require "action_view"

module Sprockets
  module Rails
    module Helpers
      module RailsHelper
        extend ActiveSupport::Concern
        include ActionView::Helpers::AssetTagHelper

        def asset_paths
          @asset_paths ||= begin
            paths = RailsHelper::AssetPaths.new(config, controller)
            paths.asset_environment = asset_environment
            paths.asset_digests     = asset_digests
            paths.compile_assets    = compile_assets?
            paths.digest_assets     = digest_assets?
            paths
          end
        end

        def javascript_include_tag(*sources)
          options = sources.extract_options!
          debug   = options.delete(:debug)  { debug_assets? }
          body    = options.delete(:body)   { false }
          digest  = options.delete(:digest) { digest_assets? }

          sources.collect do |source|
            if debug && asset = asset_paths.asset_for(source, 'js')
              asset.to_a.map { |dep|
                super(dep.pathname.to_s, { :src => path_to_asset(dep, :ext => 'js', :body => true, :digest => digest) }.merge!(options))
              }
            else
              super(source.to_s, { :src => path_to_asset(source, :ext => 'js', :body => body, :digest => digest) }.merge!(options))
            end
          end.join("\n").html_safe
        end

        def stylesheet_link_tag(*sources)
          options = sources.extract_options!
          debug   = options.delete(:debug)  { debug_assets? }
          body    = options.delete(:body)   { false }
          digest  = options.delete(:digest) { digest_assets? }

          sources.collect do |source|
            if debug && asset = asset_paths.asset_for(source, 'css')
              asset.to_a.map { |dep|
                super(dep.pathname.to_s, { :href => path_to_asset(dep, :ext => 'css', :body => true, :protocol => :request, :digest => digest) }.merge!(options))
              }
            else
              super(source.to_s, { :href => path_to_asset(source, :ext => 'css', :body => body, :protocol => :request, :digest => digest) }.merge!(options))
            end
          end.join("\n").html_safe
        end

        def asset_path(source, options = {})
          source = source.logical_path if source.respond_to?(:logical_path)
          path = asset_paths.compute_public_path(source, asset_prefix, options.merge(:body => true))
          options[:body] ? "#{path}?body=1" : path
        end
        alias_method :path_to_asset, :asset_path # aliased to avoid conflicts with an asset_path named route

        def image_path(source)
          path_to_asset(source)
        end
        alias_method :path_to_image, :image_path # aliased to avoid conflicts with an image_path named route

        def font_path(source)
          path_to_asset(source)
        end
        alias_method :path_to_font, :font_path # aliased to avoid conflicts with an font_path named route

        def javascript_path(source)
          path_to_asset(source, :ext => 'js')
        end
        alias_method :path_to_javascript, :javascript_path # aliased to avoid conflicts with an javascript_path named route

        def stylesheet_path(source)
          path_to_asset(source, :ext => 'css')
        end
        alias_method :path_to_stylesheet, :stylesheet_path # aliased to avoid conflicts with an stylesheet_path named route

      private
        def debug_assets?
          compile_assets? && (::Rails.application.config.assets.debug || params[:debug_assets])
        rescue NameError
          false
        end

        # Override to specify an alternative prefix for asset path generation.
        # When combined with a custom +asset_environment+, this can be used to
        # implement themes that can take advantage of the asset pipeline.
        #
        # If you only want to change where the assets are mounted, refer to
        # +config.assets.prefix+ instead.
        def asset_prefix
          ::Rails.application.config.assets.prefix
        end

        def asset_digests
          ::Rails.application.config.assets.digests
        end

        def compile_assets?
          ::Rails.application.config.assets.compile
        end

        def digest_assets?
          ::Rails.application.config.assets.digest
        end

        # Override to specify an alternative asset environment for asset
        # path generation. The environment should already have been mounted
        # at the prefix returned by +asset_prefix+.
        def asset_environment
          ::Rails.application.assets
        end

        class AssetPaths < ::ActionView::AssetPaths #:nodoc:
          attr_accessor :asset_environment, :asset_prefix, :asset_digests, :compile_assets, :digest_assets

          class AssetNotPrecompiledError < StandardError; end

          def asset_for(source, ext)
            source = source.to_s
            return nil if is_uri?(source)
            source = rewrite_extension(source, nil, ext)
            asset_environment[source]
          rescue Sprockets::FileOutsidePaths
            nil
          end

          def digest_for(logical_path)
            if digest_assets && asset_digests && (digest = asset_digests[logical_path])
              return digest
            end

            if compile_assets
              if digest_assets && asset = asset_environment[logical_path]
                return asset.digest_path
              end
              return logical_path
            else
              raise AssetNotPrecompiledError.new("#{logical_path} isn't precompiled")
            end
          end

          def rewrite_asset_path(source, dir, options = {})
            if source[0] == ?/
              source
            else
              source = digest_for(source) unless options[:digest] == false
              source = File.join(dir, source)
              source = "/#{source}" unless source =~ /^\//
              source
            end
          end

          def rewrite_extension(source, dir, ext)
            if ext && File.extname(source) != ".#{ext}"
              "#{source}.#{ext}"
            else
              source
            end
          end
        end
      end
    end
  end
end