defprotocol Rubbergloves.Validation do
  alias Rubbergloves.Errors.Validation.ValidationError
  @fallback_to_any true

  @spec valid?(any) :: Boolean.t
  def valid?(validation)

  @spec errors(any) :: ValidationError | []
  def errors(validation)
end


defimpl Rubbergloves.Validation, for: Justify.Dataset do
  alias Rubbergloves.Errors.Validation.ValidationError

  def valid?(dataset), do: dataset.valid?
  def errors(dataset), do: %ValidationError{ errors: dataset.errors}

end


defimpl Rubbergloves.Validation, for: Any do
  alias Rubbergloves.Errors.Validation.ValidationError

  def valid?(:ok), do: true
  def valid?(:invalid_type), do: false

  def errors(:ok), do: []
  def errors(:invalid_type), do: %ValidationError{ errors: [{:type, "Invalid type"}]}

end




defmodule Rubbergloves.Validator do

  # @callback required(struct(), atom()) :: any()
  @callback required(struct(), atom()) :: any()
  @callback type(struct(), atom(), any()) :: any()

end


defmodule Rubbergloves.Validator.Justify do
  alias Justify.Validators

  @behaviour Rubbergloves.Validator

  @impl true
  def required(struct, key), do: Justify.validate_required(struct, [key])

  @impl true
  def type(struct, key, type), do: Validators.Type.call(struct, key, type)


end


defmodule Justify.Validators.Type do
  def call(dataset, field, type) do
    dataset = Justify.Dataset.new(dataset)
    value = Map.get(dataset.data, field)

    with :ok <- confirm_type(value, type) do
      dataset
    else
      :error ->
        Justify.add_error(dataset, field, "has invalid type expected #{type}", validation: :type)
      {:error, error} ->
        Justify.add_error(dataset, field, error, validation: :type)
    end
  end

  defp confirm_type(nil, _),  do: :ok
  defp confirm_type(value, :string) when is_binary(value), do: :ok
  defp confirm_type(value, :integer) when is_integer(value), do: :ok
  defp confirm_type(value, :map) when is_map(value), do: :ok
  defp confirm_type(value, {:one, atom}) when is_atom(atom) and is_map(value) do
    type =  Map.get(value, :__struct__, nil)
    if(type == atom) do
      :ok
    else
      {:error, "has invalid type expected one #{atom} struct"}
    end
  end
  defp confirm_type(_, {:one, atom}) when is_atom(atom), do: {:error, "has invalid type expected one #{atom} struct"}


  defp confirm_type([], {:many, atom}) when is_atom(atom), do: :ok
  defp confirm_type(value, {:many, atom}) when is_atom(atom) and is_list(value) do
    all = Enum.all?(value, fn item ->
      case item do
        %{__struct__: type} ->
          type == atom
        _ -> false
      end

    end)

    if(all) do
      :ok
    else
      {:error, "has invalid type expected a list of type: #{atom}"}
    end
  end
  defp confirm_type(_, {:many, atom}) when is_atom(atom), do: {:error, "has invalid type expected a list of type: #{atom}"}

  defp confirm_type(_, _),  do: :error

end