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/>.

/**

 * Wiki module external API.

 *

 * @package    mod_wiki

 * @category   external

 * @copyright  2015 Dani Palou <dani@moodle.com>

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

 * @since      Moodle 3.1

 */

use core_course\external\helper_for_get_mods_by_courses;

use core_external\external_api;

use core_external\external_files;

use core_external\external_format_value;

use core_external\external_function_parameters;

use core_external\external_multiple_structure;

use core_external\external_single_structure;

use core_external\external_value;

use core_external\external_warnings;

use core_external\util;

defined('MOODLE_INTERNAL') || die;

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

require_once($CFG->dirroot . '/mod/wiki/locallib.php');

/**

 * Wiki module external functions.

 *

 * @package    mod_wiki

 * @category   external

 * @copyright  2015 Dani Palou <dani@moodle.com>

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

 * @since      Moodle 3.1

 */

class mod_wiki_external extends external_api {

    /**

     * Describes the parameters for get_wikis_by_courses.

     *

     * @return external_function_parameters

     * @since Moodle 3.1

     */

    public static function get_wikis_by_courses_parameters() {

        return new external_function_parameters (

            array(

                'courseids' => new external_multiple_structure(

                    new external_value(PARAM_INT, 'Course ID'), 'Array of course ids.', VALUE_DEFAULT, array()

                ),

            )

        );

    }

    /**

     * Returns a list of wikis in a provided list of courses,

     * if no list is provided all wikis that the user can view will be returned.

     *

     * @param array $courseids The courses IDs.

     * @return array Containing a list of warnings and a list of wikis.

     * @since Moodle 3.1

     */

    public static function get_wikis_by_courses($courseids = array()) {

        $returnedwikis = array();

        $warnings = array();

        $params = self::validate_parameters(self::get_wikis_by_courses_parameters(), array('courseids' => $courseids));

        $mycourses = array();

        if (empty($params['courseids'])) {

            $mycourses = enrol_get_my_courses();

            $params['courseids'] = array_keys($mycourses);

        }

        // Ensure there are courseids to loop through.

        if (!empty($params['courseids'])) {

            list($courses, $warnings) = util::validate_courses($params['courseids'], $mycourses);

            // Get the wikis in this course, this function checks users visibility permissions.

            // We can avoid then additional validate_context calls.

            $wikis = get_all_instances_in_courses('wiki', $courses);

            foreach ($wikis as $wiki) {

                $context = context_module::instance($wiki->coursemodule);

                // Entry to return.

                $module = helper_for_get_mods_by_courses::standard_coursemodule_element_values(

                        $wiki, 'mod_wiki', 'mod/wiki:viewpage', 'mod/wiki:viewpage');

                $viewablefields = [];

                if (has_capability('mod/wiki:viewpage', $context)) {

                    $viewablefields = array('firstpagetitle', 'wikimode', 'defaultformat', 'forceformat', 'editbegin', 'editend',

                                            'section', 'visible', 'groupmode', 'groupingid');

                }

                // Check additional permissions for returning optional private settings.

                if (has_capability('moodle/course:manageactivities', $context)) {

                    $additionalfields = array('timecreated', 'timemodified');

                    $viewablefields = array_merge($viewablefields, $additionalfields);

                }

                foreach ($viewablefields as $field) {

                    $module[$field] = $wiki->{$field};

                }

                // Check if user can add new pages.

                $module['cancreatepages'] = wiki_can_create_pages($context);

                $returnedwikis[] = $module;

            }

        }

        $result = array();

        $result['wikis'] = $returnedwikis;

        $result['warnings'] = $warnings;

        return $result;

    }

    /**

     * Describes the get_wikis_by_courses return value.

     *

     * @return external_single_structure

     * @since Moodle 3.1

     */

    public static function get_wikis_by_courses_returns() {

        return new external_single_structure(

            array(

                'wikis' => new external_multiple_structure(

                    new external_single_structure(array_merge(

                        helper_for_get_mods_by_courses::standard_coursemodule_elements_returns(true),

                        [

                            'timecreated' => new external_value(PARAM_INT, 'Time of creation.', VALUE_OPTIONAL),

                            'timemodified' => new external_value(PARAM_INT, 'Time of last modification.', VALUE_OPTIONAL),

                            'firstpagetitle' => new external_value(PARAM_RAW, 'First page title.', VALUE_OPTIONAL),

                            'wikimode' => new external_value(PARAM_TEXT, 'Wiki mode (individual, collaborative).', VALUE_OPTIONAL),

                            'defaultformat' => new external_value(PARAM_TEXT, 'Wiki\'s default format (html, creole, nwiki).',

                                                                            VALUE_OPTIONAL),

                            'forceformat' => new external_value(PARAM_INT, '1 if format is forced, 0 otherwise.',

                                                                            VALUE_OPTIONAL),

                            'editbegin' => new external_value(PARAM_INT, 'Edit begin.', VALUE_OPTIONAL),

                            'editend' => new external_value(PARAM_INT, 'Edit end.', VALUE_OPTIONAL),

                            'cancreatepages' => new external_value(PARAM_BOOL, 'True if user can create pages.'),

                        ]

                    ), 'Wikis')

                ),

                'warnings' => new external_warnings(),

            )

        );

    }

    /**

     * Describes the parameters for view_wiki.

     *

     * @return external_function_parameters

     * @since Moodle 3.1

     */

    public static function view_wiki_parameters() {

        return new external_function_parameters (

            array(

                'wikiid' => new external_value(PARAM_INT, 'Wiki instance ID.')

            )

        );

    }

    /**

     * Trigger the course module viewed event and update the module completion status.

     *

     * @param int $wikiid The wiki instance ID.

     * @return array of warnings and status result.

     * @since Moodle 3.1

     */

    public static function view_wiki($wikiid) {

        $params = self::validate_parameters(self::view_wiki_parameters(),

                                            array(

                                                'wikiid' => $wikiid

                                            ));

        $warnings = array();

        // Get wiki instance.

        if (!$wiki = wiki_get_wiki($params['wikiid'])) {

            throw new moodle_exception('incorrectwikiid', 'wiki');

        }

        // Permission validation.

        list($course, $cm) = get_course_and_cm_from_instance($wiki, 'wiki');

        $context = context_module::instance($cm->id);

        self::validate_context($context);

        // Check if user can view this wiki.

        // We don't use wiki_user_can_view because it requires to have a valid subwiki for the user.

        if (!has_capability('mod/wiki:viewpage', $context)) {

            throw new moodle_exception('cannotviewpage', 'wiki');

        }

        // Trigger course_module_viewed event and completion.

        wiki_view($wiki, $course, $cm, $context);

        $result = array();

        $result['status'] = true;

        $result['warnings'] = $warnings;

        return $result;

    }

    /**

     * Describes the view_wiki return value.

     *

     * @return external_single_structure

     * @since Moodle 3.1

     */

    public static function view_wiki_returns() {

        return new external_single_structure(

            array(

                'status' => new external_value(PARAM_BOOL, 'Status: true if success.'),

                'warnings' => new external_warnings()

            )

        );

    }

    /**

     * Describes the parameters for view_page.

     *

     * @return external_function_parameters

     * @since Moodle 3.1

     */

    public static function view_page_parameters() {

        return new external_function_parameters (

            array(

                'pageid' => new external_value(PARAM_INT, 'Wiki page ID.'),

            )

        );

    }

    /**

     * Trigger the page viewed event and update the module completion status.

     *

     * @param int $pageid The page ID.

     * @return array of warnings and status result.

     * @since Moodle 3.1

     * @throws moodle_exception if page is not valid.

     */

    public static function view_page($pageid) {

        $params = self::validate_parameters(self::view_page_parameters(),

                                            array(

                                                'pageid' => $pageid

                                            ));

        $warnings = array();

        // Get wiki page.

        if (!$page = wiki_get_page($params['pageid'])) {

            throw new moodle_exception('incorrectpageid', 'wiki');

        }

        // Get wiki instance.

        if (!$wiki = wiki_get_wiki_from_pageid($params['pageid'])) {

            throw new moodle_exception('incorrectwikiid', 'wiki');

        }

        // Permission validation.

        list($course, $cm) = get_course_and_cm_from_instance($wiki, 'wiki');

        $context = context_module::instance($cm->id);

        self::validate_context($context);

        // Check if user can view this wiki.

        if (!$subwiki = wiki_get_subwiki($page->subwikiid)) {

            throw new moodle_exception('incorrectsubwikiid', 'wiki');

        }

        if (!wiki_user_can_view($subwiki, $wiki)) {

            throw new moodle_exception('cannotviewpage', 'wiki');

        }

        // Trigger page_viewed event and completion.

        wiki_page_view($wiki, $page, $course, $cm, $context);

        $result = array();

        $result['status'] = true;

        $result['warnings'] = $warnings;

        return $result;

    }

    /**

     * Describes the view_page return value.

     *

     * @return external_single_structure

     * @since Moodle 3.1

     */

    public static function view_page_returns() {

        return new external_single_structure(

            array(

                'status' => new external_value(PARAM_BOOL, 'Status: true if success.'),

                'warnings' => new external_warnings()

            )

        );

    }

    /**

     * Describes the parameters for get_subwikis.

     *

     * @return external_function_parameters

     * @since Moodle 3.1

     */

    public static function get_subwikis_parameters() {

        return new external_function_parameters (

            array(

                'wikiid' => new external_value(PARAM_INT, 'Wiki instance ID.')

            )

        );

    }

    /**

     * Returns the list of subwikis the user can see in a specific wiki.

     *

     * @param int $wikiid The wiki instance ID.

     * @return array Containing a list of warnings and a list of subwikis.

     * @since Moodle 3.1

     */

    public static function get_subwikis($wikiid) {

        global $USER;

        $warnings = array();

        $params = self::validate_parameters(self::get_subwikis_parameters(), array('wikiid' => $wikiid));

        // Get wiki instance.

        if (!$wiki = wiki_get_wiki($params['wikiid'])) {

            throw new moodle_exception('incorrectwikiid', 'wiki');

        }

        // Validate context and capabilities.

        list($course, $cm) = get_course_and_cm_from_instance($wiki, 'wiki');

        $context = context_module::instance($cm->id);

        self::validate_context($context);

        require_capability('mod/wiki:viewpage', $context);

        $returnedsubwikis = wiki_get_visible_subwikis($wiki, $cm, $context);

        foreach ($returnedsubwikis as $subwiki) {

            $subwiki->canedit = wiki_user_can_edit($subwiki);

        }

        $result = array();

        $result['subwikis'] = $returnedsubwikis;

        $result['warnings'] = $warnings;

        return $result;

    }

    /**

     * Describes the get_subwikis return value.

     *

     * @return external_single_structure

     * @since Moodle 3.1

     */

    public static function get_subwikis_returns() {

        return new external_single_structure(

            array(

                'subwikis' => new external_multiple_structure(

                    new external_single_structure(

                        array(

                            'id' => new external_value(PARAM_INT, 'Subwiki ID.'),

                            'wikiid' => new external_value(PARAM_INT, 'Wiki ID.'),

                            'groupid' => new external_value(PARAM_RAW, 'Group ID.'),

                            'userid' => new external_value(PARAM_INT, 'User ID.'),

                            'canedit' => new external_value(PARAM_BOOL, 'True if user can edit the subwiki.'),

                        ), 'Subwikis'

                    )

                ),

                'warnings' => new external_warnings(),

            )

        );

    }

    /**

     * Describes the parameters for get_subwiki_pages.

     *

     * @return external_function_parameters

     * @since Moodle 3.1

     */

    public static function get_subwiki_pages_parameters() {

        return new external_function_parameters (

            array(

                'wikiid' => new external_value(PARAM_INT, 'Wiki instance ID.'),

                'groupid' => new external_value(PARAM_INT, 'Subwiki\'s group ID, -1 means current group. It will be ignored'

                                        . ' if the wiki doesn\'t use groups.', VALUE_DEFAULT, -1),

                'userid' => new external_value(PARAM_INT, 'Subwiki\'s user ID, 0 means current user. It will be ignored'

                                        .' in collaborative wikis.', VALUE_DEFAULT, 0),

                'options' => new external_single_structure(

                            array(

                                    'sortby' => new external_value(PARAM_ALPHA,

                                            'Field to sort by (id, title, ...).', VALUE_DEFAULT, 'title'),

                                    'sortdirection' => new external_value(PARAM_ALPHA,

                                            'Sort direction: ASC or DESC.', VALUE_DEFAULT, 'ASC'),

                                    'includecontent' => new external_value(PARAM_INT,

                                            'Include each page contents or just the contents size.', VALUE_DEFAULT, 1),

                            ), 'Options', VALUE_DEFAULT, array()),

            )

        );

    }

    /**

     * Returns the list of pages from a specific subwiki.

     *

     * @param int $wikiid The wiki instance ID.

     * @param int $groupid The group ID. If not defined, use current group.

     * @param int $userid The user ID. If not defined, use current user.

     * @param array $options Several options like sort by, sort direction, ...

     * @return array Containing a list of warnings and a list of pages.

     * @since Moodle 3.1

     */

    public static function get_subwiki_pages($wikiid, $groupid = -1, $userid = 0, $options = array()) {

        $returnedpages = array();

        $warnings = array();

        $params = self::validate_parameters(self::get_subwiki_pages_parameters(),

                                            array(

                                                'wikiid' => $wikiid,

                                                'groupid' => $groupid,

                                                'userid' => $userid,

                                                'options' => $options

                                                )

            );

        // Get wiki instance.

        if (!$wiki = wiki_get_wiki($params['wikiid'])) {

            throw new moodle_exception('incorrectwikiid', 'wiki');

        }

        list($course, $cm) = get_course_and_cm_from_instance($wiki, 'wiki');

        $context = context_module::instance($cm->id);

        self::validate_context($context);

        // Determine groupid and userid to use.

        list($groupid, $userid) = self::determine_group_and_user($cm, $wiki, $params['groupid'], $params['userid']);

        // Get subwiki and validate it.

        $subwiki = wiki_get_subwiki_by_group_and_user_with_validation($wiki, $groupid, $userid);

        if ($subwiki === false) {

            throw new moodle_exception('cannotviewpage', 'wiki');

        } else if ($subwiki->id != -1) {

            $options = $params['options'];

            // Set sort param.

            $sort = get_safe_orderby([

                'id' => 'id',

                'title' => 'title',

                'timecreated' => 'timecreated',

                'timemodified' => 'timemodified',

                'pageviews' => 'pageviews',

                'default' => 'title',

            ], $options['sortby'], $options['sortdirection'], false);

            $pages = wiki_get_page_list($subwiki->id, $sort);

            $caneditpages = wiki_user_can_edit($subwiki);

            $firstpage = wiki_get_first_page($subwiki->id);

            foreach ($pages as $page) {

                $retpage = array(

                        'id' => $page->id,

                        'subwikiid' => $page->subwikiid,

                        'title' => \core_external\util::format_string($page->title, $context),

                        'timecreated' => $page->timecreated,

                        'timemodified' => $page->timemodified,

                        'timerendered' => $page->timerendered,

                        'userid' => $page->userid,

                        'pageviews' => $page->pageviews,

                        'readonly' => $page->readonly,

                        'caneditpage' => $caneditpages,

                        'firstpage' => $page->id == $firstpage->id,

                        'tags' => \core_tag\external\util::get_item_tags('mod_wiki', 'wiki_pages', $page->id),

                    );

                // Refresh page cached content if needed.

                if ($page->timerendered + WIKI_REFRESH_CACHE_TIME < time()) {

                    if ($content = wiki_refresh_cachedcontent($page)) {

                        $page = $content['page'];

                    }

                }

                list($cachedcontent, $contentformat) = \core_external\util::format_text(

                    $page->cachedcontent,

                    FORMAT_HTML,

                    $context,

                    'mod_wiki',

                    'attachments',

                    $subwiki->id

                );

                if ($options['includecontent']) {

                    // Return the page content.

                    $retpage['cachedcontent'] = $cachedcontent;

                    $retpage['contentformat'] = $contentformat;

                } else {

                    // Return the size of the content.

                    $retpage['contentsize'] = \core_text::strlen($cachedcontent);

                }

                $returnedpages[] = $retpage;

            }

        }

        $result = array();

        $result['pages'] = $returnedpages;

        $result['warnings'] = $warnings;

        return $result;

    }

    /**

     * Describes the get_subwiki_pages return value.

     *

     * @return external_single_structure

     * @since Moodle 3.1

     */

    public static function get_subwiki_pages_returns() {

        return new external_single_structure(

            array(

                'pages' => new external_multiple_structure(

                    new external_single_structure(

                        array(

                            'id' => new external_value(PARAM_INT, 'Page ID.'),

                            'subwikiid' => new external_value(PARAM_INT, 'Page\'s subwiki ID.'),

                            'title' => new external_value(PARAM_RAW, 'Page title.'),

                            'timecreated' => new external_value(PARAM_INT, 'Time of creation.'),

                            'timemodified' => new external_value(PARAM_INT, 'Time of last modification.'),

                            'timerendered' => new external_value(PARAM_INT, 'Time of last renderization.'),

                            'userid' => new external_value(PARAM_INT, 'ID of the user that last modified the page.'),

                            'pageviews' => new external_value(PARAM_INT, 'Number of times the page has been viewed.'),

                            'readonly' => new external_value(PARAM_INT, '1 if readonly, 0 otherwise.'),

                            'caneditpage' => new external_value(PARAM_BOOL, 'True if user can edit the page.'),

                            'firstpage' => new external_value(PARAM_BOOL, 'True if it\'s the first page.'),

                            'cachedcontent' => new external_value(PARAM_RAW, 'Page contents.', VALUE_OPTIONAL),

                            'contentformat' => new external_format_value('cachedcontent', VALUE_OPTIONAL),

                            'contentsize' => new external_value(PARAM_INT, 'Size of page contents in bytes (doesn\'t include'.

                                                                            ' size of attached files).', VALUE_OPTIONAL),

                            'tags' => new external_multiple_structure(

                                \core_tag\external\tag_item_exporter::get_read_structure(), 'Tags', VALUE_OPTIONAL

                            ),

                        ), 'Pages'

                    )

                ),

                'warnings' => new external_warnings(),

            )

        );

    }

    /**

     * Describes the parameters for get_page_contents.

     *

     * @return external_function_parameters

     * @since Moodle 3.1

     */

    public static function get_page_contents_parameters() {

        return new external_function_parameters (

            array(

                'pageid' => new external_value(PARAM_INT, 'Page ID.')

            )

        );

    }

    /**

     * Get a page contents.

     *

     * @param int $pageid The page ID.

     * @return array of warnings and page data.

     * @since Moodle 3.1

     */

    public static function get_page_contents($pageid) {

        $params = self::validate_parameters(self::get_page_contents_parameters(),

                                            array(

                                                'pageid' => $pageid

                                            )

            );

        $warnings = array();

        // Get wiki page.

        if (!$page = wiki_get_page($params['pageid'])) {

            throw new moodle_exception('incorrectpageid', 'wiki');

        }

        // Get wiki instance.

        if (!$wiki = wiki_get_wiki_from_pageid($params['pageid'])) {

            throw new moodle_exception('incorrectwikiid', 'wiki');

        }

        // Permission validation.

        $cm = get_coursemodule_from_instance('wiki', $wiki->id, $wiki->course);

        $context = context_module::instance($cm->id);

        self::validate_context($context);

        // Check if user can view this wiki.

        if (!$subwiki = wiki_get_subwiki($page->subwikiid)) {

            throw new moodle_exception('incorrectsubwikiid', 'wiki');

        }

        if (!wiki_user_can_view($subwiki, $wiki)) {

            throw new moodle_exception('cannotviewpage', 'wiki');

        }

        $returnedpage = array();

        $returnedpage['id'] = $page->id;

        $returnedpage['wikiid'] = $wiki->id;

        $returnedpage['subwikiid'] = $page->subwikiid;

        $returnedpage['groupid'] = $subwiki->groupid;

        $returnedpage['userid'] = $subwiki->userid;

        $returnedpage['title'] = $page->title;

        $returnedpage['tags'] = \core_tag\external\util::get_item_tags('mod_wiki', 'wiki_pages', $page->id);

        // Refresh page cached content if needed.

        if ($page->timerendered + WIKI_REFRESH_CACHE_TIME < time()) {

            if ($content = wiki_refresh_cachedcontent($page)) {

                $page = $content['page'];

            }

        }

        list($returnedpage['cachedcontent'], $returnedpage['contentformat']) = \core_external\util::format_text(

            $page->cachedcontent,

            FORMAT_HTML,

            $context,

            'mod_wiki',

            'attachments',

            $subwiki->id

        );

        $returnedpage['caneditpage'] = wiki_user_can_edit($subwiki);

        // Get page version.

        $version = wiki_get_current_version($page->id);

        if (!empty($version)) {

            $returnedpage['version'] = $version->version;

        }

        $result = array();

        $result['page'] = $returnedpage;

        $result['warnings'] = $warnings;

        return $result;

    }

    /**

     * Describes the get_page_contents return value.

     *

     * @return external_single_structure

     * @since Moodle 3.1

     */

    public static function get_page_contents_returns() {

        return new external_single_structure(

            array(

                'page' => new external_single_structure(

                    array(

                        'id' => new external_value(PARAM_INT, 'Page ID.'),

                        'wikiid' => new external_value(PARAM_INT, 'Page\'s wiki ID.'),

                        'subwikiid' => new external_value(PARAM_INT, 'Page\'s subwiki ID.'),

                        'groupid' => new external_value(PARAM_INT, 'Page\'s group ID.'),

                        'userid' => new external_value(PARAM_INT, 'Page\'s user ID.'),

                        'title' => new external_value(PARAM_RAW, 'Page title.'),

                        'cachedcontent' => new external_value(PARAM_RAW, 'Page contents.'),

                        'contentformat' => new external_format_value('cachedcontent', VALUE_OPTIONAL),

                        'caneditpage' => new external_value(PARAM_BOOL, 'True if user can edit the page.'),

                        'version' => new external_value(PARAM_INT, 'Latest version of the page.', VALUE_OPTIONAL),

                        'tags' => new external_multiple_structure(

                            \core_tag\external\tag_item_exporter::get_read_structure(), 'Tags', VALUE_OPTIONAL

                        ),

                    ), 'Page'

                ),

                'warnings' => new external_warnings()

            )

        );

    }

    /**

     * Describes the parameters for get_subwiki_files.

     *

     * @return external_function_parameters

     * @since Moodle 3.1

     */

    public static function get_subwiki_files_parameters() {

        return new external_function_parameters (

            array(

                'wikiid' => new external_value(PARAM_INT, 'Wiki instance ID.'),

                'groupid' => new external_value(PARAM_INT, 'Subwiki\'s group ID, -1 means current group. It will be ignored'

                                        . ' if the wiki doesn\'t use groups.', VALUE_DEFAULT, -1),

                'userid' => new external_value(PARAM_INT, 'Subwiki\'s user ID, 0 means current user. It will be ignored'

                                        .' in collaborative wikis.', VALUE_DEFAULT, 0)

            )

        );

    }

    /**

     * Returns the list of files from a specific subwiki.

     *

     * @param int $wikiid The wiki instance ID.

     * @param int $groupid The group ID. If not defined, use current group.

     * @param int $userid The user ID. If not defined, use current user.

     * @return array Containing a list of warnings and a list of files.

     * @since Moodle 3.1

     * @throws moodle_exception

     */

    public static function get_subwiki_files($wikiid, $groupid = -1, $userid = 0) {

        $returnedfiles = array();

        $warnings = array();

        $params = self::validate_parameters(self::get_subwiki_files_parameters(),

                                            array(

                                                'wikiid' => $wikiid,

                                                'groupid' => $groupid,

                                                'userid' => $userid

                                                )

            );

        // Get wiki instance.

        if (!$wiki = wiki_get_wiki($params['wikiid'])) {

            throw new moodle_exception('incorrectwikiid', 'wiki');

        }

        list($course, $cm) = get_course_and_cm_from_instance($wiki, 'wiki');

        $context = context_module::instance($cm->id);

        self::validate_context($context);

        // Determine groupid and userid to use.

        list($groupid, $userid) = self::determine_group_and_user($cm, $wiki, $params['groupid'], $params['userid']);

        // Get subwiki and validate it.

        $subwiki = wiki_get_subwiki_by_group_and_user_with_validation($wiki, $groupid, $userid);

        // Get subwiki based on group and user.

        if ($subwiki === false) {

            throw new moodle_exception('cannotviewfiles', 'wiki');

        } else if ($subwiki->id != -1) {

            // The subwiki exists, let's get the files.

            $returnedfiles = util::get_area_files($context->id, 'mod_wiki', 'attachments', $subwiki->id);

        }

        $result = array();

        $result['files'] = $returnedfiles;

        $result['warnings'] = $warnings;

        return $result;

    }

    /**

     * Describes the get_subwiki_pages return value.

     *

     * @return external_single_structure

     * @since Moodle 3.1

     */

    public static function get_subwiki_files_returns() {

        return new external_single_structure(

            array(

                'files' => new external_files('Files'),

                'warnings' => new external_warnings(),

            )

        );

    }

    /**

     * Utility function for determining the groupid and userid to use.

     *

     * @param stdClass $cm The course module.

     * @param stdClass $wiki The wiki.

     * @param int $groupid Group ID. If not defined, use current group.

     * @param int $userid User ID. If not defined, use current user.

     * @return array Array containing the courseid and userid.

     * @since  Moodle 3.1

     */

    protected static function determine_group_and_user($cm, $wiki, $groupid = -1, $userid = 0) {

        global $USER;

        $currentgroup = groups_get_activity_group($cm);

        if ($currentgroup === false) {

            // Activity doesn't use groups.

            $groupid = 0;

        } else if ($groupid == -1) {

            // Use current group.

            $groupid = !empty($currentgroup) ? $currentgroup : 0;

        }

        // Determine user.

        if ($wiki->wikimode == 'collaborative') {

            // Collaborative wikis don't use userid in subwikis.

            $userid = 0;

        } else if (empty($userid)) {

            // Use current user.

            $userid = $USER->id;

        }

        return array($groupid, $userid);

    }

    /**

     * Describes the parameters for get_page_for_editing.

     *

     * @return external_function_parameters

     * @since Moodle 3.1

     */

    public static function get_page_for_editing_parameters() {

        return new external_function_parameters (

            array(

                'pageid' => new external_value(PARAM_INT, 'Page ID to edit.'),

                'section' => new external_value(PARAM_RAW, 'Section page title.', VALUE_DEFAULT, null),

                'lockonly' => new external_value(PARAM_BOOL, 'Just renew lock and not return content.', VALUE_DEFAULT, false)

            )

        );

    }

    /**

     * Locks and retrieves info of page-section to be edited.

     *

     * @param int $pageid The page ID.

     * @param string $section Section page title.

     * @param boolean $lockonly If true: Just renew lock and not return content.

     * @return array of warnings and page data.

     * @since Moodle 3.1

     */

    public static function get_page_for_editing($pageid, $section = null, $lockonly = false) {

        global $USER;

        $params = self::validate_parameters(self::get_page_for_editing_parameters(),

                                            array(

                                                'pageid' => $pageid,

                                                'section' => $section,

                                                'lockonly' => $lockonly

                                            )

            );

        $warnings = array();

        // Get wiki page.

        if (!$page = wiki_get_page($params['pageid'])) {

            throw new moodle_exception('incorrectpageid', 'wiki');

        }

        // Get wiki instance.

        if (!$wiki = wiki_get_wiki_from_pageid($params['pageid'])) {

            throw new moodle_exception('incorrectwikiid', 'wiki');

        }

        // Get subwiki instance.

        if (!$subwiki = wiki_get_subwiki($page->subwikiid)) {

            throw new moodle_exception('incorrectsubwikiid', 'wiki');

        }

        // Permission validation.

        $cm = get_coursemodule_from_instance('wiki', $wiki->id, $wiki->course);

        $context = context_module::instance($cm->id);

        self::validate_context($context);

        if (!wiki_user_can_edit($subwiki)) {

            throw new moodle_exception('cannoteditpage', 'wiki');

        }

        if (!wiki_set_lock($params['pageid'], $USER->id, $params['section'], true)) {

            throw new moodle_exception('pageislocked', 'wiki');

        }

        $version = wiki_get_current_version($page->id);

        if (empty($version)) {

            throw new moodle_exception('versionerror', 'wiki');

        }

        $pagesection = array();

        $pagesection['version'] = $version->version;

        // Content requested to be returned.

        if (!$lockonly) {

            if (!is_null($params['section'])) {

                $content = wiki_parser_proxy::get_section($version->content, $version->contentformat, $params['section']);

            } else {

                $content = $version->content;

            }

            $pagesection['content'] = $content;

            $pagesection['contentformat'] = $version->contentformat;

        }

        $result = array();

        $result['pagesection'] = $pagesection;

        $result['warnings'] = $warnings;

        return $result;

    }

    /**

     * Describes the get_page_for_editing return value.

     *

     * @return external_single_structure

     * @since Moodle 3.1

     */

    public static function get_page_for_editing_returns() {

        return new external_single_structure(

            array(

                'pagesection' => new external_single_structure(

                    array(

                        'content' => new external_value(PARAM_RAW, 'The contents of the page-section to be edited.',

                            VALUE_OPTIONAL),

                        'contentformat' => new external_value(PARAM_TEXT, 'Format of the original content of the page.',

                            VALUE_OPTIONAL),

                        'version' => new external_value(PARAM_INT, 'Latest version of the page.'),

                        'warnings' => new external_warnings()

                    )

                )

            )

        );

    }

    /**

     * Describes the parameters for new_page.

     *

     * @return external_function_parameters

     * @since Moodle 3.1

     */

    public static function new_page_parameters() {

        return new external_function_parameters (

            array(

                'title' => new external_value(PARAM_TEXT, 'New page title.'),

                'content' => new external_value(PARAM_RAW, 'Page contents.'),

                'contentformat' => new external_value(PARAM_TEXT, 'Page contents format. If an invalid format is provided, default

                    wiki format is used.', VALUE_DEFAULT, null),

                'subwikiid' => new external_value(PARAM_INT, 'Page\'s subwiki ID.', VALUE_DEFAULT, null),

                'wikiid' => new external_value(PARAM_INT, 'Page\'s wiki ID. Used if subwiki does not exists.', VALUE_DEFAULT,

                    null),

                'userid' => new external_value(PARAM_INT, 'Subwiki\'s user ID. Used if subwiki does not exists.', VALUE_DEFAULT,

                    null),

                'groupid' => new external_value(PARAM_INT, 'Subwiki\'s group ID. Used if subwiki does not exists.', VALUE_DEFAULT,

                    null)

            )

        );

    }

    /**

     * Creates a new page.

     *

     * @param string $title New page title.

     * @param string $content Page contents.

     * @param int $contentformat Page contents format. If an invalid format is provided, default wiki format is used.

     * @param int $subwikiid The Subwiki ID where to store the page.

     * @param int $wikiid Page\'s wiki ID. Used if subwiki does not exists.

     * @param int $userid Subwiki\'s user ID. Used if subwiki does not exists.

     * @param int $groupid Subwiki\'s group ID. Used if subwiki does not exists.

     * @return array of warnings and page data.

     * @since Moodle 3.1

     */

    public static function new_page($title, $content, $contentformat = null, $subwikiid = null, $wikiid = null, $userid = null,

        $groupid = null) {

        global $USER;

        $params = self::validate_parameters(self::new_page_parameters(),

                                            array(

                                                'title' => $title,

                                                'content' => $content,

                                                'contentformat' => $contentformat,

                                                'subwikiid' => $subwikiid,

                                                'wikiid' => $wikiid,

                                                'userid' => $userid,

                                                'groupid' => $groupid

                                            )

            );

        $warnings = array();

        // Get wiki and subwiki instances.

        if (!empty($params['subwikiid'])) {

            if (!$subwiki = wiki_get_subwiki($params['subwikiid'])) {

                throw new moodle_exception('incorrectsubwikiid', 'wiki');

            }

            if (!$wiki = wiki_get_wiki($subwiki->wikiid)) {

                throw new moodle_exception('incorrectwikiid', 'wiki');

            }

            // Permission validation.

            $cm = get_coursemodule_from_instance('wiki', $wiki->id, $wiki->course);

            $context = context_module::instance($cm->id);

            self::validate_context($context);

        } else {

            if (!$wiki = wiki_get_wiki($params['wikiid'])) {

                throw new moodle_exception('incorrectwikiid', 'wiki');

            }

            // Permission validation.

            $cm = get_coursemodule_from_instance('wiki', $wiki->id, $wiki->course);

            $context = context_module::instance($cm->id);

            self::validate_context($context);

            // Determine groupid and userid to use.

            list($groupid, $userid) = self::determine_group_and_user($cm, $wiki, $params['groupid'], $params['userid']);