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   1 # Pleroma: A lightweight social networking server
   2 # Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
   3 # SPDX-License-Identifier: AGPL-3.0-only
   4
   5 defmodule Pleroma.Formatter do
   6   alias Pleroma.HTML
   7   alias Pleroma.User
   8
   9   @safe_mention_regex ~r/^(\s*(?<mentions>(@.+?\s+){1,})+)(?<rest>.*)/s
  10   @link_regex ~r"((?:http(s)?:\/\/)?[\w.-]+(?:\.[\w\.-]+)+[\w\-\._~%:/?#[\]@!\$&'\(\)\*\+,;=.]+)|[0-9a-z+\-\.]+:[0-9a-z$-_.+!*'(),]+"ui
  11   @markdown_characters_regex ~r/(`|\*|_|{|}|[|]|\(|\)|#|\+|-|\.|!)/
  12
  13   @auto_linker_config hashtag: true,
  14                       hashtag_handler: &Pleroma.Formatter.hashtag_handler/4,
  15                       mention: true,
  16                       mention_handler: &Pleroma.Formatter.mention_handler/4,
  17                       scheme: true
  18
  19   def escape_mention_handler("@" <> nickname = mention, buffer, _, _) do
  20     case User.get_cached_by_nickname(nickname) do
  21       %User{} ->
  22         # escape markdown characters with `\\`
  23         # (we don't want something like @user__name to be parsed by markdown)
  24         String.replace(mention, @markdown_characters_regex, "\\\\\\1")
  25
  26       _ ->
  27         buffer
  28     end
  29   end
  30
  31   def mention_handler("@" <> nickname, buffer, opts, acc) do
  32     case User.get_cached_by_nickname(nickname) do
  33       %User{id: id} = user ->
  34         ap_id = get_ap_id(user)
  35         nickname_text = get_nickname_text(nickname, opts)
  36
  37         link =
  38           ~s(<span class="h-card"><a data-user="#{id}" class="u-url mention" href="#{ap_id}" rel="ugc">@<span>#{
  39             nickname_text
  40           }</span></a></span>)
  41
  42         {link, %{acc | mentions: MapSet.put(acc.mentions, {"@" <> nickname, user})}}
  43
  44       _ ->
  45         {buffer, acc}
  46     end
  47   end
  48
  49   def hashtag_handler("#" <> tag = tag_text, _buffer, _opts, acc) do
  50     tag = String.downcase(tag)
  51     url = "#{Pleroma.Web.base_url()}/tag/#{tag}"
  52     link = ~s(<a class="hashtag" data-tag="#{tag}" href="#{url}" rel="tag ugc">#{tag_text}</a>)
  53
  54     {link, %{acc | tags: MapSet.put(acc.tags, {tag_text, tag})}}
  55   end
  56
  57   @doc """
  58   Parses a text and replace plain text links with HTML. Returns a tuple with a result text, mentions, and hashtags.
  59
  60   If the 'safe_mention' option is given, only consecutive mentions at the start the post are actually mentioned.
  61   """
  62   @spec linkify(String.t(), keyword()) ::
  63           {String.t(), [{String.t(), User.t()}], [{String.t(), String.t()}]}
  64   def linkify(text, options \\ []) do
  65     options = options ++ @auto_linker_config
  66
  67     if options[:safe_mention] && Regex.named_captures(@safe_mention_regex, text) do
  68       %{"mentions" => mentions, "rest" => rest} = Regex.named_captures(@safe_mention_regex, text)
  69       acc = %{mentions: MapSet.new(), tags: MapSet.new()}
  70
  71       {text_mentions, %{mentions: mentions}} = AutoLinker.link_map(mentions, acc, options)
  72       {text_rest, %{tags: tags}} = AutoLinker.link_map(rest, acc, options)
  73
  74       {text_mentions <> text_rest, MapSet.to_list(mentions), MapSet.to_list(tags)}
  75     else
  76       acc = %{mentions: MapSet.new(), tags: MapSet.new()}
  77       {text, %{mentions: mentions, tags: tags}} = AutoLinker.link_map(text, acc, options)
  78
  79       {text, MapSet.to_list(mentions), MapSet.to_list(tags)}
  80     end
  81   end
  82
  83   @doc """
  84   Escapes a special characters in mention names.
  85   """
  86   def mentions_escape(text, options \\ []) do
  87     options =
  88       Keyword.merge(options,
  89         mention: true,
  90         url: false,
  91         mention_handler: &Pleroma.Formatter.escape_mention_handler/4
  92       )
  93
  94     if options[:safe_mention] && Regex.named_captures(@safe_mention_regex, text) do
  95       %{"mentions" => mentions, "rest" => rest} = Regex.named_captures(@safe_mention_regex, text)
  96       AutoLinker.link(mentions, options) <> AutoLinker.link(rest, options)
  97     else
  98       AutoLinker.link(text, options)
  99     end
 100   end
 101
 102   def html_escape({text, mentions, hashtags}, type) do
 103     {html_escape(text, type), mentions, hashtags}
 104   end
 105
 106   def html_escape(text, "text/html") do
 107     HTML.filter_tags(text)
 108   end
 109
 110   def html_escape(text, "text/plain") do
 111     Regex.split(@link_regex, text, include_captures: true)
 112     |> Enum.map_every(2, fn chunk ->
 113       {:safe, part} = Phoenix.HTML.html_escape(chunk)
 114       part
 115     end)
 116     |> Enum.join("")
 117   end
 118
 119   def truncate(text, max_length \\ 200, omission \\ "...") do
 120     # Remove trailing whitespace
 121     text = Regex.replace(~r/([^ \t\r\n])([ \t]+$)/u, text, "\\g{1}")
 122
 123     if String.length(text) < max_length do
 124       text
 125     else
 126       length_with_omission = max_length - String.length(omission)
 127       String.slice(text, 0, length_with_omission) <> omission
 128     end
 129   end
 130
 131   defp get_ap_id(%User{source_data: %{"url" => url}}) when is_binary(url), do: url
 132   defp get_ap_id(%User{ap_id: ap_id}), do: ap_id
 133
 134   defp get_nickname_text(nickname, %{mentions_format: :full}), do: User.full_nickname(nickname)
 135   defp get_nickname_text(nickname, _), do: User.local_nickname(nickname)
 136 end