# frozen_string_literal: true

require 'intranet/abstract_responder'
require 'intranet/core/haml_wrapper'
require 'mimemagic'
require 'pandoc-ruby'
require_relative 'version'

module Intranet
  module Pandoc
    # The responder for the Pandoc module of the Intranet.
    class Responder < AbstractResponder
      include Core::HamlWrapper # 'inherits' from methods of HamlWrapper

      # Returns the name of the module.
      # @return [String] The name of the module.
      def self.module_name
        NAME
      end

      # The version of the module, according to semantic versionning.
      # @return [String] The version of the module.
      def self.module_version
        VERSION
      end

      # The homepage of the module.
      # @return [String] The homepage URL of the module.
      def self.module_homepage
        HOMEPAGE_URL
      end

      # Initializes a new Pandoc responder instance.
      # @param title [String] The title of the module instance.
      # @param rootdir [String] The root directory of the module instance.
      # @param in_menu [Boolean] Whether the module instance should be displayed in the main
      #                          navigation menu or not.
      def initialize(logger, title, rootdir, template = nil, in_menu = true)
        @logger   = logger
        @title    = title
        @rootdir  = rootdir
        @template = template
        @in_menu  = in_menu
      end

      # Specifies if the responder instance should be displayed in the main navigation menu or not.
      # @return [Boolean] True if the responder instance should be added to the main navigation
      #                   menu, False otherwise.
      def in_menu?
        @in_menu
      end

      # Specifies the absolute path to the resources directory for that module.
      # @return [String] The absolute path to the resources directory for the module.
      def resources_dir
        File.absolute_path(File.join('..', 'resources'), __dir__)
      end

      # Generates the HTML content associated to the given +path+ and +query+.
      # @param path [String] The requested URI, relative to that module root URI.
      # @param query [Hash<String,String>] The URI variable/value pairs, if any.
      # @return [Integer, String, String] The HTTP return code, the MIME type and the answer body.
      def generate_page(path, query)
        case path
        when %r{^/.+\.html$} then serve_page(path.gsub(%r{^/(.+)\.html$}, '\\1'))
        when %r{^/.+\.(jpg|png)$} then serve_media(path.gsub(%r{^/(.+)$}, '\\1'))
        else super(path, query)
        end
      end

      # The title of the module instance, as displayed on the web page.
      # @return [String] The title of the module instance.
      attr_reader :title

      private

      # Provides the list of required stylesheets.
      # @return [Array<String>] The list of required stylesheets.
      def stylesheets
        ['design/style.css']
      end

      # Provides the list of required script files.
      # @return [Array<Hash<Symbol,String>>] The list of required scripts.
      def scripts
        []
      end

      # Provides the list of Lua filters to be passed to Pandoc when converting mardown to HTML.
      # @return [Array<String>] The list of Lua filters, relative to the .
      def lua_filters
        [
          File.join(resources_dir, 'filters', 'titles-shift-levels.lua'),
          File.join(resources_dir, 'filters', 'links-open-external-in-new-tab.lua')
        ]
      end

      ##########################################################################
      ###            Servicing of the HTML "display-able" content            ###
      ##########################################################################

      # Convert a single markdown file to HTML format and returns the markup.
      # @param path [String] The path to the markdown file, relative to the module root directory
      #                      and without extension.
      # @raise [RuntimeError] If pandoc fails for whatever reason.
      def convert_to_html(path)
        input   = "\"#{File.join(@rootdir, "#{path}.md")}\""
        filters = lua_filters.map { |filter| "--lua-filter=\"#{filter}\"" }
        options = ['--standalone', "--template=\"#{@template}\""] unless @template.to_s.empty?
        PandocRuby.new([input], filters, options).to_html
      end

      def serve_page(path)
        content = "<section>#{convert_to_html(path)}</section>"
        [206, 'text/html',
         { content: content, title: @title, stylesheets: stylesheets, scripts: scripts }]
      rescue RuntimeError => e
        @logger.debug(e.message.chomp)
        [404, '', '']
      end

      ##########################################################################
      ###                 Servicing of the media (pictures)                  ###
      ##########################################################################

      def serve_media(path)
        media_path = File.join(@rootdir, path)
        [200, MimeMagic.by_path(media_path).type, File.read(media_path)]
      rescue Errno::ENOENT
        [404, '', '']
      end
    end
  end
end