# frozen_string_literal: true

class BooruMarkdown < Redcarpet::Render::HTML
  PATTERNS = [
    [/\[spoiler\](.*?)\[\/spoiler\]/m, '<span class="spoiler">\1</span>'].freeze,
    [/\[bq\](.*?)\[\/bq\]/m, '<blockquote>\1</blockquote>'].freeze,
    [/\[bq=&quot;(.*?)&quot;\](.*?)\[\/bq\]/m, '<blockquote cite="\1">\2</blockquote>'].freeze,
    [/<\/p>\W+<p>/m, '</p><br><p>']
  ].freeze

  IMAGE_ON_SITE_LINK_PATTERN = />>((?:\d+)(?:[pts]?))/x
  MEME_ARROW_PATTERN = /^>(\S)/

  def initialize
    #noinspection RubyArgCount
    super(escape_html: true, safe_links_only: true, hard_wrap: true)
  end

  def highlight(text)
    "<span class=\"spoiler\">#{text}</span>"
  end

  def image(link, alt_text, title)
    "<img alt='Posted image' src='#{Camo.image_url(link)}' />"
  end

  def block_code(code, language)
    if ['ruby', 'html', 'json', 'js'].include? language
      "<pre class='language language-#{CGI.escapeHTML(language)}'>#{CGI.escapeHTML(code)}</pre>"
    else
      "<pre>#{CGI.escapeHTML(code)}</pre>"
    end
  end

  def preprocess(markdown)
    markdown = markdown.gsub(IMAGE_ON_SITE_LINK_PATTERN) do
      "\\>\\>#{$1}" # Escape on-site links in the input to the markdown parser. This is a hack.
    end

    markdown.gsub(MEME_ARROW_PATTERN) do
      "\\>#{$1}"
    end
  end

  def postprocess(markup)
    PATTERNS.each do |pattern, replacement|
      markup = markup.gsub(pattern, replacement)
    end

    markup
  end

  def self.instance
    #noinspection RubyArgCount
    @@markdown ||= Redcarpet::Markdown.new(BooruMarkdown.new,
                                           fenced_code_blocks: true,
                                           autolink: true,
                                           disable_indented_code_blocks: true,
                                           strikethrough: true,
                                           superscript: true,
                                           underline: true,
                                           highlight: true,
                                           space_after_headers: true)
  end
end