defmodule PotionIngredients.CQRS.Command do
  @callback changeset(Map.t()) :: Map.t()

  defmacro __using__(opts) do
    import PotionIngredients.CQRS.Handler
    import PotionIngredients.Utils, only: [to_map: 1]

    caller = __CALLER__.module
    [presenter: presenter] = opts

    quote do
      @behaviour PotionIngredients.CQRS.Command

      @spec init(Atom.t()) :: Atom.t()
      def init(i), do: i

      @spec call(Plug.Conn.t(), any) :: Plug.Conn.t()
      def call(conn, fun) do
        transformed = changeset(parse_input(conn.params))

        queried = apply(&unquote(caller).execute/1, [to_map(transformed)])

        handle(queried, unquote(presenter), conn)
      end

      defp parse_input(input) do
        Casefy.snake_case(input)
      end

      def execute(input), do: input

      def success(output)
          when is_map(output) do
        {:ok, :ok, output}
      end

      def success(output, status)
          when is_map(output) and is_atom(status) and status in [:ok, :created, :no_content] do
        {:ok, status, output}
      end

      def error(reason)
          when is_map(reason) do
        {:error, :bad_request, reason}
      end

      def error(reason, status)
          when is_map(reason) and is_atom(status) do
        {:error, status, reason}
      end

      defoverridable execute: 1
    end
  end
end