Implement module hooks

Please find enclosed a patch to create hook_cacti_stats.

I've modified the userstats statistic to be created using this hook, and also added another example stat (nodestats) which tracks thread and comment posts.

This all works perfectly for me, but needs review/committing.

Somehow that last attachment failed so trying again...

Something is wrong with attachments right now, as the patch is small, here it is:

--- cacti.module	2010-08-07 07:03:40.000000000 +1000
+++ cacti.module.new	2010-09-23 08:41:45.158950315 +1000
@@ -88,13 +88,14 @@ function cacti_dispatch($type) {
 
     // We matched an IP, so dispatch to the worker functions.
     if ($allow) {
-      // Dispatch the queries for supported statistic types
-      switch ($type) {
-        case "userstats":
-          print trim(cacti_userstats());
-          // Die so the theme layer is not output.
-          die;
-          break;
+      $value_array = module_invoke_all('cacti_stats', $type);
+      if (is_array($value_array)) {
+        $out = array();
+        foreach ($value_array as $key => $value) {
+          $out[] = trim($key) . ':' . trim($value);
+        }
+        echo join(' ', $out);
+        die;
       }
     }
   }
@@ -108,21 +109,29 @@ function cacti_dispatch($type) {
 
 
 /**
- * Dispatch function.
+ * hook_cacti_stat - Dispatch function.
  * Obtain statistics on current logged in users vs. guest users.
  */
-function cacti_userstats() {
-  // Add count of active anonymous/authenticated users. Mostly copied from the admin_menu module.
-  // @see user_block(), user.module
-  $interval = time() - variable_get('user_block_seconds_online', 900);
-  $count_anon = sess_count($interval);
-  $count_auth = db_result(db_query("SELECT COUNT(DISTINCT uid) FROM {sessions} WHERE uid > 0 AND timestamp >= %d", $interval));
-
-  // Return a count formatted for Cacti
-  $userstats = "users_anon:" . $count_anon . " users_auth:" . $count_auth;
-  return $userstats;
-}
+function cacti_cacti_stats($type) {
+  switch($type) {
+    case 'userstats':
+      // Add count of active anonymous/authenticated users. Mostly copied from the admin_menu module.
+      // @see user_block(), user.module
+      $interval = time() - variable_get('user_block_seconds_online', 900);
+      $count_anon = sess_count($interval);
+      $count_auth = db_result(db_query("SELECT COUNT(DISTINCT uid) FROM {sessions} WHERE uid > 0 AND timestamp >= %d", $interval));
+
+      // Return a count formatted for Cacti
+      return array("users_anon" => $count_anon, "users_auth" => $count_auth);
+    case 'nodestats':
+      /* Return count of nodes & comments */
+      $count_node = db_result(db_query("SELECT COUNT(DISTINCT nid) FROM {node} WHERE status = 1"));
+      $count_comment = db_result(db_query("SELECT COUNT(DISTINCT cid) FROM {comments} WHERE status = 0"));
 
+      // Return a count formatted for Cacti
+      return array("node_count" => $count_node, "comment_count" => $count_comment);
+  }
+}
 
 /**
  * Basic validation of an IP. Mainly copied from the restrict_ip module.