<?php
/* For licensing terms, see /license.txt */

use ChamiloSession as Session;

/**
 * This file contains the necessary elements to implement a Single Sign On
 * mechanism with an external Drupal application (on which the Chamilo module
 * 7.x-1.0-alpha3 or above must be implemented)
 *
 * To use this class, set variable "sso_authentication_subclass" to "Drupal"
 * in Chamilo settings.  If not yet available in the "Security" tab, execute the
 * following on the Chamilo database:
 *  INSERT INTO `settings_current` (`variable`, `type`, `category`, `selected_value`, `title`, `comment`, `access_url`)
 *  VALUES ('sso_authentication_subclass', 'textfield', 'Security', 'Drupal', 'SSOSubclass', 'SSOSubclassComment', 1);
 *
 * @package chamilo.auth.sso
 */

/**
 * The SSO class allows for management of remote Single Sign On resources
 */
class ssoDrupal
{
    public $protocol;   // 'http://',
    public $domain;     // 'localhost/project/drupal',
    public $auth_uri;   // '/?q=user',
    public $deauth_uri; // '/?q=logout',
    public $referer;    // http://my.chamilo.com/main/auth/profile.php

    /**
     * Instanciates the object, initializing all relevant URL strings
     */
    public function __construct()
    {
        $this->protocol   = api_get_setting('sso_authentication_protocol');
        // There can be multiple domains, so make sure to take only the first
        // This might be later extended with a decision process
        $domains          = preg_split('/,/', api_get_setting('sso_authentication_domain'));
        $this->domain     = trim($domains[0]);
        $this->auth_uri   = api_get_setting('sso_authentication_auth_uri');
        $this->deauth_uri = api_get_setting('sso_authentication_unauth_uri');
        //cut the string to avoid recursive URL construction in case of failure
        $this->referer    = $this->protocol.$_SERVER['HTTP_HOST'].substr($_SERVER['REQUEST_URI'], 0, strpos($_SERVER['REQUEST_URI'], 'sso'));
        $this->deauth_url = $this->protocol.$this->domain.$this->deauth_uri;
        $this->master_url = $this->protocol.$this->domain.$this->auth_uri;
        $this->referrer_uri = base64_encode($_SERVER['REQUEST_URI']);
        $this->target     = api_get_path(WEB_PATH);
    }

    /**
     * Unlogs the user from the remote server
     */
    public function logout()
    {
        // no_redirect means Drupal sent the signal to logout. When redirecting to Drupal, the $_GET['stop'] param is
        // set to 1, to allow Drupal to know that this is it, the logout is already done in Chamilo and there's no
        // need to do it again
        if (empty($_GET['no_redirect'])) {
            header('Location: '.$this->deauth_url.'&stop=1');
        } else {
            header('Location: '.$this->protocol.$this->domain);
        }
        exit;
    }

    /**
     * Sends the user to the master URL for a check of active connection
     */
    public function ask_master()
    {
        // Generate a single usage token that must be encoded by the master
        $_SESSION['sso_challenge'] = api_generate_password(48);
        // Redirect browser to the master URL
        $params = '';
        if (empty($_GET['no_redirect'])) {
            $params = 'sso_referer='.urlencode($this->referer).
                '&sso_target='.urlencode($this->target).
                '&sso_challenge='.urlencode($_SESSION['sso_challenge']).
                '&sso_ruri='.urlencode($this->referrer_uri);
            if (strpos($this->master_url, "?") === false) {
                $params = "?{$params}";
            } else {
                $params = "&{$params}";
            }
        }
        header('Location: '.$this->master_url.$params);
        exit;
    }

    /**
     * Validates the received active connection data with the database
     * @return	bool	Return the loginFailed variable value to local.inc.php
     */
    public function check_user()
    {
        global $_user;
        $loginFailed = false;

        //change the way we recover the cookie depending on how it is formed
        $sso = $this->decode_cookie($_GET['sso_cookie']);

        //get token that should have been used and delete it
        //from session since it can only be used once
        $sso_challenge = '';
        if (isset($_SESSION['sso_challenge'])) {
            $sso_challenge = $_SESSION['sso_challenge'];
            unset($_SESSION['sso_challenge']);
        }

        //lookup the user in the main database
        $user_table = Database::get_main_table(TABLE_MAIN_USER);
        $sql = "SELECT id, username, password, auth_source, active, expiration_date, status
                FROM $user_table
                WHERE username = '".trim(Database::escape_string($sso['username']))."'";
        $result = Database::query($sql);
        if (Database::num_rows($result) > 0) {
            $uData = Database::fetch_array($result);
            //Check the user's password
            if ($uData['auth_source'] == PLATFORM_AUTH_SOURCE) {

                if ($sso['secret'] === sha1($uData['username'].$sso_challenge.api_get_security_key())
                    && ($sso['username'] == $uData['username'])) {

                    //Check if the account is active (not locked)
                    if ($uData['active']=='1') {
                        // check if the expiration date has not been reached
                        if (empty($uData['expiration_date']) OR $uData['expiration_date'] > date('Y-m-d H:i:s') OR $uData['expiration_date']=='0000-00-00 00:00:00') {

                            //If Multiple URL is enabled
                            if (api_get_multiple_access_url()) {
                                //Check the access_url configuration setting if the user is registered in the access_url_rel_user table
                                //Getting the current access_url_id of the platform
                                $current_access_url_id = api_get_current_access_url_id();
                                // my user is subscribed in these
                                //sites: $my_url_list
                                $my_url_list = api_get_access_url_from_user($uData['id']);
                            } else {
                                $current_access_url_id = 1;
                                $my_url_list = array(1);
                            }

                            $my_user_is_admin = UserManager::is_admin($uData['id']);

                            if ($my_user_is_admin === false) {
                                if (is_array($my_url_list) && count($my_url_list) > 0) {
                                    if (in_array($current_access_url_id, $my_url_list)) {
                                        // the user has permission to enter at this site
                                        $_user['user_id'] = $uData['id'];
                                        $_user = api_get_user_info($_user['user_id']);
                                        $_user['uidReset'] = true;
                                        Session::write('_user', $_user);
                                        Event::event_login($_user['user_id']);
                                        // Redirect to homepage
                                        $sso_target = '';
                                        if (!empty($sso['ruri'])) {
                                            //The referrer URI is *only* used if
                                            // the user credentials are OK, which
                                            // should be protection enough
                                            // against evil URL spoofing...
                                            $sso_target = api_get_path(WEB_PATH) . base64_decode($sso['ruri']);
                                        } else {
                                            $sso_target = isset($sso['target']) ? $sso['target'] : api_get_path(WEB_PATH) . 'index.php';
                                        }
                                        header('Location: '. $sso_target);
                                        exit;
                                    } else {
                                        // user does not have permission for this site
                                        $loginFailed = true;
                                        Session::erase('_uid');
                                        header('Location: '.api_get_path(WEB_PATH).'index.php?loginFailed=1&error=access_url_inactive');
                                        exit;
                                    }
                                } else {
                                    // there is no URL in the multiple
                                    // urls list for this user
                                    $loginFailed = true;
                                    Session::erase('_uid');
                                    header('Location: '.api_get_path(WEB_PATH).'index.php?loginFailed=1&error=access_url_inactive');
                                    exit;
                                }
                            } else {
                                //Only admins of the "main" (first) Chamilo
                                // portal can login wherever they want
                                if (in_array(1, $my_url_list)) {
                                    //Check if this admin is admin on the
                                    // principal portal
                                    $_user['user_id'] = $uData['id'];
                                    $_user = api_get_user_info($_user['user_id']);
                                    $is_platformAdmin = $uData['status'] == COURSEMANAGER;
                                    Session::write('is_platformAdmin', $is_platformAdmin);
                                    Session::write('_user', $_user);
                                    Event::event_login($_user['user_id']);
                                } else {
                                    //Secondary URL admin wants to login
                                    // so we check as a normal user
                                    if (in_array($current_access_url_id, $my_url_list)) {
                                        $_user['user_id'] = $uData['user_id'];
                                        $_user = api_get_user_info($_user['user_id']);
                                        Session::write('_user', $_user);
                                        Event::event_login($_user['user_id']);
                                    } else {
                                        $loginFailed = true;
                                        Session::erase('_uid');
                                        header('Location: '.api_get_path(WEB_PATH).'index.php?loginFailed=1&error=access_url_inactive');
                                        exit;
                                    }
                                }
                            }
                        } else {
                            // user account expired
                            $loginFailed = true;
                            Session::erase('_uid');
                            header('Location: '.api_get_path(WEB_PATH).'index.php?loginFailed=1&error=account_expired');
                            exit;
                        }
                    } else {
                        //User not active
                        $loginFailed = true;
                        Session::erase('_uid');
                        header('Location: '.api_get_path(WEB_PATH).'index.php?loginFailed=1&error=account_inactive');
                        exit;
                    }
                } else {
                    //SHA1 of password is wrong
                    $loginFailed = true;
                    Session::erase('_uid');
                    header('Location: '.api_get_path(WEB_PATH).'index.php?loginFailed=1&error=wrong_password');
                    exit;
                }
            } else {
                //Auth_source is wrong
                $loginFailed = true;
                Session::erase('_uid');
                header('Location: '.api_get_path(WEB_PATH).'index.php?loginFailed=1&error=wrong_authentication_source');
                exit;
            }
        } else {
            //No user by that login
            $loginFailed = true;
            Session::erase('_uid');
            header('Location: '.api_get_path(WEB_PATH).'index.php?loginFailed=1&error=user_not_found');
            exit;
        }
        return $loginFailed;
    }

    /**
     * Decode the cookie (this function may vary depending on the
     * Single Sign On implementation
     * @param	string	Encoded cookie
     * @return  array   Parsed and unencoded cookie
     */
    private function decode_cookie($cookie)
    {
        return unserialize(base64_decode($cookie));
    }

    /**
     * Generate the URL for profile editing for a any user or the current user
     * @param int $userId Optional. The user id
     * @param boolean $asAdmin Optional. Whether get the URL for the platform admin
     * @return string If the URL is obtained return the drupal_user_id. Otherwise return false
     */
    public function generateProfileEditingURL($userId = 0, $asAdmin = false)
    {
        $userId = intval($userId);

        if (empty($userId)) {
            $userId = api_get_user_id();
        }

        $userExtraFieldValue = new ExtraFieldValue('user');
        $drupalUserIdData = $userExtraFieldValue->get_values_by_handler_and_field_variable(
            $userId,
            'drupal_user_id'
        );

        // If this is an administrator, allow him to make some changes in
        // the Chamilo profile
        if ($asAdmin && api_is_platform_admin(true)) {
            return api_get_path(WEB_CODE_PATH) . "admin/user_edit.php?user_id=$userId";
        }
        // If the user doesn't match a Drupal user, give the normal profile
        // link
        if ($drupalUserIdData === false) {
            return api_get_path(WEB_CODE_PATH) . 'auth/profile.php';
        }
        // In all other cases, generate a link to the Drupal profile edition
        $drupalUserId = $drupalUserIdData['value'];
        $url = "{$this->protocol}{$this->domain}/user/{$drupalUserId}/edit";
        return $url;
    }

}