defmodule CPSolverTest.Examples.Queens do
  use ExUnit.Case, async: false

  alias CPSolver.Examples.Queens

  ## No solutions
  test "3 Queens" do
    test_queens(3, 0)
  end

  test "4 Queens" do
    test_queens(4, 2)
  end

  test "5 Queens" do
    test_queens(5, 10)
  end

  test "6 Queens" do
    test_queens(6, 4)
  end

  test "7 Queens" do
    test_queens(7, 40)
  end

  test "8 Queens" do
    test_queens(8, 92, timeout: 500)
  end

  test "50 Queens" do
    test_queens(33, 1, timeout: 500, trials: 2, space_threads: 4, stop_on: {:max_solutions, 1})
  end

  defp test_queens(n, expected_solutions, opts \\ []) do
    opts =
      Keyword.merge([timeout: 100, trials: 10, symmetry: :half_symmetry], opts)

    Enum.each(1..opts[:trials], fn i ->
      {:ok, result} = CPSolver.solve(Queens.model(n), opts)
      Enum.each(result.solutions, &assert_solution/1)
      solution_count = result.statistics.solution_count

      if opts[:stop_on] do
        assert solution_count >= expected_solutions
      else
        assert solution_count == expected_solutions,
               "Failed on trial #{i} with #{inspect(solution_count)} out of #{expected_solutions} solution(s)"
      end
    end)
  end

  defp assert_solution(solution) do
    assert Queens.check_solution(solution)
  end
end