From 4eb0036ef5a4c980a363d5b2e100a60d34a808df Mon Sep 17 00:00:00 2001
From: J Irving <j@lollyshouse.ca>
Date: Fri, 2 Jan 2015 00:05:59 -0500
Subject: [PATCH] Use checksums instead of last modified times.

Also add pandect dependency.
---
 project.clj                  | 33 +++++++++++++++++----------------
 src/cryogen_core/watcher.clj | 27 ++++++++++++++++++---------
 2 files changed, 35 insertions(+), 25 deletions(-)

diff --git a/project.clj b/project.clj
index aad7fb2..17a465f 100644
--- a/project.clj
+++ b/project.clj
@@ -1,16 +1,17 @@
-(defproject cryogen-core "0.1.10"
-            :description "Cryogen's compiler"
-            :url "https://github.com/lacarmen/cryogen-core"
-            :license {:name "Eclipse Public License"
-                      :url  "http://www.eclipse.org/legal/epl-v10.html"}
-            :dependencies [[org.clojure/clojure "1.6.0"]
-                           [clj-rss "0.1.9"]
-                           [me.raynes/fs "1.4.6"]
-                           [crouton "0.1.2"]
-                           [cheshire "5.4.0"]
-                           [clj-text-decoration "0.0.3"]
-                           [io.aviso/pretty "0.1.13"]
-                           [hiccup "1.0.5"]
-                           [selmer "0.7.8"]
-                           [markdown-clj "0.9.61"
-                            :exclusions [com.keminglabs/cljx]]])
+(defproject cryogen-core "0.1.11-SNAPSHOT"
+  :description "Cryogen's compiler"
+  :url "https://github.com/lacarmen/cryogen-core"
+  :license {:name "Eclipse Public License"
+            :url  "http://www.eclipse.org/legal/epl-v10.html"}
+  :dependencies [[org.clojure/clojure "1.6.0"]
+                 [clj-rss "0.1.9"]
+                 [me.raynes/fs "1.4.6"]
+                 [crouton "0.1.2"]
+                 [cheshire "5.4.0"]
+                 [clj-text-decoration "0.0.3"]
+                 [io.aviso/pretty "0.1.13"]
+                 [hiccup "1.0.5"]
+                 [selmer "0.7.8"]
+                 [markdown-clj "0.9.61"
+                  :exclusions [com.keminglabs/cljx]]
+                 [pandect "0.4.1"]])
diff --git a/src/cryogen_core/watcher.clj b/src/cryogen_core/watcher.clj
index 43d478f..0694fcf 100644
--- a/src/cryogen_core/watcher.clj
+++ b/src/cryogen_core/watcher.clj
@@ -1,24 +1,33 @@
 (ns cryogen-core.watcher
   (:require [clojure.java.io :refer [file]]
-            [cryogen-core.io :refer [ignore]]))
+            [cryogen-core.io :refer [ignore]]
+            [pandect.core :refer [md5]]
+            [clojure.set :as set]))
 
-(defn get-assets [root ignored-files]
-  (->> root
+(defn get-assets [path ignored-files]
+  (->> path
        file
        file-seq
        (filter #(not (.isDirectory %)))
        (filter (ignore ignored-files))))
 
-(defn sum-times [path ignored-files]
-  (->> (get-assets path ignored-files) (map #(.lastModified %)) (reduce +)))
+(defn checksums [path ignored-files]
+  (let [files (get-assets path ignored-files)]
+    (zipmap (map md5 files) files)))
+
+(defn find-changes [old-sums new-sums]
+  (let [old-sum-set (-> old-sums keys set)
+        new-sum-set (-> new-sums keys set)]
+    (when-some [changes (set/difference new-sum-set old-sum-set)]
+      (vals (select-keys new-sums changes)))))
 
 (defn watch-assets [root ignored-files action]
-  (loop [times (sum-times root ignored-files)]
+  (loop [sums (checksums root ignored-files)]
     (Thread/sleep 300)
-    (let [new-times (sum-times root ignored-files)]
-      (when-not (= times new-times)
+    (let [new-sums (checksums root ignored-files)]
+      (when (find-changes sums new-sums)
         (action))
-      (recur new-times))))
+      (recur new-sums))))
 
 (defn start-watcher! [root ignored-files action]
   (doto (Thread. #(watch-assets root ignored-files action))