<?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/>.


< /**
<  * LTI Authentication plugin.
<  *
<  * @package auth_lti
<  * @copyright 2016 Mark Nelson <markn@moodle.com>
<  * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
<  */



> use auth_lti\local\ltiadvantage\entity\user_migration_claim;



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

require_once($CFG->libdir.'/authlib.php');

> require_once($CFG->libdir.'/accesslib.php');



/**
 * LTI Authentication plugin.
 *
 * @package auth_lti
 * @copyright 2016 Mark Nelson <markn@moodle.com>
 * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */

< class auth_plugin_lti extends auth_plugin_base {



> class auth_plugin_lti extends \auth_plugin_base {
> 
>     /**
>      * @var int constant representing the automatic account provisioning mode.
>      * On first launch, for a previously unbound user, this mode dictates that a new Moodle account will be created automatically
>      * for the user and bound to their platform credentials {iss, sub}.
>      */
>     public const PROVISIONING_MODE_AUTO_ONLY = 1;
> 
>     /**
>      * @var int constant representing the prompt for new or existing provisioning mode.
>      * On first launch, for a previously unbound user, the mode dictates that the launch user will be presented with an options
>      * view, allowing them to select either 'link an existing account' or 'create a new account for me'.
>      */
>     public const PROVISIONING_MODE_PROMPT_NEW_EXISTING = 2;
> 
>     /**
>      * @var int constant representing the prompt for existing only provisioning mode.
>      * On first launch, for a previously unbound user, the mode dictates that the launch user will be presented with a view allowing
>      * them to link an existing account only. This is useful for situations like deep linking, where an existing account is needed.
>      */
>     public const PROVISIONING_MODE_PROMPT_EXISTING_ONLY = 3;



    /**
     * Constructor.
     */
    public function __construct() {
        $this->authtype = 'lti';
    }

    /**
     * Users can not log in via the traditional login form.
     *
     * @param string $username The username
     * @param string $password The password
     * @return bool Authentication success or failure
     */
    public function user_login($username, $password) {
        return false;

>     }
    }
> 
}
>     /**
>      * Authenticate the user based on the unique {iss, sub} tuple present in the OIDC JWT.
>      *
>      * This method ensures a Moodle user account has been found or is created, that the user is linked to the relevant
>      * LTI Advantage credentials (iss, sub) and that the user account is logged in.
>      *
>      * Launch code can therefore rely on this method to get a session before doing things like calling require_login().
>      *
>      * This method supports two workflows:
>      * 1. Automatic account provisioning - where the complete_login() call will ALWAYS create/find a user and return to
>      * calling code directly. No user interaction is required.
>      *
>      * 2. Manual account provisioning - where the complete_login() call will redirect ONLY ONCE to a login page,
>      * where the user can decide whether to use an automatically provisioned account, or bind an existing user account.
>      * When the decision has been made, the relevant account is bound and the user is redirected back to $returnurl.
>      * Once an account has been bound via this selection process, subsequent calls to complete_login() will return to
>      * calling code directly. Any calling code must provide its $returnurl to support the return from the account
>      * selection process and must also take care to cache any JWT data appropriately, since the return will not inlude
>      * that information.
>      *
>      * Which workflow is chosen depends on the roles present in the JWT.
>      * For teachers/admins, manual provisioning will take place. These user type are likely to have existing accounts.
>      * For learners, automatic provisioning will take place.
>      *
>      * Migration of legacy users is supported, however, only for the Learner role (automatic provisioning). Admins and
>      * teachers are likely to have existing accounts and we want them to be able to select and bind these, rather than
>      * binding an automatically provisioned legacy account which doesn't represent their real user account.
>      *
>      * The JWT data must be verified elsewhere. The code here assumes its integrity/authenticity.
>      *
>      * @param array $launchdata the JWT data provided in the link launch.
>      * @param moodle_url $returnurl the local URL to return to if authentication workflows are required.
>      * @param int $provisioningmode the desired account provisioning mode, which controls the auth flow for unbound users.
>      * @param array $legacyconsumersecrets an array of secrets used by the legacy consumer if a migration claim exists.
>      * @throws coding_exception if the specified provisioning mode is invalid.
>      */
>     public function complete_login(array $launchdata, moodle_url $returnurl, int $provisioningmode,
>             array $legacyconsumersecrets = []): void {
> 
>         // The platform user is already linked with a user account.
>         if ($this->get_user_binding($launchdata['iss'], $launchdata['sub'])) {
>             // Always sync the PII, regardless of whether we're already authenticated as this user or not.
>             $user = $this->find_or_create_user_from_launch($launchdata, true);
> 
>             if (isloggedin()) {
>                 // If a different user is currently logged in, authenticate the linked user instead.
>                 global $USER;
>                 if ((int) $USER->id !== $user->id) {
>                     complete_user_login($user);
>                 }
>                 // If the linked user is already logged in, skip the call to complete_user_login() because this affects deep linking
>                 // workflows on sites publishing and consuming resources on the same site, due to the regenerated sesskey.
>                 return;
>             } else {
>                 complete_user_login($user);
>                 return;
>             }
>         }
> 
>         // The platform user is not bound to a user account, check provisioning mode now.
>         if (!$this->is_valid_provisioning_mode($provisioningmode)) {
>             throw new coding_exception('Invalid account provisioning mode provided to complete_login().');
>         }
> 
>         switch ($provisioningmode) {
>             case self::PROVISIONING_MODE_AUTO_ONLY:
>                 // Automatic provisioning - this will create/migrate a user account and log the user in.
>                 complete_user_login($this->find_or_create_user_from_launch($launchdata, true, $legacyconsumersecrets));
>                 break;
>             case self::PROVISIONING_MODE_PROMPT_NEW_EXISTING:
>             case self::PROVISIONING_MODE_PROMPT_EXISTING_ONLY:
>             default:
>                 // Allow linking an existing account or creation of a new account via an intermediate account options page.
>                 // Cache the relevant data and take the user to the account options page.
>                 // Note: This mode also depends on the global auth config 'authpreventaccountcreation'. If set, only existing
>                 // accounts can be bound in this provisioning mode.
>                 global $SESSION;
>                 $SESSION->auth_lti = (object)[
>                     'launchdata' => $launchdata,
>                     'returnurl' => $returnurl,
>                     'provisioningmode' => $provisioningmode
>                 ];
>                 redirect(new moodle_url('/auth/lti/login.php', [
>                     'sesskey' => sesskey(),
>                 ]));
>                 break;
>         }
>     }
> 
>     /**
>      * Get a Moodle user account for the LTI user based on the user details returned by a NRPS 2 membership call.
>      *
>      * This method expects a single member structure, in array format, as defined here:
>      * See: https://www.imsglobal.org/spec/lti-nrps/v2p0#membership-container-media-type.
>      *
>      * This method supports migration of user accounts used in legacy launches, provided the legacy consumerkey corresponding to
>      * to the legacy consumer is provided. Calling code will have verified the migration claim during initial launches and should
>      * have the consumer key mapped to the deployment, ready to pass in.
>      *
>      * @param array $member the member data, in array format.
>      * @param string $iss the issuer to which the member relates.
>      * @param string $legacyconsumerkey optional consumer key mapped to the deployment to facilitate user migration.
>      * @return stdClass a Moodle user record.
>      */
>     public function find_or_create_user_from_membership(array $member, string $iss,
>             string $legacyconsumerkey = ''): stdClass {
> 
>         // Picture is not synced with membership-based auths because sync tasks may wish to perform slow operations like this a
>         // different way.
>         unset($member['picture']);
> 
>         if ($binduser = $this->get_user_binding($iss, $member['user_id'])) {
>             $user = \core_user::get_user($binduser);
>             $this->update_user_account($user, $member, $iss);
>             return \core_user::get_user($user->id);
>         } else {
>             if (!empty($legacyconsumerkey)) {
>                 // Consumer key is required to attempt user migration because legacy users were identified by a
>                 // username consisting of the consumer key and user id.
>                 // See the legacy \enrol_lti\helper::create_username() for details.
>                 $legacyuserid = $member['lti11_legacy_user_id'] ?? $member['user_id'];
>                 $username = 'enrol_lti' .
>                     sha1($legacyconsumerkey . '::' . $legacyconsumerkey . ':' . $legacyuserid);
>                 if ($user = \core_user::get_user_by_username($username)) {
>                     $this->create_user_binding($iss, $member['user_id'], $user->id);
>                     $this->update_user_account($user, $member, $iss);
>                     return \core_user::get_user($user->id);
>                 }
>             }
>             $user = $this->create_new_account($member, $iss);
>             return \core_user::get_user($user->id);
>         }
>     }
> 
>     /**
>      * Get a Moodle user account for the LTI user corresponding to the user defined in a link launch.
>      *
>      * This method supports migration of user accounts used in legacy launches, provided the legacy consumer secrets corresponding
>      * to the legacy consumer are provided. If calling code wishes migration to be role-specific, it should check roles accordingly
>      * itself and pass relevant data in - as auth_plugin_lti::complete_login() does.
>      *
>      * @param array $launchdata all data in the decoded JWT including iss and sub.
>      * @param bool $syncpicture whether to sync the user's picture with the picture sent in the launch.
>      * @param array $legacyconsumersecrets all secrets found for the legacy consumer, facilitating user migration.
>      * @return stdClass the Moodle user who is mapped to the platform user identified in the JWT data.
>      */
>     public function find_or_create_user_from_launch(array $launchdata, bool $syncpicture = false,
>             array $legacyconsumersecrets = []): stdClass {
> 
>         if (!$syncpicture) {
>             unset($launchdata['picture']);
>         }
> 
>         if ($binduser = $this->get_user_binding($launchdata['iss'], $launchdata['sub'])) {
>             $user = \core_user::get_user($binduser);
>             $this->update_user_account($user, $launchdata, $launchdata['iss']);
>             return \core_user::get_user($user->id);
>         } else {
>             // Is the intent to migrate a user account used in legacy launches?
>             if (!empty($legacyconsumersecrets)) {
>                 try {
>                     // Validate the migration claim and try to find a legacy user.
>                     $usermigrationclaim = new user_migration_claim($launchdata, $legacyconsumersecrets);
>                     $username = 'enrol_lti' .
>                         sha1($usermigrationclaim->get_consumer_key() . '::' .
>                         $usermigrationclaim->get_consumer_key() .':' .$usermigrationclaim->get_user_id());
>                     if ($user = \core_user::get_user_by_username($username)) {
>                         $this->create_user_binding($launchdata['iss'], $launchdata['sub'], $user->id);
>                         $this->update_user_account($user, $launchdata, $launchdata['iss']);
>                         return \core_user::get_user($user->id);
>                     }
>                 } catch (Exception $e) {
>                     // There was an issue validating the user migration claim. We don't want to fail auth entirely though.
>                     // Rather, we want to fall back to new account creation and log the attempt.
>                     debugging("There was a problem migrating the LTI user '{$launchdata['sub']}' on the platform " .
>                         "'{$launchdata['iss']}'. The migration claim could not be validated. A new account will be created.");
>                 }
>             }
>             $user = $this->create_new_account($launchdata, $launchdata['iss']);
>             $this->update_user_account($user, $launchdata, $launchdata['iss']);
>             return \core_user::get_user($user->id);
>         }
>     }
> 
>     /**
>      * Create a binding between the LTI user, as identified by {iss, sub} tuple and the user id.
>      *
>      * @param string $iss the issuer URL identifying the platform to which to user belongs.
>      * @param string $sub the sub string identifying the user on the platform.
>      * @param int $userid the id of the Moodle user account to bind.
>      */
>     public function create_user_binding(string $iss, string $sub, int $userid): void {
>         global $DB;
> 
>         $timenow = time();
>         $issuer256 = hash('sha256', $iss);
>         $sub256 = hash('sha256', $sub);
>         if ($DB->record_exists('auth_lti_linked_login', ['issuer256' => $issuer256, 'sub256' => $sub256])) {
>             return;
>         }
>         $rec = [
>             'userid' => $userid,
>             'issuer' => $iss,
>             'issuer256' => $issuer256,
>             'sub' => $sub,
>             'sub256' => $sub256,
>             'timecreated' => $timenow,
>             'timemodified' => $timenow
>         ];
>         $DB->insert_record('auth_lti_linked_login', $rec);
>     }
> 
>     /**
>      * Gets the id of the linked Moodle user account for an LTI user, or null if not found.
>      *
>      * @param string $issuer the issuer to which the user belongs.
>      * @param string $sub the sub string identifying the user on the issuer.
>      * @return int|null the id of the corresponding Moodle user record, or null if not found.
>      */
>     public function get_user_binding(string $issuer, string $sub): ?int {
>         global $DB;
>         $issuer256 = hash('sha256', $issuer);
>         $sub256 = hash('sha256', $sub);
>         try {
>             $binduser = $DB->get_field('auth_lti_linked_login', 'userid',
>                 ['issuer256' => $issuer256, 'sub256' => $sub256], MUST_EXIST);
>         } catch (\dml_exception $e) {
>             $binduser = null;
>         }
>         return $binduser;
>     }
> 
>     /**
>      * Check whether a provisioning mode is valid or not.
>      *
>      * @param int $mode the mode
>      * @return bool true if valid for use, false otherwise.
>      */
>     protected function is_valid_provisioning_mode(int $mode): bool {
>         $validmodes = [
>             self::PROVISIONING_MODE_AUTO_ONLY,
>             self::PROVISIONING_MODE_PROMPT_NEW_EXISTING,
>             self::PROVISIONING_MODE_PROMPT_EXISTING_ONLY
>         ];
>         return in_array($mode, $validmodes);
>     }
> 
>     /**
>      * Create a new user account based on the user data either in the launch JWT or from a membership call.
>      *
>      * @param array $userdata the user data coming from either a launch or membership service call.
>      * @param string $iss the issuer to which the user belongs.
>      * @return stdClass a complete Moodle user record.
>      */
>     protected function create_new_account(array $userdata, string $iss): stdClass {
> 
>         global $CFG;
>         require_once($CFG->dirroot.'/user/lib.php');
> 
>         // Launches and membership calls handle the user id differently.
>         // Launch uses 'sub', whereas member uses 'user_id'.
>         $userid = !empty($userdata['sub']) ? $userdata['sub'] : $userdata['user_id'];
> 
>         $user = new stdClass();
>         $user->username = 'enrol_lti_13_' . sha1($iss . '_' . $userid);
>         // If the email was stripped/not set then fill it with a default one.
>         // This stops the user from being redirected to edit their profile page.
>         $email = !empty($userdata['email']) ? $userdata['email'] :
>             'enrol_lti_13_' . sha1($iss . '_' . $userid) . "@example.com";
>         $email = \core_user::clean_field($email, 'email');
>         $user->email = $email;
>         $user->auth = 'lti';
>         $user->mnethostid = $CFG->mnet_localhost_id;
>         $user->firstname = $userdata['given_name'] ?? $userid;
>         $user->lastname = $userdata['family_name'] ?? $iss;
>         $user->password = '';
>         $user->confirmed = 1;
>         $user->id = user_create_user($user, false);
> 
>         // Link this user with the LTI credentials for future use.
>         $this->create_user_binding($iss, $userid, $user->id);
> 
>         return (object) get_complete_user_data('id', $user->id);
>     }
> 
>     /**
>      * Update the personal fields of the user account, based on data present in either a launch of member sync call.
>      *
>      * @param stdClass $user the Moodle user account to update.
>      * @param array $userdata the user data coming from either a launch or membership service call.
>      * @param string $iss the issuer to which the user belongs.
>      */
>     protected function update_user_account(stdClass $user, array $userdata, string $iss): void {
>         global $CFG;
>         require_once($CFG->dirroot.'/user/lib.php');
>         if ($user->auth !== 'lti') {
>             return;
>         }
> 
>         // Launches and membership calls handle the user id differently.
>         // Launch uses 'sub', whereas member uses 'user_id'.
>         $platformuserid = !empty($userdata['sub']) ? $userdata['sub'] : $userdata['user_id'];
>         $email = !empty($userdata['email']) ? $userdata['email'] :
>             'enrol_lti_13_' . sha1($iss . '_' . $platformuserid) . "@example.com";
>         $email = \core_user::clean_field($email, 'email');
>         $update = [
>             'id' => $user->id,
>             'firstname' => $userdata['given_name'] ?? $platformuserid,
>             'lastname' => $userdata['family_name'] ?? $iss,
>             'email' => $email
>         ];
>         $userfieldstocompare = array_intersect_key((array) $user, $update);
> 
>         if (!empty(array_diff($update, $userfieldstocompare))) {
>             user_update_user($update); // Only update if there's a change.
>         }
> 
>         if (!empty($userdata['picture'])) {
>             try {
>                 $this->update_user_picture($user->id, $userdata['picture']);
>             } catch (Exception $e) {
>                 debugging("Error syncing the profile picture for user '$user->id' during LTI authentication.");
>             }
>         }
>     }
> 
>     /**
>      * Update the user's picture with the image stored at $url.
>      *
>      * @param int $userid the id of the user to update.
>      * @param string $url the string URL where the new image can be found.
>      * @throws moodle_exception if there were any problems updating the picture.
>      */
>     protected function update_user_picture(int $userid, string $url): void {
>         global $CFG, $DB;
> 
>         require_once($CFG->libdir . '/filelib.php');
>         require_once($CFG->libdir . '/gdlib.php');
> 
>         $fs = get_file_storage();
> 
>         $context = \context_user::instance($userid, MUST_EXIST);
>         $fs->delete_area_files($context->id, 'user', 'newicon');
> 
>         $filerecord = array(
>             'contextid' => $context->id,
>             'component' => 'user',
>             'filearea' => 'newicon',
>             'itemid' => 0,
>             'filepath' => '/'
>         );
> 
>         $urlparams = array(
>             'calctimeout' => false,
>             'timeout' => 5,
>             'skipcertverify' => true,
>             'connecttimeout' => 5
>         );
> 
>         try {
>             $fs->create_file_from_url($filerecord, $url, $urlparams);
>         } catch (\file_exception $e) {
>             throw new moodle_exception(get_string($e->errorcode, $e->module, $e->a));
>         }
> 
>         $iconfile = $fs->get_area_files($context->id, 'user', 'newicon', false, 'itemid', false);
> 
>         // There should only be one.
>         $iconfile = reset($iconfile);
> 
>         // Something went wrong while creating temp file - remove the uploaded file.
>         if (!$iconfile = $iconfile->copy_content_to_temp()) {
>             $fs->delete_area_files($context->id, 'user', 'newicon');
>             throw new moodle_exception('There was a problem copying the profile picture to temp.');
>         }
> 
>         // Copy file to temporary location and the send it for processing icon.
>         $newpicture = (int) process_new_icon($context, 'user', 'icon', 0, $iconfile);
>         // Delete temporary file.
>         @unlink($iconfile);
>         // Remove uploaded file.
>         $fs->delete_area_files($context->id, 'user', 'newicon');
>         // Set the user's picture.
>         $DB->set_field('user', 'picture', $newpicture, array('id' => $userid));