ding_provider.module

<?php
/**
 * @file
 * Implements a common interface to backend providers.
 */

/**
 * Implements hook_requirements().
 */
function ding_provider_requirements($phase) {
  $requirements = array();
  $t            = get_t();
  $providers    = array();
  $conflicting  = FALSE;

  // Check if we have conflicting provider types
  foreach (module_implements('ding_provider') as $module) {
    $provider_module = module_invoke($module, 'ding_provider');
    if (array_key_exists('provides', $provider_module)) {
      foreach ($provider_module['provides'] as $provides) {
        $providers[$provides['prefix']][] = $module;
      }
    }
  }

  foreach ($providers as $providertype => $providermodules) {
    if (count($providermodules) > 1) {
      $conflicting[] = t('%type implemented by @providers. Using @module.', array(
        '@providers' => implode(', ', $providermodules),
        '%type'      => $providertype,
        '@module'    => end($providermodules),
      )
      );
    }
  }

  switch ($phase) {
    case 'runtime':
      if ($callback = variable_get('ding_provider_ajax_disabled', FALSE)) {
        $requirements['ding_provider_ajax_conflict'] = array(
          'title'       => $t('Ding provider AJAX authentication'),
          'description' => $t('Disabled'),
          'severity'    => REQUIREMENT_ERROR,
          'value'       => t('Ding Provider is unable to override the system/ajax page, because some other module already has overridden it with %callback.', array('%callback' => $callback)),
        );
      }
      if ($conflicting == TRUE) {
        $requirements['ding_provider_conflict'] = array(
          'title'       => $t('Ding provider Information'),
          'description' => $t('Possible provider conflict'),
          'severity'    => REQUIREMENT_WARNING,
          'value'       => implode('<br />', $conflicting),
        );
      }
      break;
  }
  return $requirements;
}

/**
 * Implements hook_menu().
 */
function ding_provider_menu() {
  $items['ding_provider_error'] = array(
    'title' => 'Internal error',
    'page callback' => 'ding_provider_error_page',
    'access callback' => TRUE,
  );

  $items['admin/config/ding/provider'] = array(
    'title' => 'Ding provider',
    'page callback' => 'ding_provider_admin_overview',
    'access arguments' => array('administer ding provider'),
    'file' => 'ding_provider.admin.inc'
  );

  $items['admin/config/ding/provider/overview'] = array(
    'title' => 'Overview',
    'description' => 'Providers overview',
    'type' => MENU_DEFAULT_LOCAL_TASK,
    'weight' => -1,
    'file' => 'system.admin.inc',
  );

  $providers = _ding_provider_get_provider();
  foreach ($providers as $name => $provider) {
    if ($provider['global settings']) {
      $items['admin/config/ding/provider/' . $provider['module']] = array(
        'title' => $provider['title'],
        'page callback' => 'drupal_get_form',
        'page arguments' => array($provider['global settings']),
        'access arguments' => array('administer ding provider'),
        'type' => MENU_LOCAL_TASK,
        'weight' => -1,
      );
      if ($provider['global settings file']) {
        $items['admin/config/ding/provider/' . $provider['module']]['file'] = $provider['global settings file'];
      }
    }
  }

  return $items;
}

/**
 * Implements hook_menu_alter().
 */
function ding_provider_menu_alter(&$items) {
  // Override system/ajax with a version that caches
  // DingProviderAuthException.
  $callback = $items['system/ajax']['page callback'];
  if ($callback == 'ajax_form_callback') {
    $items['system/ajax']['page callback'] = 'ding_provider_ajax_form_callback';
    $items['system/ajax']['file path'] = drupal_get_path('module', 'ding_provider');
    $items['system/ajax']['file'] = 'ding_provider.module';
    // Delete var, but only if it is set.
    if (variable_get('ding_provider_ajax_disabled', NULL)) {
      variable_del('ding_provider_ajax_disabled');
    }
  }
  else {
    // Set a variable for hook_requirements.
    variable_set('ding_provider_ajax_disabled', $callback);
  }
}

/**
 * Implements hook_permission().
 */
function ding_provider_permission() {
  return array(
    'administer ding provider' => array(
      'title' => t('Administer Ding provider'),
    ),
  );
}

/**
 * Implements hook_ding_install_tasks().
 */
function ding_provider_ding_install_tasks() {
  $users = _ding_provider_get_provider_users();
  $providers = _ding_provider_get_provider();
  $return = array();
  foreach ($users as $provider => $info) {
    // Add global provider settings if required.
    if ($info['ding_profile'] && sizeof($info['required']) && isset($providers[$provider]) && $form_id = $providers[$provider]['global settings']) {
      $return[$form_id] = array(
        // TODO: This doesn't work for potx, we need the generated strings in
        // plain form somewhere.
        'display_name' => st($providers[$provider]['title']),
        'type' => 'form',
      );

      if ($providers[$provider]['global settings file']) {
        $return[$form_id]['file'] = $providers[$provider]['global settings file'];
      }
    }

    // Add settings for individual providers to installer if someone asked for
    // it and there's modules that requires this provider.
    if ($info['ding_profile'] && sizeof($info['required']) && $form_id = ding_provider_implements($provider, 'settings')) {
      $return[$form_id] = array(
        // TODO: This doesn't work for potx, we need the generated stings in
        // plain form somewhere.
        'display_name' => st(drupal_ucfirst($provider) . ' provider'),
        'type' => 'form',
      );
      if ($providers[$provider]['file']) {
        $return[$form_id]['file'] = $providers[$provider]['file'];
      }
    }
  }
  return $return;
}

/**
 * Error page callback.
 */
function ding_provider_error_page() {
  return array(
    '#markup' => t("Internal error. Please contact the site administrator if the problem persists."),
  );
}

/**
 * Returns whether a provider implements a given function.
 */
function ding_provider_implements($type, $hook) {
  try {
    return (bool) _ding_provider_function($type, $hook, TRUE);
  }
  catch (Exception $e) {
    return FALSE;
  }
}

/**
 * Invoke a provider function.
 *
 * Simplest of the provider invoking functions. Returns the result of calling
 * the provider function, or throws DingProviderAuthException if not
 * authenticated.
 *
 * @see ding_provider_invoke_page()
 * @see ding_provider_get_form()
 * @see ding_provider_ajax_form_callback()
 */
function ding_provider_invoke($type, $hook) {
  $args = func_get_args();
  array_shift($args);
  array_shift($args);

  $function = _ding_provider_function($type, $hook);
  if ($function) {
    return call_user_func_array($function, $args);
  }
}

/**
 * Get a form from a provider.
 */
function ding_provider_form($type, $form_id) {
  $args = func_get_args();
  array_shift($args);
  array_shift($args);

  $function = _ding_provider_function($type, $form_id);
  if ($function) {
    return drupal_get_form($function, $args);
  }
}

/**
 * Invoke a provider function, handling authentication.
 *
 * Will redirect to the authentication page if DingProviderAuthException is
 * thrown, and redirect back on successful authentication.
 *
 * @see ding_provider_invoke()
 * @see ding_provider_get_form()
 * @see ding_provider_ajax_form_callback()
 */
function ding_provider_invoke_page($type, $hook) {
  $args = func_get_args();
  array_shift($args);
  array_shift($args);

  try {
    $function = _ding_provider_function($type, $hook);
    if ($function) {
      return call_user_func_array($function, $args);
    }
  }
  catch (Exception $e) {
    if ($e instanceof DingProviderUserException) {
      // Rethrow user exceptions.
      throw $e;
    }
    elseif ($e instanceof DingProviderAuthException) {
      // Redirect to auth page
      if (module_exists('ding_user') && ($authpage = ding_user_auth_page())) {
        // @todo redirect to auth page
        drupal_goto($authpage, array('query' => ding_provider_get_destination()));
      }
    }
    if (arg(0) != 'ding_provider_error') {
      watchdog('ding_provider', 'Uncaught exception in ding_provider_invoke_page: @message', array('@message' => $e->getMessage()), WATCHDOG_ERROR);
      // Redirect to error page.
      drupal_goto('ding_provider_error');
    }
    else {
      return NULL;
    }
  }
}

/**
 * Wrapper around drupal_get_form() that handles authentication.
 *
 * Will redirect to the authentication page if DingProviderAuthException is
 * thrown, and restart form processing on successful authentication.
 *
 * @see ding_provider_invoke()
 * @see ding_provider_invoke_page()
 * @see ding_provider_ajax_form_callback()
 */
function ding_provider_get_form($form_id) {
  $form_state = array();

  $args = func_get_args();
  // Remove $form_id from the arguments.
  array_shift($args);
  $form_state['build_info']['args'] = $args;

  return ding_provider_build_form($form_id, $form_state);
}

/**
 * Wrapper around drupal_build_form() that handles authentication.
 *
 * Will redirect to the authentication page if DingProviderAuthException is
 * thrown, and restart form processing on successful authentication.
 *
 * @see ding_provider_get_form()
 */
function ding_provider_build_form($form_id, &$form_state) {
  $messages = NULL;
  try {
    if (isset($_REQUEST['dp_form_id']) && !empty($_REQUEST['dp_form_id'])) {
      // Load saved submission.
      if ($cached = cache_get('ding_provider_' . $form_id, 'cache_form')) {
        $form_state['input'] = $cached->data;
        $messages = $form_state['input']['#ding_provider_messages'];
        unset($form_state['input']['#ding_provider_messages']);
        cache_clear_all('ding_provider_' . $form_id, 'cache_form');
      }
    }
    $old_redirect = isset($form_state['no_redirect']) ? $form_state['no_redirect'] : FALSE;
    $form_state['no_redirect'] = TRUE;
    $form = drupal_build_form($form_id, $form_state);

    // Set any messages we saved.
    _ding_provider_message_reset($messages);

    $form_state['no_redirect'] = $old_redirect;
    if ($form_state['executed'] == TRUE) {
      // Redirect if the form was submitted.
      drupal_redirect_form($form_state);
    }
    return $form;
  }
  catch (Exception $e) {
    if ($e instanceof DingProviderUserException) {
      // Rethrow user exceptions.
      throw $e;
    }
    elseif ($e instanceof DingProviderAuthException) {
      if (module_exists('ding_user') && ($authpage = ding_user_auth_page())) {
        // Something needs auth, save state and redirect to authentication page.
        $expire = 21600;
        $input = $form_state['method'] == 'get' ? $_GET : $_POST;
        $input['#ding_provider_messages'] = drupal_get_messages();
        cache_set('ding_provider_' . $form_id, $input, 'cache_form', REQUEST_TIME + $expire);
        $options = array('query' => ding_provider_get_destination(array('dp_form_id' => $form_id)));
        drupal_goto($authpage, $options);
      }
    }
    elseif ($e instanceof DingProviderConsentException) {
      if (module_exists('ding_user_concent') && ($authpage = ding_user_consent_page())) {
        // Something needs auth, save state and redirect to authentication page.
        $expire = 21600;
        $input = $form_state['method'] == 'get' ? $_GET : $_POST;
        $input['#ding_provider_messages'] = drupal_get_messages();
        
        cache_set('ding_provider_' . $form_id, $input, 'cache_form', REQUEST_TIME + $expire);
        $options = array('query' => ding_provider_get_destination(array('dp_form_id' => $form_id)));
        drupal_goto($authpage, $options);
      }
    }
    watchdog('ding_provider', 'Uncaught exception in ding_provider_build_form: @message', array('@message' => $e->getMessage()), WATCHDOG_ERROR);
    // Redirect to error page.
    drupal_goto('ding_provider_error');
  }
}

/**
 * Replacement for ajax_form_callback() that handles authentication.
 *
 * Sends a log in AJAX command (implemented in ding_user), which will resubmit
 * the AJAX request on successful submission.
 *
 * @see ding_provider_invoke()
 * @see ding_provider_invoke_page()
 * @see ding_provider_get_form()
 */
function ding_provider_ajax_form_callback() {
  global $user;
  $messages = NULL;
  try {
    if (isset($_REQUEST['dp_form_id']) && !empty($_REQUEST['dp_form_id'])) {
      $form_id = (string) $_REQUEST['dp_form_id'];
      // Load saved submission.
      if ($cached = cache_get('ding_provider_' . $form_id, 'cache_form')) {
        $form_state['input'] = $cached->data;
        $messages = $form_state['input']['#ding_provider_messages'];
        $orig_user = $form_state['input']['#ding_provider_user'];
        unset($form_state['input']['#ding_provider_messages']);
        unset($form_state['input']['#ding_provider_user']);
        cache_clear_all('ding_provider_' . $form_id, 'cache_form');
      }
    }

    // If the user changed (likely because they just logged in),
    // things get complicated as ajax_get_form wont find the cached
    // form. So we reset the user momentarily.
    if (isset($orig_user) && $user->uid != $orig_user->uid) {
      $new_user = $user;
      $user = $orig_user;
    }
    list($form, $form_state, $form_id) = ajax_get_form();
    if (isset($new_user)) {
      $user = $new_user;
    }

    drupal_process_form($form['#form_id'], $form, $form_state);

    // Set any messages we saved.
    _ding_provider_message_reset($messages);

    if (!empty($form_state['triggering_element'])) {
      $callback = $form_state['triggering_element']['#ajax']['callback'];
    }
    if (!empty($callback) && function_exists($callback)) {
      $x = $callback($form, $form_state);
      return $x;
    }
  }
  catch (Exception $e) {
    if ($e instanceof DingProviderUserException) {
      // Rethrow user exceptions.
      throw $e;
    }
    elseif ($e instanceof DingProviderAuthException || $e instanceof EntityMalformedException) {
      if (module_exists('ding_user')) {
        // Something needs auth, save state and redirect to authentication page.
        $expire = 21600;
        $input = $form_state['method'] == 'get' ? $_GET : $_POST;
        $input['#ding_provider_messages'] = drupal_get_messages();
        $input['#ding_provider_user'] = $user;
        cache_set('ding_provider_' . $form_id, $input, 'cache_form', REQUEST_TIME + $expire);
        $options = array('query' => array('dp_form_id' => $form_id) + ding_provider_get_destination());

        return array(
          '#type' => 'ajax',
          '#commands' => array(
            ajax_command_ding_user_authenticate(array('dp_form_id' => $form_id))
          ),
        );
      }
    }
    elseif ($e instanceof DingProviderConsentException) {
      if (module_exists('ding_user_consent')) {
        // Something needs auth, save state and redirect to authentication page.
        $expire = 21600;
        $input = $form_state['method'] == 'get' ? $_GET : $_POST;
        $input['#ding_provider_messages'] = drupal_get_messages();
        $input['#ding_provider_user'] = $user;
        cache_set('ding_provider_' . $form_id, $input, 'cache_form', REQUEST_TIME + $expire);
        $options = array('query' => array('dp_form_id' => $form_id) + ding_provider_get_destination());
        return array(
          '#type' => 'ajax',
          '#commands' => array(
            ajax_command_ding_user_consent(array('dp_form_id' => $form_id))
          ),
        );
      }
    }
  }

  // Else show internal error.
  return array(
    '#type' => 'ajax',
    '#commands' => array(
      ajax_command_alert(t("Internal error. Please contact the site administrator if the problem persists.")),
    ),
  );
}

/**
 * Re-sets messages, avoiding duplicates.
 */
function _ding_provider_message_reset($messages) {
  if (is_array($messages)) {
    foreach ($messages as $type => $message_list) {
      foreach ($message_list as $message) {
        drupal_set_message($message, $type, FALSE);
      }
    }
  }
}

/**
 * Alternative to drupal_get_destination() which will encode an existing
 * destination into the new.
 */
function ding_provider_get_destination($query_args = array()) {
  // If destination is set, create a new one embedding the old, and
  // unset destination, so drupal_goto wont go to the old
  // destination.
  $path = $_GET['q'];
  $query = drupal_http_build_query($query_args + drupal_get_query_parameters());
  unset($_REQUEST['destination']);
  if ($query != '') {
    $path .= '?' . $query;
  }
  $destination = array(
    'destination' => $path,
  );

  return $destination;
}

/**
 * Get the provide type
 **/
function ding_provider_get_provider_type() {
  foreach (module_implements('ding_provider') as $module) {
    // simply return the first - there can be only one
    return $module;
  }
}

/**
 * Returns the given provider.
 */
function _ding_provider_get_provider($type = NULL) {
  static $providers;
  if (!isset($providers)) {
    $providers = array();
    foreach (module_implements('ding_provider') as $module) {
      $module_provides = module_invoke($module, 'ding_provider') + array(
        'title' => $module . '.module',
        'settings' => NULL,
        'file' => NULL,
        'provides' => array(),
      );
      foreach ($module_provides['provides'] as $name => $module_provider) {
        $module_provider['module'] = $module;
        $module_provider['title'] = $module_provides['title'];
        $module_provider['global settings'] = $module_provides['settings'];
        $module_provider['global settings file'] = $module_provides['file'];
        $providers[$name] = $module_provider;
      }
    }
  }

  if (!$type) {
    return $providers;
  }

  if (isset($providers[$type])) {
    return $providers[$type];
  }
  return NULL;
}

/**
 * Returns user information on the given provider.
 */
function _ding_provider_get_provider_users($type = NULL) {
  static $provider_users;
  if (!isset($provider_users)) {
    $provider_users = array();
    foreach (module_implements('ding_provider_user') as $module) {
      $module_uses = module_invoke($module, 'ding_provider_user');
      foreach ($module_uses as $name => $options) {
        if (!isset($provider_users[$name])) {
          $provider_users[$name] = array(
            'ding_profile' => FALSE,
            'required' => array(),
            'users' => array(),
          );
        }
        if (!empty($options['install time setup'])) {
          $provider_users[$name]['ding_profile'] = TRUE;
        }
        if ($options['required']) {
          $provider_users[$name]['required'][] = $module;
        }
        else {
          $provider_users[$name]['users'][] = $module;
        }
      }
    }
  }

  if (!$type) {
    return $provider_users;
  }

  if (isset($provider_users[$type])) {
    return $provider_users[$type];
  }
  return NULL;
}

/**
 * Returns the provider function for a hook, loading files if necessary. Logs
 * an error if the provider or hook isn't implemented, unless $quiet has been
 * specified.
 *
 * @param $type Provider name.
 * @param $hook Hook name.
 * @param $quiet Whether to suppress errors.
 * @return
 *  String or NULL.
 */
function _ding_provider_function($type, $hook, $quiet = FALSE) {
  $provider = _ding_provider_get_provider($type);
  if ($provider) {
    $function = $provider['module'] . '_' . (isset($provider['prefix']) ? $provider['prefix'] . '_' : '') . $hook;

    if (isset($provider['file'])) {
      require_once DRUPAL_ROOT . '/' . $provider['file'];
    }

    if (function_exists($function)) {
      return $function;
    }
    elseif (!$quiet) {
      // Trigger an error. This might be a module attempting to use a wrong
      // hook, or an improperly implemented plugin. In either case, it's
      // programmer error.
      throw new DingProviderDoesntImplement(t('Ding @type provider (@module module) does not implement @function', array('@type' => $type, '@function' => $hook, '@module' => $provider['module'])), E_USER_ERROR);
    }
  }
  elseif (!$quiet) {
    throw new DingProviderNoProvider(t("Provider module not configured for provider type @type.", array('@type' => $type)));
  }
  return NULL;
}