<?php
// $Id$

/**
 * @file
 * Adds contextual links to perform actions related to elements on a page.
 */

/**
 * Implements hook_permission().
 */
function contextual_permission() {
  return array(
    'access contextual links' => array(
      'title' => t('Use contextual links'),
      'description' => t('Use contextual links to perform actions related to elements on a page.'),
    ),
  );
}

/**
 * Implements hook_library().
 */
function contextual_library() {
  $path = drupal_get_path('module', 'contextual');
  $libraries['contextual-links'] = array(
    'title' => 'Contextual links',
    'website' => 'http://drupal.org/node/473268',
    'version' => '1.0',
    'js' => array(
      $path . '/contextual.js' => array(),
    ),
    'css' => array(
      $path . '/contextual.css' => array(),
    ),
  );
  return $libraries;
}

/**
 * Template variable preprocessor for contextual links.
 *
 * @see contextual_links_build()
 */
function contextual_preprocess(&$variables, $hook) {
  static $hooks;

  // Initialize the $contextual_links template variable.
  $variables['contextual_links'] = array();

  // Nothing to do here if the user is not permitted to access contextual links.
  if (!user_access('access contextual links')) {
    return;
  }

  if (!isset($hooks)) {
    $hooks = theme_get_registry();
  }

  // Determine the primary theme function argument.
  if (isset($hooks[$hook]['variables'])) {
    $keys = array_keys($hooks[$hook]['variables']);
    $key = $keys[0];
  }
  else {
    $key = $hooks[$hook]['render element'];
  }
  if (isset($variables[$key])) {
    $element = $variables[$key];
  }

  if (isset($element) && is_array($element) && !empty($element['#contextual_links'])) {
    $variables['contextual_links'] = contextual_links_build($element);
    if (!empty($variables['contextual_links'])) {
      $variables['classes_array'][] = 'contextual-links-region';
    }
  }
}

/**
 * Build a renderable array for contextual links.
 *
 * @param $element
 *   A renderable array containing a #contextual_links property, which is a
 *   keyed array. Each key is the name of the implementing module, and each
 *   value is an array that forms the function arguments for
 *   menu_contextual_links(). For example:
 *   @code
 *     array('#contextual_links' => array(
 *       'block' => array('admin/structure/block/manage', array('system', 'navigation')),
 *       'menu' => array('admin/structure/menu/manage', array('navigation')),
 *     ))
 *   @endcode
 *
 * @return
 *   A renderable array representing contextual links.
 *
 * @see menu_contextual_links()
 */
function contextual_links_build($element) {
  static $destination;

  // Retrieve contextual menu links.
  $items = array();
  foreach ($element['#contextual_links'] as $module => $args) {
    $items += menu_contextual_links($module, $args[0], $args[1]);
  }

  // Transform contextual links into parameters suitable for theme_link().
  if (!isset($destination)) {
    $destination = drupal_get_destination();
  }

  $links = array();
  foreach ($items as $class => $item) {
    $class = drupal_html_class($class);
    $links[$class] = array(
      'title' => $item['title'],
      'href' => $item['href'],
    );
    // @todo theme_links() should *really* use the same parameters as l()...
    if (!isset($item['localized_options']['query'])) {
      $item['localized_options']['query'] = array();
    }
    $item['localized_options']['query'] += $destination;
    $links[$class] += $item['localized_options'];
  }
  $build = array();
  if ($links) {
    $build = array(
      '#prefix' => '<div class="contextual-links-wrapper">',
      '#suffix' => '</div>',
      '#theme' => 'links',
      '#links' => $links,
      '#attributes' => array('class' => array('contextual-links')),
      '#attached' => array(
        'library' => array(array('contextual', 'contextual-links')),
      ),
    );
  }
  return $build;
}