From 2051edacf727b97dec71510281c9f55def124631 Mon Sep 17 00:00:00 2001
From: Xavier Shay <xavier@rhnh.net>
Date: Sat, 9 Jul 2011 10:26:24 +1000
Subject: [PATCH] Include last modified headers and conditional get support in
 posts controller.

---
 app/controllers/posts_controller.rb | 11 +++++++++++
 app/models/post.rb                  |  4 ++++
 2 files changed, 15 insertions(+)

diff --git a/app/controllers/posts_controller.rb b/app/controllers/posts_controller.rb
index 028d2b4..ee4246e 100644
--- a/app/controllers/posts_controller.rb
+++ b/app/controllers/posts_controller.rb
@@ -2,6 +2,7 @@ class PostsController < ApplicationController
   def index
     @tag = params[:tag]
     @posts = Post.find_recent(:tag => @tag, :include => :tags)
+    fresh_when last_modified: posts_last_updated(@posts), public: true
 
     respond_to do |format|
       format.html
@@ -11,6 +12,16 @@ def index
 
   def show
     @post = Post.find_by_permalink(*([:year, :month, :day, :slug].collect {|x| params[x] } << {:include => [:comments, :tags]}))
+    fresh_when last_modified: @post.last_changed_at.utc, public: true
     @comment = Comment.new
   end
+
+  private
+
+  def posts_last_updated(posts)
+    (
+      [Comment.where(post_id: posts.map(&:id)).maximum(:updated_at)] +
+      posts.map(&:updated_at)
+    ).max
+  end
 end
diff --git a/app/models/post.rb b/app/models/post.rb
index d8d4170..0d27208 100644
--- a/app/models/post.rb
+++ b/app/models/post.rb
@@ -37,6 +37,10 @@ def published?
     published_at?
   end
 
+  def last_changed_at
+    [comments.maximum(:updated_at), updated_at].compact.max
+  end
+
   attr_accessor :published_at_natural
   def published_at_natural
     @published_at_natural ||= published_at.send_with_default(:strftime, 'now', "%Y-%m-%d %H:%M")