require "i18n/js"

module I18n
  module JS
    # @api private
    # The class cannot be private
    class SprocketsExtension
      # Actual definition is placed below
    end

    class Engine < ::Rails::Engine
      # See https://github.com/rails/sprockets/blob/master/guides/extending_sprockets.md#supporting-all-versions-of-sprockets-in-processors
      # for reference of supporting multiple versions

      # `sprockets.environment` was used for 1.x of `sprockets-rails`
      # https://github.com/rails/sprockets-rails/issues/227
      #
      # References for current values:
      #
      # Here is where sprockets are attached with Rails. There is no 'sprockets.environment' mentioned.
      # https://github.com/rails/sprockets-rails/blob/master/lib/sprockets/railtie.rb
      #
      # Finisher hook is the place which should be used as border.
      # https://guides.rubyonrails.org/configuring.html#initializers
      #
      # For detail see Pull Request:
      # https://github.com/fnando/i18n-js/pull/371
      initializer "i18n-js.register_preprocessor", after: :engines_blank_point, before: :finisher_hook do
        # This must be called inside initializer block
        # For details see comments for `using_asset_pipeline?`
        next unless JS::Dependencies.using_asset_pipeline?

        # From README of 2.x & 3.x of `sprockets-rails`
        # It seems the `configure` block is preferred way to call `register_preprocessor`
        # Not sure if this will break older versions of rails
        #
        # https://github.com/rails/sprockets-rails/blob/v2.3.3/README.md
        # https://github.com/rails/sprockets-rails/blob/v3.0.0/README.md
        if JS::Dependencies.sprockets_rails_v2_plus?
          Rails.application.config.assets.configure do |config|
            config.register_preprocessor("application/javascript", ::I18n::JS::SprocketsExtension)
          end
        elsif Rails.application.assets.respond_to?(:register_preprocessor)
          Rails.application.assets.register_preprocessor("application/javascript", ::I18n::JS::SprocketsExtension)
        end
      end
    end

    # @api private
    class SprocketsExtension
      def initialize(filename, &block)
        @filename = filename
        @source   = block.call
      end

      def render(context, empty_hash_wtf)
        self.class.run(@filename, @source, context)
      end

      def self.run(filename, source, context)
        if context.logical_path == "i18n/filtered"
          ::I18n.load_path.each { |path| context.depend_on(File.expand_path(path)) }

          # Absolute path is required or
          # Sprockets assumes it's a logical path
          #
          # Calling `depend on` with an absent file
          # will invoke `resolve` and will throw an error in the end
          if I18n::JS.config_file_exists?
            context.depend_on(File.expand_path(I18n::JS.config_file_path))
          end
        end

        source
      end

      def self.call(input)
        filename = input[:filename]
        source   = input[:data]
        context  = input[:environment].context_class.new(input)

        result = run(filename, source, context)
        context.metadata.merge(data: result)
      end
    end
  end
end