<?php

/**
 * @file
 * This module add's an addition field to your display and gives you the unique possibility to re-use views templates
 *
 */

/**
 * Implements hook_views_api().
 */
function views_custom_template_views_api() {
  return array(
    'version' => 3,
  );
}

/**
 * Preprocess function to render certain elements into the view.
 */
function template_preprocess_views_custom_template(&$vars) {
  // Current theme hook pattern (from the theme registry alter).
  if (isset($vars['views_custom_template_theme_hook_pattern'])) {
    $view = $vars['view'];
    $pattern = $vars['views_custom_template_theme_hook_pattern'];

    // Template suggestion added in the display settings.
    $template_suggestion = $view->display_handler->get_option('template_suggestion');
    if ($template_suggestion && trim($template_suggestion)) {
      $template_suggestion = _format_views_custom_template_suggestion($template_suggestion);

      // Might be overridden already.
      $is_overridden = !empty($vars['theme_hook_suggestion']);

      // Only change the template if it's not overridden already.
      if (!$is_overridden) {
        $vars['theme_hook_suggestion'] = $pattern . $template_suggestion;
      }
    }
  }
}

/**
 * Helper function for filtering suggestion
 */
function _format_views_custom_template_suggestion($template_suggestion) {
  return trim(preg_replace('/[^a-z0-9_]+/', '_', strtolower(trim((string) $template_suggestion))), '_');
}

/**
 * Implementation of hook_theme_registry_alter().
 */
function views_custom_template_theme_registry_alter(&$theme_registry) {
  // Find interesting Views 'templates'.
  foreach ($theme_registry as $hook => &$info) {
    // Must be views, but only unspecific/default.
    if (0 === strpos($hook, 'views_view') && !is_int(strpos($hook, '__'))) {
      // Must be extensible.
      if (!empty($info['pattern']) && !empty($info['template'])) {
        $info['preprocess functions'][] = 'template_preprocess_views_custom_template';
        $info['variables']['views_custom_template_theme_hook_pattern'] = $info['pattern'];
      }
    }
    unset($info);
  }

}