extends GutTest
## Movement is the one function the client is allowed to run ahead of the
## server, so client prediction is only correct while these hold.


func test_diagonal_is_not_faster_than_cardinal() -> void:
	var straight := Movement.step_player(Vector2.ZERO, Vector2(1, 0), SimConfig.PLAYER_SPEED, SimConfig.ARENA_HALF)
	var diagonal := Movement.step_player(Vector2.ZERO, Vector2(1, 1), SimConfig.PLAYER_SPEED, SimConfig.ARENA_HALF)
	assert_almost_eq(diagonal.length(), straight.length(), 0.001,
		"a diagonal must cover the same distance as a cardinal move")


func test_oversized_input_vector_is_clamped() -> void:
	# The wire format cannot express this, but a patched client could try.
	var cheated := Movement.step_player(Vector2.ZERO, Vector2(1000, 0), SimConfig.PLAYER_SPEED, SimConfig.ARENA_HALF)
	var honest := Movement.step_player(Vector2.ZERO, Vector2(1, 0), SimConfig.PLAYER_SPEED, SimConfig.ARENA_HALF)
	assert_eq(cheated, honest, "an over-long move vector must buy no extra speed")


func test_speed_matches_config() -> void:
	var moved := Movement.step_player(Vector2.ZERO, Vector2.RIGHT, SimConfig.PLAYER_SPEED, SimConfig.ARENA_HALF)
	assert_almost_eq(moved.x, SimConfig.PLAYER_SPEED * SimConfig.TICK_DELTA, 0.001)


func test_player_is_clamped_to_the_arena() -> void:
	var far := Vector2(SimConfig.ARENA_HALF.x - 1.0, 0.0)
	var out := Movement.step_player(far, Vector2.RIGHT, 10000.0, SimConfig.ARENA_HALF)
	assert_almost_eq(out.x, SimConfig.ARENA_HALF.x, 0.001)


func test_circles_overlap_at_the_boundary() -> void:
	assert_true(Movement.circles_overlap(Vector2.ZERO, 5.0, Vector2(9.9, 0.0), 5.0))
	assert_false(Movement.circles_overlap(Vector2.ZERO, 5.0, Vector2(10.1, 0.0), 5.0))


func test_outside_arena_respects_the_cull_margin() -> void:
	var edge := SimConfig.ARENA_HALF.x + SimConfig.BULLET_CULL_MARGIN
	assert_false(Movement.outside_arena(Vector2(edge - 1.0, 0.0)))
	assert_true(Movement.outside_arena(Vector2(edge + 1.0, 0.0)))