defmodule Mix.Tasks.DigitalToken.Registry.Update do
  @moduledoc """
  Updates the digital token registry data.

  ## Usage

      mix digital_token.registry.update [path_to_json]

  If no path is given, fetches from the DTIF download URL.
  Requires the following environment variables:

  * `DTI_REGISTRY_USER_ID` — DTIF registry user ID.
  * `DTI_REGISTRY_PASSWORD` — DTIF registry password.

  """

  use Mix.Task
  require Logger

  @shortdoc "Update digital token registry data"

  @url "https://download.dtif.org/data.json"

  @tokens_file_name DigitalToken.Decode.tokens_file_name()

  @doc false
  def run(args) do
    require Logger

    raise """
    dtif.org no longer supports programmatic download of registry data.
    The package author has to download the data manually. A mechanism to
    update the data without updating the package will be delivered in the
    next release.
    """

    case args do
      [path] ->
        update_from_file(path)

      [] ->
        update_from_url()
    end
  end

  defp update_from_file(path) do
    Logger.info("Reading digital token registry from #{path}")

    body = File.read!(path)

    tokens =
      body
      |> DigitalToken.Decode.decode_tokens()
      |> :erlang.term_to_binary()

    File.write!(@tokens_file_name, tokens)
    Logger.info("Updated digital token registry at #{@tokens_file_name}")
  end

  defp update_from_url do
    user_id =
      System.get_env("DTI_REGISTRY_USER_ID") ||
        raise "Set the DTI_REGISTRY_USER_ID environment variable to download registry data"

    password =
      System.get_env("DTI_REGISTRY_PASSWORD") ||
        raise "Set the DTI_REGISTRY_PASSWORD environment variable to download registry data"

    credentials = Base.encode64("#{user_id}:#{password}")

    headers = [
      {~c"Authorization", ~c"Basic #{credentials}"},
      {~c"Accept", ~c"*/*"}
    ]

    :ssl.start()

    url = String.to_charlist(@url)
    request = {url, headers}
    http_options = [ssl: [{:verify, :verify_none}], timeout: 30000]
    options = [body_format: :binary]

    Logger.info("Fetching digital token registry from #{@url}")

    case :httpc.request(:get, request, http_options, options) do
      {:ok, {{_, 200, _}, _response_headers, body}} ->
        Logger.info("Successfully retrieved digital token registry")

        tokens =
          body
          |> DigitalToken.Decode.decode_tokens()
          |> :erlang.term_to_binary()

        File.write!(@tokens_file_name, tokens)
        Logger.info("Updated digital token registry at #{@tokens_file_name}")

      {:ok, {{_, status, _}, _headers, body}} ->
        Logger.warning("Failed to update digital token registry. HTTP #{status}: #{body}")

      {:error, reason} ->
        Logger.warning("Failed to update digital token registry. #{inspect(reason)}")
    end
  end
end