path: root/app/lib/formatter.rb

# frozen_string_literal: true

require 'singleton'
require_relative './sanitize_config'

class HTMLRenderer < Redcarpet::Render::HTML
  def block_code(code, language)
    "<pre><code>#{encode(code).gsub("\n", "<br/>")}</code></pre>"
  end

  def autolink(link, link_type)
    return link if link_type == :email
    Formatter.instance.link_url(link)
  end

  private

  def html_entities
    @html_entities ||= HTMLEntities.new
  end

  def encode(html)
    html_entities.encode(html)
  end
end

class Formatter
  include Singleton
  include RoutingHelper

  include ActionView::Helpers::TextHelper

	BBCODE_TAGS = {
    :url => {
			:html_open => '<a href="%url%" rel="noopener nofollow" target="_blank">', :html_close => '</a>',
			:description => '', :example => '',
			:allow_quick_param => true, :allow_between_as_param => false,
			:quick_param_format => /(\S+)/,
			:quick_param_format_description => 'The size parameter \'%param%\' is incorrect, a number is expected',
			:param_tokens => [{:token => :url}]
    },
		:ul => {
			:html_open => '<ul>', :html_close => '</ul>',
			:description => '', :example => '',
		},
		:ol => {
			:html_open => '<ol>', :html_close => '</ol>',
			:description => '', :example => '',
		},
		:li => {
			:html_open => '<li>', :html_close => '</li>',
			:description => '', :example => '',
		},
		:sub => {
			:html_open => '<sub>', :html_close => '</sub>',
			:description => '', :example => '',
		},
		:sup => {
			:html_open => '<sup>', :html_close => '</sup>',
			:description => '', :example => '',
		},
		:h1 => {
			:html_open => '<h1>', :html_close => '</h1>',
			:description => '', :example => '',
		},
		:h2 => {
			:html_open => '<h2>', :html_close => '</h2>',
			:description => '', :example => '',
		},
		:h3 => {
			:html_open => '<h3>', :html_close => '</h3>',
			:description => '', :example => '',
		},
		:h4 => {
			:html_open => '<h4>', :html_close => '</h4>',
			:description => '', :example => '',
		},
		:h5 => {
			:html_open => '<h5>', :html_close => '</h5>',
			:description => '', :example => '',
		},
		:h6 => {
			:html_open => '<h6>', :html_close => '</h6>',
			:description => '', :example => '',
		},
		:abbr => {
			:html_open => '<abbr>', :html_close => '</abbr>',
			:description => '', :example => '',
		},
		:hr => {
			:html_open => '<hr>', :html_close => '</hr>',
			:description => '', :example => '',
		},
		:b => {
			:html_open => '<strong>', :html_close => '</strong>',
			:description => '', :example => '',
		},
		:i => {
			:html_open => '<em>', :html_close => '</em>',
			:description => '', :example => '',
		},
		:flip => {
			:html_open => '<span class="bbcode__flip-%direction%">', :html_close => '</span>',
			:description => '', :example => '',
			:allow_quick_param => true, :allow_between_as_param => false,
			:quick_param_format => /(h|v)/,
			:quick_param_format_description => 'The size parameter \'%param%\' is incorrect, a number is expected',
			:param_tokens => [{:token => :direction}]
    },
		:size => {
			:html_open => '<span class="bbcode__size-%size%">', :html_close => '</span>',
			:description => '', :example => '',
			:allow_quick_param => true, :allow_between_as_param => false,
			:quick_param_format => /([1-6])/,
			:quick_param_format_description => 'The size parameter \'%param%\' is incorrect, a number is expected',
			:param_tokens => [{:token => :size}]
    },
		:quote => {
			:html_open => '<blockquote>', :html_close => '</blockquote>',
			:description => '', :example => '',
    },
		:kbd => {
			:html_open => '<pre><code>', :html_close => '</code></pre>',
			:description => '', :example => '',
    },
		:code => {
			:html_open => '<pre>', :html_close => '</pre>',
			:description => '', :example => '',
    },
		:u => {
			:html_open => '<u>', :html_close => '</u>',
			:description => '', :example => '',
    },
		:s => {
			:html_open => '<s>', :html_close => '</s>',
			:description => '', :example => '',
    },
		:del => {
			:html_open => '<del>', :html_close => '</del>',
			:description => '', :example => '',
    },
		:left => {
			:html_open => '<span class="bbcode__left">', :html_close => '</span>',
			:description => '', :example => '',
    },
		:center => {
			:html_open => '<span class="bbcode__center">', :html_close => '</span>',
			:description => '', :example => '',
    },
		:right => {
			:html_open => '<span class="bbcode__right">', :html_close => '</span>',
			:description => '', :example => '',
    },
		:lfloat => {
			:html_open => '<span class="bbcode__lfloat">', :html_close => '</span>',
			:description => '', :example => '',
    },
		:rfloat => {
			:html_open => '<span class="bbcode__rfloat">', :html_close => '</span>',
			:description => '', :example => '',
    },
		:spoiler => {
			:html_open => '<span class="bbcode__spoiler-wrapper"><span class="bbcode__spoiler">', :html_close => '</span></span>',
			:description => '', :example => '',
    },
	}

  def format(status, **options)
    if status.reblog?
      prepend_reblog = status.reblog.account.acct
      status         = status.proper
    else
      prepend_reblog = false
    end

    raw_content = status.text

    if options[:inline_poll_options] && status.preloadable_poll
      raw_content = raw_content + "\n\n" + status.preloadable_poll.options.map { |title| "[ ] #{title}" }.join("\n")
    end

    return '' if raw_content.blank?

    unless status.local?
      html = reformat(raw_content)
      html = encode_custom_emojis(html, status.emojis, options[:autoplay]) if options[:custom_emojify]
      return html.html_safe # rubocop:disable Rails/OutputSafety
    end

    linkable_accounts = status.active_mentions.map(&:account)
    linkable_accounts << status.account

    html = raw_content
    html = "RT @#{prepend_reblog} #{html}" if prepend_reblog

    case status.content_type
    when 'text/markdown'
      html = format_markdown(html)
    when 'text/x-bbcode'
      html = format_bbcode(html)
    when 'text/x-bbcode+markdown'
      html = format_bbdown(html)
    end

    html = encode_and_link_urls(html, linkable_accounts, keep_html: %w(text/markdown text/x-bbcode text/x-bbcode+markdown text/html).include?(status.content_type))
    html = encode_custom_emojis(html, status.emojis, options[:autoplay]) if options[:custom_emojify]

    unless %w(text/markdown text/x-bbcode text/x-bbcode+markdown text/html).include?(status.content_type)
      html = simple_format(html, {}, sanitize: false)
      html = html.delete("\n")
    end

    unless status.footer.blank?
      footer = status.footer
      footer = encode_and_link_urls(footer)
      footer = encode_custom_emojis(footer, status.emojis, options[:autoplay]) if options[:custom_emojify]
      html = "#{html.strip}<p class=\"signature\">— #{footer}</p>"
    end

    html.html_safe # rubocop:disable Rails/OutputSafety
  end

  def format_markdown(html)
    html = reformat(markdown_formatter.render(html))
    html.delete("\r").delete("\n")
  end

  def format_bbcode(html, sanitize = true)
    html = bbcode_formatter(html)
    html = html.gsub(/<hr>.*<\/hr>/im, '<hr />')
    return html unless sanitize
    html = reformat(html)
    html.delete("\r").delete("\n")
  end

  def format_bbdown(html)
    html = format_bbcode(html, false)
    html = html.gsub(/<br *\/>|<br>/, '')
    format_markdown(html)
  end

  def reformat(html)
    sanitize(html, Sanitize::Config::MASTODON_STRICT)
  end

  def plaintext(status)
    return status.text if status.local?

    text = status.text.gsub(/(<br \/>|<br>|<\/p>)+/) { |match| "#{match}\n" }
    strip_tags(text)
  end

  def simplified_format(account, **options)
    return reformat(account.note) unless account.local?
    html = format_bbdown(account.note)
    html = encode_and_link_urls(html, keep_html: true)
    html = encode_custom_emojis(html, account.emojis, options[:autoplay]) if options[:custom_emojify]
    html.html_safe # rubocop:disable Rails/OutputSafety
  end

  def sanitize(html, config)
    Sanitize.fragment(html, config)
  end

  def format_spoiler(status, **options)
    html = encode(status.spoiler_text)
    html = encode_custom_emojis(html, status.emojis, options[:autoplay])
    html.html_safe # rubocop:disable Rails/OutputSafety
  end

  def format_poll_option(status, option, **options)
    html = encode(option.title)
    html = encode_custom_emojis(html, status.emojis, options[:autoplay])
    html.html_safe # rubocop:disable Rails/OutputSafety
  end

  def format_display_name(account, **options)
    html = encode(account.display_name.presence || account.username)
    html = encode_custom_emojis(html, account.emojis, options[:autoplay]) if options[:custom_emojify]
    html.html_safe # rubocop:disable Rails/OutputSafety
  end

  def format_field(account, str, **options)
    return reformat(str).html_safe unless account.local? # rubocop:disable Rails/OutputSafety
    html = encode_and_link_urls(str, me: true)
    html = encode_custom_emojis(html, account.emojis, options[:autoplay]) if options[:custom_emojify]
    html.html_safe # rubocop:disable Rails/OutputSafety
  end

  def linkify(text)
    html = encode_and_link_urls(text)
    html = simple_format(html, {}, sanitize: false)
    html = html.delete("\n")

    html.html_safe # rubocop:disable Rails/OutputSafety
  end

  def link_url(url)
    "<a href=\"#{encode(url)}\" target=\"blank\" rel=\"nofollow noopener\">#{link_html(url)}</a>"
  end

  private

  def bbcode_formatter(html)
    begin
      html = html.bbcode_to_html(false, BBCODE_TAGS, :enable, *BBCODE_TAGS.keys)
    rescue Exception => e
    end
    html
  end

  def markdown_formatter
    return @markdown_formatter if defined?(@markdown_formatter)

    extensions = {
      autolink: true,
      no_intra_emphasis: true,
      fenced_code_blocks: true,
      disable_indented_code_blocks: true,
      strikethrough: true,
      lax_spacing: true,
      space_after_headers: true,
      superscript: true,
      underline: true,
      highlight: true,
      footnotes: false,
    }

    renderer = HTMLRenderer.new({
      filter_html: false,
      escape_html: false,
      no_images: true,
      no_styles: true,
      safe_links_only: true,
      hard_wrap: true,
      link_attributes: { target: '_blank', rel: 'nofollow noopener' },
    })

    @markdown_formatter = Redcarpet::Markdown.new(renderer, extensions)
  end

  def html_entities
    @html_entities ||= HTMLEntities.new
  end

  def encode(html)
    html_entities.encode(html)
  end

  def encode_and_link_urls(html, accounts = nil, options = {})
    if accounts.is_a?(Hash)
      options  = accounts
      accounts = nil
    end

    entities = options[:keep_html] ? html_friendly_extractor(html) : utf8_friendly_extractor(html, extract_url_without_protocol: false)

    rewrite(html.dup, entities, options[:keep_html]) do |entity|
      if entity[:url]
        link_to_url(entity, options)
      elsif entity[:hashtag]
        link_to_hashtag(entity)
      elsif entity[:screen_name]
        link = link_to_pseudo(entity[:screen_name])
        link.nil? ? link_to_mention(entity, accounts) : link
      end
    end
  end

  def count_tag_nesting(tag)
    if tag[1] == '/' then -1
    elsif tag[-2] == '/' then 0
    else 1
    end
  end

  def encode_custom_emojis(html, emojis, animate = false)
    return html if emojis.empty?

    emoji_map = if animate
                  emojis.each_with_object({}) { |e, h| h[e.shortcode] = full_asset_url(e.image.url) }
                else
                  emojis.each_with_object({}) { |e, h| h[e.shortcode] = full_asset_url(e.image.url(:static)) }
                end

    i                     = -1
    tag_open_index        = nil
    inside_shortname      = false
    shortname_start_index = -1
    invisible_depth       = 0

    while i + 1 < html.size
      i += 1

      if invisible_depth.zero? && inside_shortname && html[i] == ':'
        shortcode = html[shortname_start_index + 1..i - 1]
        emoji     = emoji_map[shortcode]

        if emoji
          replacement = "<img draggable=\"false\" class=\"emojione\" alt=\":#{encode(shortcode)}:\" title=\":#{encode(shortcode)}:\" src=\"#{encode(emoji)}\" />"
          before_html = shortname_start_index.positive? ? html[0..shortname_start_index - 1] : ''
          html        = before_html + replacement + html[i + 1..-1]
          i          += replacement.size - (shortcode.size + 2) - 1
        else
          i -= 1
        end

        inside_shortname = false
      elsif tag_open_index && html[i] == '>'
        tag = html[tag_open_index..i]
        tag_open_index = nil
        if invisible_depth.positive?
          invisible_depth += count_tag_nesting(tag)
        elsif tag == '<span class="invisible">'
          invisible_depth = 1
        end
      elsif html[i] == '<'
        tag_open_index   = i
        inside_shortname = false
      elsif !tag_open_index && html[i] == ':'
        inside_shortname      = true
        shortname_start_index = i
      end
    end

    html
  end

  def rewrite(text, entities, keep_html = false)
    text = text.to_s

    # Sort by start index
    entities = entities.sort_by do |entity|
      indices = entity.respond_to?(:indices) ? entity.indices : entity[:indices]
      indices.first
    end

    result = []

    last_index = entities.reduce(0) do |index, entity|
      indices = entity.respond_to?(:indices) ? entity.indices : entity[:indices]
      result << (keep_html ? text[index...indices.first] : encode(text[index...indices.first]))
      result << yield(entity)
      indices.last
    end

    result << (keep_html ? text[last_index..-1] : encode(text[last_index..-1]))

    result.flatten.join
  end

  UNICODE_ESCAPE_BLACKLIST_RE = /\p{Z}|\p{P}/

  def utf8_friendly_extractor(text, options = {})
    old_to_new_index = [0]

    escaped = text.chars.map do |c|
      output = begin
        if c.ord.to_s(16).length > 2 && UNICODE_ESCAPE_BLACKLIST_RE.match(c).nil?
          CGI.escape(c)
        else
          c
        end
      end

      old_to_new_index << old_to_new_index.last + output.length

      output
    end.join

    # Note: I couldn't obtain list_slug with @user/list-name format
    # for mention so this requires additional check
    special = Extractor.extract_urls_with_indices(escaped, options).map do |extract|
      new_indices = [
        old_to_new_index.find_index(extract[:indices].first),
        old_to_new_index.find_index(extract[:indices].last),
      ]

      next extract.merge(
        indices: new_indices,
        url: text[new_indices.first..new_indices.last - 1]
      )
    end

    standard = Extractor.extract_entities_with_indices(text, options)

    Extractor.remove_overlapping_entities(special + standard)
  end

  def html_friendly_extractor(html, options = {})
    gaps = []
    total_offset = 0

    escaped = html.gsub(/<[^>]*>/) do |match|
      total_offset += match.length - 1
      end_offset = Regexp.last_match.end(0)
      gaps << [end_offset - total_offset, total_offset]
      "\u200b"
    end

    entities = Extractor.extract_hashtags_with_indices(escaped, :check_url_overlap => false) +
               Extractor.extract_mentions_or_lists_with_indices(escaped)
    Extractor.remove_overlapping_entities(entities).map do |extract|
      pos = extract[:indices].first
      offset_idx = gaps.rindex { |gap| gap.first <= pos }
      offset = offset_idx.nil? ? 0 : gaps[offset_idx].last
      next extract.merge(
        :indices => [extract[:indices].first + offset, extract[:indices].last + offset]
      )
    end
  end

  def link_to_url(entity, options = {})
    url        = Addressable::URI.parse(entity[:url])
    html_attrs = { target: '_blank', rel: 'nofollow noopener' }

    html_attrs[:rel] = "me #{html_attrs[:rel]}" if options[:me]

    Twitter::Autolink.send(:link_to_text, entity, link_html(entity[:url]), url, html_attrs)
  rescue Addressable::URI::InvalidURIError, IDN::Idna::IdnaError
    encode(entity[:url])
  end

  def link_to_mention(entity, linkable_accounts)
    acct = entity[:screen_name]

    return link_to_account(acct) unless linkable_accounts

    account = linkable_accounts.find { |item| TagManager.instance.same_acct?(item.acct, acct) }
    account ? mention_html(account) : "@#{encode(acct)}"
  end

  def link_to_account(acct)
    username, domain = acct.split('@')

    domain  = nil if TagManager.instance.local_domain?(domain)
    account = EntityCache.instance.mention(username, domain)

    account ? mention_html(account) : "@#{encode(acct)}"
  end

  def link_to_hashtag(entity)
    hashtag_html(entity[:hashtag])
  end

  def link_html(url)
    url    = Addressable::URI.parse(url).to_s
    prefix = url.match(/\Ahttps?:\/\/(www\.)?/).to_s
    text   = url[prefix.length, 30]
    suffix = url[prefix.length + 30..-1]
    cutoff = url[prefix.length..-1].length > 30

    "<span class=\"invisible\">#{encode(prefix)}</span><span class=\"#{cutoff ? 'ellipsis' : ''}\">#{encode(text)}</span><span class=\"invisible\">#{encode(suffix)}</span>"
  end

  def hashtag_html(tag)
    "<a href=\"#{encode(tag_url(tag.downcase))}\" class=\"mention hashtag\" rel=\"tag\">#<span>#{encode(tag)}</span></a>"
  end

  def mention_html(account)
    "<span class=\"h-card\"><a href=\"#{encode(TagManager.instance.url_for(account))}\" class=\"u-url mention\">@<span>#{encode(account.username)}</span></a></span>"
  end

  def link_to_pseudo(acct)
    username, domain = acct.split('@')

    case domain
    when 'twitter.com'
      return link_to_twitter(username)
    when 'tumblr.com'
      return link_to_tumblr(username)
    when 'weasyl.com'
      return link_to_weasyl(username)
    when 'furaffinity.net'
      return link_to_furaffinity(username)
    when 'furrynetwork.com', 'beta.furrynetwork.com'
      return link_to_furrynetwork(username)
    when 'sofurry.com'
      return link_to_sofurry(username)
    when 'inkbunny.net'
      return link_to_inkbunny(username)
    when 'e621.net'
      return link_to_e621(username)
    when 'e926.net'
      return link_to_e926(username)
    when 'f-list.net'
      return link_to_flist(username)
    when 'deviantart.com'
      return link_to_deviantart(username)
    when 'artstation.com'
      return link_to_artstation(username)
    when 'github.com'
      return link_to_github(username)
    when 'gitlab.com'
      return link_to_gitlab(username)
    else
      return nil
    end
  end

  def link_to_twitter(username)
    "<span class=\"h-card\"><a href=\"https://twitter.com/#{username}\" target=\"blank\" rel=\"noopener noreferrer\" class=\"u-url mention\">@<span>#{username}@twitter.com</span></a></span>"
  end

  def link_to_tumblr(username)
    "<span class=\"h-card\"><a href=\"https://#{username}.tumblr.com\" target=\"blank\" rel=\"noopener noreferrer\" class=\"u-url mention\">@<span>#{username}@tumblr.com</span></a></span>"
  end

  def link_to_weasyl(username)
    "<span class=\"h-card\"><a href=\"https://weasyl.com/~#{username}\" target=\"blank\" rel=\"noopener noreferrer\" class=\"u-url mention\">@<span>#{username}@weasyl.com</span></a></span>"
  end

  def link_to_furaffinity(username)
    "<span class=\"h-card\"><a href=\"https://furaffinity.net/user/#{username}\" target=\"blank\" rel=\"noopener noreferrer\" class=\"u-url mention\">@<span>#{username}@furaffinity.net</span></a></span>"
  end

  def link_to_furrynetwork(username)
    "<span class=\"h-card\"><a href=\"https://furrynetwork.com/#{username}\" target=\"blank\" rel=\"noopener noreferrer\" class=\"u-url mention\">@<span>#{username}@furrynetwork.com</span></a></span>"
  end

  def link_to_inkbunny(username)
    "<span class=\"h-card\"><a href=\"https://inkbunny.net/#{username}\" target=\"blank\" rel=\"noopener noreferrer\" class=\"u-url mention\">@<span>#{username}@inkbunny.net</span></a></span>"
  end

  def link_to_sofurry(username)
    "<span class=\"h-card\"><a href=\"https://#{username}.sofurry.com\" target=\"blank\" rel=\"noopener noreferrer\" class=\"u-url mention\">@<span>#{username}@sofurry.com</span></a></span>"
  end

  def link_to_e621(username)
      "<span class=\"h-card\"><a href=\"https://e621.net/user/show/#{username}\" target=\"blank\" rel=\"noopener noreferrer\" class=\"u-url mention\">@<span>#{username}@e621.net</span></a></span>"
  end

  def link_to_e926(username)
      "<span class=\"h-card\"><a href=\"https://e926.net/user/show/#{username}\" target=\"blank\" rel=\"noopener noreferrer\" class=\"u-url mention\">@<span>#{username}@e926.net</span></a></span>"
  end

  def link_to_flist(username)
    "<span class=\"h-card\"><a href=\"https://f-list.net/c/#{username}\" target=\"blank\" rel=\"noopener noreferrer\" class=\"u-url mention\">@<span>#{username}@f-list.net</span></a></span>"
  end

  def link_to_deviantart(username)
    "<span class=\"h-card\"><a href=\"https://#{username}.deviantart.com\" target=\"blank\" rel=\"noopener noreferrer\" class=\"u-url mention\">@<span>#{username}@deviantart.com</span></a></span>"
  end

  def link_to_artstation(username)
    "<span class=\"h-card\"><a href=\"https://www.artstation.com/#{username}\" target=\"blank\" rel=\"noopener noreferrer\" class=\"u-url mention\">@<span>#{username}@artstation.com</span></a></span>"
  end

  def link_to_github(username)
    "<span class=\"h-card\"><a href=\"https://github.com/#{username}\" target=\"blank\" rel=\"noopener noreferrer\" class=\"u-url mention\">@<span>#{username}@github.com</span></a></span>"
  end

  def link_to_gitlab(username)
    "<span class=\"h-card\"><a href=\"https://gitlab.com/#{username}\" target=\"blank\" rel=\"noopener noreferrer\" class=\"u-url mention\">@<span>#{username}@gitlab.com</span></a></span>"
  end
end