From 21faf54420eee4199c3c490bed2fe65d09f4a98d Mon Sep 17 00:00:00 2001
From: Justin Coyne <jcoyne@justincoyne.com>
Date: Mon, 18 Oct 2021 10:48:33 -0500
Subject: [PATCH 1/3] Process css files so that they get digested paths for
 asset files

This is required so that we can use cssbundling-rails and reference images that will receive digested paths
---
 lib/sprockets/rails/asset_url_processor.rb | 16 +++++++++
 lib/sprockets/railtie.rb                   |  6 ++++
 test/test_asset_url_processor.rb           | 39 ++++++++++++++++++++++
 3 files changed, 61 insertions(+)
 create mode 100644 lib/sprockets/rails/asset_url_processor.rb
 create mode 100644 test/test_asset_url_processor.rb

diff --git a/lib/sprockets/rails/asset_url_processor.rb b/lib/sprockets/rails/asset_url_processor.rb
new file mode 100644
index 00000000..dbc92328
--- /dev/null
+++ b/lib/sprockets/rails/asset_url_processor.rb
@@ -0,0 +1,16 @@
+module Sprockets
+  module Rails
+    # Rewrites urls in CSS files with the digested paths
+    class AssetUrlProcessor
+      REGEX = /url\(\s*["']?(?!(?:\#|data|http))([^"'\s)]+)\s*["']?\)/
+      
+      def self.call(input)
+        context = input[:environment].context_class.new(input)
+        data = input[:data].gsub(REGEX) do |_match|
+          "url(#{context.asset_path($1)})"
+        end
+        { data: data }
+      end
+    end
+  end
+end
diff --git a/lib/sprockets/railtie.rb b/lib/sprockets/railtie.rb
index da5275ad..d7434523 100644
--- a/lib/sprockets/railtie.rb
+++ b/lib/sprockets/railtie.rb
@@ -4,6 +4,8 @@
 require 'active_support/core_ext/module/remove_method'
 require 'active_support/core_ext/numeric/bytes'
 require 'sprockets'
+
+require 'sprockets/rails/asset_url_processor'
 require 'sprockets/rails/context'
 require 'sprockets/rails/helper'
 require 'sprockets/rails/quiet_assets'
@@ -116,6 +118,10 @@ def configure(&block)
       end
     end
 
+    initializer :asset_url_processor do |app|
+      Sprockets.register_postprocessor "text/css", ::Sprockets::Rails::AssetUrlProcessor
+    end
+
     config.assets.version     = ""
     config.assets.debug       = false
     config.assets.compile     = true
diff --git a/test/test_asset_url_processor.rb b/test/test_asset_url_processor.rb
new file mode 100644
index 00000000..75ae5610
--- /dev/null
+++ b/test/test_asset_url_processor.rb
@@ -0,0 +1,39 @@
+require 'minitest/autorun'
+require 'sprockets/railtie'
+
+
+Minitest::Test = MiniTest::Unit::TestCase unless defined?(Minitest::Test)
+class TestAssetUrlProcessor < Minitest::Test
+  def setup
+    @env = Sprockets::Environment.new
+    @env.context_class.class_eval do
+      def asset_path(path, options = {})
+        'image-hexcodegoeshere.png'
+      end
+    end
+  end
+
+  def test_basic
+    input = { environment: @env, data: 'background: url(image.png);', filename: 'url2.css', metadata: {} }
+    output = Sprockets::Rails::AssetUrlProcessor.call(input)
+    assert_equal({ data: "background: url(image-hexcodegoeshere.png);" }, output)
+  end
+
+  def test_spaces
+    input = { environment: @env, data: 'background: url( image.png );', filename: 'url2.css', metadata: {} }
+    output = Sprockets::Rails::AssetUrlProcessor.call(input)
+    assert_equal({ data: "background: url(image-hexcodegoeshere.png);" }, output)
+  end
+
+  def test_single_quote
+    input = { environment: @env, data: "background: url('image.png');", filename: 'url2.css', metadata: {} }
+    output = Sprockets::Rails::AssetUrlProcessor.call(input)
+    assert_equal({ data: "background: url(image-hexcodegoeshere.png);" }, output)
+  end
+
+  def test_double_quote
+    input = { environment: @env, data: 'background: url("image.png");', filename: 'url2.css', metadata: {} }
+    output = Sprockets::Rails::AssetUrlProcessor.call(input)
+    assert_equal({ data: "background: url(image-hexcodegoeshere.png);" }, output)
+  end
+end

From 408aae2f7183503cc3048b067d49deaa8719b6bb Mon Sep 17 00:00:00 2001
From: David Heinemeier Hansson <david@basecamp.com>
Date: Mon, 18 Oct 2021 20:38:33 +0200
Subject: [PATCH 2/3] Style

---
 lib/sprockets/rails/asset_url_processor.rb | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/lib/sprockets/rails/asset_url_processor.rb b/lib/sprockets/rails/asset_url_processor.rb
index dbc92328..e41fb5da 100644
--- a/lib/sprockets/rails/asset_url_processor.rb
+++ b/lib/sprockets/rails/asset_url_processor.rb
@@ -6,9 +6,8 @@ class AssetUrlProcessor
       
       def self.call(input)
         context = input[:environment].context_class.new(input)
-        data = input[:data].gsub(REGEX) do |_match|
-          "url(#{context.asset_path($1)})"
-        end
+        data    = input[:data].gsub(REGEX, "url(#{context.asset_path($1)})")
+
         { data: data }
       end
     end

From 3d2e98268f3490dc7be3616267a8e577baadc180 Mon Sep 17 00:00:00 2001
From: David Heinemeier Hansson <david@basecamp.com>
Date: Fri, 5 Nov 2021 17:55:24 +0100
Subject: [PATCH 3/3] $1 is calculated before calling #gsub

---
 lib/sprockets/rails/asset_url_processor.rb | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/sprockets/rails/asset_url_processor.rb b/lib/sprockets/rails/asset_url_processor.rb
index e41fb5da..c55f4166 100644
--- a/lib/sprockets/rails/asset_url_processor.rb
+++ b/lib/sprockets/rails/asset_url_processor.rb
@@ -6,7 +6,7 @@ class AssetUrlProcessor
       
       def self.call(input)
         context = input[:environment].context_class.new(input)
-        data    = input[:data].gsub(REGEX, "url(#{context.asset_path($1)})")
+        data    = input[:data].gsub(REGEX) { |_match| "url(#{context.asset_path($1)})" }
 
         { data: data }
       end