1 files changed, 109 insertions, 0 deletions
diff --git a/lib/redmine/hook.rb b/lib/redmine/hook.rb
new file mode 100644
index 000000000..9bf92b3e7
--- /dev/null
+++ b/lib/redmine/hook.rb
@@ -0,0 +1,109 @@
+# Redmine - project management software
+# Copyright (C) 2006-2008  Jean-Philippe Lang
+#
+# This program is free software; you can redistribute it and/or
+# modify it under the terms of the GNU General Public License
+# as published by the Free Software Foundation; either version 2
+# of the License, or (at your option) any later version.
+# 
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+# 
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+
+module Redmine
+  module Hook
+    @@listener_classes = []
+    @@listeners = nil
+    @@hook_listeners = {}
+    
+    class << self
+      # Adds a listener class.
+      # Automatically called when a class inherits from Redmine::Hook::Listener.
+      def add_listener(klass)
+        raise "Hooks must include Singleton module." unless klass.included_modules.include?(Singleton)
+        @@listener_classes << klass
+        clear_listeners_instances
+      end
+      
+      # Returns all the listerners instances.
+      def listeners
+        @@listeners ||= @@listener_classes.collect {|listener| listener.instance}
+      end
+ 
+      # Returns the listeners instances for the given hook.
+      def hook_listeners(hook)
+        @@hook_listeners[hook] ||= listeners.select {|listener| listener.respond_to?(hook)}
+      end
+      
+      # Clears all the listeners.
+      def clear_listeners
+        @@listener_classes = []
+        clear_listeners_instances
+      end
+      
+      # Clears all the listeners instances.
+      def clear_listeners_instances
+        @@listeners = nil
+        @@hook_listeners = {}
+      end
+      
+      # Calls a hook.
+      # Returns the listeners response.
+      def call_hook(hook, context={})
+        response = ''
+        hook_listeners(hook).each do |listener|
+          response << listener.send(hook, context).to_s
+        end
+        response
+      end
+    end
+
+    # Base class for hook listeners.
+    class Listener
+      include Singleton
+
+      # Registers the listener
+      def self.inherited(child)
+        Redmine::Hook.add_listener(child)
+        super
+      end
+    end
+    
+    # Listener class used for views hooks.
+    # Listeners that inherit this class will include various helpers by default.
+    class ViewListener < Listener
+      include ERB::Util
+      include ActionView::Helpers::TagHelper
+      include ActionView::Helpers::FormHelper
+      include ActionView::Helpers::FormTagHelper
+      include ActionView::Helpers::FormOptionsHelper
+      include ActionView::Helpers::JavaScriptHelper
+      include ActionView::Helpers::PrototypeHelper
+      include ActionView::Helpers::NumberHelper
+      include ActionView::Helpers::UrlHelper
+      include ActionView::Helpers::AssetTagHelper
+      include ActionView::Helpers::TextHelper
+      include ActionController::UrlWriter
+      include ApplicationHelper
+    end
+
+    # Helper module included in ApplicationHelper so that hooks can be called
+    # in views like this:
+    #   <%= call_hook(:some_hook) %>
+    #   <%= call_hook(:another_hook, :foo => 'bar' %>
+    # 
+    # Current project is automatically added to the call context.
+    module Helper
+      def call_hook(hook, context={})
+        Redmine::Hook.call_hook(hook, {:project => @project}.merge(context))
+      end
+    end
+  end
+end
+
+ApplicationHelper.send(:include, Redmine::Hook::Helper)