defmodule Mix.Tasks.PreCommit do
  use Mix.Task
  @moduledoc """
    This file contains the functions that will be run when `mix pre_commit` is
    run. (we run it in the script in the `pre-commit` file in your `.git/hooks` directory but you can run it yourself if you want to see the output without committing).

    In here we just run all of the mix commands that you have put in your config file, and if they're succesful, print a success message to the
    the terminal, and if they fail we halt the process with a `1` error code (
    meaning that the command has failed), which will trigger the commit to stop,
    and print the error message to the terminal.
  """
  @commands Application.get_env(:pre_commit, :commands) || []
  @verbose Application.get_env(:pre_commit, :verbose) || false


  def run(_) do
    IO.puts "\e[95mPre-commit running...\e[0m"
    {_, 0} = System.cmd("git", String.split("stash push --keep-index --message pre_commit", " "))

    @commands
    |> Enum.each(&run_cmds/1)

    {_, 0} = System.cmd("git", String.split("stash pop", " "))
    IO.puts "\e[32mPre-commit passed!\e[0m"
    System.halt(0)
  end


  defp run_cmds(cmd) do
    into = case @verbose do
      true -> IO.stream(:stdio, :line)
      _    -> ""
    end

    System.cmd("mix", String.split(cmd, " "), stderr_to_stdout: true, into: into)
    |> case do
      {_result, 0} ->
        IO.puts "mix #{cmd} ran successfully."
      {result, _} ->
        if !@verbose, do: IO.puts result
        IO.puts "\e[31mPre-commit failed on `mix #{cmd}`.\e[0m \nCommit again with --no-verify to live dangerously and skip pre-commit."
        {_, 0} = System.cmd("git", String.split("stash pop", " "))
        System.halt(1)
    end
  end
end