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 _test_tick: int = 0
var _test_player_pos: Vector2i = Vector2i(10, 10)
var _test_facing: String = "North"
var _test_input_queue: Array = []  # Queued actions for test mode
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:
		print("SimBridge: Running in test mode (dynamic snapshot)")

# Reset test state — call before tests that use _test_snapshot()
func reset_test_state() -> void:
	_test_tick = 0
	_test_player_pos = Vector2i(10, 10)
	_test_facing = "North"
	_test_input_queue.clear()

# 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")
		var pid := _server.start(server_path, ["127.0.0.1:" + str(server_port)])
		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)

# Send input to simulation server.
# player_input: Dictionary with "action" (int from InputMapper.Action enum) and "timestamp_msec".
# In test mode, inputs are silently dropped. 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():
			_test_input_queue.append(wire_name)
		return OK
	var action_name := _action_enum_to_wire(player_input.get("action", -1))
	if action_name.is_empty():
		# _action_enum_to_wire already emits push_warning for invalid actions
		return ERR_INVALID_PARAMETER
	# Use the server's current tick so drain_for_tick processes this input immediately.
	# The client-side timestamp_msec is only useful for ordering within a frame.
	var tick: int = GameState.current_tick
	var entry: Dictionary = { "tick": tick, "action_name": action_name }
	# Data variants (e.g. UsePerceptionMode) carry payload
	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 returns hardcoded data. In live mode, returns the last decoded snapshot (if any).
func poll_snapshot() -> Variant:
	if state != ConnectionState.CONNECTED:
		return null

	if test_mode:
		var snapshot = _test_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 semantics: newer snapshots replace unconsumed ones. This is correct
# for real-time rendering (stale frames are worthless). Upgrade to queue if needed.
func receive_bytes(bytes: PackedByteArray) -> void:
	var snapshot = Protocol.decode_snapshot(bytes)
	if snapshot != null:
		if _last_snapshot != null:
			push_warning("SimBridge: overwriting unconsumed snapshot (tick %s replaced by %s)" % [_last_snapshot.tick, snapshot.tick])
		_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

# 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.OPEN_MENU:
			# Client-only action, not part of wire protocol
			push_warning("SimBridge: OPEN_MENU is client-only, not sent to server")
			return ""
		_:
			push_warning("SimBridge: unknown action enum %s" % action)
			return ""

# Dynamic test snapshot — processes queued inputs to move player, generates
# visibility based on current position. Matches Protocol.decode_snapshot() format.
# NOTE: Test coordinate space (player at 10,10; NPC at 12,9; wall at 12,10)
# is intentionally decoupled from the E2E proof room (player at 16,16; NPC at
# 16,13; wall at 16,14). This ensures standalone tests don't depend on server
# map layout and can exercise the rendering pipeline independently.
func _test_snapshot() -> Dictionary:
	_test_tick += 1

	# Process queued inputs
	for action_name in _test_input_queue:
		var delta := _action_to_delta(action_name)
		var new_pos := _test_player_pos + delta
		if _test_is_walkable(new_pos):
			_test_player_pos = new_pos
			if delta != Vector2i.ZERO:
				_test_facing = _delta_to_facing(delta)
	_test_input_queue.clear()

	var px := _test_player_pos.x
	var py := _test_player_pos.y

	# Build entities — player always visible
	var entities: Array = [{
		"entity_id": 1,
		"x": float(px),
		"y": float(py),
		"z": 0,
		"kind": { "variant": "Player", "data": null },
		"visibility": "Forward",
	}]

	# NPC at (12, 9) — visible if within range and not blocked by wall at (12, 10)
	var npc_pos := Vector2i(12, 9)
	var npc_dist := absi(px - npc_pos.x) + absi(py - npc_pos.y)
	if npc_dist <= 4 and _test_has_los(Vector2i(px, py), npc_pos):
		var sector: String = "Forward" if npc_pos.y <= py else "Peripheral"
		entities.append({
			"entity_id": 2,
			"x": float(npc_pos.x),
			"y": float(npc_pos.y),
			"z": 0,
			"kind": { "variant": "Npc", "data": null },
			"visibility": sector,
		})

	# v4: nearby_interactions when NPC is nearby and visible (#404/#405)
	var nearby: Array = []
	if npc_dist <= 2 and _test_has_los(Vector2i(px, py), npc_pos):
		nearby.append({
			"entity_id": 2,
			"entity_type": "Npc",
			"distance": npc_dist,
			"verbs": [
				{"kind": "Talk", "label": "Talk", "priority": 1, "available": true},
				{"kind": "ExamineNpc", "label": "Observe", "priority": 2, "available": true},
			],
		})

	# v5: monologue on first tick (#414)
	var monologue: Variant = null
	if _test_tick == 1:
		monologue = {
			"id": "test_enter_001",
			"text": "Sova Transit District. Population twelve thousand and change.",
			"duration_seconds": 5.0,
		}

	return {
		"tick": _test_tick,
		"version": Protocol.PROTOCOL_VERSION,
		"game_time": {
			"day": 0,
			"time_of_day": _test_tick * 10,
			"day_phase": "Morning",
			"tick_rate": "Full",
		},
		"player_facing": _test_facing,
		"entities": entities,
		"tiles": _test_tiles(),
		"visible_tiles": _test_visible_tiles(),
		"visible_positions": _test_visible_positions(),
		"nearby_interactions": nearby,
		"current_monologue": monologue,
	}

# Generate a small test room: 8x6 room with walls, a door, and floor
func _test_tiles() -> Array:
	var tiles: Array = []
	var room_x := 7
	var room_y := 7
	var room_w := 8
	var room_h := 8

	for x in range(room_x, room_x + room_w):
		for y in range(room_y, room_y + room_h):
			var is_edge := (x == room_x or x == room_x + room_w - 1
				or y == room_y or y == room_y + room_h - 1)
			var tile_type: String
			if is_edge:
				# Door on the south wall, center
				if y == room_y + room_h - 1 and x == room_x + room_w / 2:
					tile_type = "door"
				else:
					tile_type = "wall"
			else:
				tile_type = "floor"
			tiles.append({"x": x, "y": y, "z": 0, "type": tile_type})

	# Corridor south of the door
	var door_x := room_x + room_w / 2
	for y in range(room_y + room_h, room_y + room_h + 4):
		tiles.append({"x": door_x - 1, "y": y, "z": 0, "type": "wall"})
		tiles.append({"x": door_x, "y": y, "z": 0, "type": "floor"})
		tiles.append({"x": door_x + 1, "y": y, "z": 0, "type": "wall"})

	return tiles

# Test visible tiles with visibility sectors (v2 format)
# Tiles ahead of the player are Forward, others Peripheral.
func _test_visible_tiles() -> Array:
	var vtiles: Array = []
	var px := _test_player_pos.x
	var py := _test_player_pos.y
	var radius := 4
	var room_x := 7
	var room_y := 7
	var room_w := 8
	var room_h := 8

	for x in range(px - radius, px + radius + 1):
		for y in range(py - radius, py + radius + 1):
			var dist := absf(x - px) + absf(y - py)
			if dist <= radius:
				if x >= room_x and x < room_x + room_w and y >= room_y and y < room_y + room_h:
					var sector: String = "Forward" if y <= py else "Peripheral"
					vtiles.append({"x": x, "y": y, "z": 0, "visibility": sector})
	return vtiles

# Test visibility: tiles within radius 4 of player, inside room bounds
func _test_visible_positions() -> Array:
	var positions: Array = []
	var px := _test_player_pos.x
	var py := _test_player_pos.y
	var radius := 4
	var room_x := 7
	var room_y := 7
	var room_w := 8
	var room_h := 8

	for x in range(px - radius, px + radius + 1):
		for y in range(py - radius, py + radius + 1):
			var dist := absf(x - px) + absf(y - py)
			if dist <= radius:
				if x >= room_x and x < room_x + room_w and y >= room_y and y < room_y + room_h:
					positions.append({"x": x, "y": y})
	return positions


# -- Test mode helpers --

const _TEST_WALLS: Array = [
	# Room walls (8x8 room from (7,7) to (14,14))
	Vector2i(7,7), Vector2i(8,7), Vector2i(9,7), Vector2i(10,7),
	Vector2i(11,7), Vector2i(12,7), Vector2i(13,7), Vector2i(14,7),
	Vector2i(7,14), Vector2i(8,14), Vector2i(9,14), Vector2i(10,14),
	Vector2i(11,14), Vector2i(12,14), Vector2i(13,14), Vector2i(14,14),
	Vector2i(7,8), Vector2i(7,9), Vector2i(7,10), Vector2i(7,11),
	Vector2i(7,12), Vector2i(7,13),
	Vector2i(14,8), Vector2i(14,9), Vector2i(14,10), Vector2i(14,11),
	Vector2i(14,12), Vector2i(14,13),
	# Interior wall blocking NPC
	Vector2i(12, 10),
]

func _test_is_walkable(pos: Vector2i) -> bool:
	return not _TEST_WALLS.has(pos)

# Simple LOS check — blocked if a wall tile sits between start and end
func _test_has_los(from: Vector2i, to: Vector2i) -> bool:
	# Bresenham-lite: check tiles along the line
	var dx := absi(to.x - from.x)
	var dy := absi(to.y - from.y)
	var sx := 1 if from.x < to.x else -1
	var sy := 1 if from.y < to.y else -1
	var err := dx - dy
	var cx := from.x
	var cy := from.y
	while true:
		if cx == to.x and cy == to.y:
			return true
		if Vector2i(cx, cy) != from and not _test_is_walkable(Vector2i(cx, cy)):
			return false
		var e2 := 2 * err
		if e2 > -dy:
			err -= dy
			cx += sx
		if e2 < dx:
			err += dx
			cy += sy
	return true

static func _action_to_delta(action_name: String) -> Vector2i:
	match action_name:
		"MoveNorth": return Vector2i(0, -1)
		"MoveNortheast": return Vector2i(1, -1)
		"MoveEast": return Vector2i(1, 0)
		"MoveSoutheast": return Vector2i(1, 1)
		"MoveSouth": return Vector2i(0, 1)
		"MoveSouthwest": return Vector2i(-1, 1)
		"MoveWest": return Vector2i(-1, 0)
		"MoveNorthwest": return Vector2i(-1, -1)
		_: return Vector2i.ZERO

static func _delta_to_facing(delta: Vector2i) -> String:
	match delta:
		Vector2i(0, -1): return "North"
		Vector2i(1, -1): return "Northeast"
		Vector2i(1, 0): return "East"
		Vector2i(1, 1): return "Southeast"
		Vector2i(0, 1): return "South"
		Vector2i(-1, 1): return "Southwest"
		Vector2i(-1, 0): return "West"
		Vector2i(-1, -1): return "Northwest"
		_: return "North"