## D-030 Layer 3: End-to-end connection test
## Spawns the Rust simulation server, connects via LocalBridge,
## sends a MoveNorth input, and verifies the snapshot response.
## Requires: server binary built (cargo build in server/)
class_name TestE2EConnection
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")


## Pick a random high port to avoid conflicts in parallel CI runs.
## Range 49152-65535 is the dynamic/ephemeral port range (IANA).
static func _random_test_port() -> int:
	return 49152 + (randi() % (65535 - 49152 + 1))


## Spawn server with port rotation — if the port is in use, the server exits
## immediately (bind failure). Detect this and retry with a new random port.
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
		# Give server time to bind or fail
		await get_tree().create_timer(0.15).timeout
		if OS.is_process_running(_server_pid):
			return true
		# Server exited — port likely in use, try another
		_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


# -- E2E: full round-trip through server binary --------------------------------

func test_send_input_receive_snapshot() -> void:
	var server_path := _server_binary_path()
	if not FileAccess.file_exists(server_path):
		push_warning("E2E test skipped: server binary not found at %s" % server_path)
		return

	# Spawn server with port rotation (retries if port is in use)
	var spawned := await _spawn_server(server_path)
	assert_bool(spawned).is_true()

	# Connect with retries (server needs time to accept)
	_bridge = LocalBridge.new()
	var connected := false
	var elapsed := 0.0
	while elapsed < CONNECT_TIMEOUT:
		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:
			connected = true
			break
		if _bridge.get_status() == StreamPeerTCP.STATUS_ERROR:
			_bridge.disconnect_from_server()
			_bridge.reset()
		await get_tree().create_timer(0.1).timeout
		elapsed += 0.1

	assert_bool(connected).is_true()

	# Send batch input: MoveNorth at tick 0 (matching game_loop.rs test)
	var inputs: Array = [{"tick": 0, "action_name": "MoveNorth"}]
	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)

	# Poll for snapshot response
	var snapshot_bytes := PackedByteArray()
	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)

	# Decode snapshot
	var snapshot: Variant = Protocol.decode_snapshot(snapshot_bytes)
	assert_that(snapshot).is_not_null()

	# Server starts at tick 0, snapshot reflects state after processing
	assert_that(snapshot.tick).is_equal(0)
	assert_that(snapshot.entities.size()).is_greater(0)

	# Find the player entity by kind (entity order is not guaranteed)
	var player: Dictionary = {}
	for entity in snapshot.entities:
		if entity.kind.variant == "Player":
			player = entity
			break
	assert_that(player.size()).is_greater(0)

	# Player started at (16, 16, 0), moved north (y-1) to (16, 15, 0)
	# Render coords: tile center offset -> (16.5, 15.5, 0)
	assert_float(player.x).is_equal_approx(16.5, 0.001)
	assert_float(player.y).is_equal_approx(15.5, 0.001)
	assert_that(player.z).is_equal(0)