Fix css loading and add logging

lib/premailer/rails/css_helper.rb

@@ -3,16 +3,21 @@ module Rails
     module CSSHelper
       extend self
 
-      @cache = {}
-      attr :cache
-
       STRATEGIES = [
-        CSSLoaders::CacheLoader,
         CSSLoaders::FileSystemLoader,
         CSSLoaders::AssetPipelineLoader,
-        CSSLoaders::NetworkLoader
+        CSSLoaders::NetworkLoader,
       ]
 
+      def reset_cache!
+        @cache = {}
+      end
+
+      def cache
+        reset_cache! if @cache.nil?
+        @cache
+      end
+
       # Returns all linked CSS files concatenated as string.
       def css_for_doc(doc)
         urls = css_urls_in_doc(doc)
@@ -21,18 +26,40 @@ def css_for_doc(doc)
 
       private
 
+      def lookup_cached(url)
+        return yield if rails_dev_env?
+
+        if !cache.has_key?(url)
+          cache[url] = yield(url)
+        end
+
+        cache[url]
+      end
+
+      def rails_dev_env?
+        return false
+        defined?(::Rails) && ::Rails.env.development?
+      end
+
       def css_urls_in_doc(doc)
         doc.search('link[@rel="stylesheet"]').map do |link|
           link.attributes['href'].to_s
         end
       end
 
       def load_css(url)
-        @cache[url] =
+        lookup_cached(url) do |url|
+          css = nil
+
           STRATEGIES.each do |strategy|
-            css = strategy.load(url)
-            break css if css
+            if css = strategy.load(url)
+              ::Rails.logger.debug "premailer-rails: loaded asset #{url} using #{strategy}" if defined?(::Rails)
+              break
+            end
           end
+
+          css
+        end
       end
     end
   end

lib/premailer/rails/css_loaders.rb

@@ -1,6 +1,5 @@
 require 'uri'
 
-require 'premailer/rails/css_loaders/cache_loader'
 require 'premailer/rails/css_loaders/file_system_loader'
 require 'premailer/rails/css_loaders/asset_pipeline_loader'
 require 'premailer/rails/css_loaders/network_loader'

lib/premailer/rails/css_loaders/asset_pipeline_loader.rb

@@ -7,8 +7,10 @@ module AssetPipelineLoader
         def load(url)
           if asset_pipeline_present?
             file = file_name(url)
-            asset = ::Rails.application.assets.find_asset(file)
-            asset.to_s if asset
+
+            if asset = ::Rails.application.assets.find_asset(file)
+              asset.to_s
+            end
           end
         end
 

lib/premailer/rails/css_loaders/file_system_loader.rb

@@ -6,8 +6,15 @@ module FileSystemLoader
 
         def load(url)
           path = URI(url).path
-          file_path = "public#{path}"
-          File.read(file_path) if File.exist?(file_path)
+
+          # Remove leading slash if it exists
+          path = path[1..-1] if path[0,1] == "/"
+
+          file_path = ::Rails.root.join("public/#{path}").to_s
+
+          if File.exist?(file_path)
+            File.read(file_path)
+          end
         end
       end
     end

lib/premailer/rails/css_loaders/network_loader.rb

@@ -5,8 +5,9 @@ module NetworkLoader
         extend self
 
         def load(url)
-          uri = uri_for_url(url)
-          Net::HTTP.get(uri) if uri
+          if uri = uri_for_url(url)
+            Net::HTTP.get(uri)
+          end
         end
 
         def uri_for_url(url)

lib/premailer/rails/customized_premailer.rb

@@ -12,7 +12,7 @@ def initialize(html)
         Premailer.send(:include, Adapter.find(Adapter.use))
         doc = load_html(html)
 
-        options = @options.merge(css_string: CSSHelper.css_for_doc(doc))
+        options = @options.merge(include_link_tags: false, css_string: CSSHelper.css_for_doc(doc))
         super(html, options)
       end
     end

spec/integration/css_helper_spec.rb

@@ -3,7 +3,7 @@
 describe Premailer::Rails::CSSHelper do
   # Reset the CSS cache:
   after do
-    Premailer::Rails::CSSHelper.send(:instance_variable_set, '@cache', {})
+    Premailer::Rails::CSSHelper.reset_cache!
   end
 
   def load_css(path)
@@ -59,8 +59,7 @@ def expect_file(path, content='file content')
 
     context 'when file is cached' do
       it 'returns the cached value' do
-        cache =
-          Premailer::Rails::CSSHelper.send(:instance_variable_get, '@cache')
+        cache = Premailer::Rails::CSSHelper.cache
         cache['http://example.com/stylesheets/base.css'] = 'content of base.css'
 
         expect(load_css('http://example.com/stylesheets/base.css')).to \
@@ -70,8 +69,7 @@ def expect_file(path, content='file content')
 
     context 'when in development mode' do
       it 'does not return cached values' do
-        cache =
-          Premailer::Rails::CSSHelper.send(:instance_variable_get, '@cache')
+        cache = Premailer::Rails::CSSHelper.cache
         cache['http://example.com/stylesheets/base.css'] =
           'cached content of base.css'
         content = 'new content of base.css'

spec/support/stubs/rails.rb

@@ -1,6 +1,14 @@
 module Rails
   extend self
 
+  def root
+    @root ||= Pathname.new(".")
+  end
+
+  def logger
+    @logger = Logger.new(STDOUT)
+  end
+
   module Configuration
     extend self
   end