ecto_context

  @doc """
  Returns a `%EctoContext.Paginator{}` for `<%= inspect(schema) %>` within `scope`.

  ## Options

    * `:page` - page number, 1-based (default: `1`)
    * `:per_page` - number of records per page (default: `20`)
    * `:order_by` - field or keyword list passed to `Ecto.Query.order_by/2`
    * `:preload` - associations to preload
    * `:query` - 1-arity function for additional query composition

  """
  def paginate(scope, opts \\ []) when is_map(scope) do
    EctoContext.Validate.validate_opts!(opts, [:page, :per_page, :order_by, :preload, :query])

    page     = opts[:page]     || 1
    per_page = opts[:per_page] || 20

    base =
      <%= inspect(schema) %>
      |> (<%= inspect(scope) %>).(scope)
      |> EctoContext.Query.maybe_query(opts[:query])

    total = <%= inspect(repo) %>.aggregate(base, :count, :id)

    entries =
      base
      |> EctoContext.Query.maybe_order_by(opts[:order_by])
      |> EctoContext.Query.maybe_preload(opts[:preload])
      |> Ecto.Query.limit(^per_page)
      |> Ecto.Query.offset(^((page - 1) * per_page))
      |> <%= inspect(repo) %>.all()

    EctoContext.Paginator.new(entries, total, page, per_page)
  end