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/>.

/**

 * This is the external API for this tool.

 *

 * @package    tool_mobile

 * @copyright  2016 Juan Leyva

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

 */

namespace tool_mobile;

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

require_once("$CFG->dirroot/webservice/lib.php");

use core_external\external_api;

use core_external\external_files;

use core_external\external_function_parameters;

use core_external\external_multiple_structure;

use core_external\external_single_structure;

use core_external\external_settings;

use core_external\external_value;

use core_external\external_warnings;

use context_system;

use moodle_exception;

use moodle_url;

use core_user;

use coding_exception;

/**

 * This is the external API for this tool.

 *

 * @copyright  2016 Juan Leyva

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

 */

class external extends external_api {

    /**

     * Returns description of get_plugins_supporting_mobile() parameters.

     *

     * @return external_function_parameters

     * @since  Moodle 3.1

     */

    public static function get_plugins_supporting_mobile_parameters() {

        return new external_function_parameters(array());

    }

    /**

     * Returns a list of Moodle plugins supporting the mobile app.

     *

     * @return array an array of warnings and objects containing the plugin information

     * @since  Moodle 3.1

     */

    public static function get_plugins_supporting_mobile() {

        return array(

            'plugins' => api::get_plugins_supporting_mobile(),

            'warnings' => array(),

        );

    }

    /**

     * Returns description of get_plugins_supporting_mobile() result value.

     *

     * @return \core_external\external_description

     * @since  Moodle 3.1

     */

    public static function get_plugins_supporting_mobile_returns() {

        return new external_single_structure(

            array(

                'plugins' => new external_multiple_structure(

                    new external_single_structure(

                        array(

                            'component' => new external_value(PARAM_COMPONENT, 'The plugin component name.'),

                            'version' => new external_value(PARAM_NOTAGS, 'The plugin version number.'),

                            'addon' => new external_value(PARAM_COMPONENT, 'The Mobile addon (package) name.'),

                            'dependencies' => new external_multiple_structure(

                                                new external_value(PARAM_COMPONENT, 'Mobile addon name.'),

                                                'The list of Mobile addons this addon depends on.'

                                               ),

                            'fileurl' => new external_value(PARAM_URL, 'The addon package url for download

                                                            or empty if it doesn\'t exist.'),

                            'filehash' => new external_value(PARAM_RAW, 'The addon package hash or empty if it doesn\'t exist.'),

                            'filesize' => new external_value(PARAM_INT, 'The addon package size or empty if it doesn\'t exist.'),

                            'handlers' => new external_value(PARAM_RAW, 'Handlers definition (JSON)', VALUE_OPTIONAL),

                            'lang' => new external_value(PARAM_RAW, 'Language strings used by the handlers (JSON)', VALUE_OPTIONAL),

                        )

                    )

                ),

                'warnings' => new external_warnings(),

            )

        );

    }

    /**

     * Returns description of get_public_config() parameters.

     *

     * @return external_function_parameters

     * @since  Moodle 3.2

     */

    public static function get_public_config_parameters() {

        return new external_function_parameters(array());

    }

    /**

     * Returns a list of the site public settings, those not requiring authentication.

     *

     * @return array with the settings and warnings

     * @since  Moodle 3.2

     */

    public static function get_public_config() {

        $result = api::get_public_config();

        $result['warnings'] = array();

        return $result;

    }

    /**

     * Returns description of get_public_config() result value.

     *

     * @return \core_external\external_description

     * @since  Moodle 3.2

     */

    public static function get_public_config_returns() {

        return new external_single_structure(

            array(

                'wwwroot' => new external_value(PARAM_RAW, 'Site URL.'),

                'httpswwwroot' => new external_value(PARAM_RAW, 'Site https URL (if httpslogin is enabled).'),

                'sitename' => new external_value(PARAM_RAW, 'Site name.'),

                'guestlogin' => new external_value(PARAM_INT, 'Whether guest login is enabled.'),

                'rememberusername' => new external_value(PARAM_INT, 'Values: 0 for No, 1 for Yes, 2 for optional.'),

                'authloginviaemail' => new external_value(PARAM_INT, 'Whether log in via email is enabled.'),

                'registerauth' => new external_value(PARAM_PLUGIN, 'Authentication method for user registration.'),

                'forgottenpasswordurl' => new external_value(PARAM_URL, 'Forgotten password URL.'),

                'authinstructions' => new external_value(PARAM_RAW, 'Authentication instructions.'),

                'authnoneenabled' => new external_value(PARAM_INT, 'Whether auth none is enabled.'),

                'enablewebservices' => new external_value(PARAM_INT, 'Whether Web Services are enabled.'),

                'enablemobilewebservice' => new external_value(PARAM_INT, 'Whether the Mobile service is enabled.'),

                'maintenanceenabled' => new external_value(PARAM_INT, 'Whether site maintenance is enabled.'),

                'maintenancemessage' => new external_value(PARAM_RAW, 'Maintenance message.'),

                'logourl' => new external_value(PARAM_URL, 'The site logo URL', VALUE_OPTIONAL),

                'compactlogourl' => new external_value(PARAM_URL, 'The site compact logo URL', VALUE_OPTIONAL),

                'typeoflogin' => new external_value(PARAM_INT, 'The type of login. 1 for app, 2 for browser, 3 for embedded.'),

                'launchurl' => new external_value(PARAM_URL, 'SSO login launch URL.', VALUE_OPTIONAL),

                'mobilecssurl' => new external_value(PARAM_URL, 'Mobile custom CSS theme', VALUE_OPTIONAL),

                'tool_mobile_disabledfeatures' => new external_value(PARAM_RAW, 'Disabled features in the app', VALUE_OPTIONAL),

                'identityproviders' => new external_multiple_structure(

                    new external_single_structure(

                        array(

                            'name' => new external_value(PARAM_TEXT, 'The identity provider name.'),

                            'iconurl' => new external_value(PARAM_URL, 'The icon URL for the provider.'),

                            'url' => new external_value(PARAM_URL, 'The URL of the provider.'),

                        )

                    ),

                    'Identity providers', VALUE_OPTIONAL

                ),

                'country' => new external_value(PARAM_NOTAGS, 'Default site country', VALUE_OPTIONAL),

                'agedigitalconsentverification' => new external_value(PARAM_BOOL, 'Whether age digital consent verification

                    is enabled.', VALUE_OPTIONAL),

                'supportname' => new external_value(PARAM_NOTAGS, 'Site support contact name

                    (only if age verification is enabled).', VALUE_OPTIONAL),

                'supportemail' => new external_value(PARAM_EMAIL, 'Site support contact email

                    (only if age verification is enabled).', VALUE_OPTIONAL),

                'supportpage' => new external_value(PARAM_URL, 'Site support page link.', VALUE_OPTIONAL),

                'supportavailability' => new external_value(PARAM_INT, 'Determines who has access to contact site support.',

                    VALUE_OPTIONAL),

                'autolang' => new external_value(PARAM_INT, 'Whether to detect default language

                    from browser setting.', VALUE_OPTIONAL),

                'lang' => new external_value(PARAM_LANG, 'Default language for the site.', VALUE_OPTIONAL),

                'langmenu' => new external_value(PARAM_INT, 'Whether the language menu should be displayed.', VALUE_OPTIONAL),

                'langlist' => new external_value(PARAM_RAW, 'Languages on language menu.', VALUE_OPTIONAL),

                'locale' => new external_value(PARAM_RAW, 'Sitewide locale.', VALUE_OPTIONAL),

                'tool_mobile_minimumversion' => new external_value(PARAM_NOTAGS, 'Minimum required version to access.',

                    VALUE_OPTIONAL),

                'tool_mobile_iosappid' => new external_value(PARAM_ALPHANUM, 'iOS app\'s unique identifier.',

                    VALUE_OPTIONAL),

                'tool_mobile_androidappid' => new external_value(PARAM_NOTAGS, 'Android app\'s unique identifier.',

                    VALUE_OPTIONAL),

                'tool_mobile_setuplink' => new external_value(PARAM_URL, 'App download page.', VALUE_OPTIONAL),

                'tool_mobile_qrcodetype' => new external_value(PARAM_INT, 'QR login configuration.', VALUE_OPTIONAL),

                'warnings' => new external_warnings(),

                'showloginform' => new external_value(PARAM_INT, 'Display default login form.'),

            )

        );

    }

    /**

     * Returns description of get_config() parameters.

     *

     * @return external_function_parameters

     * @since  Moodle 3.2

     */

    public static function get_config_parameters() {

        return new external_function_parameters(

            array(

                'section' => new external_value(PARAM_ALPHANUMEXT, 'Settings section name.', VALUE_DEFAULT, ''),

            )

        );

    }

    /**

     * Returns a list of site settings, filtering by section.

     *

     * @param string $section settings section name

     * @return array with the settings and warnings

     * @since  Moodle 3.2

     */

    public static function get_config($section = '') {

        $params = self::validate_parameters(self::get_config_parameters(), array('section' => $section));

        $settings = api::get_config($params['section']);

        $result['settings'] = array();

        foreach ($settings as $name => $value) {

            $result['settings'][] = array(

                'name' => $name,

                'value' => $value,

            );

        }

        $result['warnings'] = array();

        return $result;

    }

    /**

     * Returns description of get_config() result value.

     *

     * @return \core_external\external_description

     * @since  Moodle 3.2

     */

    public static function get_config_returns() {

        return new external_single_structure(

            array(

                'settings' => new external_multiple_structure(

                    new external_single_structure(

                        array(

                            'name' => new external_value(PARAM_RAW, 'The name of the setting'),

                            'value' => new external_value(PARAM_RAW, 'The value of the setting'),

                        )

                    ),

                    'Settings'

                ),

                'warnings' => new external_warnings(),

            )

        );

    }

    /**

     * Returns description of get_autologin_key() parameters.

     *

     * @return external_function_parameters

     * @since  Moodle 3.2

     */

    public static function get_autologin_key_parameters() {

        return new external_function_parameters (

            array(

                'privatetoken' => new external_value(PARAM_ALPHANUM, 'Private token, usually generated by login/token.php'),

            )

        );

    }

    /**

     * Creates an auto-login key for the current user. Is created only in https sites and is restricted by time and ip address.

     *

     * Please note that it only works if the request comes from the Moodle mobile or desktop app.

     *

     * @param string $privatetoken the user private token for validating the request

     * @return array with the settings and warnings

     * @since  Moodle 3.2

     */

    public static function get_autologin_key($privatetoken) {

        global $CFG, $DB, $USER;

        $params = self::validate_parameters(self::get_autologin_key_parameters(), array('privatetoken' => $privatetoken));

        $privatetoken = $params['privatetoken'];

        $context = context_system::instance();

        // We must toletare these two exceptions: forcepasswordchangenotice and usernotfullysetup.

        try {

            self::validate_context($context);

        } catch (moodle_exception $e) {

            if ($e->errorcode != 'usernotfullysetup' && $e->errorcode != 'forcepasswordchangenotice') {

                // In case we receive a different exception, throw it.

                throw $e;

            }

        }

        // Only requests from the Moodle mobile or desktop app. This enhances security to avoid any type of XSS attack.

        // This code goes intentionally here and not inside the check_autologin_prerequisites() function because it

        // is used by other PHP scripts that can be opened in any browser.

        if (!\core_useragent::is_moodle_app()) {

            throw new moodle_exception('apprequired', 'tool_mobile');

        }

        api::check_autologin_prerequisites($USER->id);

        if (isset($_GET['privatetoken']) or empty($privatetoken)) {

            throw new moodle_exception('invalidprivatetoken', 'tool_mobile');

        }

        // Check the request counter, we must limit the number of times the privatetoken is sent.

        // Between each request 6 minutes are required.

        $last = get_user_preferences('tool_mobile_autologin_request_last', 0, $USER);

        // Check if we must reset the count.

        $mintimereq = get_config('tool_mobile', 'autologinmintimebetweenreq');

        $mintimereq = empty($mintimereq) ? 6 * MINSECS : $mintimereq;

        $timenow = time();

        if ($timenow - $last < $mintimereq) {

            $minutes = $mintimereq / MINSECS;

            throw new moodle_exception('autologinkeygenerationlockout', 'tool_mobile', '', $minutes);

        }

        set_user_preference('tool_mobile_autologin_request_last', $timenow, $USER);

        // We are expecting a privatetoken linked to the current token being used.

        // This WS is only valid when using mobile services via REST (this is intended).

        $currenttoken = required_param('wstoken', PARAM_ALPHANUM);

        $conditions = array(

            'userid' => $USER->id,

            'token' => $currenttoken,

            'privatetoken' => $privatetoken,

        );

        if (!$token = $DB->get_record('external_tokens', $conditions)) {

            throw new moodle_exception('invalidprivatetoken', 'tool_mobile');

        }

        $result = array();

        $result['key'] = api::get_autologin_key();

        $autologinurl = new moodle_url("/$CFG->admin/tool/mobile/autologin.php");

        $result['autologinurl'] = $autologinurl->out(false);

        $result['warnings'] = array();

        return $result;

    }

    /**

     * Returns description of get_autologin_key() result value.

     *

     * @return \core_external\external_description

     * @since  Moodle 3.2

     */

    public static function get_autologin_key_returns() {

        return new external_single_structure(

            array(

                'key' => new external_value(PARAM_ALPHANUMEXT, 'Auto-login key for a single usage with time expiration.'),

                'autologinurl' => new external_value(PARAM_URL, 'Auto-login URL.'),

                'warnings' => new external_warnings(),

            )

        );

    }

    /**

     * Returns description of get_content() parameters

     *

     * @return external_function_parameters

     * @since Moodle 3.5

     */

    public static function get_content_parameters() {

        return new external_function_parameters(

            array(

                'component' => new external_value(PARAM_COMPONENT, 'Component where the class is e.g. mod_assign.'),

                'method' => new external_value(PARAM_ALPHANUMEXT, 'Method to execute in class \$component\output\mobile.'),

                'args' => new external_multiple_structure(

                    new external_single_structure(

                        array(

                            'name' => new external_value(PARAM_ALPHANUMEXT, 'Param name.'),

                            'value' => new external_value(PARAM_RAW, 'Param value.')

                        )

                    ), 'Args for the method are optional.', VALUE_OPTIONAL

                )

            )

        );

    }

    /**

     * Returns a piece of content to be displayed in the Mobile app, it usually returns a template, javascript and

     * other structured data that will be used to render a view in the Mobile app.

     *

     * Callbacks (placed in \$component\output\mobile) that are called by this web service are responsible for doing the

     * appropriate security checks to access the information to be returned.

     *

     * @param string $component name of the component.

     * @param string $method function method name in class \$component\output\mobile.

     * @param array $args optional arguments for the method.

     * @return array HTML, JavaScript and other required data and information to create a view in the app.

     * @since Moodle 3.5

     * @throws coding_exception

     */

    public static function get_content($component, $method, $args = array()) {

        global $OUTPUT, $PAGE, $USER;

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

            array(

                'component' => $component,

                'method' => $method,

                'args' => $args

            )

        );

        // Reformat arguments into something less unwieldy.

        $arguments = array();

        foreach ($params['args'] as $paramargument) {

            $arguments[$paramargument['name']] = $paramargument['value'];

        }

        // The component was validated via the PARAM_COMPONENT parameter type.

        $classname = '\\' . $params['component'] .'\output\mobile';

        if (!method_exists($classname, $params['method'])) {

            throw new coding_exception("Missing method in $classname");

        }

        $result = call_user_func_array(array($classname, $params['method']), array($arguments));

        // Populate otherdata.

        $otherdata = array();

        if (!empty($result['otherdata'])) {

            $result['otherdata'] = (array) $result['otherdata'];

            foreach ($result['otherdata'] as $name => $value) {

                $otherdata[] = array(

                    'name' => $name,

                    'value' => $value

                );

            }

        }

        return array(

            'templates'  => !empty($result['templates']) ? $result['templates'] : array(),

            'javascript' => !empty($result['javascript']) ? $result['javascript'] : '',

            'otherdata'  => $otherdata,

            'files'      => !empty($result['files']) ? $result['files'] : array(),

            'restrict'   => !empty($result['restrict']) ? $result['restrict'] : array(),

            'disabled'   => !empty($result['disabled']) ? true : false,

        );

    }

    /**

     * Returns description of get_content() result value

     *

     * @return array

     * @since Moodle 3.5

     */

    public static function get_content_returns() {

        return new external_single_structure(

            array(

                'templates' => new external_multiple_structure(

                    new external_single_structure(

                        array(

                            'id' => new external_value(PARAM_TEXT, 'ID of the template.'),

                            'html' => new external_value(PARAM_RAW, 'HTML code.'),

                        )

                    ),

                    'Templates required by the generated content.'

                ),

                'javascript' => new external_value(PARAM_RAW, 'JavaScript code.'),

                'otherdata' => new external_multiple_structure(

                    new external_single_structure(

                        array(

                            'name' => new external_value(PARAM_RAW, 'Field name.'),

                            'value' => new external_value(PARAM_RAW, 'Field value.')

                        )

                    ),

                    'Other data that can be used or manipulated by the template via 2-way data-binding.'

                ),

                'files' => new external_files('Files in the content.'),

                'restrict' => new external_single_structure(

                    array(

                        'users' => new external_multiple_structure(

                            new external_value(PARAM_INT, 'user id'), 'List of allowed users.', VALUE_OPTIONAL

                        ),

                        'courses' => new external_multiple_structure(

                            new external_value(PARAM_INT, 'course id'), 'List of allowed courses.', VALUE_OPTIONAL

                        ),

                    ),

                    'Restrict this content to certain users or courses.'

                ),

                'disabled' => new external_value(PARAM_BOOL, 'Whether we consider this disabled or not.', VALUE_OPTIONAL),

            )

        );

    }

    /**

     * Returns description of method parameters

     *

     * @return external_function_parameters

     * @since Moodle 3.7

     */

    public static function call_external_functions_parameters() {

        return new external_function_parameters([

            'requests' => new external_multiple_structure(

                new external_single_structure([

                    'function' => new external_value(PARAM_ALPHANUMEXT, 'Function name'),

                    'arguments' => new external_value(PARAM_RAW, 'JSON-encoded object with named arguments', VALUE_DEFAULT, '{}'),

                    'settingraw' => new external_value(PARAM_BOOL, 'Return raw text', VALUE_DEFAULT, false),

                    'settingfilter' => new external_value(PARAM_BOOL, 'Filter text', VALUE_DEFAULT, false),

                    'settingfileurl' => new external_value(PARAM_BOOL, 'Rewrite plugin file URLs', VALUE_DEFAULT, true),

                    'settinglang' => new external_value(PARAM_LANG, 'Session language', VALUE_DEFAULT, ''),

                ])

            )

        ]);

    }

    /**

     * Call multiple external functions and return all responses.

     *

     * @param array $requests List of requests.

     * @return array Responses.

     * @since Moodle 3.7

     */

    public static function call_external_functions($requests) {

        global $SESSION;

        $params = self::validate_parameters(self::call_external_functions_parameters(), ['requests' => $requests]);

        // We need to check if the functions being called are included in the service of the current token.

        // This function only works when using mobile services via REST (this is intended).

        $webservicemanager = new \webservice;

        $token = $webservicemanager->get_user_ws_token(required_param('wstoken', PARAM_ALPHANUM));

        $settings = external_settings::get_instance();

        $defaultlang = current_language();

        $responses = [];

        foreach ($params['requests'] as $request) {

            // Some external functions modify _GET or $_POST data, we need to restore the original data after each call.

            $originalget = fullclone($_GET);

            $originalpost = fullclone($_POST);

            // Set external settings and language.

            $settings->set_raw($request['settingraw']);

            $settings->set_filter($request['settingfilter']);

            $settings->set_fileurl($request['settingfileurl']);

            $settings->set_lang($request['settinglang']);

            $SESSION->lang = $request['settinglang'] ?: $defaultlang;

            // Parse arguments to an array, validation is done in external_api::call_external_function.

            $args = @json_decode($request['arguments'], true);

            if (!is_array($args)) {

                $args = [];

            }

            if ($webservicemanager->service_function_exists($request['function'], $token->externalserviceid)) {

                $response = external_api::call_external_function($request['function'], $args, false);

            } else {

                // Function not included in the service, return an access exception.

                $response = [

                    'error' => true,

                    'exception' => [

                        'errorcode' => 'accessexception',

                        'module' => 'webservice'

                    ]

                ];

                if (debugging('', DEBUG_DEVELOPER)) {

                    $response['exception']['debuginfo'] = 'Access to the function is not allowed.';

                }

            }

            if (isset($response['data'])) {

                $response['data'] = json_encode($response['data']);

            }

            if (isset($response['exception'])) {

                $response['exception'] = json_encode($response['exception']);

            }

            $responses[] = $response;

            // Restore original $_GET and $_POST.

            $_GET = $originalget;

            $_POST = $originalpost;

            if ($response['error']) {

                // Do not process the remaining requests.

                break;

            }

        }

        return ['responses' => $responses];

    }

    /**

     * Returns description of method result value

     *

     * @return external_single_structure

     * @since Moodle 3.7

     */

    public static function call_external_functions_returns() {

        return new external_function_parameters([

            'responses' => new external_multiple_structure(

                new external_single_structure([

                    'error' => new external_value(PARAM_BOOL, 'Whether an exception was thrown.'),

                    'data' => new external_value(PARAM_RAW, 'JSON-encoded response data', VALUE_OPTIONAL),

                    'exception' => new external_value(PARAM_RAW, 'JSON-encoed exception info', VALUE_OPTIONAL),

                ])

             )

        ]);

    }

    /**

     * Returns description of get_tokens_for_qr_login() parameters.

     *

     * @return external_function_parameters

     * @since  Moodle 3.9

     */

    public static function get_tokens_for_qr_login_parameters() {

        return new external_function_parameters (

            [

                'qrloginkey' => new external_value(PARAM_ALPHANUMEXT, 'The user key for validating the request.'),

                'userid' => new external_value(PARAM_INT, 'The user the key belongs to.'),

            ]

        );

    }

    /**

     * Returns a WebService token (and private token) for QR login

     *

     * @param string $qrloginkey the user key generated and embedded into the QR code for validating the request

     * @param int $userid the user the key belongs to

     * @return array with the tokens and warnings

     * @since  Moodle 3.9

     */

    public static function get_tokens_for_qr_login($qrloginkey, $userid) {

        global $PAGE, $DB;

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

            ['qrloginkey' => $qrloginkey, 'userid' => $userid]);

        $context = context_system::instance();

        // We need this to make work the format text functions.

        $PAGE->set_context($context);

        $qrcodetype = get_config('tool_mobile', 'qrcodetype');

        if ($qrcodetype != api::QR_CODE_LOGIN) {

            throw new moodle_exception('qrcodedisabled', 'tool_mobile');

        }

        // Only requests from the Moodle mobile or desktop app. This enhances security to avoid any type of XSS attack.

        // This code goes intentionally here and not inside the check_autologin_prerequisites() function because it

        // is used by other PHP scripts that can be opened in any browser.

        if (!\core_useragent::is_moodle_app()) {

            throw new moodle_exception('apprequired', 'tool_mobile');

        }

        api::check_autologin_prerequisites($params['userid']);  // Checks https, avoid site admins using this...

        // Validate and delete the key.

        $key = validate_user_key($params['qrloginkey'], 'tool_mobile/qrlogin', null);

        delete_user_key('tool_mobile/qrlogin', $params['userid']);

        // Double check key belong to user.

        if ($key->userid != $params['userid']) {

            throw new moodle_exception('invalidkey');

        }

        // Key validated, check user.

        $user = core_user::get_user($key->userid, '*', MUST_EXIST);

        core_user::require_active_user($user, true, true);

        // Generate WS tokens.

        \core\session\manager::set_user($user);

        // Check if the service exists and is enabled.

        $service = $DB->get_record('external_services', ['shortname' => MOODLE_OFFICIAL_MOBILE_SERVICE, 'enabled' => 1]);

        if (empty($service)) {

            // will throw exception if no token found

            throw new moodle_exception('servicenotavailable', 'webservice');

        }

        // Get an existing token or create a new one.

        $token = \core_external\util::generate_token_for_current_user($service);

        $privatetoken = $token->privatetoken; // Save it here, the next function removes it.

        \core_external\util::log_token_request($token);

        $result = [

            'token' => $token->token,

            'privatetoken' => $privatetoken ?: '',

            'warnings' => [],

        ];

        return $result;

    }

    /**

     * Returns description of get_tokens_for_qr_login() result value.

     *

     * @return \core_external\external_description

     * @since  Moodle 3.9

     */

    public static function get_tokens_for_qr_login_returns() {

        return new external_single_structure(

            [

                'token' => new external_value(PARAM_ALPHANUM, 'A valid WebService token for the official mobile app service.'),

                'privatetoken' => new external_value(PARAM_ALPHANUM, 'Private token used for auto-login processes.'),

                'warnings' => new external_warnings(),

            ]

        );

    }

    /**

     * Returns description of validate_subscription_key() parameters.

     *

     * @return external_function_parameters

     * @since  Moodle 3.9

     */

    public static function validate_subscription_key_parameters() {

        return new external_function_parameters(

            [

                'key' => new external_value(PARAM_RAW, 'Site subscription temporary key.'),

            ]

        );

    }

    /**

     * Check if the given site subscription key is valid

     *

     * @param string $key subscriptiion temporary key

     * @return array with the settings and warnings

     * @since  Moodle 3.9

     */

    public static function validate_subscription_key(string $key): array {

        global $CFG, $PAGE;

        $params = self::validate_parameters(self::validate_subscription_key_parameters(), ['key' => $key]);

        $context = context_system::instance();

        $PAGE->set_context($context);

        $validated = false;

        $sitesubscriptionkey = get_config('tool_mobile', 'sitesubscriptionkey');

        if (!empty($sitesubscriptionkey) && $CFG->enablemobilewebservice && empty($CFG->disablemobileappsubscription)) {

            $sitesubscriptionkey = json_decode($sitesubscriptionkey);

            $validated = time() < $sitesubscriptionkey->validuntil && $params['key'] === $sitesubscriptionkey->key;

            // Delete existing, even if not validated to enforce security and attacks prevention.

            unset_config('sitesubscriptionkey', 'tool_mobile');

        }

        return [

            'validated' => $validated,

            'warnings' => [],

        ];

    }

    /**

     * Returns description of validate_subscription_key() result value.

     *

     * @return \core_external\external_description

     * @since  Moodle 3.9

     */

    public static function validate_subscription_key_returns() {

        return new external_single_structure(

            [

                'validated' => new external_value(PARAM_BOOL, 'Whether the key is validated or not.'),

                'warnings' => new external_warnings(),

            ]

        );

    }

}