fb.module

<?php

  // Ops for hook_fb.
define('FB_OP_INITIALIZE', 'init'); // Start a FB callback
define('FB_OP_POST_INIT', 'post init'); // Another chance to start FB callback
define('FB_OP_EXIT', 'exit'); // End an FB callback
define('FB_OP_GET_FBU', 'get_fbu'); // Query the local user's FB account
define('FB_OP_GET_APP', 'get_app'); // Query which app a FB callback addresses
define('FB_OP_GET_INFINITE_SESSION', 'get_inf_sess'); // Query infinite session data
define('FB_OP_PRE_USER', 'pre_user'); // Before account creation, fb_user.module

define('FB_GRANT_REALM_FRIEND', 'fb_friend');
define('FB_GRANT_REALM_GROUP', 'fb_group');

define('FB_HOOK', 'fb');

define('FB_FBU_INFINITE_SESSION', 'fbu_infinite');
define('FB_FBU_CURRENT', 'fbu_current'); // Canvas pages only
define('FB_FBU_ANY', 'fbu_any'); // Use current user on canvas page, fall back to infinite session otherwise.

define('FB_APP_CURRENT', '000_app_current'); // Canvas pages only.  000 makes it appear first in options list

define('FB_USE_PHP4_API', variable_get('fb_use_php4_api', TRUE)); // Force the use of facebook's php4 api until we decide to require php5.  The php5 api throws exceptions, and there's no clean way to handle them in code that will also run in php4.

/**
 * Include the necessary facebook-platform code and initialize the API object.
 * 
 * @param fbu To log into facebook as a particular user, pass the facebook id.
 * This is useful during cron jobs, for example, but rarely if ever needed on
 * a canvas page.  If no valid session key is known for the user, this call
 * will still return a facebook reference.
 * 
 * If FB_FBU_INFINITE_SESSION is passed, we attempt to log into an infinite
 * session we've configured.
 * 
 * If FB_FBU_ANY is passed in, we will log in as the canvas page user if
 * already logged in.  Otherwise we try the infinite session, if configured.
 * 
 * Future calls into the the facebook api could fail for various reasons.  For
 * one, we may fail to log in as the specified user.  This call does not
 * actually contact facebook to test the connection, it just sets things up so
 * that when the connection is needed, it might work.  Even if the connection
 * is established, the user may not have sufficient permission to whatever you
 * are asking facebook to do.
 * 
 */
function fb_api_init($fb_app, $fbu) {
  static $cache = array();

  if (!count($cache)) {
    // Include FB API code.
    if (substr(phpversion(), 0, 1) == '4' || FB_USE_PHP4_API) {
      require_once('facebook-platform/php4client/facebook.php');
    }
    else {
      require_once('facebook-platform/client/facebook.php');
      // Ideally, we'd check that drupal has not already specified an exception handler.
      set_exception_handler('fb_report_exception');
    }
  }
  
  global $facebook_config;
  $facebook_config['debug'] = FALSE; // set TRUE for debug output from FB API
  
  if (!$cache[$fb_app->apikey]) {
    $cache[$fb_app->apikey] = array();
  }
  
  if (!$cache[$fb_app->apikey][$fbu]) {
    $fb = new Facebook($fb_app->apikey, $fb_app->secret);
    
    if ($fbu == FB_FBU_CURRENT || 
        ($fbu == FB_FBU_ANY && $fb->get_loggedin_user())) {
      // We're on a canvas page and we're already logged in.
    }
    else if ($fbu == FB_FBU_INFINITE_SESSION || $fbu == FB_FBU_ANY) {
      // Learn the infinite session id and key
      $data = _fb_invoke($fb_app, FB_OP_GET_INFINITE_SESSION, array());
      if (count($data) && $data[0] && $data[1]) {
        $fb->set_user($data[0], $data[1]);
      }
    }
    else {
      // FB user id passed in.  If we happen to have session info for them, we
      // can log in as them.
      $data = _fb_invoke($fb_app, FB_OP_GET_USER_SESSION, array(), array('fbu' => $fbu));
      if (count($data) && $data[0] && $data[1]) {
        $fb->set_user($data[0], $data[1]);
      }
      
    }
    $cache[$fb_app->apikey][$fbu] = $fb;
    // Note that facebook api has not actually logged into facebook yet.
    // We won't really know if our session is valid until later.
    // get_loggedin_user does not really test it.
    if ($fbu != FB_FBU_CURRENT && !$fb->get_loggedin_user()) {
      // An FBU other than CURRENT was specified, but we failed to log in.
      watchdog('fb', t('Failed to log into facebook app %app as user %user',
                       array('%app' => $fb_app->title,
                             '%user' => $fbu)), WATCHDOG_ERROR);
    }
  }
  
  $fb = $cache[$fb_app->apikey][$fbu];
  return $fb;
}


function fb_init_path($fb_app, $restore = FALSE) {
  // Here's one of the uglier parts...
  // Fool url() function into linking back to facebook
  // Note that elsewhere we get forms to submit directly to us by tweaking their action parameter.
  global $base_path, $base_url;
  // The old paths will actually be used to modify form actions.  That's why these are global as opposed to static.
  global $fb_old_base_url, $fb_old_base_path;
  // But we also support a stack of paths, in case we need to log into more than one app in a single request.
  static $stack = array();
  if (!$restore) {
    if (!$fb_old_base_path) {
      $fb_old_base_url = $base_url;
      $fb_old_base_path = $base_path;
    }
    $original = array('base_url' => $base_url,
                      'base_path' => $base_path);
    
    $base_path = "/$fb_app->canvas/";
    // TODO: make the "apps.facebook.com" part configurable.
    $base_url = "http://apps.facebook.com/$fb_app->canvas";
    
    if (!variable_get('clean_url', FALSE)) {
      $original['clean_url'] = FALSE;
      // Force clean URLs because links between canvas pages will work this way.
      // In settings.inc we do this more cleanly.  However, for cron jobs this is necessary.
      variable_set('clean_url', TRUE);
    }
    // Save settings so they may be restored
    array_push($stack, $original);
  }
  else {
    // restore original settings.
    $original = array_pop($stack);
    $base_url = $original['base_url'];
    $base_path = $original['base_path'];  
    if (isset($original['clean_url']))
      variable_set('clean_url', $old_clean_url);
  }
}

/**
 * Our intialization routine for canvas pages.
 * 
 * We invoke our hook, first to determine which application is being invoked.
 * (Because we support more than one in the same Drupal instance.)  Then, we
 * notify interested modules in various events.
 * 
 * We're still figuring out exactly which events trigger our hook.  So look
 * for more detailed documentation later.
 */
function fb_initialize() {
  global $fb_app;
  global $custom_theme; // Set by this function.
  global $fb, $fb_app_node; // Set by this function.

  // Perform a sanity check, because too many users report issues without completing the install.
  if (!variable_get('fb_settings_check', FALSE) && user_access('access administration pages')) {
    drupal_set_message(t('!drupal_for_facebook has been enabled, but not properly installed.  Please read the !readme.',
                         array('!drupal_for_facebook' => l(t('Drupal for Facebook'), 'http://drupal.org/project/fb'),
                               // This link should work with clean URLs
                               // disabled.
                               '!readme' => '<a href='.base_path() . '/' . drupal_get_path('module', 'fb') . '/README.txt>README.txt</a>')), 'error');
  }

  // Ask other modules for app detail
  $fb_app = _fb_invoke(NULL, FB_OP_GET_APP);

  if ($fb_app) {
    // dpm($fb_app, "fb_initialize()"); // debug
    // dpm($_REQUEST, 'request');
    // dpm(session_id(), 'session_id');
    // dpm($_SERVER, "server");
    //global $db_prefix;
    //dpm($db_prefix, 'db_prefix');
    // we are in a callback
 
    // For canvas pages, use current user, never infinite session.
    $fb = fb_api_init($fb_app, FB_FBU_CURRENT);

    // drupal_set_message("fb object:" . dpr($fb, 1));
    if ($fb) {
      // Output FBML
      $custom_theme = variable_get('fb_theme', 'fb_fbml');

      // this is a test of whether sessions are working.
      global $user;
      //drupal_set_message("Before fb_op_initialize, user->uid is $user->uid, $\user->fbu is $user->fbu.");

      //drupal_set_message("After fb_op_initialize, user->uid is $user->uid, $\user->fbu is $user->fbu.");
      
      // make sure global user is correct
      /** XXX deprecated in favor of FB_OP_INITIALIZE above. 
      if (!$user->fbu || ($user->fbu != fb_facebook_user()))
        $user = fb_user_load(fb_facebook_user());
      **/

      fb_init_path($fb_app);

      // Give other modules a chance to initialize, require login, etc...
      _fb_invoke($fb_app, FB_OP_INITIALIZE);
    }
    else
      watchdog('fb', "URL indicates a facebook app, but could not initialize Facebook");
    
    // Special handling for forms, as they are submitted directly to us, not
    // to apps.facebook.com/canvas
    // we will buffer, and later cache, the results
    if (_fb_handling_form())
      ob_start();


    // debug
    global $user;
    //drupal_set_message("after initializing, local user is $user->uid " . theme('username', $user) . dpr($user, 1));
  }
  _fb_invoke($fb_app, FB_OP_POST_INIT);
}

// deprecated in favor of fb_local_file_url.  Do we need both???
function fb_local_url($path) {
  global $base_url, $base_path, $fb_old_base_url, $fb_old_base_path;
  if (!$fb_old_base_path)
    return url($path, NULL, NULL, TRUE);

  $url = url($path, NULL, NULL, TRUE);
  $local = strtr($url, array($base_url => $fb_old_base_url,
                             // base_url includes base path, this get's rid of it if it appears twice.
                             $base_path => '',
                 ));

  return $local;
}

function fb_local_file_url($path) {
  global $base_url, $base_path, $fb_old_base_url, $fb_old_base_path;
  $base = $fb_old_base_url;
  if (!$base)
    // Not in a facebook canvas page.
    $base = $base_url;
  return $base .'/'. $path; // that simple???
}

// This may need work
function _fb_make_form_action_local($action) {
  global $fb_old_base_path, $fb_app;
  
  // drupal_set_message("form action originally " . $action); // debug
  // if the action starts with the canvas page, it most likely was created by a
  // call to (url), we need to change it to point to our real location
  if (strpos($action, '/'.$fb_app->canvas) ===0) {
    $action = str_replace('/'.$fb_app->canvas.'/', $fb_old_base_path . '?q=', $action);
  }

  // I'm not sure where the problem is, but sometimes actions have two question marks.  I.e.
  // /htdocs/?app=foo&q=user/login?destination=comment/reply/1%2523comment-form
  // Here we replace 3rd (or more) '?' with '&'.
  $parts = explode('?', $action);
  if (count($parts) > 2) {
    $action = array_shift($parts) . '?' . array_shift($parts);
    $action .= '&' . implode('&', $parts);
  }

  //drupal_set_message("form action now " . "http://".$_SERVER['HTTP_HOST']. $action); // debug
  return "http://".$_SERVER['HTTP_HOST']. $action;
}

function _fb_handling_form() {
  global $fb;
  // Test whether a form has been submitted via facebook canvas page.
  if (!$fb && $_REQUEST['form_id'] && $_REQUEST['fb_sig'])
    return TRUE;
}

function fb_facebook_user() {
  global $user, $fb;
  static $fbu;

  if (!$fb)
    return;
  
  if (!isset($fbu)) {
    $fbu = $fb->get_loggedin_user();
    if ($fb->api_client->error_code) {
      watchdog('fb', 'Failed to get Facebook user id.', 'error');
    }
    else {
    }
  }
  return $fbu;
}

/**
 * Given a local user id, find the facebook id.
 */
function fb_get_fbu($uid, $fb_app = NULL) {
  // default to current app (only set if we're in a FB callback)
  if (!$fb_app)
    $fb_app = $GLOBALS['fb_app'];
  
  // Accept either a user object or uid passed in.
  if (is_object($uid) && $uid->fbu)
    return $uid->fbu;
  else if (is_object($uid))
    $uid = $uid->uid;

  // User management is handled by another module.  Use our hook to ask for mapping.
  $fbu = _fb_invoke($fb_app, FB_OP_GET_FBU, NULL, array('uid' => $uid));
  
  return $fbu;
}

/**
 * Convenience method to get app info based on apikey or nid.
 */
function fb_get_app($search_data) {
  // $search_data can be an apikey, or an array of other search params.
  if (!is_array($search_data))
    $search_data = array('apikey' => $search_data);
  
  $fb_app = _fb_invoke(NULL, FB_OP_GET_APP, NULL, $search_data);
  return $fb_app;
}

/**
 * Convenience method to return a list of all known apps, suitable for form
 * elements.
 */
function fb_get_app_options($include_current) {
  $apps = fb_get_all_apps();
  $options = array();
  if ($include_current)
    $options[FB_APP_CURRENT] = t('<current>');
  foreach ($apps as $app) {
    $options[$app->nid] = $app->title;
  }
  return $options;
}

/**
 * Convenience method to return array of all know fb_apps.
 */
function fb_get_all_apps() {
  $apps = _fb_invoke(NULL, FB_OP_GET_ALL_APPS, array());
  return $apps;
}

// return array of facebook uids
function fb_get_friends($fbu) {
  static $cache = array();
  global $fb;
  if (!$fb || !$fbu)
    return;

  if (!isset($cache[$fbu])) {
    if ($fbu == fb_facebook_user())
      $items = $fb->api_client->friends_get();
    // friends_get does not work in cron call, so we double check.
    if (!$items || !count($items)) {
      $result = $fb->api_client->fql_query("SELECT uid2 FROM friend WHERE uid1=$fbu");
      $items = array();
      if (count($result)) 
        foreach ($result as $data) {
          $items[] = $data['uid2'];
        }
    }
    // Facebook's API has the annoying habit of returning an item even if user
    // has no friends.  We need to clean that up.
    if (!$items[0])
      unset($items[0]);

    $cache[$fbu] = $items;
  }
  
  return $cache[$fbu];
}

// Return array of facebook gids
function fb_get_groups($fbu) {
  $items = array();
  $groups = fb_get_groups_data($fbu);

  if ($groups && count($groups))
    foreach ($groups as $data) {
      $items[] = $data['gid'];
    }
  return $items;
}

function fb_get_groups_data($fbu) {
  static $cache = array();
  global $fb;
  if (!$fb || !$fbu)
    return;
  
  if (!isset($cache[$fbu])) {
    $cache[$fbu] = $fb->api_client->groups_get($fbu, NULL);    
  }
  
  return $cache[$fbu];
}


// deprecated since creation of fb_user module, but cron hook still uses this.
function fb_user_load($fbu = NULL) {
  global $user;
  if (!$fbu)
    // default to current logged in user
    $fbu = fb_facebook_user();
  if ($fbu && $user->fbu == $fbu) {
    return $user;
  }
  if ($fbu) {
    $account = user_external_load("$fbu-$fb_app->apikey@facebook.com");
    if (!$account)
      $account = user_external_load("$fbu@facebook.com");
    if (!$account)
      $account = user_load(array('uid' => variable_get('fb_facebook_user', 2)));
    if (!$account)
      watchdog('fb', t('Failed to load user from facebook fbu=%fbu',
                       array('%fbu' => $fbu)), 'error');
    $account->fbu = $fbu;
    return $account;
  }
}


function fb_form_alter($form_id, &$form) {
  // We will send all form submission directly to us, not via
  // app.facebook.com/whatever.  Since we've tricked drupal into writing our
  // URLs as if we were there, we need to untrick the form action.
  if ($_REQUEST['fb_sig']) {
    global $fb_app;
    // We're in a facebook callback
    if ($form['#action'] == '') {
      $form['#action'] = $_GET['q'];
    }
    else {
    }
    $form['#action'] = _fb_make_form_action_local($form['#action']);
    // Let's hope no subsequent hook_form_alters mess with #action.
  }

  // Because facebook users don't have email, it can't be required on user form
  if ($form_id == 'user_register') {
    if (user_access('administer users')) {
      $form['mail']['#required'] = FALSE;
    }
  }
  if ($form_id == 'user_edit') {
    if (user_access('administer users')) {
      $form['account']['mail']['#required'] = FALSE;
    }
  }
}


function fb_menu($may_cache) {
  $items = array();
  
  if (!$may_cache) {
    // Initialization code is run here, for non-cached pages only.  Not in hook_init.
    fb_initialize();
  }
  else {
    // When forms are submitted directly to us, we cache the results,
    // and show them later via this callback
    $items[] = array('path' => 'fb/form_cache',
                     'callback' => '_fb_form_cache_cb',
                     'type' => MENU_CALLBACK,
                     'access' => TRUE);

    // A page to help determine infinite session keys
    $items[] = array('path' => 'fb/session',
                     'callback' => '_fb_session_cb',
                     'type' => MENU_CALLBACK,
                     'access' => TRUE); // TODO: restrict access?

    $items[] = array('path' => 'fb/debug',
                     'callback' => '_fb_debug_cb',
                     'type' => MENU_CALLBACK,
                     'access' => TRUE, // TODO: restrict access
    );
  }
  return $items;
}

/**
 * When exiting we need to do some special stuff for forms
 */
function fb_exit($destination = NULL) {
  global $fb_app, $fb;
  _fb_invoke($fb_app, FB_OP_EXIT);

  if (_fb_handling_form()) {
    $output = ob_get_contents();
    ob_end_clean();

    if ($destination) {
      // Destination is set when a node is submitted, for example.
      // just let the redirect happen
      return;
    }
    
    // Save the results to show the user later
    $token = uniqid('fb_');
    $cid = session_id() . "_$token";
    watchdog('fb', "Storing cached form page $cid, then redirecting");
    cache_set($cid, 'cache_page', $output, time() + (60 * 5), drupal_get_headers()); // (60 * 5) == 5 minutes
    
    $dest = 'http://apps.facebook.com/' . $fb_app->canvas."/fb/form_cache/$cid";
    // $fb->redirect($url); // Does not work!
    drupal_goto($dest,'', NULL, 303); // appears to work
  }
}

function _fb_form_cache_cb($cid) {
  // Facebook started appending a '?', we need to get rid of it.
  if ($pos = strpos($cid, '?'))
    $cid = substr($cid, 0, $pos);

  watchdog('fb', "Returning cached form page $cid");
  $cache = cache_get($cid, 'cache_page');
  // Don't clear, as user may refresh browser.  Cache will expire eventually.
  // cache_clear_all($cid, 'cache_page');
  print $cache->data;
  exit();
}

function _fb_session_cb() {
  global $fb, $fb_app;
  global $user;
  drupal_set_message("_fb_session_cb" . dpr($_REQUEST, 1));
  $output = '<p>'.t('You are logged in as local user !username, with Facebook user id %fbu.',
                    array('!username' => theme('username', $user),
                          '%fbu' => fb_get_fbu($user))).'</p>';
  $output .= '<p>'.l(t('Request an infinite session key.'),
                       'http://www.facebook.com/code_gen.php?v=1.0&api_key='.$fb_app->apikey).'</p>';
  
  $output .= drupal_get_form('fb_session_key_form');

  $output .= '<p>'.t('Current session key: %key',
                     array('%key' => htmlentities($fb->api_client->session_key)))."</p>\n";

  return $output;
}

function fb_session_key_form() {
  global $fb_app;
  $form = array('auth_token' => array('#type' => 'textfield',
                                      '#title' => t('One-time code'),
                                      '#description' => t('If you do not have a one-time code, you can get one !here.',
                                                          array('!here' => l(t('here'), 'http://www.facebook.com/code_gen.php?v=1.0&api_key='.$fb_app->apikey))),
                ),
                'submit' => array('#type' => 'submit',
                                  '#value' => t('Submit')),

                '#redirect' => FALSE, // necessary when submitting via facebook
  );
  return $form;
}

/**
 * Provides a page with useful debug info.
 * 
 * TODO: remove dependencies on devel package.
 */
function _fb_debug_cb() {
  global $fb, $fb_app;
  global $user;

  if ($fb) {
    // These will work in a canvas page.
    drupal_set_message("in_fb_canvas returns " . $fb->in_fb_canvas());
    drupal_set_message("get_loggedin_user returns " . $fb->get_loggedin_user());
    drupal_set_message("current_url returns " . $fb->current_url());
    
  }

  dpm(fb_get_fbu($user), 'Facebook user via fb_get_fbu');
  dpm($user, "Local user " . theme('username', $user));
  
  dpm($_REQUEST, "Request");
  dpm($fb_app, "fb_app");
  dpm($fb->api_client->session_key, "session key ");
  
  //watchdog('fb_debug', 'debug callback called.  Request is ' . dpr($_REQUEST, 1));

  return "This is the facebook debug page.";
}

function _fb_invoke($fb_app, $op, $return = NULL, $data = NULL) {
  global $fb;
  foreach (module_implements(FB_HOOK) as $name) {
    $function = $name . '_' . FB_HOOK;
    $function($fb, $fb_app, $op, $return, $data);
  }
  return $return;
}

/**
 * Implementation of hook_node_grants.
 * 
 * We put this here so all facebook modules have a standard way to implement
 * hook_node_access_records.  They use that hook to insert records into the
 * node access table.  We use this hook to allow access when the grants are
 * there.
 */
function fb_node_grants($account, $op) {
  $grants = array();
  $fbu = fb_get_fbu($account);
  if ($fbu) { // If not anonymous (facebook user not logged in to this app)
    $friends = fb_get_friends($fbu);
    // For access purposes, consider a users to be a friend of themself
    $friends[] = $fbu;
    if (count($friends))
      $grants[FB_GRANT_REALM_FRIEND] = $friends;
    
    $groups = fb_get_groups($fbu);
    if (count($groups))
      $grants[FB_GRANT_REALM_GROUP] = $groups;
  }

  return $grants;
}

/**
 * Convenience method for displaying facebook api errors.
 */
function fb_report_errors($fb = FB_APP_CURRENT) {
  if ($fb == FB_APP_CURRENT) {
    $fb = $GLOBALS['fb'];
  }
  if ($fb) {
    if ($fb->api_client->error_code) {
      $message = t('Facebook API error %code (see !link).',
                   array('%code' => $fb->api_client->error_code,
                         '!link' => l(t('error codes'), "http://wiki.developers.facebook.com/index.php/Error_codes"),
                   ));
      watchdog('fb', $message, WATCHDOG_ERROR);
      drupal_set_message($message, 'error');
    }
  }
}

/**
 * Exception handler for PHP5 exceptions.
 */
function fb_report_exception($exception) {
  $message = t('Facebook API exception %message.  !trace',
               array('%message' => $exception->getMessage(),
                     '!trace' => '<pre>'.$exception->getTraceAsString().'</pre>',
               ));
  watchdog('fb', $message, WATCHDOG_ERROR);
  drupal_set_message($message, 'error');
  print $message;
}

?>