# Pleroma: A lightweight social networking server
# Copyright © 2017-2020 Pleroma Authors <https://pleroma.social/>
# SPDX-License-Identifier: AGPL-3.0-only

defmodule Pleroma.Emoji do
  @moduledoc """
  This GenServer stores in an ETS table the list of the loaded emojis,
  and also allows to reload the list at runtime.
  """
  use GenServer

  alias Pleroma.Emoji.Loader

  require Logger

  @ets __MODULE__.Ets
  @ets_options [
    :ordered_set,
    :protected,
    :named_table,
    {:read_concurrency, true}
  ]

  defstruct [:code, :file, :tags, :safe_code, :safe_file]

  @doc "Build emoji struct"
  def build({code, file, tags}) do
    %__MODULE__{
      code: code,
      file: file,
      tags: tags,
      safe_code: Pleroma.HTML.strip_tags(code),
      safe_file: Pleroma.HTML.strip_tags(file)
    }
  end

  def build({code, file}), do: build({code, file, []})

  @doc false
  def start_link(_) do
    GenServer.start_link(__MODULE__, [], name: __MODULE__)
  end

  @doc "Reloads the emojis from disk."
  @spec reload() :: :ok
  def reload do
    GenServer.call(__MODULE__, :reload)
  end

  @doc "Returns the path of the emoji `name`."
  @spec get(String.t()) :: String.t() | nil
  def get(name) do
    case :ets.lookup(@ets, name) do
      [{_, path}] -> path
      _ -> nil
    end
  end

  @doc "Returns all the emojos!!"
  @spec get_all() :: list({String.t(), String.t(), String.t()})
  def get_all do
    :ets.tab2list(@ets)
  end

  @doc "Clear out old emojis"
  def clear_all, do: :ets.delete_all_objects(@ets)

  @doc false
  def init(_) do
    @ets = :ets.new(@ets, @ets_options)
    GenServer.cast(self(), :reload)
    {:ok, nil}
  end

  @doc false
  def handle_cast(:reload, state) do
    update_emojis(Loader.load())
    {:noreply, state}
  end

  @doc false
  def handle_call(:reload, _from, state) do
    update_emojis(Loader.load())
    {:reply, :ok, state}
  end

  @doc false
  def terminate(_, _) do
    :ok
  end

  @doc false
  def code_change(_old_vsn, state, _extra) do
    update_emojis(Loader.load())
    {:ok, state}
  end

  defp update_emojis(emojis) do
    :ets.insert(@ets, emojis)
  end

  @external_resource "lib/pleroma/emoji-data.txt"

  emojis =
    @external_resource
    |> File.read!()
    |> String.split("\n")
    |> Enum.filter(fn line -> line != "" and not String.starts_with?(line, "#") end)
    |> Enum.map(fn line ->
      line
      |> String.split(";", parts: 2)
      |> hd()
      |> String.trim()
      |> String.split("..")
      |> case do
        [number] ->
          <<String.to_integer(number, 16)::utf8>>

        [first, last] ->
          String.to_integer(first, 16)..String.to_integer(last, 16)
          |> Enum.map(&<<&1::utf8>>)
      end
    end)
    |> List.flatten()
    |> Enum.uniq()

  for emoji <- emojis do
    def is_unicode_emoji?(unquote(emoji)), do: true
  end

  def is_unicode_emoji?(_), do: false
end