defmodule Ami.CourseResource do
  use Ecto.Schema

  import Ecto.{
    Query,
    Changeset
  }

  alias Ami.{
    Repo,
    Course,
    ResourceAttachment
  }

  schema "courses_resources" do
    field(:position, :integer)
    timestamps()

    belongs_to(:course, Course)
    belongs_to(:resource_attachment, ResourceAttachment)
  end

  def changeset(struct, params \\ %{}) do
    struct
    |> cast(params, [:course_id, :resource_attachment_id, :position])
    |> cast_assoc(:resource_attachment)
    |> case do
      %{valid?: true, changes: changes} = changeset when changes == %{} ->
        %{changeset | action: :ignore}

      changeset ->
        changeset
    end
  end

  def update_position(id, position) do
    Repo.get!(__MODULE__, id)
    |> change(%{position: position})
    |> Repo.update()
  end
end