $file, $this->urlbase, $this->topvisiblename,

                                                 $this->itemidused, $this->readaccess, $this->writeaccess, false);

                if (!$file->is_directory() || $fileinfo->count_non_empty_children($extensions)) {

                    $result[] = $fileinfo;

                }

            }

        }

        return $result;

    }

}

/**

 * Represents a course category context in the tree navigated by {@link file_browser}.

 *

 * @package    core_files

 * @copyright  2008 Petr Skoda (http://skodak.org)

 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later

 */

class file_info_area_course_section extends file_info {

    /** @var stdClass course object */

    protected $course;

    /** @var file_info_context_course course file info object */

    protected $courseinfo;

    /**

     * Constructor

     *

     * @param file_browser $browser file browser instance

     * @param stdClass $context context object

     * @param stdClass $course course object

     * @param file_info_context_course $courseinfo file info instance

     */

    public function __construct($browser, $context, $course, file_info_context_course $courseinfo) {

        parent::__construct($browser, $context);

        $this->course     = $course;

        $this->courseinfo = $courseinfo;

    }

    /**

     * Returns list of standard virtual file/directory identification.

     * The difference from stored_file parameters is that null values

     * are allowed in all fields

     *

     * @return array with keys contextid, filearea, itemid, filepath and filename

     */

    public function get_params() {

        return array('contextid' => $this->context->id,

                     'component' => 'course',

                     'filearea'  => 'section',

                     'itemid'    => null,

                     'filepath'  => null,

                     'filename'  => null);

    }

    /**

     * Returns localised visible name.

     *

     * @return string

     */

    public function get_visible_name() {

        //$format = $this->course->format;

        $sectionsname = get_string("coursesectionsummaries");

        return $sectionsname;

    }

    /**

     * Return whether or not new files or directories can be added

     *

     * @return bool

     */

    public function is_writable() {

        return false;

    }

    /**

     * Return whether or not this is a empty area

     *

     * @return bool

     */

    public function is_empty_area() {

        $fs = get_file_storage();

        return $fs->is_area_empty($this->context->id, 'course', 'section');

    }

    /**

     * Return whether or not this is a empty area

     *

     * @return bool

     */

    public function is_directory() {

        return true;

    }

    /**

     * Returns list of children.

     *

     * @return array of file_info instances

     */

    public function get_children() {

        global $DB;

        $children = array();

        $course_sections = $DB->get_records('course_sections', array('course'=>$this->course->id), 'section');

        foreach ($course_sections as $section) {

            if ($child = $this->courseinfo->get_file_info('course', 'section', $section->id, '/', '.')) {

                $children[] = $child;

            }

        }

        return $children;

    }

    /**

     * Returns the number of children which are either files matching the specified extensions

     * or folders containing at least one such file.

     *

     * @param string|array $extensions, for example '*' or array('.gif','.jpg')

     * @param int $limit stop counting after at least $limit non-empty children are found

     * @return int

     */

    public function count_non_empty_children($extensions = '*', $limit = 1) {

        global $DB;

        $params1 = array(

            'courseid' => $this->course->id,

            'contextid' => $this->context->id,

            'component' => 'course',

            'filearea' => 'section',

            'emptyfilename' => '.');

        $sql1 = "SELECT DISTINCT cs.id FROM {files} f, {course_sections} cs

            WHERE cs.course = :courseid

            AND f.contextid = :contextid

            AND f.component = :component

            AND f.filearea = :filearea

            AND f.itemid = cs.id

            AND f.filename <> :emptyfilename";

        list($sql2, $params2) = $this->build_search_files_sql($extensions);

        $rs = $DB->get_recordset_sql($sql1. ' '. $sql2, array_merge($params1, $params2));

        $cnt = 0;

        foreach ($rs as $record) {

            if ((++$cnt) >= $limit) {

                break;

            }

        }

        $rs->close();

        return $cnt;

    }

    /**

     * Returns parent file_info instance

     *

     * @return file_info|null file_info or null for root

     */

    public function get_parent() {

        return $this->courseinfo;

    }

}

/**

 * Implementation of course section backup area

 *

 * @package    core_files

 * @copyright  2008 Petr Skoda (http://skodak.org)

 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later

 */

class file_info_area_backup_section extends file_info {

    /** @var stdClass course object */

    protected $course;

    /** @var file_info_context_course course file info object */

    protected $courseinfo;

    /**

     * Constructor

     *

     * @param file_browser $browser file browser instance

     * @param stdClass $context context object

     * @param stdClass $course course object

     * @param file_info_context_course $courseinfo file info instance

     */

    public function __construct($browser, $context, $course, file_info_context_course $courseinfo) {

        parent::__construct($browser, $context);

        $this->course     = $course;

        $this->courseinfo = $courseinfo;

    }

    /**

     * Returns list of standard virtual file/directory identification.

     * The difference from stored_file parameters is that null values

     * are allowed in all fields

     *

     * @return array with keys contextid, component, filearea, itemid, filepath and filename

     */

    public function get_params() {

        return array('contextid' => $this->context->id,

                     'component' => 'backup',

                     'filearea'  => 'section',

                     'itemid'    => null,

                     'filepath'  => null,

                     'filename'  => null);

    }

    /**

     * Returns localised visible name.

     *

     * @return string

     */

    public function get_visible_name() {

        return get_string('sectionbackup', 'repository');

    }

    /**

     * Return whether or not new files and directories can be added

     *

     * @return bool

     */

    public function is_writable() {

        return false;

    }

    /**

     * Whether or not this is an empty area

     *

     * @return bool

     */

    public function is_empty_area() {

        $fs = get_file_storage();

        return $fs->is_area_empty($this->context->id, 'backup', 'section');

    }

    /**

     * Return whether or not this is a directory

     *

     * @return bool

     */

    public function is_directory() {

        return true;

    }

    /**

     * Returns list of children.

     *

     * @return array of file_info instances

     */

    public function get_children() {

        global $DB;

        $children = array();

        $course_sections = $DB->get_records('course_sections', array('course'=>$this->course->id), 'section');

        foreach ($course_sections as $section) {

            if ($child = $this->courseinfo->get_file_info('backup', 'section', $section->id, '/', '.')) {

                $children[] = $child;

            }

        }

        return $children;

    }

    /**

     * Returns the number of children which are either files matching the specified extensions

     * or folders containing at least one such file.

     *

     * @param string|array $extensions, for example '*' or array('.gif','.jpg')

     * @param int $limit stop counting after at least $limit non-empty children are found

     * @return int

     */

    public function count_non_empty_children($extensions = '*', $limit = 1) {

        global $DB;

        $params1 = array(

            'courseid' => $this->course->id,

            'contextid' => $this->context->id,

            'component' => 'backup',

            'filearea' => 'section',

            'emptyfilename' => '.');

        $sql1 = "SELECT DISTINCT cs.id AS sectionid FROM {files} f, {course_sections} cs

            WHERE cs.course = :courseid

            AND f.contextid = :contextid

            AND f.component = :component

            AND f.filearea = :filearea

            AND f.itemid = cs.id

            AND f.filename <> :emptyfilename";

        list($sql2, $params2) = $this->build_search_files_sql($extensions);

        $rs = $DB->get_recordset_sql($sql1. ' '. $sql2, array_merge($params1, $params2));

        $cnt = 0;

        foreach ($rs as $record) {

            if ((++$cnt) >= $limit) {

                break;

            }

        }

        $rs->close();

        return $cnt;

    }

    /**

     * Returns parent file_info instance

     *

     * @return file_info or null for root

     */

    public function get_parent() {

        return $this->browser->get_file_info($this->context);

    }

}