Rework the theme loading code to allow themes to be treated as Gallery

modules, and have an admin subdirectory that is treated like a Kohana
module (as distinct from a Gallery module).

The main advantage of creating the separate admin subdirectory is that
we will not load an admin theme and a site theme at the same time.
We'll only load a few specialized bits of the site theme while the
admin theme is active.

Concrete examples. A site theme named "xxx":
- will receive events at themes/xxx/helpers/xxx_event.php
- will have working controllers at themes/xxx/controllers/xxx.php

If theme xxx has an admin subdir, then in admin mode it:
- will receive events at themes/xxx/admin/helpers/xxx_event.php
- will have working controllers at themes/xxx/admin/controllers/xxx.php

2 files changed, 38 insertions, 12 deletions

diff --git a/modules/gallery/helpers/module.php b/modules/gallery/helpers/module.php
index e6c196ce..50abdaae 100644
--- a/modules/gallery/helpers/module.php
+++ b/modules/gallery/helpers/module.php
@@ -335,6 +335,21 @@ class module_Core {
         call_user_func_array(array($class, $function), $args);
       }
     }
+
+    // Give the admin theme a chance to respond, if we're in admin mode.
+    if (theme::$is_admin) {
+      $class = theme::$admin_theme_name . "_event";
+      if (method_exists($class, $function)) {
+        call_user_func_array(array($class, $function), $args);
+      }
+    }
+
+    // Give the site theme a chance to respond as well.  It gets a chance even in admin mode, as
+    // long as the theme has an admin subdir.
+    $class = theme::$site_theme_name . "_event";
+    if (method_exists($class, $function)) {
+      call_user_func_array(array($class, $function), $args);
+    }
   }
 
   /**
diff --git a/modules/gallery/helpers/theme.php b/modules/gallery/helpers/theme.php
index 19737c0e..75b48bcc 100644
--- a/modules/gallery/helpers/theme.php
+++ b/modules/gallery/helpers/theme.php
@@ -24,7 +24,8 @@
  * Note: by design, this class does not do any permission checking.
  */
 class theme_Core {
-  public static $active_theme;
+  public static $admin_theme_name;
+  public static $site_theme_name;
   public static $is_admin;
 
   /**
@@ -38,22 +39,32 @@ class theme_Core {
       $path = "/" . $input->get("kohana_uri");
     }
 
+    $modules = Kohana::config("core.modules");
     self::$is_admin = $path == "/admin" || !strncmp($path, "/admin/", 7);
-    $setting_name = self::$is_admin ? "active_admin_theme" : "active_site_theme";
-    if (!(identity::active_user()->admin && $theme_name = $input->get("theme"))) {
-      $theme_name = module::get_var("gallery", $setting_name);
+    self::$site_theme_name = module::get_var("gallery", "active_site_theme");
+    if (self::$is_admin) {
+      // Load the admin theme
+      self::$admin_theme_name = module::get_var("gallery", "active_admin_theme");
+      array_unshift($modules, THEMEPATH . self::$admin_theme_name);
 
-      if (!file_exists(THEMEPATH . $theme_name)) {
-        Kohana::log("error", "Unable to locate theme '$theme_name', switching to default theme.");
-        $theme_name = self::$is_admin ? "admin_wind" : "wind";
-        module::set_var("gallery", $setting_name, $theme_name);
+      // If the site theme has an admin subdir, load that as a module so that
+      // themes can provide their own code.
+      if (file_exists(THEMEPATH . self::$site_theme_name . "/admin")) {
+        array_unshift($modules, THEMEPATH . self::$site_theme_name . "/admin");
+      }
+    } else {
+      // Admins can override the site theme, temporarily.  This lets us preview themes.
+      if (identity::active_user()->admin && $override = $input->get("theme")) {
+        if (file_exists(THEMEPATH . $override)) {
+          self::$site_theme_name = $override;
+        } else {
+          Kohana::log("error", "Missing override theme: '$override'");
+        }
       }
+      array_unshift($modules, THEMEPATH . self::$site_theme_name);
     }
-    $modules = Kohana::config("core.modules");
-    array_unshift($modules, THEMEPATH . $theme_name);
-    Kohana::config_set("core.modules", $modules);
 
-    self::$active_theme = $theme_name;
+    Kohana::config_set("core.modules", $modules);
   }
 
   static function get_edit_form_admin() {