# Pleroma: A lightweight social networking server
# Copyright © 2017-2022 Pleroma Authors <https://pleroma.social/>
# SPDX-License-Identifier: AGPL-3.0-only

defmodule Pleroma.Emoji.Loader do
  @moduledoc """
  The Loader emoji from:

    * emoji packs in INSTANCE-DIR/emoji
    * the files: `config/emoji.txt` and `config/custom_emoji.txt`
    * glob paths, nested folder is used as tag name for grouping e.g. priv/static/emoji/custom/nested_folder
  """
  alias Pleroma.Config
  alias Pleroma.Emoji

  require Logger

  @mix_env Mix.env()

  @type pattern :: Regex.t() | module() | String.t()
  @type patterns :: pattern() | [pattern()]
  @type group_patterns :: keyword(patterns())
  @type emoji :: {String.t(), Emoji.t()}

  @doc """
  Loads emojis from files/packs.

  returns list emojis in format:
  `{"000", "/emoji/freespeechextremist.com/000.png", ["Custom"]}`
  """
  @spec load() :: list(emoji)
  def load do
    emoji_dir_path = Path.join(Config.get!([:instance, :static_dir]), "emoji")

    emoji_groups = Config.get([:emoji, :groups])

    emojis =
      case File.ls(emoji_dir_path) do
        {:error, :enoent} ->
          # The custom emoji directory doesn't exist,
          # don't do anything
          []

        {:error, e} ->
          # There was some other error
          Logger.error("Could not access the custom emoji directory #{emoji_dir_path}: #{e}")
          []

        {:ok, results} ->
          grouped =
            Enum.group_by(results, fn file ->
              File.dir?(Path.join(emoji_dir_path, file))
            end)

          packs = grouped[true] || []
          files = grouped[false] || []

          # Print the packs we've found
          Logger.info("Found emoji packs: #{Enum.join(packs, ", ")}")

          if not Enum.empty?(files) do
            Logger.warn(
              "Found files in the emoji folder. These will be ignored, please move them to a subdirectory\nFound files: #{Enum.join(files, ", ")}"
            )
          end

          emojis =
            Enum.flat_map(packs, fn pack ->
              load_pack(Path.join(emoji_dir_path, pack), emoji_groups)
            end)

          Emoji.clear_all()
          emojis
      end

    # Compat thing for old custom emoji handling & default emoji,
    # it should run even if there are no emoji packs
    shortcode_globs = Config.get([:emoji, :shortcode_globs], [])

    # for testing emoji.txt entries we do not want exposed in normal operation
    test_emoji =
      if @mix_env == :test do
        load_from_file("test/config/emoji.txt", emoji_groups)
      else
        []
      end

    emojis_txt =
      (load_from_file("config/emoji.txt", emoji_groups) ++
         load_from_file("config/custom_emoji.txt", emoji_groups) ++
         load_from_globs(shortcode_globs, emoji_groups) ++
         test_emoji)
      |> Enum.reject(fn value -> value == nil end)

    Enum.map(emojis ++ emojis_txt, &prepare_emoji/1)
  end

  defp prepare_emoji({code, _, _} = emoji), do: {code, Emoji.build(emoji)}

  defp load_pack(pack_dir, emoji_groups) do
    pack_name = Path.basename(pack_dir)

    pack_file = Path.join(pack_dir, "pack.json")

    if File.exists?(pack_file) do
      Logger.info("Loading emoji pack from JSON: #{pack_file}")
      contents = Jason.decode!(File.read!(pack_file))

      contents["files"]
      |> Enum.map(fn {name, rel_file} ->
        filename = Path.join("/emoji/#{pack_name}", rel_file)
        {name, filename, ["pack:#{pack_name}"]}
      end)
    else
      # Load from emoji.txt / all files
      emoji_txt = Path.join(pack_dir, "emoji.txt")

      if File.exists?(emoji_txt) do
        Logger.info("Loading emoji pack from emoji.txt: #{emoji_txt}")
        load_from_file(emoji_txt, emoji_groups)
      else
        extensions = Config.get([:emoji, :pack_extensions])

        Logger.info(
          "No emoji.txt found for pack \"#{pack_name}\", assuming all #{Enum.join(extensions, ", ")} files are emoji"
        )

        make_shortcode_to_file_map(pack_dir, extensions)
        |> Enum.map(fn {shortcode, rel_file} ->
          filename = Path.join("/emoji/#{pack_name}", rel_file)

          {shortcode, filename, [to_string(match_extra(emoji_groups, filename))]}
        end)
      end
    end
  end

  def make_shortcode_to_file_map(pack_dir, exts) do
    find_all_emoji(pack_dir, exts)
    |> Enum.map(&Path.relative_to(&1, pack_dir))
    |> Enum.map(fn f -> {f |> Path.basename() |> Path.rootname(), f} end)
    |> Enum.into(%{})
  end

  def find_all_emoji(dir, exts) do
    dir
    |> File.ls!()
    |> Enum.flat_map(fn f ->
      filepath = Path.join(dir, f)

      if File.dir?(filepath) do
        find_all_emoji(filepath, exts)
      else
        [filepath]
      end
    end)
    |> Enum.filter(fn f -> Path.extname(f) in exts end)
  end

  defp load_from_file(file, emoji_groups) do
    if File.exists?(file) do
      load_from_file_stream(File.stream!(file), emoji_groups)
    else
      []
    end
  end

  defp load_from_file_stream(stream, emoji_groups) do
    stream
    |> Stream.map(&String.trim/1)
    |> Stream.map(fn line ->
      case String.split(line, ~r/,\s*/) do
        [name, file] ->
          {name, file, [to_string(match_extra(emoji_groups, file))]}

        [name, file | tags] ->
          {name, file, tags}

        _ ->
          nil
      end
    end)
    |> Enum.to_list()
  end

  defp load_from_globs(globs, emoji_groups) do
    static_path = Path.join(:code.priv_dir(:pleroma), "static")

    paths =
      Enum.map(globs, fn glob ->
        Path.join(static_path, glob)
        |> Path.wildcard()
      end)
      |> Enum.concat()

    Enum.map(paths, fn path ->
      tag = match_extra(emoji_groups, Path.join("/", Path.relative_to(path, static_path)))
      shortcode = Path.basename(path, Path.extname(path))
      external_path = Path.join("/", Path.relative_to(path, static_path))
      {shortcode, external_path, [to_string(tag)]}
    end)
  end

  @doc """
  Finds a matching group for the given emoji filename
  """
  @spec match_extra(group_patterns(), String.t()) :: atom() | nil
  def match_extra(group_patterns, filename) do
    match_group_patterns(group_patterns, fn pattern ->
      case pattern do
        %Regex{} = regex -> Regex.match?(regex, filename)
        string when is_binary(string) -> filename == string
      end
    end)
  end

  defp match_group_patterns(group_patterns, matcher) do
    Enum.find_value(group_patterns, fn {group, patterns} ->
      patterns =
        patterns
        |> List.wrap()
        |> Enum.map(fn pattern ->
          if String.contains?(pattern, "*") do
            ~r(#{String.replace(pattern, "*", ".*")})
          else
            pattern
          end
        end)

      Enum.any?(patterns, matcher) && group
    end)
  end
end