<?php
/**
 * @file
 * Provides API integration with the Twitter microblogging service.
 */

define ('TWITTER_HOST',         'http://twitter.com');
define ('TWITTER_API',          'https://api.twitter.com');
define ('TWITTER_SEARCH',       'http://search.twitter.com');
define ('TWITTER_TINYURL',      'http://tinyurl.com');

/**
 * Implements hook_menu().
 */
function twitter_menu() {
  $items['twitter/oauth'] = array(
    'title' => 'Twitter OAuth',
    'access callback' => TRUE,
    'page callback' => 'drupal_get_form',
    'page arguments' => array('twitter_oauth_callback'),
    'type' => MENU_CALLBACK,
    'file' => 'twitter.pages.inc',
  );

  $items['admin/config/services/twitter'] = array(
    'title' => 'Twitter',
    'description' => 'Twitter accounts and settings.',
    'page callback' => 'twitter_user_settings',
    'access arguments' => array('administer twitter accounts'),
    'file' => 'twitter.pages.inc',
  );

  $items['admin/config/services/twitter/default'] = array(
    'title' => 'Twitter',
    'type' => MENU_DEFAULT_LOCAL_TASK,
  );

  $items['admin/config/services/twitter/settings'] = array(
    'title' => 'Settings',
    'description' => 'Twitter settings.',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('twitter_admin_form'),
    'access arguments' => array('administer site configuration'),
    'file' => 'twitter.pages.inc',
    'type' => MENU_LOCAL_TASK,
  );

  $items['user/%user/edit/twitter'] = array(
    'title' => 'Twitter accounts',
    'page callback' => 'twitter_user_settings',
    'page arguments' => array(1),
    'access callback' => 'twitter_account_access',
    'weight' => 10,
    'file' => 'twitter.pages.inc',
    'type' => MENU_LOCAL_TASK,
  );

  return $items;
}

/**
 * Implements hook_permission().
 */
function twitter_permission() {
  return array(
    'add twitter accounts' => array(
      'title' => t('Add Twitter accounts'),
    ),
    'add authenticated twitter accounts' => array(
      'title' => t('Add authenticated Twitter accounts'),
    ),
    'administer twitter accounts' => array(
      'title' => t('Administer Twitter accounts'),
    ),
  );
}

/**
 * Access callback for the Twitter accounts page.
 *
 * @return
 *   Boolean TRUE if the current user has access.
 */
function twitter_account_access() {
  return user_access('add twitter accounts') || user_access('add authenticated twitter accounts');
}

/**
 * Implements hook_theme().
 */
function twitter_theme() {
  return array(
    'twitter_account_list_form' => array(
      'render element' => 'form',
    ),
    'twitter_status' => array(
      'variables' => array(
        'status' => NULL,
        'author' => NULL,
      ),
      'template' => 'tweet',
      'path' => drupal_get_path('module', 'twitter'),
    ),
    'twitter_user_accounts' => array(
      'variables' => array(
        'accounts' => array(),
      ),
    ),
  );
}

/**
 * Default callback for theme('twitter_user_accounts');
 *
 * Renders a list of Twitter accounts for the user profile page.
 */
function theme_twitter_user_accounts($variables) {
  module_load_include('inc', 'twitter');
  $accounts = $variables['accounts'];
  $items = array();
  foreach ($accounts as $twitter_account) {
    $tweets = twitter_tweets($twitter_account->screen_name);
    // If we have tweets for this Twitter account, link to the View. If not, link to Twitter.
    if (count($tweets)) {
      $items[] = l('@' . $twitter_account->screen_name, 'tweets/' . $twitter_account->screen_name);
    }
    else {
      $items[] = _twitter_user_profile($twitter_account->screen_name);
    }
  }
  return theme('item_list', array('items' => $items));
}

/**
 * Very lightweight helper function to generate a TinyURL for a given post.
 */
function twitter_shorten_url($url) {
  if (module_exists('shorten')) {
    return shorten_url($url);
  }
  else {
    $response = drupal_http_request(variable_get('twitter_tinyurl', TWITTER_TINYURL) . "/api-create.php?url=" . $url);
    if ($response->code == 200) {
      return $response->data;
    }
    else {
      return $url;
    }
  }
}

/**
 * Implements hook_cron().
 *
 * Imports new Twitter statuses for site users, and deletes expired tweets.
 */
function twitter_cron() {
  if (!variable_get('twitter_import', TRUE)) {
    return;
  }
  // Check if we can connect to Twitter before proceeding.
  module_load_include('inc', 'twitter');
  $twitter = twitter_connect();
  if (!$twitter) {
    return;
  }

  // Pull up a list of Twitter accounts that are flagged for updating,
  // sorted by how long it's been since we last updated them. This ensures
  // that the most out-of-date accounts get updated first.
  $result = db_query_range("SELECT twitter_uid
                            FROM {twitter_account}
                            WHERE uid <> 0 AND import = 1
                            ORDER BY last_refresh ASC",
                            0, 20);
  try {
    foreach ($result as $account) {
      // Fetch tweets and mentions.
      twitter_fetch_user_timeline($account->twitter_uid);
      $twitter_account = twitter_account_load($account->twitter_uid);
      if ($twitter_account->is_auth() && $twitter_account->mentions) {
        twitter_fetch_mentions_timeline($twitter_account->id);
      }
      // Mark the time this account was updated.
      db_update('twitter_account')
        ->fields(array(
          'last_refresh' => REQUEST_TIME,
        ))
        ->condition('twitter_uid', $twitter_account->id)
        ->execute();
    }
  } catch (TwitterException $e) {
    // The exception has already been logged so we do not need to do anything here apart from catching it.
  }

  // Nuke old statuses.
  if ($age = variable_get('twitter_expire', 0)) {
    db_delete('twitter')
      ->condition('created_time', REQUEST_TIME - $age, '<')
      ->execute();
  }
}

/**
 * Implements hook_filter_info()
 */
function twitter_filter_info() {
  $filters['twitter_username'] = array(
    'title' => t('Twitter @username converter'),
    'description' => t('Converts Twitter-style @usernames into links to Twitter account pages.'),
    'process callback' => '_twitter_filter_username',
    'tips callback' => '_twitter_filter_tip_username',
  );
  $filters['twitter_hashtag'] = array(
    'title' => t('Twitter #hashtag converter'),
    'description' => t('Converts Twitter-style #hashtags into links to hashtags.org.'),
    'process callback' => '_twitter_filter_hashtag',
    'tips callback' => '_twitter_filter_tip_hashtag',
  );
  $filters['twitter_links'] = array(
    'title' => t('Twitter link converter'),
    'description' => t('Makes links in Twitter messages to be opened in new windows and adds ' .
                       'rel="nofollow" so these links do not penalize SEO.'),
    'process callback' => '_twitter_filter_link',
    'tips callback' => '_twitter_filter_tip_link',
  );

  return $filters;
}

/**
 * Filter tips callback function for Twitter usernames.
 */
function _twitter_filter_tip_username($filter, $format, $long = FALSE) {
  return t('Twitter-style @usernames are linked to their Twitter account pages.');
}

/**
 * Filter tips callback function for Twitter hashtags.
 */
function _twitter_filter_tip_hashtag($format, $long = FALSE) {
  return t('Twitter-style #hashtags are linked to !url.', array(
    '!url' => '<a href="http://search.twitter.com/">search.twitter.com</a>')
  );
}

/**
 * Filter tips callback function for Twitter links.
 */
function _twitter_filter_tip_link($filter, $format, $long = FALSE) {
  return t('Twitter message links are opened in new windows and rel="nofollow" is added.');
}

/**
 * Callback for twitter @username converter.
 */
function _twitter_filter_username($text, $filter) {
  $prefix = '@';
  $destination = variable_get('twitter_host', TWITTER_HOST) . '/';
  return _twitter_filter_text($text, $prefix, $destination);
}

/**
 * Callback for twitter #hashtag converter.
 */
function _twitter_filter_hashtag($text, $filter) {
  $prefix = '#';
  $destination = variable_get('twitter_search', TWITTER_SEARCH) . '/search?q=%23';
  return _twitter_filter_text($text, $prefix, $destination);
}

/**
 * This helper function converts Twitter-style @usernames and #hashtags into
 * actual links.
 */
function _twitter_filter_text($text, $prefix, $destination) {
  $matches = array(
    '/\>' . $prefix . '(\w+)/ui',
    '/^' . $prefix . '(\w+)/ui',
    '/(\s+)' . $prefix . '(\w+)/ui',
  );
  $replacements = array(
    '><a href="' . $destination . '${1}">' . $prefix . '${1}</a>',
    '<a href="' . $destination . '${1}">' . $prefix . '${1}</a>',
    '${1}<a href="' . $destination . '${2}">' . $prefix . '${2}</a>',
  );
  return preg_replace($matches, $replacements, $text);
}

/**
 * Callback for twitter link converter.
 */
function _twitter_filter_link($text, $filter) {
  return str_replace("<a ", '<a target="_blank" rel="nofollow" ', $text);
}

/**
 * Implements hook_views_api().
 */
function twitter_views_api() {
  return array('api' => 2);
}

/**
 * Implements hook_user_load().
 */
function twitter_user_load($accounts) {
  foreach ($accounts as $uid => $account) {
    $accounts[$uid]->twitter_accounts = module_invoke_all('twitter_accounts', $account);
  }
}

/**
 * Implements hook_twitter_accounts().
 *
 * @return
 *   array with Twitter accounts
 */
function twitter_twitter_accounts($account) {
  module_load_include('inc', 'twitter');

  $query = db_select('twitter_account', 'ta')
    ->fields('ta', array('twitter_uid'))
    ->condition('ta.uid', $account->uid);

  $twitter_accounts = array();
  foreach ($query->execute()->fetchCol() as $twitter_uid) {
    $twitter_accounts[] = twitter_account_load($twitter_uid);
  }
  return $twitter_accounts;
}

/**
 * Implements hook_user_delete().
 *
 * Removes user's Twitter accounts and tweets
 */
function twitter_user_delete($account) {
  module_load_include('inc', 'twitter');
  foreach ($account->twitter_accounts as $twitter_account) {
    twitter_account_delete($twitter_account->id);
  }
}

/**
 * Implements hook_user_view_alter()
 *
 * Adds Twitter account information to the user profile.
 */
function twitter_user_view_alter(&$build) {
  $user = $build['#account'];
  if (!empty($user->twitter_accounts)) {
    $build['twitter'] = array(
      '#type' => 'user_profile_item',
      '#title' => t('Twitter accounts'),
      '#markup' => theme('twitter_user_accounts', array('accounts' => $user->twitter_accounts)),
      '#weight' => 10,
    );
  }
}

/**
 * Checks if the Twitter Application keys are set.
 *
 * @return
 *   boolean TRUE if both the Twitter Application key and secret are set.
 */
function twitter_api_keys() {
  $key = variable_get('twitter_consumer_key');
  $secret = variable_get('twitter_consumer_secret');
  return !(empty($key) && empty($secret));
}

/**
 * Helper to build a Twitter profile URL
 */
function _twitter_user_profile($screen_name) {
  return l('@' . $screen_name, TWITTER_HOST . '/' . $screen_name);
}