From 4bc72609a24d5d8d60a0b503cad22c7e8b08e08a Mon Sep 17 00:00:00 2001
From: Lorenz Schori <lo@znerol.ch>
Date: Sat, 19 Jan 2013 13:48:31 +0100
Subject: [PATCH 2/3] Implement hook_requirements

---
 authcache.install |   40 ++++++++++++++++++++++++++++++++++++++--
 1 file changed, 38 insertions(+), 2 deletions(-)

diff --git a/authcache.install b/authcache.install
index e1702f3..b4d5725 100644
--- a/authcache.install
+++ b/authcache.install
@@ -13,8 +13,7 @@ function authcache_enable() {
   global $user;
 
   // Did admin follow install instructions?
-  //if (substr(variable_get('cache_inc', FALSE), -13) != 'authcache.inc') {
-  if (!variable_get('cache_class_cache_page', false)) {
+  if (!_authcache_backendstatus()) {
     drupal_set_message(st('Your settings.php file must be modified to enable Authcache. See <a href="@url">README.txt</a>.', array('@url' => base_path() . drupal_get_path('module', 'authcache') . '/README.txt')), 'error');
   }
 
@@ -32,6 +31,32 @@ function authcache_disable() {
 }
 
 /**
+ * Implements hook_requirements().
+ */
+function authcache_requirements($phase) {
+  $requirements = array();
+  // Ensure translations don't break during installation.
+  $t = get_t();
+
+  // Retrieve the name of the cache class used for the cache_page bin.
+  $page_cache_class = get_class(_cache_get_object('cache_page'));
+
+  $requirements['authcache'] = array(
+    'title' => $t('Authcache'),
+  );
+  if (_authcache_backendstatus()) {
+    $requirements['authcache']['value'] = $t('Using %class as cache backend', array('%class' => $page_cache_class));
+  }
+  else {
+    $requirements['authcache']['value'] = $t('authcache.inc is not the last entry in cache_backends variable.');
+    $requirements['authcache']['description'] = $t('Your settings.php file must be modified to enable Authcache. See <a href="@url">README.txt</a>.', array('@url' => base_path() . drupal_get_path('module', 'authcache') . '/README.txt'));
+    $requirements['authcache']['severity'] = REQUIREMENT_ERROR;
+  }
+
+  return $requirements;
+}
+
+/**
  * Implements hook_install().
  */
 function authcache_install() {
@@ -57,3 +82,14 @@ function authcache_uninstall() {
   ->execute();
   cache_clear_all('variables', 'cache');
 }
+
+/**
+ * Return true if settings.php is properly configured and authcache.inc is the
+ * last entry in the cache_backends array.
+ */
+function _authcache_backendstatus() {
+  // Check whether authcache.inc is last in cache_backends.
+  $last_in_backends = end(variable_get('cache_backends', array()));
+  $authcache_inc = drupal_get_path('module', 'authcache') . '/authcache.inc';
+  return $authcache_inc == $last_in_backends;
+}
-- 
1.7.10.4