defmodule EView.Views.ValidationError do
  @moduledoc """
  This module provides renders that can be used whenever you want to show validation error.

  # Example:

      changeset = %SampleSchema{}
      |> SampleSchema.changeset(params)

      case changeset.valid? do
        true ->
          conn
          |> put_status(200)
          |> render("page.json", map_keys_to_atom(params))
        _ ->
          conn
          |> put_status(422)
          |> render(EView.Views.ValidationError, "422.json", changeset)
      end
  """

  if Code.ensure_loaded?(Ecto) do
    @doc """
    Use this render template whenever you want to return validation error. Currently is supports:
      * `Ecto.Changeset` errors (you can pass Schema that failed validation or changeset by itself);
      * `ex_json_schema` validation errors.
    """
    def render("422.json", %Ecto.Changeset{} = ch), do: render("422.json", ch, "json_data_property")
    def render("422.json", %{changeset: ch}), do: render("422.json", ch)

    def render("422.query.json", %Ecto.Changeset{} = ch), do: render("422.json", ch, "query_parameter")
    def render("422.query.json", %{changeset: ch}), do: render("422.json", ch, "query_parameter")

    def render("422.query.json", %{schema: errors} = params) when is_list(errors) do
      render("422.json", params, "query_parameter")
    end

    def render("422.json", %Ecto.Changeset{} = changeset, entry_type) do
      %{
        type: :validation_failed,
        invalid: EView.Helpers.ChangesetValidationsParser.changeset_to_rules(changeset, entry_type),
        message:
          "Validation failed. You can find validators description at our API Manifest: " <>
            "http://docs.apimanifest.apiary.io/#introduction/interacting-with-api/errors."
      }
    end
  end

  if Code.ensure_loaded?(NExJsonSchema) do
    @doc """
    Render a JSON Schema validation error.
    """
    def render("422.json", %{schema: errors}, entry_type \\ "json_data_property") when is_list(errors) do
      errors =
        errors
        |> Enum.map(&map_schema_errors(&1, entry_type))

      %{
        type: :validation_failed,
        invalid: errors,
        message:
          "Validation failed. You can find validators description at our API Manifest: " <>
            "http://docs.apimanifest.apiary.io/#introduction/interacting-with-api/errors."
      }
    end

    defp map_schema_errors({rule, path}, entry_type) do
      %{
        entry_type: entry_type,
        entry: path,
        rules: [EView.Helpers.Sanitizer.sanitize(rule)]
      }
    end
  end
end