defmodule Mix.Tasks.ExBitcoin.GenerateRpc do
  @moduledoc """
  This CLI utilize the functionality of bitcoin-cli. If you want to generate your own elixir RPC with this CLI, please install bitcoin firstly.
  """
  use Mix.Task
  require Logger
  alias ExBitcoinTask.GenerateRpc.{ListCmd, SingleCmd}

  @list_cmd "bitcoin-cli help"

  def run(_) do
    IO.puts("Scraping #{@list_cmd}")

    @list_cmd
    |> run_bitcoin_cli
    |> ListCmd.format_response()
    |> Enum.map(fn {k, data} ->
      items =
        data
        |> Map.get("items", [])
        |> process_commands

      content = Map.put(data, "items", items)
      write_file("#{String.downcase(k)}.json", content)
    end)
  end

  defp run_bitcoin_cli(cmd) do
    cmd
    |> to_charlist
    |> :os.cmd()
    |> to_string
  end

  defp process_commands(commands) do
    Enum.map(commands, fn cmd_name ->
      cli = @list_cmd <> " #{cmd_name}"

      IO.puts("Scraping #{cli}")

      cli
      |> run_bitcoin_cli
      |> SingleCmd.format_response()
    end)
  end

  defp write_file(filename, content) do
    path =
      :ex_bitcoin
      |> Application.app_dir()
      |> Path.join("priv/rpc/#{filename}")

    case Poison.encode_to_iodata(content, pretty: true) do
      {:ok, data} ->
        File.write!(path, data)

      err ->
        IO.puts("#{inspect(content)}")
        throw(err)
    end
  end
end