ixti/jekyll-assets

# Frozen-string-literal: true
# rubocop:disable Style/AccessModifierDeclarations
# Copyright: 2012 - 2020 - ISC License
# Encoding: utf-8

require 'fastimage'
require 'liquid/tag/parser'
require 'nokogiri'

module Jekyll
  module Assets
    class Tag < Liquid::Tag
      class << self
        public :new
      end

      class MixedArg < StandardError
        def initialize(arg, mixed)
          super "cannot use #{arg} w/ #{mixed}"
        end
      end

      class InvalidExternal < StandardError
        def initialize(arg)
          super "cannot use `#{arg}' with external url's"
        end
      end

      attr_reader :name
      attr_reader :tokens
      attr_reader :args
      attr_reader :tag

      #
      # initialize a new instance
      # @param tag [String,Symbol] the current tag ('asset')
      # @param args [Hash, String, Liquid::Tag::Parser] the arguments
      # @param tokens [Liquid::ParseContext] the tokens
      # @return [void]
      #
      def initialize(tag, args, tokens)
        @tag = tag.to_sym
        @tokens = tokens
        @args = args
        super
      end

      #
      # parse, or return the args
      # @note you can pass in parsed args
      # @return [Liquid::Tag::Parser]
      #
      def parse_args(args)
        return args if args.is_a?(Liquid::Tag::Parser) || args.is_a?(Hash)
        Liquid::Tag::Parser.new(
          @args
        )
      end

      def render_raw(ctx)
        args = parse_args(@args)
        env = ctx.registers[:site].sprockets
        args = env.parse_liquid(args, ctx: ctx)
        raise_unfound_asset_on(ctx: ctx, with: args) unless args.key?(:argv1)
        asset = external(ctx, args: args) if env.external?(args)
        asset ||= internal(ctx, args: args)

        [
          args, asset
        ]
      end

      #
      # @return [String]
      # Render the tag, run the proxies, set the defaults.
      # @note Defaults are ran twice just incase the content type
      #   changes, at that point there might be something that
      #   has to change in the new content.
      #
      def render(ctx)
        env = ctx.registers[:site].sprockets
        args, asset = render_raw(
          ctx
        )

        env.logger.debug args.to_h(html: false).inspect
        return_or_build(ctx, args: args, asset: asset) do
          HTML.build(
            args: args,
            asset: asset,
            ctx: ctx,
          )
        end
      #
      rescue Sprockets::FileNotFound => e
        e_not_found(e,
          ctx: ctx
        )
      #
      rescue ExecJS::RuntimeError => e
        e_exjs(e,
          args: args,
          ctx: ctx
        )
      #
      # @note you can --trace to get this same info
      # Handle errors that Sass ships because Jekyll finds
      # error handling hard, and makes it even harder, so we
      # need to ship debug info to the user, or they'll
      # never get it. That's not very good.
      #
      rescue SassC::SyntaxError => e
        e_sass(e,
          args: args,
          ctx: ctx,
        )
      end

      def return_or_build(ctx, args:, asset:)
        methods.grep(%r@^on_(?!or_build$)@).each do |m|
          out = send(m, args, ctx: ctx, asset: asset)
          if out
            regenerate(asset,
              ctx: ctx
            )

            return out
          end
        end

        regenerate(asset,
          ctx: ctx
        )

        yield
      end

      def regenerate(asset, ctx:)
        r = ctx.registers[:site].regenerator
        r.add(asset.filename)

        Array(asset.metadata[:dependencies]).each do |d|
          next unless d.start_with?('file-digest:')
          p = URI.parse(d).path
          r.add(p)
        end
      end

      #
      # Returns the path to the asset.
      # @example {% asset img.png @path %}
      # @return [String]
      #
      def on_path(args, ctx:, asset:)
        env = ctx.registers[:site].sprockets

        return unless args[:path]
        raise InvalidExternal, '@path' if env.external?(args)
        env.prefix_url(asset.digest_path)
      end

      #
      # Returns the data uri of an object.
      # @example {% asset img.png @data-url %}
      # @example {% asset img.png @data_uri %}
      # @return [String]
      #
      def on_data(args, ctx:, asset:)
        env = ctx.registers[:site].sprockets

        return unless args[:data]
        raise InvalidExternal '@data' if env.external?(args)
        asset.data_uri
      end

      #
      # @param [Liquid::Context] ctx
      # Set's up an external url using `Url`
      # @return [Url]
      #
      def external(ctx, args:)
        env = ctx.registers[:site].sprockets
        out = env.external_asset(args[:argv1], args: args)
        Default.set(args, ctx: ctx, asset: out)

        out
      end

      #
      # @param [Liquid::Context] ctx
      # Set's up an internal asset using `Sprockets::Asset`
      # @return [Sprockets::Asset]
      #
      def internal(ctx, args:)
        env = ctx.registers[:site].sprockets
        original = env.find_asset!(args[:argv1])
        Default.set(args, ctx: ctx, asset: original)
        out = Proxy.proxy(original, args: args, ctx: ctx)
        env.assets_to_write |= [out.logical_path]

        Default.set(args,
          ctx: ctx, asset: out
        )

        out
      end

      private
      def raise_unfound_asset_on(ctx:, with:)
        raise Sprockets::FileNotFound, "Unknown asset `#{with[:argv1]}'" \
          " in #{ctx.registers[:page]['relative_path']}"
      end

      private
      def e_not_found(e, ctx:)
        lines = e.message.each_line.to_a
        page = ctx.registers[:page]&.[]('relative_path') || ctx.registers[:page]&.[]('path')
        lines[0] = lines[0].strip + " in `#{page || 'Untraceable'}'\n\n"
        raise e.class, lines.join
      end

      private
      def e_exjs(e, ctx:, args:)
        env = ctx.registers[:site].sprockets

        env.logger.error e.message
        env.logger.err_file args[:argv1]
        raise e.class, 'JS Error'
      end

      private
      def e_sass(e, ctx:, args:)
        env = ctx.registers[:site].sprockets

        env.logger.error e.message
        env.logger.err_file env.strip_paths(e.backtrace.first)
        env.logger.error "error from file #{args[:argv1]}" if args
        raise e.class, 'Sass Error'
      end

      #
      # Register the tag
      # @see `jekyll/assets.rb`
      # @return [nil]
      #
      public
      def self.register
        Liquid::Template.register_tag(
          'asset', self
        )
      end
    end
  end
end