# frozen_string_literal: true

require "cgi"
HTML::Pipeline.require_dependency("negarmoji", "NegarehEmojiFilter")

module HTML
  class Pipeline
    class NegarMojiHtmlPipeline
      # HTML filter that replaces :emoji: with images.
      #
      # Context:
      #   :asset_root (required) - base url to link to emoji sprite.
      #
      #   :asset_path (optional) - url path to link to emoji sprite. :file_name can be used as
      #   a placeholder for the sprite file name.
      #   If no asset_path is set ":file_name" is used.
      #
      #   :extension (optional) - extension to be use for emoji files, default extension is svg.
      #
      #   :ignored_ancestor_tags (optional) - Tags to stop the emojification. Node has matched
      #   ancestor HTML tags will not be emojified. Default to pre, code, and tt tags. Extra tags
      #   please pass in the form of array, e.g., %w(blockquote summary).
      #
      #   :img_attrs (optional) - Attributes for generated img tag.
      #   E.g. Pass { "draggble" => true, "height" => nil } to set draggable attribute to "true"
      #   and clear height attribute of generated img tag.
      class NegarehEmojiFilter < Filter
        DEFAULT_IGNORED_ANCESTOR_TAGS = %w(pre code tt).freeze

        def call
          doc.search(".//text()").each do |node|
            content = node.text

            next unless content.include?(":")
            next if has_ancestor?(node, ignored_ancestor_tags)

            html = emoji_image_filter(content)

            next if html == content

            node.replace(html)
          end
          doc
        end

        # Implementation of validate hook.
        # Errors should raise exceptions or use an existing validator.
        def validate
          needs :asset_root
        end

        # Replace :emoji: with corresponding images.
        #
        # text - String text to replace :emoji: in.
        #
        # Returns a String with :emoji: replaced with images.
        def emoji_image_filter(text)
          text.gsub(emoji_pattern) do |_match|
            emoji_image_tag(Regexp.last_match(1))
          end
        end

        # The base url to link emoji sprites
        #
        # Raises ArgumentError if context option has not been provided.
        # Returns the context's asset_root.
        def asset_root
          context[:asset_root]
        end

        # The url path to link emoji sprites
        #
        # :file_name can be used in the asset_path as a placeholder for the sprite file name.
        # If no asset_path is set in the context ":file_name" is used.
        # Returns the context's asset_path or the default path if no context asset_path is given.
        def asset_path(name)
          if context[:asset_path]
            context[:asset_path].gsub(":file_name", emoji_filename(name))
          else
            File.join(emoji_filename(name))
          end
        end

        # Emoji file extension.
        #
        # Extension to be use for emoji files, default extension is svg.
        def emoji_extension
          context[:extension] || "svg"
        end

        private

        # Build an emoji image tag
        def emoji_image_tag(name)
          require "active_support/core_ext/hash/indifferent_access"
          html_attrs =
            default_img_attrs(name)
              .merge!((context[:img_attrs] || {}).with_indifferent_access)
              .map do |attr, value|
                !value.nil? && %(#{attr}="#{value.respond_to?(:call) && value.call(name) || value}")
              end
              .reject(&:blank?).join(" ")

          "<img #{html_attrs}>"
        end

        # Default attributes for img tag
        def default_img_attrs(name)
          {
            :class  => "emoji",
            :title  => ":#{name}:",
            :alt    => ":#{name}:",
            :src    => emoji_url(name).to_s,
            :height => "20",
            :width  => "20",
            :align  => "absmiddle",
          }
        end

        def emoji_url(name)
          File.join(asset_root, asset_path(name))
        end

        def emoji_pattern
          self.class.emoji_pattern
        end

        def emoji_filename(name)
          Emoji.find_by_alias(name).image_filename(emoji_extension)
        end

        # Return ancestor tags to stop the emojification.
        #
        # @return [Array<String>] Ancestor tags.
        def ignored_ancestor_tags
          if context[:ignored_ancestor_tags]
            DEFAULT_IGNORED_ANCESTOR_TAGS | context[:ignored_ancestor_tags]
          else
            DEFAULT_IGNORED_ANCESTOR_TAGS
          end
        end

        class << self
          # Build a regexp that matches all valid :emoji: names.
          def self.emoji_pattern
            @emoji_pattern ||= %r!:(#{emoji_names.map { |name| Regexp.escape(name) }.join("|")}):!
          end

          def self.emoji_names
            Emoji.all.map(&:aliases).flatten.sort
          end
        end
      end
    end
  end
end