## Sprint 2 Proof: Fog of Perception (#357)
## Verifies all 7 acceptance criteria through the full server pipeline:
## AC1: Player moves, AC2: Camera follows (via player_position),
## AC3: Tiles render (visible_tiles non-empty), AC4: Entities via LOS,
## AC5: Fog (not all tiles visible), AC6: Walls hide, AC7: Corner reveal.
## Requires: server binary built (cargo build in server/)
##
## Server proof room layout:
##   (16,13) = NPC1   (16,14) = WALL    (16,16) = Player start
##   (14,18) = NPC2   (18,14) = NPC3
##   Player facing North → NPC1 blocked by wall.
##   Move East+North around the wall → NPC1 becomes visible.
class_name TestSprint2Proof
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


## Send a batch input and receive the snapshot response.
func _send_and_receive(action_name: String, tick: int = 0) -> Variant:
	var inputs: Array = [{"tick": tick, "action_name": action_name}]
	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


## Connect to server, returning true on success.
func _connect_to_server() -> bool:
	var server_path := _server_binary_path()
	if not FileAccess.file_exists(server_path):
		push_warning("Sprint 2 proof 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


# -- AC#1, AC#2, AC#3, AC#5: Movement, camera, tiles, fog -------------------------

func test_proof_player_moves_and_v2_snapshot() -> void:
	var ok := await _connect_to_server()
	if not ok:
		return

	var snapshot: Dictionary = await _send_and_receive("MoveNorth")

	# AC#1: Player moved from (16,16) to (16,15)
	var player: Dictionary = {}
	for entity in snapshot.entities:
		if entity.kind.variant == "Player":
			player = entity
			break
	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(15.5, 0.001)

	# v4 protocol fields present
	assert_that(snapshot.version).is_equal(Protocol.PROTOCOL_VERSION)
	assert_that(snapshot.player_facing).is_equal("North")
	assert_that(snapshot.game_time).is_not_null()

	# AC#3: Tiles flowing through bridge (visible_tiles non-empty)
	assert_that(snapshot.visible_tiles.size()).is_greater(0)

	# AC#5: Not all 1024 tiles visible — blind spot behind player
	assert_that(snapshot.visible_tiles.size()).is_less(1024)


# -- AC#6: Wall hides entity -------------------------------------------------------

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

	# After MoveNorth: player at (16,15) facing North.
	# Wall at (16,14) blocks LOS to NPC1 at (16,13).
	var snapshot: Dictionary = await _send_and_receive("MoveNorth")

	# NPC1 at (16,13) should be hidden — wall at (16,14) blocks LOS.
	# Other NPCs (NPC2 at (14,18), NPC3 at (18,14)) may be visible.
	var hidden_npc_visible := false
	for entity in snapshot.entities:
		if entity.kind.variant == "Npc":
			if is_equal_approx(entity.x, 16.5) and is_equal_approx(entity.y, 13.5):
				hidden_npc_visible = true
				break
	assert_that(hidden_npc_visible).is_false()


# -- AC#4, AC#7: Entity appears via LOS / corner reveal ----------------------------

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

	# Step 1: Move East twice to get beside the wall
	# (16,16) → MoveEast → (17,16) → MoveEast → (18,16)
	await _send_and_receive("MoveEast", 0)
	await _send_and_receive("MoveEast", 1)

	# Step 2: Move North past the wall line (y=14)
	# (18,16) → MoveNorth → (18,15) → MoveNorth → (18,14) → MoveNorth → (18,13)
	await _send_and_receive("MoveNorth", 2)
	await _send_and_receive("MoveNorth", 3)
	var snapshot: Dictionary = await _send_and_receive("MoveNorth", 4)

	# Player at (18,13) facing North. NPC1 at (16,13) is 2 tiles west —
	# within peripheral cone, no wall between. NPC1 should be visible.
	var npc1_found := false
	for entity in snapshot.entities:
		if entity.kind.variant == "Npc":
			if is_equal_approx(entity.x, 16.5) and is_equal_approx(entity.y, 13.5):
				npc1_found = true
				break
	assert_that(npc1_found).is_true()