<?php
// $Id: og_context.module,v 1.1.2.9 2010-12-15 09:14:12 amitaibu Exp $

/**
 * @file
 * Get a group from a viewed page.
 */


/**
 * Implements hook_menu().
 */
function og_context_menu() {
  $items['admin/config/group/context'] = array(
    'title' => 'Group context',
    'description' => 'Group context detection and selection',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('og_context_configure_form'),
    'access arguments' => array('administer group'),
    'file' => 'og_context.admin.inc',
    'type' => MENU_LOCAL_TASK,
  );

  return $items;
}

/**
 * Implements hook_theme().
 */
function og_context_theme() {
  return array(
    'og_context_configure_form' => array(
      'render element' => 'form',
    ),
  );
}

/**
 * Implement hook_preprocess_html().
 *
 * HTML preprocess; Add context related templates and CSS.
 */
function og_context_preprocess_html(&$variables) {
  if ($group = og_context()) {
    // Add template suggestions.
    $variables['theme_hook_suggestions'][] = 'page__group_context';
    $variables['theme_hook_suggestions'][] = 'page__group_context__group_' . $group->gid;
    $variables['theme_hook_suggestions'][] = 'page__group_context__' . $group->entity_type;
    $variables['theme_hook_suggestions'][] = 'page__group_context__' . $group->entity_type . '_' . $group->etid;

    // Add CSS.
    $clean_html = drupal_html_class('group-context-' . $group->entity_type);
    $variables['classes_array'][] = 'group-context';
    $variables['classes_array'][] = 'group-context-group-' . $group->gid;
    $variables['classes_array'][] = $clean_html;
    $variables['classes_array'][] = $clean_html . '-' . $group->etid;

    // Add context to JS.
    og_context_add_js($group);
  }
}

/**
 * Implements hook_og_context_negotiation_info().
 */
function og_context_og_context_negotiation_info() {
  $providers = array();

  $providers['url'] = array(
    'name' => t('URL'),
    'description' => t("Select groups if they were passed in the URL (e.g. node/add/post?gids_node[]=4,5,6)."),
    'callback' => 'og_context_handler_url',
  );

  $providers['node'] = array(
    'name' => t('Node'),
    'description' => t("Determine context by checking if a node is a group or a group content."),
    'callback' => 'og_context_handler_node',
    'menu path' => array('node/%', 'node/%/edit'),
  );

  $providers['user-view'] = array(
    'name' => t('User view'),
    'description' => t("Determine context by checking if a user is a group or a group content on the 'user view' page."),
    'callback' => 'og_context_handler_user_view',
    'menu path' => array('user/%'),
  );

  $providers['user-edit'] = array(
    'name' => t('User edit'),
    'description' => t("Determine context by checking if a user is a group or a group content on the 'user edit' page."),
    'callback' => 'og_context_handler_user_edit',
    'menu path' => array('user/%/edit'),
  );

  return $providers;
}

/**
 * Implement hook_init().
 */
function og_context_init() {
  og_context();
}

/**
 * Implements hook_views_api().
 */
function og_context_views_api() {
  return array(
    'api' => 2,
    'path' => drupal_get_path('module', 'og_context') . '/includes',
  );
}

/**
 * Implements hook_og_invalidate_cache().
 */
function og_context_og_invalidate_cache($gids = array()) {
  $caches = array(
    'og_context',
    'og_context_js',
  );

  foreach ($caches as $cache) {
    drupal_static_reset($cache);
  }

  if ($gids && !empty($_SESSION['og_context']) && in_array($_SESSION['og_context'], $gids)) {
    // Remove group's context.
    $_SESSION['og_context'] = NULL;
  }
}


/**
 * Get or set group context using the menu system.
 *
 * @param $group
 *   Optional; The group entity to set as the context.
 * @param $account
 *   Optional; The user entity to determine context form.
 *
 * @return
 *   A group entity, or FALSE if no context was found.
 */
function og_context($group = NULL, $account = NULL) {
  global $user;
  $context = &drupal_static(__FUNCTION__, FALSE);

  if (!empty($group)) {
    $context = $group;
  }

  if (empty($context)) {
    // Get context from context handlers.
    if (($context = og_context_determine_context()) && $user->uid) {
      // TODO: Add option to save session for anonymous users as-well?
      // Save the group ID in the authenticated user's session,
      $_SESSION['og_context'] = $context->gid;
    }
  }

  return $context;
}

/**
 * Add the group entity of the context to the Drupal javascript entity.
 *
 * @param $group
 *   A group entity.
 */
function og_context_add_js($group) {
  // Static variable to indicate if group was already added to javascript.
  $js = &drupal_static(__FUNCTION__, FALSE);

  if (empty($js)) {
    drupal_add_js(array('group' => array('og_context' => $group)), 'setting');
    $js = TRUE;
  }
}

/**
 * Return all the defined group context providers.
 *
 * @return
 *   An array of group context providers.
 */
function og_context_negotiation_info() {
  $group_context_providers = &drupal_static(__FUNCTION__);

  if (!isset($group_context_providers)) {
    // Collect all the module-defined og_context negotiation providers.
    $group_context_providers = module_invoke_all('og_context_negotiation_info');

    // Let other modules alter the list of og_context providers.
    drupal_alter('og_context_negotiation_info', $group_context_providers);
  }

  // Assign default values.
  foreach ($group_context_providers as &$group_context_provider) {
    $group_context_provider += array(
      'menu path' => array(),
    );
  }

  return $group_context_providers;
}


/**
 * Save a list of language providers.
 *
 * @param $type
 *   The language negotiation type.
 * @param $language_providers
 *   An array of language provider ids.
 */
function og_context_negotiation_set($group_context_providers) {
  $type = 'group_context';
  // Save only the necessary fields.
  $provider_fields = array('callbacks');

  $negotiation = array();
  $providers_weight = array();
  $defined_providers = og_context_negotiation_info();

  // Initialize the providers weight list.
  foreach ($group_context_providers as $id => $provider) {
    $providers_weight[$id] = og_context_provider_weight($provider);
  }

  // Order providers list by weight.
  asort($providers_weight);

  foreach ($providers_weight as $id => $weight) {
    if (isset($defined_providers[$id])) {
      $provider = $defined_providers[$id];

      $provider_data = array();
      foreach ($provider_fields as $field) {
        if (isset($provider[$field])) {
          $provider_data[$field] = $provider[$field];
        }
      }
      $negotiation[$id] = $provider_data;
    }
  }

  variable_set("og_context_negotiation_$type", $negotiation);
}


/**
 * Return the passed group context provider weight or a default value.
 *
 * @param $provider
 *   A group context provider data structure.
 *
 * @return
 *   A numeric weight.
 */
function og_context_provider_weight($provider) {
  $default = is_numeric($provider) ? $provider : 0;
  return isset($provider['weight']) && is_numeric($provider['weight']) ? $provider['weight'] : $default;
}


/**
 * Determine the best matching context of a viewed page.
 *
 * @param $item
 *   Optional; A menu item that context should be extracted from. If empty
 *   defaults to the current menu item by using menu_get_item().
 */
function og_context_determine_context($item = NULL) {
  $context = FALSE;

  // Enable url and node context handlers by default.
  $defaults = array('url' => -5, 'node' => -4);
  if ($enabled_providers = array_keys(variable_get("og_context_negotiation_group_context", $defaults))) {


    if (empty($item)) {
      $item = menu_get_item();
    }

    foreach (og_context_negotiation_info() as $name => $provider) {
      if (in_array($name, $enabled_providers)) {
        $invoke = FALSE;
        if (!empty($provider['menu path'])) {
          foreach ($provider['menu path'] as $path) {
            if (strpos($item['path'], $path) === 0) {
              $invoke = TRUE;
              // Path matches, so we can break.
              break;
            }
          }
        }
        else {
          // Context isn't determined by the menu item.
          $invoke = TRUE;
        }

        $gids = array();

        if ($invoke && ($gids = call_user_func($provider['callback']))) {
          // Check if one of the group IDs already exists in the session, and if
          // so use it.
          if (!empty($_SESSION['og_context']) && in_array($_SESSION['og_context'], $gids)) {
            $gid = $_SESSION['og_context'];
          }
          else {
            // Grab the first group ID.
            $gid = reset($gids);
          }

          $context = og_load($gid);
          // We found the first context, so we can break.
          break;
        }
      }
    }
  }

  return $context;
}

/**
 * Context handler; Get groups from URL.
 */
function og_context_handler_url() {
  $context = array();
  if ($gids = og_get_context_by_url()) {
    $context = $gids;
  }

  return $context;
}

/**
 * Context handler; Get groups from existing node.
 */
function og_context_handler_node() {
  $return = array();
  // menu_get_object() doesn't play nicely if the path is node/%/foo, so we load
  // it ourself.
  $item = menu_get_item();
  if (!empty($item['map'][1])) {
    if (is_object($item['map'][1])) {
      $node = $item['map'][1];
    }
    else {
      $node = node_load($item['map'][1]);
    }
    $return = _group_context_handler_entity('node', $node);
  }
  return $return;
}

/**
 * Context handler; Get groups from user view.
 */
function og_context_handler_user_view() {
  global $user;
  return _group_context_handler_entity('user', $user);
}

/**
 * Context handler; Get groups from user edit.
 */
function og_context_handler_user_edit() {
  return _group_context_handler_entity('user');
}

/**
 * Helper function to get group context from an entity.
 *
 * @param $entity_type
 *   The entity type.
 * @param $entity
 *   Optional; The entity object.
 * @param $position
 *   Optional; The position that should be used in menu_get_object().
 */
function _group_context_handler_entity($entity_type = 'node', $entity = NULL, $position = 1) {
  $context = array();

  if (empty($entity)) {
    $entity = menu_get_object($entity_type, $position);
  }
  if ($entity) {
    // Check if the entity is itself a group.
    list($id) = entity_extract_ids($entity_type, $entity);
    if ($group = og_get_group($entity_type, $id)) {
      $context = drupal_map_assoc(array($group->gid));
    }

    elseif ($gids = og_get_entity_groups($entity_type, $entity)) {
      $context = $gids;
    }
  }

  return $context;
}