From 95842dfa09b662b4372ef15dbd353330670616e7 Mon Sep 17 00:00:00 2001
From: Michael Moussa <michael.moussa@gmail.com>
Date: Wed, 11 Mar 2015 10:56:23 -0400
Subject: [PATCH] Added support for an automatic cache buster suffix on the bg
 image

---
 bin/cli.js         |  5 +++++
 lib/css-sprite.js  | 10 ++++++++--
 test/css-sprite.js | 24 ++++++++++++++++++++++++
 3 files changed, 37 insertions(+), 2 deletions(-)

diff --git a/bin/cli.js b/bin/cli.js
index fcfc7af..c68f3aa 100755
--- a/bin/cli.js
+++ b/bin/cli.js
@@ -69,6 +69,11 @@ var opts = require('nomnom')
     default: '#FFFFFF',
     help: 'background color of the sprite in hex'
   })
+  .option('cachebuster', {
+    choices: ['random'],
+    default: false,
+    help: 'appends a "cache buster" to the background image in the form "?<...>" (random)'
+  })
   .option('margin', {
     default: 4,
     help: 'margin in px between tiles'
diff --git a/lib/css-sprite.js b/lib/css-sprite.js
index 5930e46..51eb635 100644
--- a/lib/css-sprite.js
+++ b/lib/css-sprite.js
@@ -1,6 +1,7 @@
 'use strict';
 
 var async = require('async');
+var crypto = require('crypto');
 var through2 = require('through2');
 var lodash = require('lodash');
 var path = require('path');
@@ -107,11 +108,16 @@ module.exports = function (opt) {
       });
     });
 
+    var cachebuster = '';
+    if (opt.cachebuster === 'random') {
+      cachebuster = '?' + crypto.randomBytes(20).toString('hex');
+    }
+
     if (retinaSprite) {
       sprites.unshift({
         name: retinaSprite.relative,
         type: 'retina',
-        image: (!opt.base64) ? url.resolve(opt.cssPath.replace(/\\/g, '/'), retinaSprite.relative) : 'data:' + imageinfo(retinaSprite.buffer).mimeType + ';base64,' + retinaSprite.buffer.toString('base64'),
+        image: (!opt.base64) ? url.resolve(opt.cssPath.replace(/\\/g, '/'), retinaSprite.relative) + cachebuster : 'data:' + imageinfo(retinaSprite.buffer).mimeType + ';base64,' + retinaSprite.buffer.toString('base64'),
         total_width: sprite.canvas.width(),
         total_height: sprite.canvas.height()
       });
@@ -127,7 +133,7 @@ module.exports = function (opt) {
     sprites.unshift({
       name: sprite.relative,
       type: 'sprite',
-      image: (!opt.base64) ? url.resolve(opt.cssPath.replace(/\\/g, '/'), sprite.relative) : 'data:' + imageinfo(sprite.buffer).mimeType + ';base64,' + sprite.buffer.toString('base64'),
+      image: (!opt.base64) ? url.resolve(opt.cssPath.replace(/\\/g, '/'), sprite.relative) + cachebuster : 'data:' + imageinfo(sprite.buffer).mimeType + ';base64,' + sprite.buffer.toString('base64'),
       total_width: sprite.canvas.width,
       total_height: sprite.canvas.height
     });
diff --git a/test/css-sprite.js b/test/css-sprite.js
index 8bf507e..6af5d39 100644
--- a/test/css-sprite.js
+++ b/test/css-sprite.js
@@ -237,6 +237,30 @@ describe('css-sprite (lib/css-sprite.js)', function () {
         done();
       });
   });
+  it('should include a random cache buster hash on the background-image, if desired', function (done) {
+    var css;
+    vfs.src('./test/fixtures/**')
+      .pipe(sprite({
+        out: './dist/img',
+        name: 'sprites',
+        style: './dist/css/sprites.css',
+        cachebuster: 'random'
+      }))
+      .pipe(through2.obj(function (file, enc, cb) {
+        if (file.relative.indexOf('css') > -1) {
+          css = file;
+        }
+        cb();
+      }))
+      .on('data', noop)
+      .on('end', function () {
+        css.should.be.ok;
+        css.path.should.equal('./dist/css/sprites.css');
+        css.relative.should.equal('sprites.css');
+        css.contents.toString('utf-8').should.match(/background-image: url\('..\/sprites.png\?[0-9a-f]{40}'\)/);
+        done();
+      });
+  });
   it('should return a object stream with a sprite and a scss file', function (done) {
     var png, css;
     vfs.src('./test/fixtures/**')