defmodule Frenzy.Paginator do
  import Ecto.Query
  alias Frenzy.{Repo, Item}

  @spec paginate(query :: Ecto.Queryable.t(), params :: map()) :: Ecto.Query.t()

  def paginate(query, %{"before" => before_id}) do
    before = Repo.get(Item, before_id)

    query
    # |> where([o], o.id < ^before_id)
    |> where([i], i.date < ^before.date)
    |> order_by(desc: :date)
  end

  def paginate(query, %{"after" => after_id}) do
    after_item = Repo.get(Item, after_id)

    query
    |> where([i], i.date > ^after_item.date)
    |> order_by(asc: :date)
  end

  def paginate(query, _) do
    query
    |> order_by(desc: :date)
  end
end