# encoding: utf-8

require 'classy_assets'
require 'rack/file'
require 'rack/utils'
require 'rack/mime'

module Rack
  class ClassyAssets
    def initialize(app)
      @app = app
      @file_server = ::Rack::File.new(::ClassyAssets.config.asset_public_path, { 'Cache-Control' => 'public, max-age=31536000' })
    end

    def call(env)
      if %w(GET HEAD).include?(env['REQUEST_METHOD']) and env['PATH_INFO'].start_with?("/#{::ClassyAssets.config.asset_prefix}")
        request = Rack::Request.new(env)
        encoding = Rack::Utils.select_best_encoding(%w(gzip identity), request.accept_encoding)
        if encoding == 'gzip'
          return serve_gzipped_asset(env)
        else
          return serve_asset(env)
        end
      end
      
      status, headers, body = @app.call(env)
      body.close if body.respond_to?(:close)
      [status, headers, body]
    end

    private

    def asset_path_exists?(path)
      full_path = ::File.join(::ClassyAssets.config.asset_public_path, path)
      ::File.exists?(full_path)
    end

    def serve_gzipped_asset(env)
      compressed_path = env['PATH_INFO'] + '.gz'
      if asset_path_exists?(compressed_path)
        env["PATH_INFO"] = compressed_path
        status, headers, body = @file_server.call(env)
        path = env["PATH_INFO"] = env["PATH_INFO"].chomp('.gz')

        vary = headers["Vary"].to_s.split(",").map { |v| v.strip }
        unless vary.include?("*") || vary.include?("Accept-Encoding")
          headers["Vary"] = vary.push("Accept-Encoding").join(",")
        end

        headers['Content-Encoding'] = 'gzip'
        headers['Content-Type'] = Rack::Mime.mime_type(::File.extname(path), 'text/plain')
        headers.delete('Content-Length')

        if headers.has_key? 'Cache-Control'
          headers['Cache-Control'] += ', no-transform' unless headers['Cache-Control'].include?('no-transform')
        else
          headers['Cache-Control'] = 'no-transform'
        end
      else
        status, headers, body = serve_sprockets_asset(env)
      end

      [status, headers, body]
    end

    def serve_asset(env)
      if asset_path_exists?(env['PATH_INFO'])
        status, headers, body = @file_server.call(env)
      else
        status, headers, body = serve_sprockets_asset(env)
      end
      
      [status, headers, body]
    end

    def serve_sprockets_asset(env)
      env["PATH_INFO"].gsub!("/#{::ClassyAssets.config.asset_prefix}", '')
      ::ClassyAssets.sprockets.call(env)
    end
  end
end