extends Node

# Connection states
enum ConnectionState { DISCONNECTED, CONNECTING, CONNECTED, ERROR }

var state: ConnectionState = ConnectionState.DISCONNECTED
var test_mode: bool = OS.get_environment("SR_LIVE") != "1"  # SR_LIVE=1 connects to real server
var harness: TestHarness = null  # Test simulation (D-020: game logic lives outside production client)
var _last_snapshot: Variant = null  # Most recent decoded snapshot (consumed by poll_snapshot)
var _outbound_buffer: Array[Dictionary] = []  # Raw inputs awaiting batch encode + transport

# Transport layer (non-test mode)
var _bridge: LocalBridge = null
var _server: ServerProcess = null
var server_port: int = 9876  # Default matches server's default bind address
var server_path: String = ""  # Path to server binary — set before connect_to_sim()

# Connection retry state — handles server startup delay (Critical fix #1)
const MAX_CONNECT_RETRIES: int = 20  # ~2 seconds at 60fps with 100ms delay
const CONNECT_RETRY_INTERVAL: float = 0.1  # Seconds between retry attempts
var _connect_retries: int = 0
var _retry_timer: float = 0.0

# Signals
signal connection_state_changed(old_state: ConnectionState, new_state: ConnectionState)
signal snapshot_received(snapshot: Dictionary)

func _ready() -> void:
	if test_mode:
		harness = TestHarness.new()
		print("SimBridge: Running in test mode (dynamic snapshot)")


# -- Test mode proxy API (backward compat for 13+ test files) ------------------

func reset_test_state() -> void:
	if harness: harness.reset()

func _test_snapshot() -> Dictionary:
	return harness.snapshot()

func _test_has_los(from: Vector2i, to: Vector2i) -> bool:
	return harness.has_los(from, to)

var _test_tick: int:
	get: return harness.tick if harness else 0
	set(v):
		if harness: harness.tick = v

var _test_player_pos: Vector2i:
	get: return harness.player_pos if harness else Vector2i.ZERO
	set(v):
		if harness: harness.player_pos = v

var _test_facing: String:
	get: return harness.facing if harness else "North"
	set(v):
		if harness: harness.facing = v

var _test_in_dialogue: bool:
	get: return harness.in_dialogue if harness else false
	set(v):
		if harness: harness.in_dialogue = v

var _test_gauntlet_mode: bool:
	get: return harness.gauntlet_mode if harness else false
	set(v):
		if harness: harness.gauntlet_mode = v

var _test_npc_relationship: String:
	get: return harness.npc_relationship if harness else "Unknown"
	set(v):
		if harness: harness.npc_relationship = v

var _test_input_queue: Array:
	get: return harness.input_queue if harness else []


# -- Connection lifecycle ------------------------------------------------------

# Change connection state and emit signal
func _set_state(new_state: ConnectionState) -> void:
	if state != new_state:
		var old_state = state
		state = new_state
		connection_state_changed.emit(old_state, new_state)

# Connect to simulation server.
# In test mode, immediately transitions to CONNECTED.
# In live mode, spawns server subprocess and defers TCP connection to _process()
# to allow the server time to bind its port.
func connect_to_sim() -> void:
	_set_state(ConnectionState.CONNECTING)

	if test_mode:
		_set_state(ConnectionState.CONNECTED)
		return

	# Spawn server subprocess
	if not server_path.is_empty():
		_server = ServerProcess.new()
		# Server reads first positional arg as bind address (e.g. "127.0.0.1:9876").
		# D-085 (#258): pass --game-id <id> so server logs use the same session identifier.
		var args := ["127.0.0.1:" + str(server_port)]
		var game_id: String = GameState.current_game_id
		if not game_id.is_empty():
			args.append_array(["--game-id", game_id])
		var pid := _server.start(server_path, args)
		if pid <= 0:
			push_error("SimBridge: failed to start server")
			_set_state(ConnectionState.ERROR)
			return

	# Defer TCP connection to _process() — server needs time to bind its port
	_connect_retries = 0
	_retry_timer = 0.0
	_bridge = null

# Disconnect from simulation server
func disconnect_from_sim() -> void:
	if _bridge != null:
		_bridge.disconnect_from_server()
		_bridge = null
	if _server != null:
		_server.stop()
		_server = null
	_connect_retries = 0
	_set_state(ConnectionState.DISCONNECTED)

# Attempt TCP connection. Called from _process() during CONNECTING state.
func _try_connect() -> void:
	_bridge = LocalBridge.new()
	var err := _bridge.connect_to_server("127.0.0.1", server_port)
	if err != OK:
		push_warning("SimBridge: TCP connect attempt %d/%d failed: %s" % [
			_connect_retries + 1, MAX_CONNECT_RETRIES, error_string(err)])
		_bridge = null

# Poll transport layer every frame (non-test mode only)
func _process(delta: float) -> void:
	if test_mode:
		return

	# CONNECTING state: retry TCP connection until server is ready
	if state == ConnectionState.CONNECTING:
		if _bridge == null:
			_retry_timer += delta
			if _retry_timer >= CONNECT_RETRY_INTERVAL or _connect_retries == 0:
				_retry_timer = 0.0
				_connect_retries += 1
				if _connect_retries > MAX_CONNECT_RETRIES:
					push_error("SimBridge: TCP connection failed after %d retries" % MAX_CONNECT_RETRIES)
					_set_state(ConnectionState.ERROR)
					return
				_try_connect()
			return

		# Bridge exists — poll for connection completion
		_bridge.poll()
		match _bridge.get_status():
			StreamPeerTCP.STATUS_CONNECTED:
				_set_state(ConnectionState.CONNECTED)
			StreamPeerTCP.STATUS_CONNECTING:
				pass  # Still connecting, wait
			StreamPeerTCP.STATUS_ERROR:
				# Connection attempt failed — retry
				_bridge = null
				if _connect_retries >= MAX_CONNECT_RETRIES:
					push_error("SimBridge: TCP connection failed after %d retries" % MAX_CONNECT_RETRIES)
					_set_state(ConnectionState.ERROR)
			StreamPeerTCP.STATUS_NONE:
				_bridge = null  # Reset and retry
		return

	if _bridge == null:
		return

	_bridge.poll()

	match _bridge.get_status():
		StreamPeerTCP.STATUS_CONNECTED:
			# Receive: drain all complete messages from the bridge
			var msg := _bridge.poll_message()
			while msg.size() > 0:
				receive_bytes(msg)
				msg = _bridge.poll_message()
			# Send: batch-encode and flush outbound buffer as one frame (Vec<PlayerInput>).
			# Inputs are drained before encoding. On encode failure the inputs are
			# intentionally dropped — re-queuing would retry the same bad data and
			# the server tick has already advanced, making stale inputs invalid.
			var outbound := drain_outbound()
			if outbound.size() > 0:
				var encoded := Protocol.encode_player_inputs(outbound)
				if encoded.size() > 0:
					var err := _bridge.send_message(encoded)
					if err != OK:
						push_error("SimBridge: failed to send message: %s" % error_string(err))
				else:
					push_error("SimBridge: failed to batch-encode %d inputs (dropped)" % outbound.size())
		StreamPeerTCP.STATUS_CONNECTING:
			pass  # Should not happen in CONNECTED state
		StreamPeerTCP.STATUS_ERROR:
			if state != ConnectionState.ERROR:
				push_error("SimBridge: TCP connection error")
				_set_state(ConnectionState.ERROR)
		StreamPeerTCP.STATUS_NONE:
			if state == ConnectionState.CONNECTED:
				push_warning("SimBridge: connection lost")
				_set_state(ConnectionState.DISCONNECTED)


# -- Input / snapshot ----------------------------------------------------------

# Send input to simulation server.
# player_input: Dictionary with "action" (int from InputMapper.Action enum) and "timestamp_msec".
# In test mode, inputs are delegated to the test harness.
# In live mode, encoded and buffered for transport.
# Returns OK on success, or an error code on failure.
func send_input(player_input: Dictionary) -> Error:
	if state != ConnectionState.CONNECTED:
		return ERR_CONNECTION_ERROR
	if test_mode:
		var action: int = player_input.get("action", -1)
		var wire_name: String = action_enum_to_wire(action)
		if not wire_name.is_empty():
			if wire_name == "SetFacing":
				var facing: String = ""
				var action_data: Variant = player_input.get("action_data")
				if action_data is Dictionary:
					facing = str(action_data.get("facing", ""))
				if not facing.is_empty():
					harness.process_facing(facing)
			else:
				harness.process_input(wire_name)
		return OK
	var action_name := action_enum_to_wire(player_input.get("action", -1))
	if action_name.is_empty():
		return ERR_INVALID_PARAMETER
	var tick: int = GameState.current_tick
	var entry: Dictionary = { "tick": tick, "action_name": action_name }
	var action_data: Variant = player_input.get("action_data")
	if action_data != null:
		entry["action_data"] = action_data
	_outbound_buffer.append(entry)
	return OK

# Poll for snapshot from simulation.
# In test mode delegates to test harness. In live mode, returns the last decoded snapshot.
func poll_snapshot() -> Variant:
	if state != ConnectionState.CONNECTED:
		return null

	if test_mode:
		var snapshot = harness.snapshot()
		snapshot_received.emit(snapshot)
		return snapshot

	if _last_snapshot != null:
		var snapshot = _last_snapshot
		_last_snapshot = null
		snapshot_received.emit(snapshot)
		return snapshot

	return null

# Called by transport layer when raw bytes arrive from the server.
# Latest-wins for positional state (stale frames are worthless), but one-shot
# events (monologue, dialogue) are carried forward from overwritten snapshots
# so they aren't silently dropped when server ticks faster than client consumes.
func receive_bytes(bytes: PackedByteArray) -> void:
	var snapshot = Protocol.decode_snapshot(bytes)
	if snapshot == null:
		push_warning("SimBridge: decode_snapshot returned null for %d bytes" % bytes.size())
		return
	if _last_snapshot != null:
		# Carry forward one-shot events the client hasn't consumed yet.
		if snapshot.get("current_monologue") == null and _last_snapshot.get("current_monologue") != null:
			snapshot["current_monologue"] = _last_snapshot["current_monologue"]
		if snapshot.get("current_dialogue") == null and _last_snapshot.get("current_dialogue") != null:
			snapshot["current_dialogue"] = _last_snapshot["current_dialogue"]
		# #535: Carry forward one-shot dialogue events (arrays merge, scalar falls through)
		if snapshot.get("dialogue_response") == null and _last_snapshot.get("dialogue_response") != null:
			snapshot["dialogue_response"] = _last_snapshot["dialogue_response"]
		var old_conv_events: Array = _last_snapshot.get("conversation_events", [])
		if old_conv_events.size() > 0:
			var new_conv_events: Array = snapshot.get("conversation_events", [])
			snapshot["conversation_events"] = old_conv_events + new_conv_events
		var old_conv_ended: Array = _last_snapshot.get("conversation_ended", [])
		if old_conv_ended.size() > 0:
			var new_conv_ended: Array = snapshot.get("conversation_ended", [])
			snapshot["conversation_ended"] = old_conv_ended + new_conv_ended
		# #554: Carry forward save/load result (one-shot, consumed by main.gd)
		if snapshot.get("save_result") == null and _last_snapshot.get("save_result") != null:
			snapshot["save_result"] = _last_snapshot["save_result"]
	_last_snapshot = snapshot

# Drain the outbound buffer. Returns raw input entries for batch encoding.
func drain_outbound() -> Array[Dictionary]:
	var inputs = _outbound_buffer.duplicate()
	_outbound_buffer.clear()
	return inputs


# -- Wire protocol mapping -----------------------------------------------------

# Map InputMapper.Action enum values to wire-format action names (matching Rust PlayerAction).
# OPEN_MENU is client-only — no Rust equivalent, not sent over the wire.
static func action_enum_to_wire(action: int) -> String:
	match action:
		InputMapper.Action.MOVE_NORTH: return "MoveNorth"
		InputMapper.Action.MOVE_NORTHEAST: return "MoveNortheast"
		InputMapper.Action.MOVE_EAST: return "MoveEast"
		InputMapper.Action.MOVE_SOUTHEAST: return "MoveSoutheast"
		InputMapper.Action.MOVE_SOUTH: return "MoveSouth"
		InputMapper.Action.MOVE_SOUTHWEST: return "MoveSouthwest"
		InputMapper.Action.MOVE_WEST: return "MoveWest"
		InputMapper.Action.MOVE_NORTHWEST: return "MoveNorthwest"
		InputMapper.Action.INTERACT: return "Interact"
		InputMapper.Action.USE_PERCEPTION_MODE: return "UsePerceptionMode"
		InputMapper.Action.PAUSE: return "Pause"
		InputMapper.Action.UNPAUSE: return "Unpause"
		InputMapper.Action.TOGGLE_STANCE_UP: return "ToggleStanceUp"
		InputMapper.Action.TOGGLE_STANCE_DOWN: return "ToggleStanceDown"
		InputMapper.Action.OPEN_MENU:
			return ""  # Client-only action, not part of wire protocol
		InputMapper.Action.BUG_REPORT:
			return ""  # Client-only action (#495), not part of wire protocol
		InputMapper.Action.SET_FACING:
			return "SetFacing"  # D-054: facing octant update (no movement)
		InputMapper.Action.TELEPORT_HUB:
			return "TeleportToHub"  # #501: Gauntlet dev teleport (not production fast-travel)
		InputMapper.Action.SAVE_GAME:
			return "SaveGame"  # #554: F5 quicksave (D-085)
		InputMapper.Action.LOAD_GAME:
			return "LoadGame"  # #554: F6 quickload (D-085)
		_:
			push_warning("SimBridge: unknown action enum %s" % action)
			return ""