defmodule Enumerati do
  @moduledoc """
  Filter and order an enumerable collection of structs
  """

  @spec filter([struct], list) :: [struct]
  def filter(items, filters) do
    items
    |> Enum.filter(fn item ->
      filters
      |> Enum.map(fn {k, v} -> Map.fetch!(item, k) == v end)
      |> Enum.all?()
    end)
  end

  @spec order([struct], list) :: [struct]
  def order(items, sort_by) do
    sort_by
    |> Enum.reverse()
    |> Enum.reduce(
      items,
      fn s, acc ->
        acc
        |> Enum.sort(fn a, b ->
          av = Map.get(a, s)
          bv = Map.get(b, s)
          lte(av, bv)
        end)
      end
    )
  end

  defp lte(%Decimal{} = av, %Decimal{} = bv), do: Decimal.cmp(av, bv) != :gt
  defp lte(av, bv), do: av <= bv
end