defmodule Ami.Tag do
  use Ecto.Schema

  import Ecto.{
    Query,
    Changeset
  }

  alias Ami.{
    Repo,
    Course,
    Lesson
  }

  schema "tags" do
    field(:name, :string)
    timestamps()
    many_to_many(:lessons, Lesson, join_through: "lessons_tags")
  end

  def find_or_build_tag(tag_name) do
    case Repo.get_by(__MODULE__, name: tag_name) do
      tag = %__MODULE__{} -> tag
      nil -> %__MODULE__{name: tag_name}
    end
  end

  def changeset(struct, params \\ %{}) do
    struct
    |> cast(params, [:name])
    |> validate_required([:name])
    |> unique_constraint(:name)
  end
end