require 'fileutils'
require 'jsmin'
require 'sass'
require 'pyro/asset'

# Public: Manage Assets.
#
# Examples
#
#   Pyro::Assets.compress('./tmp/public')
module Pyro
  module Assets
    def self.included(base)
      base.extend(ClassMethods)
    end

    module ClassMethods

      # Public: Helpers for index.erb.
      #
      # src      - Path to source file.
      # dir      - Path to directory of source files.
      # prod_src - Path to production version of source file.
      # prod_dir - Path to directory of production versions of source files.
      # target   - Path to output file (defaults to build path + source path).
      # name     - String to name a Handlebars template.
      #
      # Examples
      #
      #   <%= script src: '/lib/app.coffee' %>
      #
      # Returns an asset tag (<script> or <link>).
      def script(*args)
        build(args.first, ['js', 'coffee'])
      end
      def stylesheet(*args)
        build(args.first, ['css', 'scss'])
      end
      def template(*args)
        build(args.first, ['hbs', 'handlebars'])
      end
      def test(*args)
        build(args.first, ['js', 'coffee', 'css', 'scss']) if @target == 'test'
      end

      private

      # Private: Find and compile assets.
      #
      # args    - Args.first from the helpers.
      # src_ext - The source file extensions filter by.
      #
      # Examples
      #
      #   build(args.first, 'css, scss')
      #
      # Returns an asset tag (<script> or <link>).
      def build(args, src_ext)
        tags = ''
        find_assets(args, src_ext).each do |asset|
          asset.generate_file
          link = asset.generate_link
          unless @links.include? link
            @links << link
            tags << link
          end
        end
        tags
      end

      # Private: Find assets.
      #
      # args - Args from build().
      # exts - The source file extensions filter by.
      #
      # Examples
      #
      #   find_assets(args, src_ext)
      #
      # Returns an Array of Asset instances.
      def find_assets(args, exts)
        if @target == 'production'
          args[:src] = args[:prod_src] if args[:prod_src]
          args[:dir] = args[:prod_dir] if args[:prod_dir]
        end

        assets = []
        if args[:src]
          assets << Asset.new(file: "#{@working_dir}/#{args[:src]}",
                         build_dir: @build_dir,
                       working_dir: @working_dir,
                       helper_args: args)
        elsif args[:dir]
          exts.each do |ext|
            Dir.glob("#{@working_dir}/#{args[:dir]}/**/*.{#{ext}}").each do |f|
              assets << Asset.new(file: f,
                             build_dir: @build_dir,
                           working_dir: @working_dir,
                           helper_args: args)
            end
          end
        end
        assets
      end

      # Private: Compress all assets in a directory.
      #
      # dir - Path of directory to compress.
      #
      # Examples
      #
      #   Pyro::Assets.compress('./tmp/lib')
      #
      # Asset files are overwritten with their own compressed contents.
      def compress(dir)
        Dir.glob("#{dir}/**/*.js").each do |file|
          contents = File.read(file)
          File.open(file, 'w+') do |f|
            f.write(JSMin.minify(contents).strip)
          end
        end

        Dir.glob("#{dir}/**/*.css").each do |file|
          contents = File.read(file)
          File.open(file, 'w+') do |f|
            f.write(Sass::Engine.new( contents, { style: :compressed,
                                                 syntax: :scss } ).render)
          end
        end
      end

    end
  end
end