<?php

/**
 * @file
 * Enables users to authenticate via a Central Authentication Service (CAS)
 * Cas will currently work if the auto registration is turned on and will
 * create user accounts automatically.
 */

define('CAS_NO_LINK', 0);
define('CAS_ADD_LINK', 1);
define('CAS_MAKE_DEFAULT', 2);
define('CAS_REDIRECT', 3);
define('CAS_LOGIN_INVITE_DEFAULT', 'Log in using CAS');
define('CAS_LOGIN_DRUPAL_INVITE_DEFAULT', 'Cancel CAS login');
define('CAS_LOGIN_REDIR_MESSAGE', 'You will be redirected to the secure CAS login page.');
define('CAS_EXCLUDE', 'services/*');

// Frequency of CAS Gateway checking.
define('CAS_CHECK_NEVER', -2);
define('CAS_CHECK_ONCE', -1);
define('CAS_CHECK_ALWAYS', 0);

/**
 * Implements hook_init().
 *
 * Traps a page load to see if authentication is required.
 */
function cas_init() {
  global $user;

  if (module_exists('cas_test') && arg(0) == 'cas_test') {
    // We are destined for a page handled by the cas_test module, so do not
    // do any processing here. Necessary for CAS gateway tests.
    return;
  }
  elseif (defined('MAINTENANCE_MODE') && MAINTENANCE_MODE === 'install') {
    // Do nothing on profile install.
    return;
  }

  // Process a single-sign out request.
  _cas_single_sign_out_check();

  // If a user is not logged in, consider using CAS authentication.
  if (!$user->uid) {
    $force_authentication = _cas_force_login();
    $check_authentication = _cas_allow_check_for_login();
    $request_type = $_SERVER['REQUEST_METHOD'];
    $perform_login_check = $force_authentication || ($check_authentication && ($request_type == 'GET'));
    if ($perform_login_check) {
      cas_login_check($force_authentication);
    }
  }
}

/**
 * Checks to see if the user needs to be logged in.
 *
 * @param $force_authentication
 *   If TRUE, require that the user be authenticated with the CAS server
 *   before proceeding. Otherwise, check with the CAS server to see if the
 *   user is already logged in.
 */
function cas_login_check($force_authentication = TRUE) {
  global $user;
  if ($user->uid) {
    //Don't Login  because we already are
    return;
  }

  if (!cas_phpcas_load()) {
    // No need to print a message, as the user will already see the failed
    // include_once calls.
    return;
  }

  // Start a drupal session
  drupal_session_start();
  _cas_single_sign_out_save_ticket();  // We use this later for CAS 3 logoutRequests

  // Initialize phpCAS if possible, otherwise just back out.
  if (cas_phpcas_init() === FALSE) {
    return;
  }

  // We're going to try phpCAS auth test
  if ($force_authentication) {
    try {
      phpCAS::forceAuthentication();
    }
    catch (CAS_AuthenticationException $e) {
      drupal_set_message(t('Error authenticating with CAS. Please try again or contact your website administrator if the problem persists.'), 'error');
      watchdog_exception('cas', $e);
      // We have to redirect the user somewhere else because the CAS exception
      // will have written error details directly to stdout, and we don't want
      // to show anything like that to the user.
      // This bring users to the homepage or to the page set in destination
      // param.
      drupal_goto('');
    }
  }
  else {
    $logged_in = phpCAS::checkAuthentication();

    // We're done cause we're not logged in.
    if (!$logged_in) {
      return;
    }
  }

  // Build the cas_user object and allow modules to alter it.
  $cas_user = array(
    'name' => phpCAS::getUser(),
    'login' => TRUE,
    'register' => variable_get('cas_user_register', TRUE),
    'attributes' => cas_phpcas_attributes(),
  );
  drupal_alter('cas_user', $cas_user);

  // Bail out if a module denied login access for this user or unset the user
  // name.
  if (empty($cas_user['login']) || empty($cas_user['name'])) {
    // Only set a warning if we forced login.
    if ($force_authentication) {
      drupal_set_message(t('The user account %name is not available on this site.', array('%name' => $cas_user['name'])), 'error');
    }
    return;
  }

  // Proceed with the login process, using the altered CAS username.
  $cas_name = $cas_user['name'];

  // blocked user check
  $blocked = FALSE;
  if (_cas_external_user_is_blocked($cas_name)) {
      $blocked = 'The username %cas_name has been blocked.';
  }
  // @todo The D7 equivalent here must have been renamed.
  // elseif (drupal_is_denied('user', $cas_name)) {
  //   // denied by access controls
  //   return 'The name %cas_name is a reserved username.';
  // }

  if ($blocked) {
    // Only display error messages only if the user intended to log in.
    if ($force_authentication) {
      watchdog('cas', $blocked, array('%cas_name' => $cas_name), WATCHDOG_WARNING);
      drupal_set_message(t($blocked, array('%cas_name' => $cas_name)), 'error');
    }
    return;
  }

  $account = cas_user_load_by_name($cas_name);

  // Automatic user registration.
  if (!$account && $cas_user['register']) {
    // No account could be found and auto registration is enabled, so attempt
    // to register a new user.
    $account = cas_user_register($cas_name);
    if (!$account) {
      // The account could not be created, set a message.
      if ($force_authentication) {
        drupal_set_message(t('A new account could not be created for %cas_name. The username is already in use on this site.', array('%cas_name' => $cas_name)), 'error');
      }
      return;
    }
  }

  // final check to make sure we have a good user
  if ($account && $account->uid > 0) {
    // Save the altered CAS name for future use.
    $_SESSION['cas_name'] = $cas_name;

    $cas_first_login = !$account->login;

    // Save single sign out information
    if (!empty($_SESSION['cas_ticket'])) {
      _cas_single_sign_out_save_token($account);
    }

    // Populate $edit with some basic properties.
    $edit['cas_user'] = $cas_user;
    $edit['roles'] = $account->roles + cas_roles();
    if (module_exists('persistent_login') && !empty($_SESSION['cas_remember'])) {
      $edit['values']['persistent_login'] = 1;
    }
    // Allow other modules to make their own custom changes.
    cas_user_module_invoke('presave', $edit, $account);

    // Save the user account and log the user in.
    $user = user_save($account, $edit);
    user_login_finalize($edit);

    drupal_set_message(t(variable_get('cas_login_message', 'Logged in via CAS as %cas_username.'), array('%cas_username' => format_username($user))));
    if (!empty($edit['persistent_login'])) {
      drupal_set_message(t('You will remain logged in on this computer even after you close your browser.'));
    }

    _cas_redirect_after_login($cas_first_login);

  }
  else {
    $user = drupal_anonymous_user();
    unset($_SESSION['phpCAS']);

    // Only display error messages only if the user intended to log in.
    if ($force_authentication) {
      drupal_set_message(t('No account found for %cas_name.', array('%cas_name' => $cas_name)), 'error');
    }
  }
}

/**
 * Loads the phpCAS library.
 *
 * @param $path
 *   Attempt to load phpCAS using this path. If omitted, phpCAS will be loaded
 *   using Libraries API or the configured value.
 *
 * @return
 *   The phpCAS version if the phpCAS was successfully loaded, FALSE otherwise.
 */
function cas_phpcas_load($path = NULL) {
  if (!isset($path)) {
    if (module_exists('libraries')) {
      $path = libraries_get_path('CAS');
    }
    else {
      $path = variable_get('cas_library_dir', 'CAS');
    }
  }

  // Build the name of the file to load.
  if ($path != '') {
    $path = rtrim($path, '/') . '/';
  }
  $filename = $path . 'CAS.php';

  include_once($filename);

  if (!defined('PHPCAS_VERSION') || !class_exists('phpCAS')) {
    // The file could not be loaded successfully.
    return FALSE;
  }
  return PHPCAS_VERSION;
}

/**
 * Initialize phpCAS.
 *
 * Will load phpCAS if necessary.
 */
function cas_phpcas_init() {
  if (!defined('PHPCAS_VERSION') || !class_exists('phpCAS')) {
    cas_phpcas_load();
  }

  $initialized = &drupal_static(__FUNCTION__, FALSE);
  if ($initialized) {
    // phpCAS cannot be initialized twice. If you need to force this function
    // to run again, call drupal_static_reset('cas_phpcas_init') first.
    return;
  }
  $initialized = TRUE;

  // Variable set
  $server_version    = (string)variable_get('cas_version', '3.0');
  $server_cas_server = (string)variable_get('cas_server', '');
  $server_port       = (int)variable_get('cas_port', '443');
  $server_uri        = (string)variable_get('cas_uri', '');
  $cas_cert          = (string)variable_get('cas_cert', '');
  $debug_file        = (string)variable_get('cas_debugfile', '');

  // Back out if there's no configured CAS server hostname. This is the
  // minimum required configuration to initialize phpCAS.
  if (empty($server_cas_server)) {
    watchdog('cas', 'Unable to initialize phpCAS because no CAS server hostname has been configured.', array(), WATCHDOG_ERROR);
    return FALSE;
  }

  if ($debug_file != '') {
    phpCAS::setDebug($debug_file);
  }
  $start_session = (boolean)FALSE;
  if (variable_get('cas_proxy', 0)) {
    phpCAS::proxy($server_version, $server_cas_server, $server_port, $server_uri, $start_session);
    $cas_pgt_storage_path = variable_get('cas_pgtpath', '');
    if ($cas_pgt_storage_path != '') {
      if (version_compare(PHPCAS_VERSION, '1.3', '>=')) {
        phpCAS::setPGTStorageFile($cas_pgt_storage_path);
      }
      else {
        $cas_pgt_format = variable_get('cas_pgtformat', 'plain');
        phpCAS::setPGTStorageFile($cas_pgt_format, $cas_pgt_storage_path);
      }
    }
  }
  else {
    phpCAS::client($server_version, $server_cas_server, $server_port, $server_uri, $start_session);
  }

  //Add CAS proxy lists allowed
  $proxy_list = variable_get('cas_proxy_list', '');
  if ($proxy_list) {
    $proxy_list = explode("\n", $proxy_list);
    phpCAS::allowProxyChain(new CAS_ProxyChain($proxy_list));
  }

  // force CAS authentication
  if ($cas_cert = variable_get('cas_cert', '')) {
    phpCAS::setCasServerCACert($cas_cert);
  }
  else {
    phpCAS::setNoCasServerValidation();
  }

  phpCAS::setFixedServiceURL(url(current_path(), array('query' => drupal_get_query_parameters(), 'absolute' => TRUE)));
  phpCAS::setCacheTimesForAuthRecheck((int) variable_get('cas_check_frequency', CAS_CHECK_NEVER));

  // Allow other modules to call phpCAS routines. We do not call
  // drupal_alter() since there are no parameters to pass.
  module_invoke_all('cas_phpcas_alter');
}


/**
 * Implements hook_permission().
 */
function cas_permission() {
  return array(
    'administer cas' => array(
      'title' => t('Administer CAS'),
      'description' => t('Configure CAS server, default CAS user roles, login/logout redirection, and other settings.'),
      'restrict access' => TRUE,
    )
  );
}

/**
 * Implements hook_help().
 */
function cas_help($section) {
  switch ($section) {
    case 'admin/help#cas':
      return t("Allows users to authenticate via a Central Authentication Service.");
  }
}

/**
 * Implements hook_menu().
 */
function cas_menu() {
  global $user;
  $items = array();
  //cas_login_check();
  $items['admin/config/people/cas'] = array(
    'title' => 'CAS settings',
    'description' => 'Configure central authentication services',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('cas_admin_settings'),
    'access arguments' => array('administer cas'),
    'type' => MENU_NORMAL_ITEM,
    'file' => 'cas.admin.inc',
  );
  $items['admin/config/people/cas/settings'] = array(
    'title' => 'CAS',
    'type' => MENU_DEFAULT_LOCAL_TASK,
    'weight' => -10,
  );
  $items['admin/people/cas/create'] = array(
    'title' => 'Add CAS user(s)',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('cas_add_user_form'),
    'access arguments' => array('administer users'),
    'type' => MENU_LOCAL_ACTION,
    'file' => 'cas.user.inc',
    'tab_parent' => 'admin/people',
    'weight' => 1,
  );
  $items['user/%user/cas'] = array(
    'title' => 'CAS',
    'page callback' => 'cas_user_identities',
    'page arguments' => array(1),
    'access arguments' => array('administer users'),
    'type' => MENU_LOCAL_TASK,
    'file' => 'cas.pages.inc',
    'tab_parent' => 'user/%/edit',
    'weight' => 1,
  );
  $items['user/%user/cas/delete'] = array(
    'title' => 'Delete CAS username',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('cas_user_delete_form', 1),
    'access arguments' => array('administer users'),
    'file' => 'cas.pages.inc',
  );
  $items['cas'] = array(
    'path' => 'cas',
    'title' => 'CAS Login',
    'page callback' => 'cas_login_page',
    'access callback' => 'user_is_anonymous',
    'type' => MENU_SUGGESTED_ITEM,
  );
  $items['caslogout'] = array(
    'title' => 'CAS Logout',
    'page callback' => 'cas_logout',
    'access callback' => 'cas_user_is_logged_in',
    'type' => MENU_SUGGESTED_ITEM,
  );
  return $items;
}

/**
 * Implements hook_cron().
 */
function cas_cron() {
  // Clear old single logout session mapping data.
  $max_days = (int) variable_get('cas_single_logout_session_lifetime', 25);
  $seconds_in_day = 86400;
  $seconds = $max_days * $seconds_in_day;
  if ($seconds > 0) {
    db_delete('cas_login_data')
      ->condition('created', time() - $seconds, '<=')
      ->execute();
  }
}

function cas_user_is_logged_in() {
  return user_is_logged_in() || !empty($_SESSION['phpCAS']['user']);
}

/**
 * Implements hook_menu_site_status_alter().
 */
function cas_menu_site_status_alter(&$menu_site_status, $path) {
  if (user_is_logged_in() && strtolower($path) == 'cas') {
    // If user is logged in, redirect to '<front>' instead of giving 403.
    drupal_goto('');
  }
}

/**
 * Implements hook_menu_link_alter().
 *
 * Flag this link as needing alter at display time.
 * @see cas_translated_menu_link_alter()
 */
function cas_menu_link_alter(&$item) {
  $link_path = strtolower($item['link_path']);
  if ($link_path == 'cas' || $link_path == 'caslogout') {
    $item['options']['alter'] = TRUE;
  }
}

/**
 * Implements hook_translated_menu_item_alter().
 *
 * Append dynamic query 'destination' to CAS menu links.
 */
function cas_translated_menu_link_alter(&$item) {
  $href = strtolower($item['href']);
  $append_destination = $href == 'cas' || ($href == 'caslogout' && !variable_get('cas_logout_destination', ''));
  if ($append_destination) {
    // Don't overwrite existing query params that may exist in the menu link.
    if (isset($item['localized_options']['query'])) {
      $menu_link_query_params = array_merge(drupal_get_destination(), $item['localized_options']['query']);
    }
    else {
      $menu_link_query_params = drupal_get_destination();
    }
    $item['localized_options']['query'] = $menu_link_query_params;
  }
}

/**
 * Implements hook_user_operations().
 */
function cas_user_operations($form = array(), $form_state = array()) {
  $operations['cas_create'] = array(
    'label' => t('Create CAS username'),
    'callback' => 'cas_user_operations_create_username',
  );
  $operations['cas_remove'] = array(
    'label' => t('Remove CAS usernames'),
    'callback' => 'cas_user_operations_remove_usernames',
  );
  return $operations;
}

/**
 * Callback function to assign a CAS username to the account.
 *
 * @param $uids
 *   An array of user ids. For each account, a CAS username is created with
 *   the same name as the Drupal username.
 *
 * @see cas_user_operations()
 */
function cas_user_operations_create_username($uids) {
  $accounts = user_load_multiple($uids);
  foreach ($accounts as $account) {
    $count = db_select('cas_user', 'c')
      ->condition('cas_name', $account->name)
      ->condition('uid', $account->uid, '<>')
      ->countQuery()->execute()->fetchfield();
    if ($count) {
      drupal_set_message(t('CAS username %username already in use.', array('%username' => $account->name)), 'error');
      continue;
    }
    db_merge('cas_user')
      ->key(array('cas_name' => $account->name))
      ->fields(array('uid' => $account->uid))
      ->execute();
  }
}

/**
 * Callback function to remove CAS usernames from the account.
 *
 * @param $uids
 *   An array of user ids. For each account, all CAS usernames are removed.
 *
 * @see cas_user_operations()
 */
function cas_user_operations_remove_usernames($uids) {
  db_delete('cas_user')
    ->condition('uid', $uids, 'IN')
    ->execute();
}

/**
 * Implements hook_admin_paths().
 */
function cas_admin_paths() {
  $paths = array(
    'user/*/cas' => TRUE,
    'user/*/cas/delete/*' => TRUE,
  );
  return $paths;
}

/**
 * Implements hook_user_load().
 *
 * Adds an associative array 'cas_names' to each user. The array keys are
 * unique authentication mapping ids, with CAS usernames as the values.
 */
function cas_user_load($users) {
  foreach (array_keys($users) as $uid) {
    $users[$uid]->cas_names = array();
  }
  $result = db_query('SELECT aid, uid, cas_name FROM {cas_user} WHERE uid IN (:uids)', array(':uids' => array_keys($users)));
  foreach ($result as $record) {
    $users[$record->uid]->cas_names[$record->aid] = $record->cas_name;
  }
  foreach (array_keys($users) as $uid) {
    $users[$uid]->cas_name = reset($users[$uid]->cas_names);
  }
}

/**
 * Implements hook_user_insert().
 *
 * When a user is created, record their CAS username if provided.
 */
function cas_user_insert(&$edit, $account, $category) {
  if (!empty($edit['cas_name'])) {
    db_insert('cas_user')
      ->fields(array(
        'cas_name' => $edit['cas_name'],
        'uid' => $account->uid,
      ))
      ->execute();
  }
  // Update $account to reflect changes.
  $users = array($account->uid => $account);
  cas_user_load($users);
}

/**
 * Implements hook_user_update().
 *
 * When a user is updated, change their CAS username if provided.
 */
function cas_user_update(&$edit, $account, $category) {
  if (!array_key_exists('cas_name', $edit)) {
    // If the cas_name key is not provided, there is nothing to do.
    return;
  }
  $cas_name = $edit['cas_name'];

  // See if the user currently has any CAS names.
  reset($account->cas_names);
  if ($aid = key($account->cas_names)) {
    // The user already has CAS username(s) set.
    if (empty($cas_name)) {
      // Remove a CAS username.
      db_delete('cas_user')
        ->condition('uid', $account->uid)
        ->condition('aid', $aid)
        ->execute();
    }
    else {
      // Change a CAS username.
      if ($cas_name != $account->cas_names[$aid]) {
        db_update('cas_user')
          ->fields(array('cas_name' => $cas_name))
          ->condition('uid', $account->uid)
          ->condition('aid', $aid)
          ->execute();
      }
    }
  }
  else {
    // No current CAS usernames.
    if (!empty($cas_name)) {
      // Add a CAS username.
      db_insert('cas_user')
        ->fields(array(
          'uid' => $account->uid,
          'cas_name' => $cas_name,
        ))
        ->execute();
    }
  }
  // Update $account to reflect changes.
  $users = array($account->uid => $account);
  cas_user_load($users);
}

/**
 * Implement hook_user_delete().
 *
 * When a CAS user is deleted, we need to clean up the entry in {cas_user}.
 */
function cas_user_delete($account) {
  db_delete('cas_user')
    ->condition('uid', $account->uid)
    ->execute();
}

/**
 * Fetch a user object by CAS name.
 *
 * @param $cas_name
 *   The name of the CAS user.
 * @param $alter
 *   If TRUE, run the CAS username through hook_cas_user_alter() before
 *   loading the account.
 * @param $reset
 *   TRUE to reset the internal cache and load from the database; FALSE
 *   (default) to load from the internal cache, if set.
 *
 * @return
 *   A fully-loaded $user object upon successful user load or FALSE if user
 *   cannot be loaded.
 */
function cas_user_load_by_name($cas_name, $alter = FALSE, $reset = FALSE) {
  if ($alter) {
    $cas_user = array(
      'name' => $cas_name,
      'login' => TRUE,
      'register' => FALSE,
    );
    drupal_alter('cas_user', $cas_user);
    $cas_name = $cas_user['name'];
  }

  $uid = db_select('cas_user')->fields('cas_user', array('uid'))->condition('cas_name', db_like($cas_name), 'LIKE')->range(0, 1)->execute()->fetchField();
  if ($uid) {
    return user_load($uid, $reset);
  }
  return FALSE;
}

/**
 * This is the page callback for the /cas page, which is used only to
 * trigger a forced CAS authentication.
 *
 * In almost all cases, the user will have been redirected before even
 * hitting this page (see hook_init implementation). But as a stop gap
 * just redirect to the homepage.
 */
function cas_login_page() {
  drupal_goto('');
}

/**
 * Logs a user out of Drupal and then out of CAS.
 *
 * This function does not return, but instead immediately redirects the user
 * to the CAS server to complete the CAS logout process.
 *
 * Other modules intending to call this from their implementation of
 * hook_user_logout() will need to pass $invoke_hook = FALSE to avoid an
 * infinite recursion. WARNING: since this function does not return, any
 * later implementations of hook_user_logout() will not run. You may wish to
 * adjust the hook execution order using hook_module_implements_alter().
 *
 * @param $invoke_hook
 *   If TRUE, invoke hook_user_logout() and save a watchdog message indicating
 *   that the user has logged out.
 */
function cas_logout($invoke_hook = TRUE) {
  global $user;

  // Build the logout URL.
  cas_phpcas_init();

  if (isset($_GET['destination']) && !url_is_external($_GET['destination'])) {
    // Add destination override so that a destination can be specified on the
    // logout link, e.g., caslogout?destination=http://foo.bar.com/foobar. We do
    // not allow absolute URLs to be passed via $_GET, as this can be an attack
    // vector.
    $destination = $_GET['destination'];
  }
  else {
    $destination = variable_get('cas_logout_destination', '');
  }

  //Make it an absolute url.  This will also convert <front> to the front page.
  if ($destination) {
    $destination_url = url($destination, array('absolute' => TRUE));
    $options = array(
      'service' => $destination_url,
      'url' => $destination_url,
    );
  }
  else {
    $options = array();
  }

  // Mimic user_logout().
  if ($invoke_hook) {
    watchdog('user', 'Session closed for %name.', array('%name' => format_username($user)));
    module_invoke_all('user_logout', $user);
  }

  // phpCAS automatically calls session_destroy().
  phpCAS::logout($options);
}

/**
 * Implements hook_block_info().
 */
function cas_block_info() {
  $blocks['login']['info'] = t('CAS login');
  // Not worth caching.
  $blocks['login']['cache'] = DRUPAL_NO_CACHE;

  return $blocks;
}

/**
 * Implements hook_block_view().
 */
function cas_block_view($delta = '') {
  global $user;

  $block = array();

  switch ($delta) {
    case 'login':
      // For usability's sake, avoid showing two login forms on one page.
      if (!$user->uid && !(arg(0) == 'user' && !is_numeric(arg(1)))) {
        $block['subject'] = t('User login');
        $block['content'] = drupal_get_form('cas_login_block');
      }
      return $block;
  }
}

/**
 * Login form for the CAS login block.
 */
function cas_login_block($form) {
  $form['#action'] = url('cas', array('query' => drupal_get_destination()));
  $form['#id'] = 'cas-login-form';

  $form['cas_login_redirection_message'] = array(
    '#type' => 'item',
    '#markup' => t(variable_get('cas_login_redir_message', CAS_LOGIN_REDIR_MESSAGE)),
    '#weight' => -1,
  );
  $form['actions'] = array('#type' => 'actions');
  $form['actions']['submit'] = array(
    '#type' => 'submit',
    '#value' => t(variable_get('cas_login_invite', CAS_LOGIN_INVITE_DEFAULT)),
  );

  return $form;
}

/**
 * Determine if we should automatically check if the user is authenticated.
 *
 * This implements part of the CAS gateway feature.
 * @see phpCAS::checkAuthentication()
 *
 * @return
 *   TRUE if we should query the CAS server to see if the user is already
 *   authenticated, FALSE otherwise.
 */
function _cas_allow_check_for_login() {
  // Do not process in maintenance mode.
  if (variable_get('maintenance_mode', 0)) {
    return FALSE;
  }

  if (variable_get('cas_check_frequency', CAS_CHECK_NEVER) == CAS_CHECK_NEVER) {
    // The user has disabled the feature.
    return FALSE;
  }

  // Check to see if we've got a search bot.
  if (isset($_SERVER['HTTP_USER_AGENT'])) {
    $crawlers = array(
      'Google',
      'msnbot',
      'Rambler',
      'Yahoo',
      'AbachoBOT',
      'accoona',
      'AcoiRobot',
      'ASPSeek',
      'CrocCrawler',
      'Dumbot',
      'FAST-WebCrawler',
      'GeonaBot',
      'Gigabot',
      'Lycos',
      'MSRBOT',
      'Scooter',
      'AltaVista',
      'IDBot',
      'eStyle',
      'Scrubby',
      'gsa-crawler',
      );
    // Return on the first find.
    foreach ($crawlers as $c) {
      if (stripos($_SERVER['HTTP_USER_AGENT'], $c) !== FALSE) {
        return FALSE;
      }
    }
  }

  // Do not force login for XMLRPC, Cron, or Drush.
  if (stristr($_SERVER['SCRIPT_FILENAME'], 'xmlrpc.php')) {
    return FALSE;
  }
  if (stristr($_SERVER['SCRIPT_FILENAME'], 'cron.php')) {
    return FALSE;
  }
  if (stristr($_SERVER['SCRIPT_FILENAME'], 'drush')) {
    return FALSE;
  }
  if (!empty($_SERVER['argv'][0]) && stristr($_SERVER['argv'][0], 'drush')) {
    return FALSE;
  }

  // Test against exclude pages.
  if ($pages = variable_get('cas_exclude', CAS_EXCLUDE)) {
    $path = drupal_get_path_alias($_GET['q']);
    if (drupal_match_path($path, $pages)) {
      return FALSE;
    }
  }

  return TRUE;
}

/**
 * Determine if we should require the user be authenticated.
 *
 * @return
 *   TRUE if we should require the user be authenticated, FALSE otherwise.
 */
function _cas_force_login() {
  // The 'cas' page is a shortcut to force authentication.
  if (strtolower(arg(0)) == 'cas') {
    return TRUE;
  }

  // Do not process in maintenance mode.
  if (variable_get('maintenance_mode', 0)) {
    return FALSE;
  }

  // Do not force login for XMLRPC, Cron, or Drush.
  if (stristr($_SERVER['SCRIPT_FILENAME'], 'xmlrpc.php')) {
    return FALSE;
  }
  if (stristr($_SERVER['SCRIPT_FILENAME'], 'cron.php')) {
    return FALSE;
  }
  if (function_exists('drush_verify_cli') && drush_verify_cli()) {
    return FALSE;
  }

  // Excluded page do not need login.
  if ($pages = variable_get('cas_exclude', CAS_EXCLUDE)) {
    $path = drupal_get_path_alias($_GET['q']);
    if (drupal_match_path($path, $pages)) {
      return FALSE;
    }
  }

  // Set the default behavior.
  $force_login = variable_get('cas_access', 0);

  // If we match the specified paths, reverse the behavior.
  if ($pages = variable_get('cas_pages', '')) {
    $path = drupal_get_path_alias($_GET['q']);
    if (drupal_match_path($path, $pages)) {
      $force_login = !$force_login;
    }
  }

  return $force_login;
}
/**
 * Implements hook_form_alter().
 *
 * Overrides specific from settings based on user policy.
 */
function cas_form_alter(&$form, &$form_state, $form_id) {
  // Special handling of the user login page when the CAS login form is set to
  // redirect.
  if ($form_id == 'user_login' && variable_get('cas_login_form', CAS_NO_LINK) == CAS_REDIRECT) {
    drupal_goto('cas');
  }

  switch ($form_id) {
    case 'user_login':
    case 'user_login_block':
      if (variable_get('cas_login_form', CAS_NO_LINK) != CAS_NO_LINK) {
        $form['#attached']['css'][] = drupal_get_path('module', 'cas') . '/cas.css';
        $form['#attached']['js'][] = drupal_get_path('module', 'cas') . '/cas.js';

        if (!empty($form_state['input']['cas_identifier'])) {
          $form['name']['#required'] = FALSE;
          $form['pass']['#required'] = FALSE;
          unset($form['#validate']);
          $form['#submit'] = array('cas_login_submit');
        }

        $items = array();
        $items[] = array(
          'data' => l(t(variable_get('cas_login_invite', CAS_LOGIN_INVITE_DEFAULT)), '#'),
          'class' => array('cas-link'),
        );

        $items[] = array(
          'data' => l(t(variable_get('cas_login_drupal_invite', CAS_LOGIN_DRUPAL_INVITE_DEFAULT)), '#'),
          'class' => array('uncas-link'),
        );

        $form['cas_links'] = array(
          '#theme' => 'item_list',
          '#items' => $items,
          '#attributes' => array('class' => array('cas-links')),
          '#weight' => 101,
        );

        $form['links']['#weight'] = 2;

        $form['cas_login_redirection_message'] = array(
          '#type' => 'item',
          '#markup' => t(variable_get('cas_login_redir_message', CAS_LOGIN_REDIR_MESSAGE)),
          '#weight' => -1,
        );

        $form['cas_identifier'] = array(
          '#type' => 'checkbox',
          '#title' => t(variable_get('cas_login_invite', CAS_LOGIN_INVITE_DEFAULT)),
          '#default_value' => variable_get('cas_login_form', CAS_NO_LINK) == CAS_MAKE_DEFAULT,
          '#weight' => -1,
          '#description' => t(variable_get('cas_login_redir_message', CAS_LOGIN_REDIR_MESSAGE)),
        );
        $form['cas.return_to'] = array('#type' => 'hidden', '#value' => user_login_destination());
      }
      break;

    case 'user_profile_form':
      $account = $form['#user'];
      if (user_access('administer users')) {
        // The user is an administrator, so add fields to allow changing the
        // CAS username(s) associated with the account.
        $cas_names = $account->cas_names;
        $aids = array_keys($cas_names);

        $element = array(
          '#type' => 'textfield',
          '#title' => t('CAS username'),
          '#default_value' => array_shift($cas_names),
          '#cas_user_aid' => array_shift($aids),
          '#description' => t('<a href="@url">Create, edit or delete</a> additional CAS usernames associated with this account.', array('@url' => url('user/' . $account->uid . '/cas'))),
          '#element_validate' => array('_cas_name_element_validate'),
          '#weight' => -9,
        );

        // See if any additional CAS usernames exist.
        if (!empty($cas_names)) {
          $element['#description'] .= ' <br />' . t('Other CAS usernames: %cas_names.', array('%cas_names' => implode(', ', $cas_names)));
        }
        $form['account']['cas_name'] = $element;
      }
      elseif (cas_is_external_user($account)) {
        // The user is not an administrator, so selectively remove the e-mail
        // and password fields.
        if (variable_get('cas_hide_email', 0)) {
          $form['account']['mail']['#access'] = FALSE;
        }
        if (variable_get('cas_hide_password', 0)) {
          $form['account']['pass']['#access'] = FALSE;
        }
      }
      if (cas_is_external_user($account) && variable_get('cas_hide_password', 0)) {
        // Also remove requirement to validate your current password before
        // changing your e-mail address.
        $form['account']['current_pass']['#access'] = FALSE;
        $form['account']['current_pass_required_values']['#access'] = FALSE;
        $form['account']['current_pass_required_values']['#value'] = array();
        $form['#validate'] = array_diff($form['#validate'], array('user_validate_current_pass'));
      }
      break;

    case 'user_pass':
      if (!user_access('administer users') && variable_get('cas_changePasswordURL', '') != '') {
        drupal_goto(variable_get('cas_changePasswordURL', ''));
      }
      break;

    case 'user_register_form':
      if (user_access('administer users')) {
        $form['account']['cas_name'] = array(
          '#type' => 'textfield',
          '#title' => t('CAS username'),
          '#default_value' => '',
          '#description' => t('If necessary, additional CAS usernames can be added after the account is created.'),
          '#element_validate' => array('_cas_name_element_validate'),
          '#weight' => -9,
        );
      }
      elseif (variable_get('cas_registerURL', '') != '') {
        drupal_goto(variable_get('cas_registerURL', ''));
      }
      break;

    case 'user_admin_account':
      // Insert the CAS username into the second column.
      _cas_array_insert($form['accounts']['#header'], 1, array(
        'cas' => array(
          'data' => 'CAS usernames',
        ),
      ));
      foreach ($form['accounts']['#options'] as $uid => &$row) {
        $cas_usernames = db_query('SELECT cas_name FROM {cas_user} WHERE uid = :uid', array(':uid' => $uid))->fetchCol();
        $row['cas'] = theme('item_list', array('items' => $cas_usernames));
      }
      break;
  }
}

/**
 * Form element 'cas_name' validator.
 *
 * If the element is displaying an existing {cas_user} entry, set
 * #cas_user_aid to the corresponding authmap id to avoid spurious
 * validation errors.
 */
function _cas_name_element_validate($element, &$form_state) {
  if (empty($element['#value'])) {
    // Nothing to validate if the name is empty.
    return;
  }

  $query = db_select('cas_user')
    ->fields('cas_user', array('uid'))
    ->condition('cas_name', $element['#value']);

  // If set, we ignore entries with a specified authmap id. This is used on
  // the user/%user/edit page to not throw validation errors when we do not
  // change the CAS username.
  if (isset($element['#cas_user_aid'])) {
    $query->condition('aid', $element['#cas_user_aid'], '<>');
  }

  $uid = $query->execute()->fetchField();

  if ($uid !== FALSE) {
    // Another user is using this CAS username.
    form_set_error('cas_name', t('The CAS username is <a href="@edit-user-url">already in use</a> on this site.', array('@edit-user-url' => url('user/' . $uid . '/edit'))));
  }
}

/**
 * Login form _validate hook
 */
function cas_login_submit(&$form, &$form_state) {
  if (!empty($form_state['values']['persistent_login'])) {
    $_SESSION['cas_remember'] = 1;
  }
  // Force redirection.
  unset($_GET['destination']);
  drupal_goto('cas', array('query' => $form_state['values']['cas.return_to']));
}

function _cas_single_sign_out_check() {
  if (isset($_POST["logoutRequest"])) {
    $cas_logout_request_xml_string = utf8_encode(urldecode($_POST["logoutRequest"]));
    $cas_logout_request_xml = new SimpleXMLElement($cas_logout_request_xml_string);
    if (is_object($cas_logout_request_xml)) {
      $namespaces = $cas_logout_request_xml->getNameSpaces();
      $xsearch = 'SessionIndex';
      if (isset($namespaces['samlp'])) {
        $cas_session_indexes = $cas_logout_request_xml->children($namespaces['samlp'])->SessionIndex;
      }
      else {
        $cas_session_indexes = $cas_logout_request_xml->xpath($xsearch);
      }
      if ($cas_session_indexes) {
        $cas_session_index = (string)$cas_session_indexes[0];
        // Log them out now.
        // first lets find out who we want to log off

        $hashed_ticket = hash('sha256', $cas_session_index);
        $record = db_query_range("SELECT cld.uid, u.name FROM {users} u JOIN {cas_login_data} cld ON u.uid = cld.uid WHERE cld.cas_session_id = :ticket", 0, 1, array(':ticket' => $hashed_ticket))->fetchObject();
        if ($record) {
          watchdog('user', 'Session closed for %name by CAS logout request.', array('%name' => $record->name));
          //remove all entry for user id in cas_login_data
          db_delete('cas_login_data')
            ->condition('uid', $record->uid)
            ->execute();

          // remove their session
          db_delete('sessions')
            ->condition('uid', $record->uid)
            ->execute();
        }
      }
    }
    // This request is done, so just exit.
    exit();
  }
}

/**
 * Return the current CAS username.
 */
function cas_current_user() {
  return isset($_SESSION['cas_name']) ? $_SESSION['cas_name'] : FALSE;
}

/**
 * Determine whether the specified user is an "external" CAS user.
 * When settings are set to use drupal as the user repository, then this
 * function will always return true.
 *
 * @param $account
 *   The user object for the user to query. If omitted, the current user is
 *   used.
 *
 * @return
 *   TRUE if the user is logged in via CAS.
 */
function cas_is_external_user($account = NULL) {
  if (!isset($account)) {
    $account = $GLOBALS['user'];
  }
  return in_array(cas_current_user(), $account->cas_names);
}


function _cas_single_sign_out_save_token($user) {
  // Ok lets save the CAS service ticket to DB so
  // we can handle CAS logoutRequests when they come
  if ($user->uid && $user->uid > 0 && !empty($_SESSION['cas_ticket'])) {
    $hashed_ticket = hash('sha256', $_SESSION['cas_ticket']);
    db_merge('cas_login_data')
      ->key(array('cas_session_id' => $hashed_ticket))
      ->fields(array(
        'cas_session_id' => $hashed_ticket,
        'uid' => $user->uid,
        'created' => time(),
      ))
      ->execute();
    unset($_SESSION['cas_ticket']);
  }
}

/**
 * Make sure that we persist ticket because of redirects performed by CAS.
 *
 */
function _cas_single_sign_out_save_ticket() {
  if (isset($_GET['ticket'])) {
    $_SESSION['cas_ticket'] = $_GET['ticket'];
  }
}

/**
 * Determine whether a CAS user is blocked.
 *
 * @param $cas_name
 *   The CAS username.
 *
 * @return
 *   Boolean TRUE if the user is blocked, FALSE if the user is active.
 */
function _cas_external_user_is_blocked($cas_name) {
  return db_query("SELECT name FROM {users} u JOIN {cas_user} c ON u.uid = c.uid WHERE u.status = 0 AND c.cas_name = :cas_name", array(':cas_name' => $cas_name))->fetchField();
}

/**
 * Invokes hook_cas_user_TYPE() in every module.
 *
 * We cannot use module_invoke() because the arguments need to be passed by
 * reference.
 */
function cas_user_module_invoke($type, &$edit, $account) {
  foreach (module_implements('cas_user_' . $type) as $module) {
    $function = $module . '_cas_user_' . $type;
    $function($edit, $account);
  }
}

/**
 * Roles which should be granted to all CAS users.
 *
 * @return
 *   An associative array with the role id as the key and the role name as value.
 */
function cas_roles() {
  $cas_roles = &drupal_static(__FUNCTION__);
  if (!isset($cas_roles)) {
    $cas_roles = array_intersect_key(user_roles(), array_filter(variable_get('cas_auto_assigned_role', array(DRUPAL_AUTHENTICATED_RID => TRUE))));
  }
  return $cas_roles;
}

/**
 * Register a CAS user with some default values.
 *
 * @param $cas_name
 *   The name of the CAS user.
 * @param $options
 *   An associative array of options, with the following elements:
 *    - 'edit': An array of fields and values for the new user. If omitted,
 *      reasonable defaults are used.
 *    - 'invoke_cas_user_presave': Defaults to FALSE. Whether or not to invoke
 *      hook_cas_user_presave() on the newly created account.
 *
 * @return
 *   The user object of the created user, or FALSE if the user cannot be
 *   created.
 */
function cas_user_register($cas_name, $options = array()) {
  // Add some reasonable defaults if they have not yet been provided.
  $edit = isset($options['edit']) ? $options['edit'] : array();
  $edit += array(
    'name' => $cas_name,
    'pass' => user_password(),
    'init' => $cas_name,
    'mail' => variable_get('cas_domain', '') ? $cas_name . '@' . variable_get('cas_domain', '') : '',
    'status' => 1,
    'roles' => array(),
  );
  $edit['roles'] += cas_roles();
  $edit['cas_name'] = $cas_name;

  // See if the user name is already taken.
  if ((bool) db_select('users')->fields('users', array('name'))->condition('name', db_like($edit['name']), 'LIKE')->range(0, 1)->execute()->fetchField()) {
    return FALSE;
  }

  // Create the user account.
  $account = user_save(drupal_anonymous_user(), $edit);
  watchdog("user", 'new user: %n (CAS)', array('%n' => format_username($account)), WATCHDOG_NOTICE, l(t("edit user"), "user/edit/$account->uid"));

  if (!empty($options['invoke_cas_user_presave'])) {
    // Populate $edit with some basic properties.
    $edit = array(
      'cas_user' => array(
        'name' => $cas_name,
      ),
    );

    // Allow other modules to make their own custom changes.
    cas_user_module_invoke('presave', $edit, $account);

    // Clean up extra variables before saving.
    unset($edit['cas_user']);

    $account = user_save($account, $edit);
  }

  // Reload to ensure that we have a fully populated user object.
  return user_load($account->uid);
}

/**
 * Get the CAS attributes of the current CAS user.
 *
 * Ensures that phpCAS is properly initialized before getting the attributes.
 * @see phpCAS::getAttributes()
 *
 * @param $cas_name
 *   If provided, ensure that the currently logged in CAS user matches this
 *   CAS username.
 *
 * @return
 *   An associative array of CAS attributes.
 */
function cas_phpcas_attributes($cas_name = NULL) {
  if (isset($cas_name) && $cas_name != cas_current_user()) {
    // Attributes cannot be extracted for other users, since they are
    // stored in the session variable.
    return array();
  }

  cas_phpcas_init();
  if (phpCAS::isAuthenticated()) {
    if (method_exists('phpCAS', 'getAttributes')) {
      return phpCAS::getAttributes();
    }
  }

  return array();
}


/**
 * Insert an array into the specified position of another array.
 *
 * Preserves keys in associative arrays.
 * @see http://www.php.net/manual/en/function.array-splice.php#56794
 */
function _cas_array_insert(&$array, $position, $insert_array) {
  $first_array = array_splice($array, 0, $position);
  $array = array_merge($first_array, $insert_array, $array);
}

/**
 * Implements hook_views_api().
 */
function cas_views_api() {
  return array(
    'api' => 3,
    'path' => drupal_get_path('module', 'cas') . '/includes/views',
  );
}

/**
 * Redirect a user after they have logged into the website through CAS
 *
 * @param $cas_first_login - TRUE if this is the first time the CAS user
 * logged into the site
 */
function _cas_redirect_after_login($cas_first_login) {
  // When users first log in, we may want to redirect them to a special page if specified   
  if ($cas_first_login && variable_get('cas_first_login_destination', '')) {
    $destination = variable_get('cas_first_login_destination', '');     
    drupal_goto($destination);
  }
  else {    
    // If logged in through forced authentication ('/cas'), then redirect user to the
    // homepage, or to wherever the current "destination" parameter points.
    if (strtolower(current_path()) == 'cas') {
      drupal_goto('');
    }
    // If logged in through gateway feature, then just reload the current path
    // and preserve any query string args that were set
    else {
      drupal_goto(current_path(), array('query' => drupal_get_query_parameters()));
    }
  }
}