# frozen_string_literal: true

module Repubmark
  module Elems
    class Chapter < Base
      parents :Article, :Chapter

      def initialize(parent, level = 1, title = nil)
        super parent
        self.level = level
        self.title = title
        verify!

        @canvas = Canvas.new self
        @chapters = []
      end

      #################
      # Basic methods #
      #################

      def word_count
        (@title ? count_words(@title) : 0) +
          @canvas.word_count +
          @chapters.sum(&:word_count)
      end

      def to_html
        [
          build_title_html,
          @canvas.to_html,
          *@chapters.map(&:to_html),
        ].join.freeze
      end

      def to_gemtext
        [
          build_title_gemtext,
          @canvas.to_gemtext,
          *@chapters.map(&:to_gemtext),
        ].join.freeze
      end

      ###################
      # Builder methods #
      ###################

      def chapter(title)
        chapter = Chapter.new self, @level + 1, title
        @chapters << chapter
        yield chapter
        nil
      end

      def respond_to_missing?(method_name, _include_private)
        @canvas.respond_to?(method_name) || super
      end

      def method_missing(method_name, ...)
        if @canvas.respond_to? method_name
          raise 'Intro after chapters' unless @chapters.empty?

          @canvas.public_send(method_name, ...)
        else
          super
        end
      end

    private

      def level=(level)
        level = Integer level
        raise unless level.positive?

        @level = level
      end

      def title=(title)
        return @title = nil if title.nil?

        title = String(title).strip.freeze
        raise 'Empty title' if title.empty?

        @title = title
      end

      def verify!
        raise 'Non-empty title for level 1' if @level == 1 && @title
        raise 'Empty title for level >= 2'  if @level != 1 && @title.nil?
      end

      def build_title_html
        "<h#@level>#@title</h#@level>\n" if @level != 1
      end

      def build_title_gemtext
        "\n#{'#' * @level} #@title\n\n" if @level != 1
      end
    end
  end
end