1 files changed, 158 insertions, 0 deletions
diff --git a/app/lib/text_formatter.rb b/app/lib/text_formatter.rb
new file mode 100644
index 000000000..48e2fc233
--- /dev/null
+++ b/app/lib/text_formatter.rb
@@ -0,0 +1,158 @@
+# frozen_string_literal: true
+
+class TextFormatter
+  include ActionView::Helpers::TextHelper
+  include ERB::Util
+  include RoutingHelper
+
+  URL_PREFIX_REGEX = /\A(https?:\/\/(www\.)?|xmpp:)/.freeze
+
+  DEFAULT_REL = %w(nofollow noopener noreferrer).freeze
+
+  DEFAULT_OPTIONS = {
+    multiline: true,
+  }.freeze
+
+  attr_reader :text, :options
+
+  # @param [String] text
+  # @param [Hash] options
+  # @option options [Boolean] :multiline
+  # @option options [Boolean] :with_domains
+  # @option options [Boolean] :with_rel_me
+  # @option options [Array<Account>] :preloaded_accounts
+  def initialize(text, options = {})
+    @text    = text
+    @options = DEFAULT_OPTIONS.merge(options)
+  end
+
+  def entities
+    @entities ||= Extractor.extract_entities_with_indices(text, extract_url_without_protocol: false)
+  end
+
+  def to_s
+    return ''.html_safe if text.blank?
+
+    html = rewrite do |entity|
+      if entity[:url]
+        link_to_url(entity)
+      elsif entity[:hashtag]
+        link_to_hashtag(entity)
+      elsif entity[:screen_name]
+        link_to_mention(entity)
+      end
+    end
+
+    html = simple_format(html, {}, sanitize: false).delete("\n") if multiline?
+
+    html.html_safe # rubocop:disable Rails/OutputSafety
+  end
+
+  private
+
+  def rewrite
+    entities.sort_by! do |entity|
+      entity[:indices].first
+    end
+
+    result = ''.dup
+
+    last_index = entities.reduce(0) do |index, entity|
+      indices = entity[:indices]
+      result << h(text[index...indices.first])
+      result << yield(entity)
+      indices.last
+    end
+
+    result << h(text[last_index..-1])
+
+    result
+  end
+
+  def link_to_url(entity)
+    url = Addressable::URI.parse(entity[:url]).to_s
+    rel = with_rel_me? ? (DEFAULT_REL + %w(me)) : DEFAULT_REL
+
+    prefix      = url.match(URL_PREFIX_REGEX).to_s
+    display_url = url[prefix.length, 30]
+    suffix      = url[prefix.length + 30..-1]
+    cutoff      = url[prefix.length..-1].length > 30
+
+    <<~HTML.squish
+      <a href="#{h(url)}" target="_blank" rel="#{rel.join(' ')}"><span class="invisible">#{h(prefix)}</span><span class="#{cutoff ? 'ellipsis' : ''}">#{h(display_url)}</span><span class="invisible">#{h(suffix)}</span></a>
+    HTML
+  rescue Addressable::URI::InvalidURIError, IDN::Idna::IdnaError
+    h(entity[:url])
+  end
+
+  def link_to_hashtag(entity)
+    hashtag = entity[:hashtag]
+    url     = tag_url(hashtag)
+
+    <<~HTML.squish
+      <a href="#{h(url)}" class="mention hashtag" rel="tag">#<span>#{h(hashtag)}</span></a>
+    HTML
+  end
+
+  def link_to_mention(entity)
+    username, domain = entity[:screen_name].split('@')
+    domain           = nil if local_domain?(domain)
+    account          = nil
+
+    if preloaded_accounts?
+      same_username_hits = 0
+
+      preloaded_accounts.each do |other_account|
+        same_username = other_account.username.casecmp(username).zero?
+        same_domain   = other_account.domain.nil? ? domain.nil? : other_account.domain.casecmp(domain)&.zero?
+
+        if same_username && !same_domain
+          same_username_hits += 1
+        elsif same_username && same_domain
+          account = other_account
+        end
+      end
+    else
+      account = entity_cache.mention(username, domain)
+    end
+
+    return "@#{h(entity[:screen_name])}" if account.nil?
+
+    url = ActivityPub::TagManager.instance.url_for(account)
+    display_username = same_username_hits&.positive? || with_domains? ? account.pretty_acct : account.username
+
+    <<~HTML.squish
+      <span class="h-card"><a href="#{h(url)}" class="u-url mention">@<span>#{h(display_username)}</span></a></span>
+    HTML
+  end
+
+  def entity_cache
+    @entity_cache ||= EntityCache.instance
+  end
+
+  def tag_manager
+    @tag_manager ||= TagManager.instance
+  end
+
+  delegate :local_domain?, to: :tag_manager
+
+  def multiline?
+    options[:multiline]
+  end
+
+  def with_domains?
+    options[:with_domains]
+  end
+
+  def with_rel_me?
+    options[:with_rel_me]
+  end
+
+  def preloaded_accounts
+    options[:preloaded_accounts]
+  end
+
+  def preloaded_accounts?
+    preloaded_accounts.present?
+  end
+end