<?php

/**
 * @file
 * Support for Facebook's Stream API.
 *
 * http://wiki.developers.facebook.com/index.php/Using_the_Open_Stream_API
 *
 * At the moment we support only fb_stream_publish_dialog() for
 * writing to a stream via a javascript dialog.  The Stream API allows
 * for much more, so eventually this module will do more.
 */

define('FB_STREAM_DIALOGS', 'fb_stream_dialogs');

/**
 * Publish to a user's stream, or update their status.  
 *
 * Calling this method will, through javascript, add content to a
 * user's wall or update their status.  The javascript will be written
 * either during the current page request, or the next complete page
 * that Drupal serves.  (So it is safe to call this during requests
 * which end in a drupal_goto() rather than a page.)
 *
 * When invoked on an FBML canvas page request,
 * http://wiki.developers.facebook.com/index.php/Facebook.streamPublish
 * will be invoked.  When a Facebook Connect page,
 * http://developers.facebook.com/docs/?u=facebook.jslib.FB.Connect.streamPublish
 * will be called instead.  The result should be the same.
 *
 * @param $params
 *   An associative array of parameters to pass to Facebook's API.
 *   See Facebook's doc for additional detail.  Pass in strings and
 *   data structures.  Drupal for Facebook will json encode them
 *   before passing to javascript.  Use these keys:
 *   - 'user_message'
 *   - 'attachment'
 *   - 'action_links'
 *   - 'target_id'
 *   - 'user_message_prompt'
 *   - 'auto_publish'
 *   - 'actor_id'
 */
function fb_stream_publish_dialog($params, $fb_app = NULL) {
  if (!isset($_SESSION[FB_STREAM_DIALOGS])) {
    $_SESSION[FB_STREAM_DIALOGS] = array();
  }
  
  if (!isset($fb_app)) {
    $fb_app = $GLOBALS['fb_app'];
  }
  
  if (!isset($_SESSION[FB_STREAM_DIALOGS][$fb_app->apikey])) {
    $_SESSION[FB_STREAM_DIALOGS][$fb_app->apikey] = array();
  }
  $_SESSION[FB_STREAM_DIALOGS][$fb_app->apikey][] = $params;
}

/**
 * Get the data for one or more stream dialogs.  Use this function in
 * ajax callbacks, where you want to publish dialog(s) in response to
 * javascript events.
 */
function fb_stream_get_stream_dialog_data($fb_app = null) {
  if (!$fb_app)
    $fb_app = $GLOBALS['fb_app'];
  
  if (isset($_SESSION[FB_STREAM_DIALOGS]) &&
      isset($_SESSION[FB_STREAM_DIALOGS][$fb_app->apikey])) {
    $data = $_SESSION[FB_STREAM_DIALOGS][$fb_app->apikey];
    unset($_SESSION[FB_STREAM_DIALOGS][$fb_app->apikey]);
    return $data;
  }
  else {
    return array();
  }
}

/**
 * Implementation of hook_fb().
 *
 * When adding javascript to FBML and Conect pages, we add 
 */
function fb_stream_fb($op, $data, &$return) {
  if ($op == FB_OP_CONNECT_JS_INIT || $op == FB_OP_CANVAS_FBJS_INIT) {
    // arguments for JS and FBJS methods are the same!
    $params_array = fb_stream_get_stream_dialog_data($data['fb_app']);
    $js = fb_stream_js($params_array);
    $return += $js;
  }
}

/**
 * Convert our data structure in javascript.
 */
function fb_stream_js($params_array) {
  $return = array();
  foreach ($params_array as $params) {
    $args = array();
    // These are the defaults:
    foreach (array('user_message' => '',
                   'attachment' => '{}',
                   'action_links' => '{}',
                   'target_id' => 'null',
                   'user_message_prompt' => 'null',
                   'callback' => 'null',
                   'auto_publish' => 'null',
                   'actor_id' => 'null',
             ) as $key => $default) {
      if (isset($params[$key])) {
        // Encode the params passed to fb_stream_publish_dialog.
        if (in_array($key, array('callback', 'auto_publish'))) {
          // no encoding
          $args[] = $params[$key];
        }
        else {
          $args[] = json_encode($params[$key]);
        }
        
      }
      else {
        // Use default
        $args[] = $default;
      }
    }
    
    if (!fb_is_fbml_canvas()) {
      // Add stream dialog javascript to a facebook connect page.
      $return[] = "FB.Connect.streamPublish(" . implode(', ', $args) . ");\n";
    }
    else {
      // Add stream dialog javascript to a canvas page.
      $return[] = "Facebook.streamPublish(" . implode(', ', $args) . ");\n";
    }
      
    // debug
    //dpm($return, "fb_stream_fb added javascript");
  }
  
  return $return;
}