<?php
// $Id: me.module,v 1.5.2.7.2.4 2009-03-30 11:17:42 cdale Exp $

/**
 * @file
 *
 * Provides 'me' aliases to allow users to enter 'me' in common paths instead of their user id.
 */

/**
 * Constants defining the different ways paths can be matched.
 */
// Exclude paths
define('ME_PATH_EXCLUDE', 0);

// Include paths
define('ME_PATH_INCLUDE', 1);

// PHP for paths
define('ME_PATH_PHP', 2);

/**
 * Implementation of hook_help().
 */
function me_help($path, $arg) {
  switch ($path) {
    case 'admin/help#me':
      return t("Allows a user to enter user/me, blog/me etc.. using 'me' in place of their user id.");
  }
}

/**
 * Implementation of hook_theme_registry_alter().
 */
function me_theme_registry_alter(&$theme_registry) {
  if (isset($theme_registry['menu_item_link']['function'])) {
    $theme_registry['menu_item_link']['function'] = 'me_theme_menu_item_link';
  }
}

/**
 * Implementaiton of moduleName_preprocess_hook() for theme_menu_item_link.
 */
function me_preprocess_menu_item_link(&$vars) {
  _me_check_path($vars['link']);
}

/**
 * Implementation of theme_menu_item_link().
 */
function me_theme_menu_item_link($link) {
  _me_check_path($link);

  if (isset($GLOBALS['custom_theme']) && function_exists($GLOBALS['custom_theme'] .'_menu_item_link')) {
    $function = $GLOBALS['custom_theme'] .'_menu_item_link';
  }
  elseif (isset($GLOBALS['theme_key']) && function_exists($GLOBALS['theme_key'] .'_menu_item_link')) {
    $function = $GLOBALS['theme_key'] .'_menu_item_link';
  }
  elseif (isset($GLOBALS['theme_engine']) && function_exists($GLOBALS['theme_engine'] .'_menu_item_link')) {
    $function = $GLOBALS['theme_engine'] .'_menu_item_link';
  }
  else {
    $function = 'theme_menu_item_link';
  }

  return $function($link);
}

/**
 * Helper function to check if a path can be rewritten or not.
 *
 * By this stage, the path is already rewritten, so we need to
 * reverse the process.
 *
 * @param &$link
 *   The link object to check.
 */
function _me_check_path(&$link) {
  // If the link has been rewritten, and we are not supposed to be handling this
  // path, then rewite it back to its original.
  if (me_variable_get('me_rewrite_link') && !_me_handle_path($link['href'])) {
    $path_parts = explode('/', $link['href'], MENU_MAX_PARTS);

    // The wildcarded path will either be in $link['path'], or $link['router_path'].
    $wild_parts = explode('/', (isset($link['path']) ? $link['path'] : $link['router_path']), MENU_MAX_PARTS);

    // Go over each of the path parts and if one is equal to the me alias, make sure it is a wildcard,
    // and if so, switch it back out.
    while (list($key, $val) = each($path_parts)) {
      if (_me_is_alias($val) && $wild_parts[$key] == '%') {
        $path_parts[$key] = $GLOBALS['user']->uid;
      }
    }

    $link['href'] = implode('/', $path_parts);
  }
}

/**
 * Helper function to keep all the variable gets in one place.
 *
 * @param $name
 *   The variable we wish to retrieve.
 *
 * @return mixed
 *   The value of the requested variable.
 */
function me_variable_get($name) {
  static $defaults = array(
    'me_alias' => 'me',
    'me_case_insensitive' => FALSE,
    'me_redirect' => FALSE,
    'me_path_rule' => ME_PATH_EXCLUDE,
    'me_paths' => '',
    'me_redirect_anonymous' => '',
    'me_rewrite_link' => TRUE,
    'me_user_override' => FALSE,
  );

  return variable_get($name, $defaults[$name]);
}

/**
 * Helper function to check if me should handle a given path.
 *
 * @param $path
 *   The path to check
 *
 * @return boolean
 *   TRUE if the path is handled by the me module. FALSE otherwise.
 */
function _me_handle_path($path) {
  // Match path if necessary
  $paths = me_variable_get('me_paths');
  $path_rule = me_variable_get('me_path_rule');
  $path_match = TRUE;

  if (!empty($paths)) {
    if ($path_rule !== ME_PATH_PHP) {
      $path = drupal_get_path_alias($_GET['q']);

      // Compare with the internal and path alias (if any).
      $path_match = drupal_match_path($path, $paths);
      if ($path != $_GET['q']) {
        $path_match = $path_match || drupal_match_path($_GET['q'], $paths);
      }

      // When $path_rule has a value of ME_PATH_EXCLUDE, then me works on
      // all paths except those listed in $paths. When set to ME_PATH_INCLUDE, it
      // is used only on those pages listed in $paths.
      $path_match = !($path_rule xor $path_match);
    }
    else {
      $path_match = drupal_eval($paths);
    }
  }

  return $path_match;
}

/**
 * A special menu callback function that either redirects to
 * a page with the uid in the path, or calls the real menu handler.
 *
 * @param $parts
 *   The menu parts we are working with.
 * @param $callback
 *   The page callback to call.
 * @param ...
 *   count($parts) arguments for each part of the actual path
 * @param ...
 *   Any extra arguments will be the real page arguments.
 *
 * @return mixed
 *   Whatever the real page callback returns.
 */
function me_handler($parts, $callback) {
  // Get the arguments, and shift off $parts and $callback.
  $args = func_get_args();
  array_shift($args);
  array_shift($args);

  // If we want the uid shown in the address bar, we need to do a redirect.
  if (me_variable_get('me_redirect') || _me_user_disabled() || !_me_handle_path($_GET['q'])) {
    $redirect = FALSE;
    // Get the menu path arguments.
    $menu_parts = explode('/', $_GET['q'], MENU_MAX_PARTS);

    // Loop over each part. If it's a %me wildcard, then
    // check the corresponding menu part for the me alias,
    // if so, replace it out with the user id so we can redirect correctly.
    // If no changes are required, then call the required function.
    while (list($key, $val) = each($parts)) {
      if (0 === strpos($val, '%me') && _me_is_alias($menu_parts[$key])) {
        $redirect = TRUE;
        $menu_parts[$key] = $GLOBALS['user']->uid;
      }
    }

    if ($redirect) {
      $path = implode('/', $menu_parts);
      // Save on an extra redirect by also checking the anonymous redirect here.
      $redirect_path = me_variable_get('me_redirect_anonymous');
      if ($GLOBALS['user']->uid == 0 && !empty($redirect_path)) {
        $path = $redirect_path;
      }
      drupal_goto($path);
    }
  }

  // Before going any further, set the current menu router item to include
  // paths with %user, which allows modules to use menu_get_object() instead
  // of arg() in blocks and the like.
  $router_item = menu_get_item();
  foreach ($router_item['load_functions'] as $index => $function) {
    // If the function is a me handled function, then swap the handler out with user.
    if (0 === strpos($function, 'me')) {
      $router_item['load_functions'][$index] = 'user_load';
    }
  }
  menu_set_item($_GET['q'], $router_item);

  return call_user_func_array($callback, $args);
}

/**
 * Helper function to check if a user can have, and has me disabled.
 *
 * @return boolean
 *   TRUE if the user has me disabled. FALSE otherwise.
 */
function _me_user_disabled() {
  return me_variable_get('me_user_override') && !empty($GLOBALS['user']->me_disable);
}

/**
 * Implementation of hook_menu_alter().
 */
function me_menu_alter(&$callbacks) {
  // Loop over each of the paths, finding all %user* loaders,
  // and replace them with a %me equivelant. This should catch
  // all drupal modules that use the %user loader to load up
  // user objects, which should be most well written D6 modules.
  // Certainly all of core.
  $processed = array();
  //XXX: For now, we only handle known user loaders. I might make a module hook, or a configuration
  // area to allow these to be exteneded if users make the requests.
  $handlers = array(
    '%user' => '%me',
    '%user_uid_optional' => '%me_uid_optional',
    '%user_category' => '%me_category',
  );
  foreach ($callbacks as $path => $data) {
    $found = FALSE;
    $parts = explode('/', $path, MENU_MAX_PARTS);
    foreach ($handlers as $user_handler => $me_handler) {
      if (in_array($user_handler, $parts)) {
        $found = TRUE;
        break;
      }
    }

    if ($found) {
      // We need to make sure that the correct files are loaded up. when the path is used.
      if (isset($data['file']) && !isset($data['file path'])) {
        $data['file path'] = drupal_get_path('module', $data['module']);
      }

      // We need to find the right page callback and page arguments to make
      // the me handler work correctly.
      $new_parts = array();

      while (list($key, $val) = each($parts)) {
        if (array_key_exists($val, $handlers)) {
          $val = $handlers[$val];
        }
        $new_parts[] = $val;
      }
      $new_path = implode('/', $new_parts);

      // We need to be careful with load arguments due too http://drupal.org/node/373568.
      // We therefore only add load arguments if there are some there already.
      // The only load argument that needs to be passed by reference is map.
      // We make sure that we have map in the right place to be passed by reference.
      if (is_array($data['load arguments'])) {
        // Find the current map index, and add our load arguments, putting map
        // in the place we expect it to be.
        if (FALSE !== ($map_index = array_search('%map', $data['load arguments']))) {
          unset($data['load arguments'][$map_index]);
          array_unshift($data['load arguments'], '%map', '%index', strval($map_index));
        }
      }

      // First, we need to find the parent.
      $parent_path = implode('/', array_slice($parts, 0, count($parts) - 1));
      if (in_array($parent_path, $processed)) {
        $parts = explode('/', $new_path, MENU_MAX_PARTS);
        $parent_path = implode('/', array_slice($parts, 0, count($parts) - 1));
      }
      $parent = $callbacks[$parent_path];

      if (!isset($data['page callback']) && isset($parent['page callback'])) {
        $data['page callback'] = $parent['page callback'];
        if (!isset($data['page arguments']) && isset($parent['page arguments'])) {
          $data['page arguments'] = $parent['page arguments'];
        }
        if (!isset($data['file']) && isset($parent['file'])) {
          $data['file'] = $parent['file'];
        }
        if (!isset($data['file path']) && isset($parent['file path'])) {
          $data['file path'] = $parent['file path'];
        }
      }

      if (isset($data['page callback'])) {
        if (!is_array($data['page arguments'])) {
          $data['page arguments'] = array();
        }

        $parts = explode('/', $new_path, MENU_MAX_PARTS);
        $data['page arguments'] = array_merge(array($parts, $data['page callback']), $data['page arguments']);
        $data['page callback'] = 'me_handler';
      }

      $callbacks[$new_path] = $data;
      unset($callbacks[$path]);
      $processed[] = $path;
    }
  }
}

/**
 * Helper function to set up arguments in meun _load callbacks.
 */
function _me_load_arguments($uid, &$map = NULL, $index = NULL, $map_index = FALSE, $args = array(), $function = 'user_load') {
  // We need to get all the arguments, remove our custom ones,
  // put %map in the right place, then call the menu load callack.
  array_splice($args, 0, min(4, count($args)));

  if (!is_null($map) && FALSE !== $map_index) {
    $insert = array(
      &$map,
    );
    array_splice($args, $map_index, 0, $insert);
    $map[$index] = _me_check_arg($uid);
  }

  array_unshift($args, _me_check_arg($uid));

  // If we have a valid function to call, call it.
  if (function_exists($function)) {
    return call_user_func_array($function, $args);
  }

  return FALSE;
}

/**
 * Menu load callback in place of user_load().
 */
function me_load($uid, &$map = NULL, $index = NULL, $map_index = FALSE) {
  $args = func_get_args();
  return _me_load_arguments($uid, $map, $index, $map_index, $args);
}

/**
 * Menu load callback in place of user_uid_optional_load().
 */
function me_uid_optional_load($uid, &$map = NULL, $index = NULL, $map_index = FALSE) {
  $args = func_get_args();
  return _me_load_arguments((isset($uid) ? $uid : $GLOBALS['user']->uid), $map, $index, $map_index, $args);
}

/**
 * Menu load callback in place of user_category_load().
 */
function me_category_load($uid, &$map = NULL, $index = NULL, $map_index = FALSE) {
  $args = func_get_args();
  return _me_load_arguments($uid, $map, $index, $map_index, $args, 'user_category_load');
}

/**
 * Menu to_arg function for %me.
 */
function me_to_arg($arg, $map, $index) {
  $uid = user_uid_optional_to_arg($arg, $map, $index);
  if (me_variable_get('me_rewrite_link') && !_me_user_disabled()) {
    return $uid == $GLOBALS['user']->uid ? me_variable_get('me_alias') : $uid;
  }
  else {
    return $uid;
  }
}

/**
 * Menu to_arg function for %me_uid_optional.
 */
function me_uid_optional_to_arg($arg, $map, $index) {
  return me_to_arg($arg, $map, $index);
}

/**
 * Menu to_arg function for %me_category.
 */
function me_category_to_arg($arg, $map, $index) {
  return me_to_arg($arg, $map, $index);
}

/**
 * A Helper function to check for the 'me' alias.
 *
 * @param $arg
 *   The argument to check.
 * @param $username
 *   If TRUE, will return the username instead of the users id.
 * @param $redirect
 *   When TRUE, anonymous users will be redirected if a path is available.
 *
 * @return mixed
 *   The current user id if a match is found, or the given argument
 *   if no match.
 */
function _me_check_arg($arg, $username = FALSE, $redirect = TRUE) {
  $return = _me_is_alias($arg) ? $username ? $GLOBALS['user']->name : $GLOBALS['user']->uid : $arg;

  $redirect_path = me_variable_get('me_redirect_anonymous');

  if ($redirect && $GLOBALS['user']->uid == 0 &&  !empty($redirect_path)) {
    // Copied from menu_get_item(). We can't call that here as it might cause a recursion loop.
    $original_map = arg(NULL, $_GET['q']);
    $parts = array_slice($original_map, 0, MENU_MAX_PARTS);
    list($ancestors, $placeholders) = menu_get_ancestors($parts);

    if (($router_item = db_fetch_array(db_query_range('SELECT * FROM {menu_router} WHERE path IN ('. implode (',', $placeholders) .') ORDER BY fit DESC', $ancestors, 0, 1))) && $router_item['page_callback'] == 'me_handler') {
      // Not unsetting the destination can cause evil redirect loops.
      unset($_REQUEST['destination'], $_REQUEST['edit']['destination']);
      drupal_goto($redirect_path);
    }
  }

  return $return;
}

/**
 * A helper function to check if a string is equal to the 'me' alias.
 *
 * @param $arg
 *   The argument to check.
 *
 * @return boolean
 *   TRUE if the argument given is a 'me' alias. FALSE otherwise.
 */
function _me_is_alias($arg) {
  $compare_function = me_variable_get('me_case_insensitive') ? 'strcasecmp' : 'strcmp';
  return $compare_function($arg, me_variable_get('me_alias')) === 0;
}

/**
 * Implementation of hook_views_api().
 */
function me_views_api() {
  return array(
    'api' => views_api_version(),
    'path' => drupal_get_path('module', 'me') .'/includes',
  );
}

/**
 * Implementation of hook_menu().
 */
function me_menu() {
  $items = array();

  $items['admin/settings/me'] = array(
    'title' => "'Me' Aliases",
    'description' => "Configure the 'me' aliases, and how they're matched.",
    'page callback' => 'drupal_get_form',
    'page arguments' => array('me_admin_settings_form'),
    'access arguments' => array('administer site configuration'),
    'type' => MENU_NORMAL_ITEM,
  );

  return $items;
}

/**
 * Implementation of hook_perm().
 */
function me_perm() {
  return array(
    'use PHP for me alias paths',
  );
}

/**
 * Form callback for the admin settings form.
 */
function me_admin_settings_form(&$form_state) {
  $form = array();

  $form['me_alias'] = array(
    '#type' => 'textfield',
    '#title' => t("'Me' Alias"),
    '#description' => t('The alias to use to represent the current users uid.'),
    '#default_value' => me_variable_get('me_alias'),
    '#required' => TRUE,
  );

  $form['me_case_insensitive'] = array(
    '#type' => 'checkbox',
    '#title' => t('Case Insensitive Alias Checking'),
    '#description' => t('When checked, "Me" will be matched the same as "me", "ME", and "mE".'),
    '#default_value' => me_variable_get('me_case_insensitive'),
  );

  $form['me_rewrite_link'] = array(
    '#type' => 'checkbox',
    '#title' => t('Rewrite links generated by the drupal menu system'),
    '#description' => t('When checked, links output by the drupal menu system will replace uid with the me alias.'),
    '#default_value' => me_variable_get('me_rewrite_link'),
  );

  $form['me_user_override'] = array(
    '#type' => 'checkbox',
    '#title' => t('Allow users to turn off me for their account'),
    '#default_value' => me_variable_get('me_user_override'),
  );

  $form['me_redirect'] = array(
    '#type' => 'checkbox',
    '#title' => t('Redirect to uid'),
    '#description' => t('When checked, perform a redirect so the users uid is shown in the address bar instead of the me alias.'),
    '#default_value' => me_variable_get('me_redirect'),

  );

  $form['me_redirect_anonymous'] = array(
    '#type' => 'textfield',
    '#title' => t('Redirect anonymous users'),
    '#description' => t('When this is non-empty, anonymous users will be redirected to the specified drupal path.'),
    '#default_value' => me_variable_get('me_redirect_anonymous'),
  );

  $access = user_access('use PHP for me alias paths');
  $path_rule = me_variable_get('me_path_rule');
  $paths = me_variable_get('me_paths');

  if ($path_rule == ME_PATH_PHP && !$access) {
    $form['me_paths_settings'] = array();
    $form['me_paths_settings']['me_path_rule'] = array('#type' => 'value', '#value' => $path_rule);
    $form['me_paths_settings']['me_paths'] = array('#type' => 'value', '#value' => $paths);
  }
  else {
    $options = array(
      ME_PATH_EXCLUDE => t('Use me alias on every path except the listed paths.'),
      ME_PATH_INCLUDE => t('Use me alias only on the listed paths.'),
    );
    $description = t("Enter one path per line as Drupal paths. The '*' character is a wildcard. Example paths are %blog for the '
      .'blog page and %blog-wildcard for every personal blog. %front is the front page.",
      array('%blog' => 'blog', '%blog-wildcard' => 'blog/*', '%front' => '<front>'));

    if ($access) {
      $options[ME_PATH_PHP] = t('Use me alias if the following PHP code returns <code>TRUE</code> (PHP-mode, experts only).');
      $description .= ' '. t('If the PHP-mode is chosen, enter PHP code between %php. Note that executing incorrect PHP-code can '
        .'break your Drupal site.', array('%php' => '<?php ?>'));
    }
    $form['me_paths_settings']['me_path_rule'] = array(
      '#type' => 'radios',
      '#title' => t('Use me alias on specific paths'),
      '#options' => $options,
      '#default_value' => $path_rule,
    );
    $form['me_paths_settings']['me_paths'] = array(
      '#type' => 'textarea',
      '#title' => t('Paths'),
      '#default_value' => $paths,
      '#description' => $description . t('<p>NOTE: This option simply ensures that the browser address bar for these paths have '
        .'the uid and not me. The me alias will still work for these paths. It will have no effect on specific uids in paths, '
        .'but if the path includes the me alias, then me will be affected for those paths. This will only affect paths '
        .'that me can already handle. It will not allow me to work for unknown paths.</p>'),
    );
  }

  $form['#validate'] = array('me_admin_settings_form_validate');

  $form = system_settings_form($form);

  // Quite a few options only have an affect on theme and menu rebuilds. We just do them here
  // to make sure the options have an instant effect.
  $form['#submit'][] = 'menu_rebuild';
  $form['#submit'][] = 'drupal_rebuild_theme_registry';

  return $form;
}

/**
 * Validation callback for me_admin_settings_form.
 */
function me_admin_settings_form_validate($form, &$form_state) {
  if (preg_match('/[^a-zA-Z]/', $form_state['values']['me_alias'])) {
    form_set_error('me_alias', t('The alias can only contain characters from a-z and A-Z.'));
  }
}

/**
 * Implementation of hook_user().
 */
function me_user($op, &$edit, &$account, $category = NULL) {
  switch ($op) {
    case 'categories':
      if (me_variable_get('me_user_override')) {
        return array(
          array(
            'name' => 'me',
            'title' => t("'@me' alias", array('@me' => me_variable_get('me_alias'))),
            'weight' => 2,
          ),
        );
      }
      break;
    case 'form' && $category == 'me':
      $form = array();

      $form['me_uid'] = array(
        '#type' => 'item',
        '#title' => t('User id'),
        '#value' => $account->uid,
      );

      $form['me_disable'] = array(
        '#type' => 'checkbox',
        '#title' => t("Disable '%me' alias for this account", array('%me' => me_variable_get('me_alias'))),
        '#description' => t('This option stops your user id from being replaced with %me. %me will still work when entered '
          .'into the address bar, but you will be redirected to a page with your uid in its place.',
          array('%me' => me_variable_get('me_alias'))),
        '#default_value' => !empty($account->me_disable),
      );

      return $form;
    case 'view':
      if (me_variable_get('me_user_override')) {
        $enabled = 'enabled';
        if (!empty($account->me_disable)) {
          $enabled = 'disabled';
        }

        $account->content['me'] = array(
          '#type' => 'markup',
          '#value' => t("'%me' aliases are $enabled for this account. Account user id is '@uid'.",
            array('%me' => me_variable_get('me_alias'), '@uid' => $account->uid)),
          '#weight' => 10,
        );
      }
      break;
  }
}