defmodule Mix.Tasks.Emqx.Proper do
  use Mix.Task

  # Code.require_file("emqx.ct.ex", __DIR__)

  alias Mix.Tasks.Emqx.Ct, as: ECt

  # todo: invoke the equivalent of `make merge-config` as a requirement...
  @requirements ["compile", "loadpaths"]

  @impl true
  def run(args) do
    Mix.debug(true)
    IO.inspect(args)


    Enum.each([:common_test, :eunit, :mnesia], &ECt.add_to_path_and_cache/1)

    ECt.ensure_whole_emqx_project_is_loaded!()
    ECt.unload_emqx_applications!()

    {_, 0} = System.cmd("epmd", ["-daemon"])
    node_name = :"test@127.0.0.1"
    :net_kernel.start([node_name, :longnames])

    # unmangle PROFILE env because some places (`:emqx_conf.resolve_schema_module`) expect
    # the version without the `-test` suffix.
    System.fetch_env!("PROFILE")
    |> String.replace_suffix("-test", "")
    |> then(& System.put_env("PROFILE", &1))

    for {mod, fun} <- discover_props() do
      Mix.shell().info("testing #{mod}:#{fun}")
      opts = fetch_opts(mod, fun)
      :proper.quickcheck(apply(mod, fun, []), opts)
    end
    |> IO.inspect()
  end

  defp add_to_path_and_cache(lib_name) do
    :code.lib_dir()
    |> Path.join("#{lib_name}-*")
    |> Path.wildcard()
    |> hd()
    |> Path.join("ebin")
    |> to_charlist()
    |> :code.add_path(:cache)
  end

  ## TODO: allow filtering modules and test names
  defp discover_props() do
    Mix.Dep.Umbrella.cached()
    |> Enum.map(fn dep ->
      dep.opts[:path]
      |> Path.join("test")
    end)
    |> Mix.Utils.extract_files("prop_*.erl")
    |> Enum.flat_map(fn suite_path ->
      suite_path
      |> Path.basename(".erl")
      |> String.to_atom()
      |> then(fn suite_mod ->
        suite_mod.module_info(:exports)
        |> Enum.filter(fn {name, _arity} -> to_string(name) =~ ~r/^prop_/ end)
        |> Enum.map(fn {name, _arity} -> {suite_mod, name} end)
      end)
    end)
  end

  defp fetch_opts(mod, fun) do
    try do
      mod.fun(:opts)
    rescue
      e in [FunctionClauseError, UndefinedFunctionError] -> []
    end
  end
end