<?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/>.

/**
 * Multiple plugin authentication Support library
 *
 * 2006-08-28  File created, AUTH return values defined.
 *
 * @package    core
 * @subpackage auth
 * @copyright  1999 onwards Martin Dougiamas  http://dougiamas.com
 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */

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

/**
 * Returned when the login was successful.
 */
define('AUTH_OK',     0);

/**
 * Returned when the login was unsuccessful.
 */
define('AUTH_FAIL',   1);

/**
 * Returned when the login was denied (a reason for AUTH_FAIL).
 */
define('AUTH_DENIED', 2);

/**
 * Returned when some error occurred (a reason for AUTH_FAIL).
 */
define('AUTH_ERROR',  4);

/**
 * Authentication - error codes for user confirm
 */
define('AUTH_CONFIRM_FAIL', 0);
define('AUTH_CONFIRM_OK', 1);
define('AUTH_CONFIRM_ALREADY', 2);
define('AUTH_CONFIRM_ERROR', 3);

# MDL-14055
define('AUTH_REMOVEUSER_KEEP', 0);
define('AUTH_REMOVEUSER_SUSPEND', 1);
define('AUTH_REMOVEUSER_FULLDELETE', 2);

/** Login attempt successful. */
define('AUTH_LOGIN_OK', 0);

/** Can not login because user does not exist. */
define('AUTH_LOGIN_NOUSER', 1);

/** Can not login because user is suspended. */
define('AUTH_LOGIN_SUSPENDED', 2);

/** Can not login, most probably password did not match. */
define('AUTH_LOGIN_FAILED', 3);

/** Can not login because user is locked out. */
define('AUTH_LOGIN_LOCKOUT', 4);

/** Can not login becauser user is not authorised. */
define('AUTH_LOGIN_UNAUTHORISED', 5);

/**
 * Abstract authentication plugin.
 *
 * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 * @package moodlecore
 */
class auth_plugin_base {

    /**
     * The configuration details for the plugin.
     * @var object
     */
    var $config;

    /**
     * Authentication plugin type - the same as db field.
     * @var string
     */
    var $authtype;
    /*
     * The fields we can lock and update from/to external authentication backends
     * @var array
     */
    var $userfields = array(
        'firstname',
        'lastname',
        'email',
        'city',
        'country',
        'lang',
        'description',
        'url',
        'idnumber',
        'institution',
        'department',
        'phone1',
        'phone2',
        'address',
        'firstnamephonetic',
        'lastnamephonetic',
        'middlename',
        'alternatename'
    );

    /**
     * Moodle custom fields to sync with.
     * @var array()
     */
    var $customfields = null;

    /**
     * This is the primary method that is used by the authenticate_user_login()
     * function in moodlelib.php.
     *
     * This method should return a boolean indicating
     * whether or not the username and password authenticate successfully.
     *
     * Returns true if the username and password work and false if they are
     * wrong or don't exist.
     *
     * @param string $username The username (with system magic quotes)
     * @param string $password The password (with system magic quotes)
     *
     * @return bool Authentication success or failure.
     */
    function user_login($username, $password) {
        print_error('mustbeoveride', 'debug', '', 'user_login()' );
    }

    /**
     * Returns true if this authentication plugin can change the users'
     * password.
     *
     * @return bool
     */
    function can_change_password() {
        //override if needed
        return false;
    }

    /**
     * Returns the URL for changing the users' passwords, or empty if the default
     * URL can be used.
     *
     * This method is used if can_change_password() returns true.
     * This method is called only when user is logged in, it may use global $USER.
     * If you are using a plugin config variable in this method, please make sure it is set before using it,
     * as this method can be called even if the plugin is disabled, in which case the config values won't be set.
     *
     * @return moodle_url url of the profile page or null if standard used
     */
    function change_password_url() {
        //override if needed
        return null;
    }

    /**
     * Returns true if this authentication plugin can edit the users'
     * profile.
     *
     * @return bool
     */
    function can_edit_profile() {
        //override if needed
        return true;
    }

    /**
     * Returns the URL for editing the users' profile, or empty if the default
     * URL can be used.
     *
     * This method is used if can_edit_profile() returns true.
     * This method is called only when user is logged in, it may use global $USER.
     *
     * @return moodle_url url of the profile page or null if standard used
     */
    function edit_profile_url() {
        //override if needed
        return null;
    }

    /**
     * Returns true if this authentication plugin is "internal".
     *
     * Internal plugins use password hashes from Moodle user table for authentication.
     *
     * @return bool
     */
    function is_internal() {
        //override if needed
        return true;
    }

    /**
     * Returns false if this plugin is enabled but not configured.
     *
     * @return bool
     */
    public function is_configured() {
        return false;
    }

    /**
     * Indicates if password hashes should be stored in local moodle database.
     * @return bool true means md5 password hash stored in user table, false means flag 'not_cached' stored there instead
     */
    function prevent_local_passwords() {
        return !$this->is_internal();
    }

    /**
     * Indicates if moodle should automatically update internal user
     * records with data from external sources using the information
     * from get_userinfo() method.
     *
     * @return bool true means automatically copy data from ext to user table
     */
    function is_synchronised_with_external() {
        return !$this->is_internal();
    }

    /**
     * Updates the user's password.
     *
     * In previous versions of Moodle, the function
     * auth_user_update_password accepted a username as the first parameter. The
     * revised function expects a user object.
     *
     * @param  object  $user        User table object
     * @param  string  $newpassword Plaintext password
     *
     * @return bool                  True on success
     */
    function user_update_password($user, $newpassword) {
        //override if needed
        return true;
    }

    /**
     * Called when the user record is updated.
     * Modifies user in external database. It takes olduser (before changes) and newuser (after changes)
     * compares information saved modified information to external db.
     *
     * @param mixed $olduser     Userobject before modifications    (without system magic quotes)
     * @param mixed $newuser     Userobject new modified userobject (without system magic quotes)
     * @return boolean true if updated or update ignored; false if error
     *
     */
    function user_update($olduser, $newuser) {
        //override if needed
        return true;
    }

    /**
     * User delete requested - internal user record is mared as deleted already, username not present anymore.
     *
     * Do any action in external database.
     *
     * @param object $user       Userobject before delete    (without system magic quotes)
     * @return void
     */
    function user_delete($olduser) {
        //override if needed
        return;
    }

    /**
     * Returns true if plugin allows resetting of internal password.
     *
     * @return bool
     */
    function can_reset_password() {
        //override if needed
        return false;
    }

    /**
     * Returns true if plugin allows resetting of internal password.
     *
     * @return bool
     */
    function can_signup() {
        //override if needed
        return false;
    }

    /**
     * Sign up a new user ready for confirmation.
     * Password is passed in plaintext.
     *
     * @param object $user new user object
     * @param boolean $notify print notice with link and terminate
     */
    function user_signup($user, $notify=true) {
        //override when can signup
        print_error('mustbeoveride', 'debug', '', 'user_signup()' );
    }

    /**
     * Return a form to capture user details for account creation.
     * This is used in /login/signup.php.
     * @return moodle_form A form which edits a record from the user table.
     */
    function signup_form() {
        global $CFG;

        require_once($CFG->dirroot.'/login/signup_form.php');
        return new login_signup_form(null, null, 'post', '', array('autocomplete'=>'on'));
    }

    /**
     * Returns true if plugin allows confirming of new users.
     *
     * @return bool
     */
    function can_confirm() {
        //override if needed
        return false;
    }

    /**
     * Confirm the new user as registered.
     *
     * @param string $username
     * @param string $confirmsecret
     */
    function user_confirm($username, $confirmsecret) {
        //override when can confirm
        print_error('mustbeoveride', 'debug', '', 'user_confirm()' );
    }

    /**
     * Checks if user exists in external db
     *
     * @param string $username (with system magic quotes)
     * @return bool
     */
    function user_exists($username) {
        //override if needed
        return false;
    }

    /**
     * return number of days to user password expires
     *
     * If userpassword does not expire it should return 0. If password is already expired
     * it should return negative value.
     *
     * @param mixed $username username (with system magic quotes)
     * @return integer
     */
    function password_expire($username) {
        return 0;
    }
    /**
     * Sync roles for this user - usually creator
     *
     * @param $user object user object (without system magic quotes)
     */
    function sync_roles($user) {
        //override if needed
    }

    /**
     * Read user information from external database and returns it as array().
     * Function should return all information available. If you are saving
     * this information to moodle user-table you should honour synchronisation flags
     *
     * @param string $username username
     *
     * @return mixed array with no magic quotes or false on error
     */
    function get_userinfo($username) {
        //override if needed
        return array();
    }

    /**
     * Prints a form for configuring this authentication plugin.
     *
     * This function is called from admin/auth.php, and outputs a full page with
     * a form for configuring this plugin.
     *
     * @param object $config
     * @param object $err
     * @param array $user_fields
     */
    function config_form($config, $err, $user_fields) {
        //override if needed
    }

    /**
     * A chance to validate form data, and last chance to
     * do stuff before it is inserted in config_plugin
     * @param object object with submitted configuration settings (without system magic quotes)
     * @param array $err array of error messages
     */
     function validate_form($form, &$err) {
        //override if needed
    }

    /**
     * Processes and stores configuration data for this authentication plugin.
     *
     * @param object object with submitted configuration settings (without system magic quotes)
     */
    function process_config($config) {
        //override if needed
        return true;
    }

    /**
     * Hook for overriding behaviour of login page.
     * This method is called from login/index.php page for all enabled auth plugins.
     *
     * @global object
     * @global object
     */
    function loginpage_hook() {
        global $frm;  // can be used to override submitted login form
        global $user; // can be used to replace authenticate_user_login()

        //override if needed
    }

    /**
     * Hook for overriding behaviour before going to the login page.
     *
     * This method is called from require_login from potentially any page for
     * all enabled auth plugins and gives each plugin a chance to redirect
     * directly to an external login page, or to instantly login a user where
     * possible.
     *
     * If an auth plugin implements this hook, it must not rely on ONLY this
     * hook in order to work, as there are many ways a user can browse directly
     * to the standard login page. As a general rule in this case you should
     * also implement the loginpage_hook as well.
     *
     */
    function pre_loginpage_hook() {
        // override if needed, eg by redirecting to an external login page
        // or logging in a user:
        // complete_user_login($user);
    }

    /**
     * Pre user_login hook.
     * This method is called from authenticate_user_login() right after the user
     * object is generated. This gives the auth plugins an option to make adjustments
     * before the verification process starts.
     *
     * @param object $user user object, later used for $USER
     */
    public function pre_user_login_hook(&$user) {
        // Override if needed.
    }

    /**
     * Post authentication hook.
     * This method is called from authenticate_user_login() for all enabled auth plugins.
     *
     * @param object $user user object, later used for $USER
     * @param string $username (with system magic quotes)
     * @param string $password plain text password (with system magic quotes)
     */
    function user_authenticated_hook(&$user, $username, $password) {
        //override if needed
    }

    /**
     * Pre logout hook.
     * This method is called from require_logout() for all enabled auth plugins,
     *
     * @global object
     */
    function prelogout_hook() {
        global $USER; // use $USER->auth to find the plugin used for login

        //override if needed
    }

    /**
     * Hook for overriding behaviour of logout page.
     * This method is called from login/logout.php page for all enabled auth plugins.
     *
     * @global object
     * @global string
     */
    function logoutpage_hook() {
        global $USER;     // use $USER->auth to find the plugin used for login
        global $redirect; // can be used to override redirect after logout

        //override if needed
    }

    /**
     * Hook called before timing out of database session.
     * This is useful for SSO and MNET.
     *
     * @param object $user
     * @param string $sid session id
     * @param int $timecreated start of session
     * @param int $timemodified user last seen
     * @return bool true means do not timeout session yet
     */
    function ignore_timeout_hook($user, $sid, $timecreated, $timemodified) {
        return false;
    }

    /**
     * Return the properly translated human-friendly title of this auth plugin
     *
     * @todo Document this function
     */
    function get_title() {
        return get_string('pluginname', "auth_{$this->authtype}");
    }

    /**
     * Get the auth description (from core or own auth lang files)
     *
     * @return string The description
     */
    function get_description() {
        $authdescription = get_string("auth_{$this->authtype}description", "auth_{$this->authtype}");
        return $authdescription;
    }

    /**
     * Returns whether or not the captcha element is enabled.
     *
     * @abstract Implement in child classes
     * @return bool
     */
    function is_captcha_enabled() {
        return false;
    }

    /**
     * Returns whether or not this authentication plugin can be manually set
     * for users, for example, when bulk uploading users.
     *
     * This should be overriden by authentication plugins where setting the
     * authentication method manually is allowed.
     *
     * @return bool
     * @since Moodle 2.6
     */
    function can_be_manually_set() {
        // Override if needed.
        return false;
    }

    /**
     * Returns a list of potential IdPs that this authentication plugin supports.
     * This is used to provide links on the login page.
     *
     * @param string $wantsurl the relative url fragment the user wants to get to.  You can use this to compose a returnurl, for example
     *
     * @return array like:
     *              array(
     *                  array(
     *                      'url' => 'http://someurl',
     *                      'icon' => new pix_icon(...),
     *                      'name' => get_string('somename', 'auth_yourplugin'),
     *                 ),
     *             )
     */
    function loginpage_idp_list($wantsurl) {
        return array();
    }

    /**
     * Return custom user profile fields.
     *
     * @return array list of custom fields.
     */
    public function get_custom_user_profile_fields() {
        global $DB;
        // If already retrieved then return.
        if (!is_null($this->customfields)) {
            return $this->customfields;
        }

        $this->customfields = array();
        if ($proffields = $DB->get_records('user_info_field')) {
            foreach ($proffields as $proffield) {
                $this->customfields[] = 'profile_field_'.$proffield->shortname;
            }
        }
        unset($proffields);

        return $this->customfields;
    }

    /**
     * Post logout hook.
     *
     * This method is used after moodle logout by auth classes to execute server logout.
     *
     * @param stdClass $user clone of USER object before the user session was terminated
     */
    public function postlogout_hook($user) {
    }
}

/**
 * Verify if user is locked out.
 *
 * @param stdClass $user
 * @return bool true if user locked out
 */
function login_is_lockedout($user) {
    global $CFG;

    if ($user->mnethostid != $CFG->mnet_localhost_id) {
        return false;
    }
    if (isguestuser($user)) {
        return false;
    }

    if (empty($CFG->lockoutthreshold)) {
        // Lockout not enabled.
        return false;
    }

    if (get_user_preferences('login_lockout_ignored', 0, $user)) {
        // This preference may be used for accounts that must not be locked out.
        return false;
    }

    $locked = get_user_preferences('login_lockout', 0, $user);
    if (!$locked) {
        return false;
    }

    if (empty($CFG->lockoutduration)) {
        // Locked out forever.
        return true;
    }

    if (time() - $locked < $CFG->lockoutduration) {
        return true;
    }

    login_unlock_account($user);

    return false;
}

/**
 * To be called after valid user login.
 * @param stdClass $user
 */
function login_attempt_valid($user) {
    global $CFG;

    // Note: user_loggedin event is triggered in complete_user_login().

    if ($user->mnethostid != $CFG->mnet_localhost_id) {
        return;
    }
    if (isguestuser($user)) {
        return;
    }

    // Always unlock here, there might be some race conditions or leftovers when switching threshold.
    login_unlock_account($user);
}

/**
 * To be called after failed user login.
 * @param stdClass $user
 */
function login_attempt_failed($user) {
    global $CFG;

    if ($user->mnethostid != $CFG->mnet_localhost_id) {
        return;
    }
    if (isguestuser($user)) {
        return;
    }

    $count = get_user_preferences('login_failed_count', 0, $user);
    $last = get_user_preferences('login_failed_last', 0, $user);
    $sincescuccess = get_user_preferences('login_failed_count_since_success', $count, $user);
    $sincescuccess = $sincescuccess + 1;
    set_user_preference('login_failed_count_since_success', $sincescuccess, $user);

    if (empty($CFG->lockoutthreshold)) {
        // No threshold means no lockout.
        // Always unlock here, there might be some race conditions or leftovers when switching threshold.
        login_unlock_account($user);
        return;
    }

    if (!empty($CFG->lockoutwindow) and time() - $last > $CFG->lockoutwindow) {
        $count = 0;
    }

    $count = $count+1;

    set_user_preference('login_failed_count', $count, $user);
    set_user_preference('login_failed_last', time(), $user);

    if ($count >= $CFG->lockoutthreshold) {
        login_lock_account($user);
    }
}

/**
 * Lockout user and send notification email.
 *
 * @param stdClass $user
 */
function login_lock_account($user) {
    global $CFG;

    if ($user->mnethostid != $CFG->mnet_localhost_id) {
        return;
    }
    if (isguestuser($user)) {
        return;
    }

    if (get_user_preferences('login_lockout_ignored', 0, $user)) {
        // This user can not be locked out.
        return;
    }

    $alreadylockedout = get_user_preferences('login_lockout', 0, $user);

    set_user_preference('login_lockout', time(), $user);

    if ($alreadylockedout == 0) {
        $secret = random_string(15);
        set_user_preference('login_lockout_secret', $secret, $user);

        $oldforcelang = force_current_language($user->lang);

        $site = get_site();
        $supportuser = core_user::get_support_user();

        $data = new stdClass();
        $data->firstname = $user->firstname;
        $data->lastname  = $user->lastname;
        $data->username  = $user->username;
        $data->sitename  = format_string($site->fullname);
        $data->link      = $CFG->wwwroot.'/login/unlock_account.php?u='.$user->id.'&s='.$secret;
        $data->admin     = generate_email_signoff();

        $message = get_string('lockoutemailbody', 'admin', $data);
        $subject = get_string('lockoutemailsubject', 'admin', format_string($site->fullname));

        if ($message) {
            // Directly email rather than using the messaging system to ensure its not routed to a popup or jabber.
            email_to_user($user, $supportuser, $subject, $message);
        }

        force_current_language($oldforcelang);
    }
}

/**
 * Unlock user account and reset timers.
 *
 * @param stdClass $user
 */
function login_unlock_account($user) {
    unset_user_preference('login_lockout', $user);
    unset_user_preference('login_failed_count', $user);
    unset_user_preference('login_failed_last', $user);

    // Note: do not clear the lockout secret because user might click on the link repeatedly.
}

/**
 * Returns whether or not the captcha element is enabled, and the admin settings fulfil its requirements.
 * @return bool
 */
function signup_captcha_enabled() {
    global $CFG;
    $authplugin = get_auth_plugin($CFG->registerauth);
    return !empty($CFG->recaptchapublickey) && !empty($CFG->recaptchaprivatekey) && $authplugin->is_captcha_enabled();
}

/**
 * Validates the standard sign-up data (except recaptcha that is validated by the form element).
 *
 * @param  array $data  the sign-up data
 * @param  array $files files among the data
 * @return array list of errors, being the key the data element name and the value the error itself
 * @since Moodle 3.2
 */
function signup_validate_data($data, $files) {
    global $CFG, $DB;

    $errors = array();
    $authplugin = get_auth_plugin($CFG->registerauth);

    if ($DB->record_exists('user', array('username' => $data['username'], 'mnethostid' => $CFG->mnet_localhost_id))) {
        $errors['username'] = get_string('usernameexists');
    } else {
        // Check allowed characters.
        if ($data['username'] !== core_text::strtolower($data['username'])) {
            $errors['username'] = get_string('usernamelowercase');
        } else {
            if ($data['username'] !== core_user::clean_field($data['username'], 'username')) {
                $errors['username'] = get_string('invalidusername');
            }

        }
    }

    // Check if user exists in external db.
    // TODO: maybe we should check all enabled plugins instead.
    if ($authplugin->user_exists($data['username'])) {
        $errors['username'] = get_string('usernameexists');
    }

    if (! validate_email($data['email'])) {
        $errors['email'] = get_string('invalidemail');

    } else if ($DB->record_exists('user', array('email' => $data['email']))) {
        $errors['email'] = get_string('emailexists').' <a href="forgot_password.php">'.get_string('newpassword').'?</a>';
    }
    if (empty($data['email2'])) {
        $errors['email2'] = get_string('missingemail');

    } else if ($data['email2'] != $data['email']) {
        $errors['email2'] = get_string('invalidemail');
    }
    if (!isset($errors['email'])) {
        if ($err = email_is_not_allowed($data['email'])) {
            $errors['email'] = $err;
        }
    }

    $errmsg = '';
    if (!check_password_policy($data['password'], $errmsg)) {
        $errors['password'] = $errmsg;
    }

    // Validate customisable profile fields. (profile_validation expects an object as the parameter with userid set).
    $dataobject = (object)$data;
    $dataobject->id = 0;
    $errors += profile_validation($dataobject, $files);

    return $errors;
}

/**
 * Add the missing fields to a user that is going to be created
 *
 * @param  stdClass $user the new user object
 * @return stdClass the user filled
 * @since Moodle 3.2
 */
function signup_setup_new_user($user) {
    global $CFG;

    $user->confirmed   = 0;
    $user->lang        = current_language();
    $user->firstaccess = 0;
    $user->timecreated = time();
    $user->mnethostid  = $CFG->mnet_localhost_id;
    $user->secret      = random_string(15);
    $user->auth        = $CFG->registerauth;
    // Initialize alternate name fields to empty strings.
    $namefields = array_diff(get_all_user_name_fields(), useredit_get_required_name_fields());
    foreach ($namefields as $namefield) {
        $user->$namefield = '';
    }
    return $user;
}

/**
 * Check if user confirmation is enabled on this site and return the auth plugin handling registration if enabled.
 *
 * @return stdClass the current auth plugin handling user registration or false if registration not enabled
 * @since Moodle 3.2
 */
function signup_get_user_confirmation_authplugin() {
    global $CFG;

    if (empty($CFG->registerauth)) {
        return false;
    }
    $authplugin = get_auth_plugin($CFG->registerauth);

    if (!$authplugin->can_confirm()) {
        return false;
    }
    return $authplugin;
}

/**
 * Check if sign-up is enabled in the site. If is enabled, the function will return the authplugin instance.
 *
 * @return mixed false if sign-up is not enabled, the authplugin instance otherwise.
 * @since  Moodle 3.2
 */
function signup_is_enabled() {
    global $CFG;

    if (!empty($CFG->registerauth)) {
        $authplugin = get_auth_plugin($CFG->registerauth);
        if ($authplugin->can_signup()) {
            return $authplugin;
        }
    }
    return false;
}
