<?php
/**
 * @file
 * Exposes Drupal actions for sending Twitter messages.
 */

/**
 * Implements hook_action_info().
 */
function twitter_actions_action_info() {
  return array(
    'twitter_actions_set_status_action' => array(
      'type' => 'system',
      'label' => t('Post a message to Twitter'),
      'configurable' => TRUE,
      'triggers' => array(
        'node_view',
        'node_insert',
        'node_update',
        'node_delete',
        'comment_view',
        'comment_insert',
        'comment_update',
        'comment_delete',
        'user_view',
        'user_insert',
        'user_update',
        'user_delete',
        'user_login',
        'cron',
      ),
    ),
  );
}

/**
 * Returns a form definition so the Twitter action can be configured.
 *
 * @param array $context
 *   Default values (if we are editing an existing action instance).
 * @return
 *   Form definition.
 */
function twitter_actions_set_status_action_form($context) {
  $options = twitter_actions_account_options();
  // Set default values for form.
  $form['screen_name'] = array(
    '#type' => 'select',
    '#title' => t('Twitter account name'),
    '#description' => t('Twitter account which will be used. ' .
      'By selecting [current user] the rule will check if the user ' .
      'has authenticated a Twitter account to use.'),
    '#options' => $options,
    '#default_value' => isset($context['screen_name']) ? $context['screen_name'] : '',
    '#required' => TRUE,
  );

  $form['message'] = array(
    '#type' => 'textarea',
    '#title' => t('Message'),
    '#default_value' => isset($context['message']) ? $context['message'] : '',
    '#cols' => '80',
    '#rows' => '3',
    '#description' => t('The message that should be sent. You may include the following variables: ' .
                        '%site_name, %username, %node_url, %node_type, %title, %summary, %body, ' .
                        '%tinyurl. Not all variables will be available in all contexts.'),
    '#required' => TRUE,
  );

  return $form;
}

/**
 * Returns a list of authenticated Twitter accounts to be used as options.
 *
 * @return
 *   array of screen_name => screen_name entries.
 */
function twitter_actions_account_options() {
  module_load_include('inc', 'twitter');
  $twitter_accounts = twitter_load_authenticated_accounts();
  $options = array();
  foreach ($twitter_accounts as $twitter_account) {
    $options[$twitter_account->screen_name] = '@' . $twitter_account->screen_name;
  }
  // Extra token to use current user's account.
  $options['[current user]'] = '[current user]';
  return $options;
}

/**
 * Submits the form and sets the twitter account pulling the data from the
 * twitter_account table.
 */
function twitter_actions_set_status_action_submit($form, $form_state) {
  $form_values = $form_state['values'];
  // Process the HTML form to store configuration. The keyed array that
  // we return will be serialized to the database.
  $params = array(
    'screen_name' => $form_values['screen_name'],
    'message' => $form_values['message'],
  );

  return $params;
}

/**
 * Validates the Twitter account to use to send a Tweet.
 *
 * If it is a Twitter account, it will check it still exists.
 * If it is [current user], it will see if the current user has an
 * authenticated Twitter account to use.
 *
 * @param string $screen_name
 *   The selected value that represents a Twitter account to use.
 * @return
 *   Integer the Twitter ID of the account to use or NULL.
 */
function _twitter_actions_get_twitter_id($screen_name) {
  $twitter_uid = NULL;
  // Find out the Twitter ID to use.
  if ($screen_name == '[current user]') {
    // Check if this user has an authenticated account.
    global $user;
    $account = user_load($user->uid);
    foreach ($account->twitter_accounts as $twitter_account) {
      if ($twitter_account->is_auth()) {
        $twitter_uid = $twitter_account->id;
      }
    }
  }
  else {
    $twitter_uid = db_query("SELECT twitter_uid FROM {twitter_account} WHERE screen_name = :screen_name",
      array(':screen_name' => $screen_name))->fetchField();
  }
  return $twitter_uid;
}

/**
 * Implementation of a configurable Twitter action.
 * @todo Implementation for language negotiation for the body and sumary. Also
 * need implementation for bodies with multiple values. Right now it is hard
 * coded and it will only get body and summary for 'und' language and only
 * the first value of the body field.
 * If the final message is over 140 chars, there is no feedback to the user.
 */
function twitter_actions_set_status_action($object, $context) {
  $twitter_uid = _twitter_actions_get_twitter_id($context['screen_name']);
  if ($twitter_uid) {
    global $user;
    $variables['%site_name'] = variable_get('site_name', 'Drupal');
    // Seting variables array depending on action's group
    switch ($context['group']) {
      case 'node':
        $node = $context['node'];
        if (isset($node)) {
          $variables = array_merge($variables, array(
            '%uid' => $node->uid,
            '%username' => $node->name,
            '%node_url' => url('node/' . $node->nid, array('absolute' => TRUE)),
            '%node_type' => node_type_get_name($node),
            '%title' => $node->title,
            '%summary' => isset($node->body['und'][0]['value']) ? $node->body['und'][0]['summary'] : '',
            '%body' => isset($node->body['und'][0]['value']) ? $node->body['und'][0]['value'] : '',
            )
          );
        }
        break;

      case 'comment':
        $node = node_load($context['comment']->nid);
        if (isset($node)) {
          $variables = array_merge($variables, array(
            '%uid' => $context['comment']->uid,
            '%username' => $context['comment']->name,
            '%node_url' => url('node/' . $node->nid, array('absolute' => TRUE)),
            '%node_type' => node_type_get_name($node),
            '%title' => $node->title,
            '%summary' => isset($node->body[LANGUAGE_NONE][0]['value']) ? $node->body['und'][0]['summary'] : '',
            '%body' => isset($node->body[LANGUAGE_NONE][0]['value']) ? $node->body['und'][0]['value'] : '',
            )
          );
        }
        break;

      case 'user':
        $variables['%username'] = $context['user']->name;
        break;

      case 'cron':
        break;

      default:
        // We are being called directly.
        $node = $object;
        if (isset($node)  && is_object($node)) {
          $variables = array_merge($variables, array(
            '%uid' => $node->uid,
            '%username' => $node->name,
            '%node_url' => url('node/' . $node->nid, array('absolute' => TRUE)),
            '%node_type' => node_type_get_name($node),
            '%title' => $node->title,
            '%summary' => isset($node->body[LANGUAGE_NONE][0]['value']) ? $node->body['und'][0]['summary'] : '',
            '%body' => isset($node->body[LANGUAGE_NONE][0]['value']) ? $node->body['und'][0]['value'] : '',
            )
          );
        }
    }

    // Only make a tinyurl if it was asked for.
    if (strstr($context['message'], '%tinyurl') !== FALSE) {
      $variables = array_merge($variables, array(
        '%tinyurl' => twitter_shorten_url(url('node/' . $node->nid, array('absolute' => TRUE))),
      ));
    }

    // Send the tweet.
    $message = strtr($context['message'], $variables);
    module_load_include('inc', 'twitter');
    try {
      $twitter_account = twitter_account_load($twitter_uid);
      twitter_set_status($twitter_account, $message);
      drupal_set_message(t('Successfully posted to Twitter'));
    }
    catch (TwitterException $e) {
      drupal_set_message(t('An error occurred when posting to Twitter: @message',
                           array('@message' => $e->getMessage())), 'warning');
    }
  }
}