defmodule Dry do
  @moduledoc """
  """

  defmacro __using__(_) do
    quote do
      import Dry, only: [schema: 1]

      Module.register_attribute(__MODULE__, :attributes, accumulate: true)
    end
  end

  defmacro schema(do: block) do
    prelude =
      quote do
        try do
          import Dry

          unquote(block)
        after
          :ok
        end
      end

    postlude =
      quote unquote: false do
        @attributes
        |> Enum.map(fn attr -> Enum.at(attr, 0) end)
        |> Kernel.defstruct()

        def __attributes__(), do: @attributes

        def new(attr) do
          processed =
            __attributes__()
            |> Enum.map(fn a -> Dry.Processor.process(a, attr, __MODULE__) end)
            |> Enum.into(%{})

          struct(__MODULE__, processed)
        end
      end

    quote do
      unquote(prelude)
      unquote(postlude)
    end
  end

  defmacro attribute(name, do: block) do
    quote do
      attribute = [unquote(name), :__func__]

      def unquote(name)(e) do
        Kernel.var!(entity) = e
        unquote(block)
      end

      Module.put_attribute(__MODULE__, :attributes, attribute)
    end
  end

  defmacro attribute(name, type \\ nil, opts \\ []) do
    quote do
      attribute = [unquote(name), unquote(type), unquote(opts)]
      Module.put_attribute(__MODULE__, :attributes, attribute)
    end
  end
end