## #411: Integration test — full input roundtrip through live server.
## Validates the complete path: encode inputs → TCP wire → server deserialize →
## simulation systems → ObserverSnapshot → client decode.
## Catches integration seams that unit tests miss by exercising both movement
## and interaction actions against the real server binary.
## Requires: server binary built (cargo build in server/)
class_name TestInputRoundtrip
extends GdUnitTestSuite

const CONNECT_TIMEOUT: float = 3.0
const RESPONSE_TIMEOUT: float = 5.0
const MAX_PORT_ATTEMPTS: int = 5

var _server_pid: int = -1
var _bridge: LocalBridge = null
var _test_port: int = 0


func _server_binary_path() -> String:
	var project_dir := ProjectSettings.globalize_path("res://")
	return project_dir.path_join("../server/target/debug/settled-reach-server")


static func _random_test_port() -> int:
	return 49152 + (randi() % (65535 - 49152 + 1))


func _spawn_server(server_path: String) -> bool:
	for attempt in range(MAX_PORT_ATTEMPTS):
		_test_port = _random_test_port()
		var addr := "127.0.0.1:%d" % _test_port
		_server_pid = OS.create_process(server_path, [addr])
		if _server_pid <= 0:
			continue
		await get_tree().create_timer(0.15).timeout
		if OS.is_process_running(_server_pid):
			return true
		_server_pid = -1
	return false


func after_test() -> void:
	if _bridge != null:
		_bridge.disconnect_from_server()
		_bridge = null
	if _server_pid > 0 and OS.is_process_running(_server_pid):
		OS.kill(_server_pid)
		_server_pid = -1


func _connect_to_server() -> bool:
	var server_path := _server_binary_path()
	if not FileAccess.file_exists(server_path):
		push_warning("Input roundtrip test skipped: server binary not found at %s" % server_path)
		return false

	var spawned := await _spawn_server(server_path)
	if not spawned:
		return false

	_bridge = LocalBridge.new()
	var elapsed := 0.0
	while elapsed < CONNECT_TIMEOUT:
		if _server_pid > 0 and not OS.is_process_running(_server_pid):
			push_warning("Server process died during connection")
			return false
		if _bridge.get_status() == StreamPeerTCP.STATUS_NONE:
			_bridge.connect_to_server("127.0.0.1", _test_port)
		_bridge.poll()
		if _bridge.get_status() == StreamPeerTCP.STATUS_CONNECTED:
			return true
		if _bridge.get_status() == StreamPeerTCP.STATUS_ERROR:
			_bridge.disconnect_from_server()
			_bridge.reset()
		await get_tree().create_timer(0.1).timeout
		elapsed += 0.1

	return false


## Send a batch input and receive the snapshot response.
func _send_and_receive(action_name: String, tick: int = 0, action_data: Variant = null) -> Variant:
	var input_entry := {"tick": tick, "action_name": action_name}
	if action_data != null:
		input_entry["action_data"] = action_data
	var inputs: Array = [input_entry]
	var encoded := Protocol.encode_player_inputs(inputs)
	assert_that(encoded.size()).is_greater(0)
	var send_err := _bridge.send_message(encoded)
	assert_that(send_err).is_equal(OK)

	var snapshot_bytes := PackedByteArray()
	var elapsed := 0.0
	while elapsed < RESPONSE_TIMEOUT:
		_bridge.poll()
		snapshot_bytes = _bridge.poll_message()
		if snapshot_bytes.size() > 0:
			break
		await get_tree().create_timer(0.05).timeout
		elapsed += 0.05

	assert_that(snapshot_bytes.size()).is_greater(0)
	var snapshot: Variant = Protocol.decode_snapshot(snapshot_bytes)
	assert_that(snapshot).is_not_null()
	return snapshot


## Find the player entity in a snapshot by kind.
static func _find_player(snapshot: Dictionary) -> Dictionary:
	for entity in snapshot.entities:
		if entity.kind.variant == "Player":
			return entity
	return {}


# -- Movement roundtrip: send movement, verify position changes ----------------

func test_movement_roundtrip() -> void:
	var ok := await _connect_to_server()
	if not ok:
		return

	# Use Interact (server no-op) to get a baseline snapshot without moving.
	var baseline: Dictionary = await _send_and_receive("Interact", 0)
	var player := _find_player(baseline)
	assert_that(player.size()).is_greater(0)

	# Player starts at (16,16) → render coords (16.5, 16.5)
	var start_x: float = player.x
	var start_y: float = player.y
	assert_float(start_x).is_equal_approx(16.5, 0.001)
	assert_float(start_y).is_equal_approx(16.5, 0.001)

	# Send MoveNorth — player should move to (16, 15) → (16.5, 15.5)
	var snap1: Dictionary = await _send_and_receive("MoveNorth", 1)
	var p1 := _find_player(snap1)
	assert_that(p1.size()).is_greater(0)
	assert_float(p1.x).is_equal_approx(16.5, 0.001)
	assert_float(p1.y).is_equal_approx(15.5, 0.001)

	# Send MoveEast — player should move to (17, 15) → (17.5, 15.5)
	var snap2: Dictionary = await _send_and_receive("MoveEast", 2)
	var p2 := _find_player(snap2)
	assert_that(p2.size()).is_greater(0)
	assert_float(p2.x).is_equal_approx(17.5, 0.001)
	assert_float(p2.y).is_equal_approx(15.5, 0.001)

	# Verify position actually changed from baseline
	assert_that(p2.x != start_x or p2.y != start_y).is_true()


# -- Interact roundtrip: server accepts without crashing -----------------------

func test_interact_roundtrip() -> void:
	var ok := await _connect_to_server()
	if not ok:
		return

	# Send Interact action — unit variant, no target data.
	# Server accepts it (currently a no-op) and responds with a valid snapshot.
	var snapshot: Dictionary = await _send_and_receive("Interact", 0)

	# Snapshot should be valid with correct protocol version
	assert_that(snapshot.version).is_equal(Protocol.PROTOCOL_VERSION)
	assert_that(snapshot.entities.size()).is_greater(0)

	# Player should be at start position (Interact doesn't move)
	var player := _find_player(snapshot)
	assert_that(player.size()).is_greater(0)
	assert_float(player.x).is_equal_approx(16.5, 0.001)
	assert_float(player.y).is_equal_approx(16.5, 0.001)

	# Send Interact again at next tick — server should still accept it
	var snap2: Dictionary = await _send_and_receive("Interact", 1)
	assert_that(snap2).is_not_null()
	assert_that(snap2.version).is_equal(Protocol.PROTOCOL_VERSION)


# -- Mixed sequence: movement then interact in one session ---------------------

func test_move_then_interact() -> void:
	var ok := await _connect_to_server()
	if not ok:
		return

	# Move player first
	var snap1: Dictionary = await _send_and_receive("MoveNorth", 0)
	var p1 := _find_player(snap1)
	assert_that(p1.size()).is_greater(0)
	var moved_x: float = p1.x
	var moved_y: float = p1.y

	# Now send Interact — player should stay where they moved to
	var snap2: Dictionary = await _send_and_receive("Interact", 1)
	var p2 := _find_player(snap2)
	assert_that(p2.size()).is_greater(0)
	assert_float(p2.x).is_equal_approx(moved_x, 0.001)
	assert_float(p2.y).is_equal_approx(moved_y, 0.001)