gtm.module

<?php 
/**
 * @file
 * Drupal Module: Google Tag Manager
 * Provides integration with Google Tag Manager.
 */

/**
 * Implements hook_permission().
 */
function gtm_permission() {
  return array(
    'administer google tag manager' => array(
      'title' => t('Administer Google Tag Manager'),
      'description' => 'Configure Google Tag Manager.'
    ),
  );
}

/**
 * Implements hook_menu().
 */
function gtm_menu() {
  $items['admin/settings/gtm'] = array(
    'title' => 'Google Tag Manager',
    'description' => 'Configure the settings for Google Tag Manager.',
    'page callback' => 'drupal_get_form',
    'page arguments' => array('gtm_admin_settings_form'),
    'access arguments' => array('administer google tag manager'),
    'file' => 'gtm.admin.inc',
    'type' => MENU_NORMAL_ITEM,
  );

  return $items;
}

/**
 * Implements hook_theme
 */

function gtm_theme() {
  return array(
    'gtm_container' => array(
      'variables' => array('gtm_id' => NULL),
      'file' => 'gtm.theme.inc'
    ),
    'gtm_datalayer' => array(
      'variables' => array('dataLayer' => NULL),
      'file' => 'gtm.theme.inc'
    ),
  );
}

/**
 * Implements hook_page_alter().
 *
 * Adds a post_render callback and loads the include file.
 *
 * @see drupal_render_page()
 */
function gtm_page_alter(&$page) {
  if (!gtm_should_track()) {
    return;
  }

  // Call sequence:
  // - drupal_render_page()
  //   - hook_page_alter()
  //   - drupal_render()
  // - drupal_render()
  //   - callbacks in $elements['#theme_wrappers']
  //     - hook_preprocess_html(): 'html' is the wrapper for page
  //     - templates may add tags after body tag
  //   - callbacks in $elements['#post_render']
  //     - gtm_page_process(): callback set here

  // Add callback routine.
  $page['#post_render'][] = 'gtm_page_process';
}

/**
 * CTools plugin API hook for Context. Note that a proper entry in
 * hook_ctools_plugin_api() must exist for this hook to be called.
 */
function gtm_context_plugins() {
  $plugins = array();
  $plugins['context_reaction_data_layer'] = array(
    'handler' => array(
      'path' => drupal_get_path('module', 'gtm') .'/plugins',
      'file' => 'context_reaction_data_layer.inc',
      'class' => 'context_reaction_data_layer',
      'parent' => 'context_reaction',
    ),
  );
  $plugins['context_reaction_gtm_container'] = array(
    'handler' => array(
      'path' => drupal_get_path('module', 'gtm') .'/plugins',
      'file' => 'context_reaction_gtm_container.inc',
      'class' => 'context_reaction_gtm_container',
      'parent' => 'context_reaction',
    ),
  );
  return $plugins;
}

/**
 * Register a reaction
 * @return array
 */

function gtm_context_registry() {
  return array(
    'reactions' => array(
      'data_layer' => array(
        'title' => t('GTM dataLayer'),
        'plugin' => 'context_reaction_data_layer',
      ),
      'gtm_container' => array(
        'title' => t('GTM Container'),
        'plugin' => 'context_reaction_gtm_container',
      )
    ),
  );
}

/**
 * Determines if the current role(s) should be tracked
 */
function gtm_should_track() {
  global $user;
  $id = variable_get('gtm', NULL);
  $track = array();

  if (is_array($user->roles)) {
    foreach ($user->roles as $role) {
      $role = str_replace(' ', '_', $role);
      $track[] = variable_get('gtm_track_' . $role, FALSE) ? TRUE : FALSE;
    }
  }
  // Don't track page views in the admin sections, or for certain roles.
  // Check if we should track the currently active user's role.
  if(in_array(TRUE, $track) && arg(0) != 'admin' && !is_null($id)) {
    return TRUE;
  }
  return FALSE;
}

/**
 * Implements hook_gtm_data_layer
 */

function gtm_gtm_data_layer() {
 if($plugin = context_get_plugin('reaction', 'data_layer')) {
  return $plugin->execute();
 }
 return FALSE;
}


/**
 * Implements callback_post_render().
 *
 * Inserts JavaScript snippet immediately following the opening body tag.
 *
 * @see gtm_page_alter()
 * @see drupal_render()
 */
function gtm_page_process(&$children, $elements) {
  // Insert snippet after the opening body tag.
  if($plugin = context_get_plugin('reaction', 'gtm_container')) {
    $script = $plugin->execute();
    $children = preg_replace('@<body[^>]*>@', '$0' . $script, $children, 1);
  }
  return $children;
}