tekton/scripts/managers/stop_n_go_manager.gd

extends Node
class_name StopNGoManager

# StopNGoManager - Handles phase transitions, missions, and movement penalties

signal phase_changed(new_phase: String, remaining_time: float)
signal mission_status_updated(player_id: int, completed: bool)
signal player_penalized(player_id: int)

enum Phase {GO, STOP}

const GO_DURATION: float = 8.0
const STOP_DURATION: float = 4.0
const REQUIRED_GOALS: int = 8

# Dynamic Safe Zone
const SAFE_ZONE_PRE_TIME: float = 5.0 # Seconds before STOP to spawn safe zone
const SAFE_ZONE_RADIUS: int = 2 # 5x5 area (radius 2 from center)
var safe_zone_center: Vector2i = Vector2i(-1, -1)
var safe_zone_spawned: bool = false

# Power-Up Tile Spawning
const POWERUP_TILES = [11, 14] # Speed (11) and Ghost (14)
const POWERUP_SPAWN_COUNT: int = 5 # Number of power-up tiles to spawn

var current_phase: Phase = Phase.GO
var phase_timer: float = GO_DURATION
var is_active: bool = false

var player_missions: Dictionary = {} # player_id -> {target_tile: int, required: int, current: int}
var finish_line_x: int = 21 # Right side of the map for win condition

# Tile IDs
const TILE_WALKABLE = 0
const TILE_START = 3 # Start Line
const TILE_FINISH = 3 # Finish Line
const TILE_SAFE = 2 # Green Safe Zone
const TILE_OBSTACLE = 4 # Wall

var hud_layer: CanvasLayer
var mission_label: Label
var red_tint_overlay: ColorRect

# Traffic Light / StopTimer Visuals
var stop_timer_node: PanelContainer
var stop_segments: Array[Panel] = []
var lit_style: StyleBoxFlat
var dim_style: StyleBoxFlat
var red_style: StyleBoxFlat

func _ready():
	set_process(false)
	_setup_hud()

func _setup_hud():
	hud_layer = CanvasLayer.new()
	hud_layer.layer = 5 # Ensure it's above normal UI but below Pause Menu (10)
	hud_layer.visible = false
	add_child(hud_layer)
	
	# Full-screen red tint overlay (below everything else in this layer, but above game)
	red_tint_overlay = ColorRect.new()
	red_tint_overlay.color = Color(1.0, 0.0, 0.0, 0.25) # Transparent red
	red_tint_overlay.set_anchors_preset(Control.PRESET_FULL_RECT) # Cover whole screen
	red_tint_overlay.visible = false # Hidden initially
	hud_layer.add_child(red_tint_overlay)
	
	# New container for bottom-mid label
	var bottom_container = CenterContainer.new()
	bottom_container.set_anchors_preset(Control.PRESET_CENTER_BOTTOM)
	bottom_container.grow_horizontal = Control.GROW_DIRECTION_BOTH
	bottom_container.grow_vertical = Control.GROW_DIRECTION_BEGIN
	bottom_container.offset_bottom = -50
	hud_layer.add_child(bottom_container)
	
	var custom_font = load("res://assets/fonts/Nougat-ExtraBlack.ttf")
	
	mission_label = Label.new()
	mission_label.text = "MISSION: Collect Goals"
	mission_label.horizontal_alignment = HORIZONTAL_ALIGNMENT_CENTER
	if custom_font: mission_label.add_theme_font_override("font", custom_font)
	mission_label.add_theme_font_size_override("font_size", 28) # Slightly larger since it's centered
	mission_label.add_theme_color_override("font_outline_color", Color.BLACK)
	mission_label.add_theme_constant_override("outline_size", 8)
	bottom_container.add_child(mission_label)

func _process(delta):
	if not is_active:
		return
		
	# Decrement timer locally for all peers (smoother HUD than waiting for RPC)
	phase_timer -= delta
		
	if multiplayer.is_server():
		# Spawn safe zone 5 seconds before STOP phase begins
		if current_phase == Phase.GO and not safe_zone_spawned and phase_timer <= SAFE_ZONE_PRE_TIME:
			_spawn_safe_zone()
		
		if phase_timer <= 0:
			if current_phase == Phase.GO:
				_start_phase(Phase.STOP)
			else:
				_start_phase(Phase.GO)
	
	# Update HUD locally
	_update_hud_visuals()

func _on_goal_count_updated(_peer_id: int, _count: int):
	# Refresh visuals whenever points change
	_update_hud_visuals()

var _has_notified_mission_complete: bool = false

func _update_hud_visuals():
	# Toggle Red Screen Tint
	if red_tint_overlay:
		red_tint_overlay.visible = (current_phase == Phase.STOP)
	
	var my_id = multiplayer.get_unique_id()
	if mission_label:
		var main = get_node_or_null("/root/Main")
		var goals_cycle_manager = main.get_node_or_null("GoalsCycleManager") if main else null
		
		# Get count from GoalsCycleManager (Source of truth for PlayerBoardLabel)
		var completed_count = goals_cycle_manager.player_goal_counts.get(my_id, 0) if goals_cycle_manager else 0
		
		mission_label.text = "GOALS (%d/%d)" % [completed_count, REQUIRED_GOALS]
		
		if completed_count >= REQUIRED_GOALS:
			mission_label.text = "ALL GOALS COMPLETE!\nREACH THE FINISH!"
			mission_label.add_theme_color_override("font_color", Color.GOLD)
			
			# Notify player once
			if my_id == multiplayer.get_unique_id() and not _has_notified_mission_complete:
				_has_notified_mission_complete = true
				var player_node = main.get_node_or_null(str(my_id))
				if player_node:
					NotificationManager.send_message(player_node, "ALL GOALS COMPLETE!", NotificationManager.MessageType.GOAL)
		else:
			mission_label.add_theme_color_override("font_color", Color.WHITE)
			_has_notified_mission_complete = false
			
	# Update StopTimer (Traffic Light)
	_update_stop_timer_visuals()

func _update_stop_timer_visuals():
	if not stop_timer_node:
		# Try to find it once
		var main = get_node_or_null("/root/Main")
		if main:
			stop_timer_node = main.get_node_or_null("StopTimer")
			if stop_timer_node:
				var hbox = stop_timer_node.get_node_or_null("HBox")
				if hbox:
					stop_segments.clear()
					for i in range(3):
						var seg = hbox.get_node_or_null("Segment%d" % i)
						if seg: stop_segments.append(seg)
				
				# Prepare styles
				lit_style = StyleBoxFlat.new()
				lit_style.bg_color = Color.YELLOW
				lit_style.border_width_left = 2
				lit_style.border_width_top = 2
				lit_style.border_width_right = 2
				lit_style.border_width_bottom = 2
				lit_style.border_color = Color(1.0, 1.0, 1.0, 0.5)
				
				dim_style = StyleBoxFlat.new()
				dim_style.bg_color = Color(0.1, 0.1, 0.1, 0.8) # Dark dim
				
				red_style = StyleBoxFlat.new()
				red_style.bg_color = Color.RED
				red_style.border_width_left = 2
				red_style.border_width_top = 2
				red_style.border_width_right = 2
				red_style.border_width_bottom = 2
				red_style.border_color = Color(1.0, 0.5, 0.5, 0.5)
	
	if not stop_timer_node: return

	# ALWAYS VISIBLE in Stop n Go mode
	stop_timer_node.visible = true

	if current_phase == Phase.GO:
		# GO Phase: All dim unless in last 3 seconds
		for i in range(stop_segments.size()):
			var threshold = 3.0 - i
			if phase_timer <= threshold:
				stop_segments[i].add_theme_stylebox_override("panel", lit_style)
			else:
				stop_segments[i].add_theme_stylebox_override("panel", dim_style)
	else:
		# STOP Phase: All Red
		for seg in stop_segments:
			seg.add_theme_stylebox_override("panel", red_style)

func activate_client_side():
	is_active = true
	if hud_layer:
		hud_layer.visible = true
	
	# Connect to GoalsCycleManager for immediate HUD updates
	var main = get_node_or_null("/root/Main")
	if main:
		var gcm = main.get_node_or_null("GoalsCycleManager")
		if gcm and not gcm.goal_count_updated.is_connected(_on_goal_count_updated):
			gcm.goal_count_updated.connect(_on_goal_count_updated)
			
	set_process(true)

func start_game_mode():
	# This should primarily be called by the Server
	# Clients get activated via RPCs (sync_phase, etc)
	if multiplayer.is_server():
		activate_client_side() # Server also needs local processing
		# _setup_arena() # REMOVED: Already explicitly called in main.gd _setup_host_game to prepare floor before spawns!
		_assign_missions()
		_start_phase(Phase.GO)
	else:
		# Clients just wait for updates, but can enable HUD if needed
		# activate_client_side() can be called when first sync arrives
		pass

func _start_phase(phase: Phase):
	current_phase = phase
	phase_timer = GO_DURATION if phase == Phase.GO else STOP_DURATION
	
	var phase_name = "GO" if phase == Phase.GO else "STOP"
	if can_rpc():
		rpc("sync_phase", phase_name, phase_timer)
		
		if phase == Phase.STOP:
			# --- DYNAMIC SAFE ZONE: Penalize players outside the zone ---
			if safe_zone_spawned:
				var all_players = get_tree().get_nodes_in_group("Players")
				for p in all_players:
					if not _is_in_safe_zone(p.current_position):
						_scatter_player_tiles(p)
			
			# --- POWER-UP TILES: Spawn 5 Speed & Ghost tiles ---
			_spawn_powerup_tiles()
		
		# If GO phase starts, clear all STOP phase freezes and safe zone
		if phase == Phase.GO:
			_clear_safe_zone()
			var all_players = get_tree().get_nodes_in_group("Players")
			for p in all_players:
				if p.has_method("sync_stop_freeze"):
					p.rpc("sync_stop_freeze", false)
					
	emit_signal("phase_changed", phase_name, phase_timer)

func can_rpc() -> bool:
	if not multiplayer.has_multiplayer_peer() or multiplayer.multiplayer_peer.get_connection_status() != MultiplayerPeer.CONNECTION_CONNECTED:
		return false
	return true

@rpc("authority", "call_local", "reliable")
func sync_phase(phase_name: String, duration: float):
	if not is_active:
		activate_client_side()
	current_phase = Phase.GO if phase_name == "GO" else Phase.STOP
	phase_timer = duration

func _setup_arena():
	var gridmap = get_parent().get_node_or_null("EnhancedGridMap")
	if not gridmap:
		gridmap = get_node_or_null("/root/Main/EnhancedGridMap")
	if not gridmap: return
	
	print("[StopNGo] Setting up 22x10 Arena with Randomized Obstacles...")
	
	# Explicitly sync dimensions and clear grid on all clients
	if can_rpc():
		rpc("sync_arena_setup")
			
	# Apply locally for Server (RPC is call_remote)
	_apply_arena_setup()

@rpc("authority", "call_remote", "reliable")
func sync_arena_setup():
	print("[StopNGo] Client: Syncing Arena Setup (22x10)...")
	_apply_arena_setup()
	
func _apply_arena_setup():
	# Shared logic for resizing and clearing
	var gridmap = get_parent().get_node_or_null("EnhancedGridMap")
	if not gridmap:
		# Fallback just in case
		gridmap = get_node_or_null("/root/Main/EnhancedGridMap")
	if not gridmap: return

	# Set Size for Stop n Go explicitly, bypassing setters that wipe the map
	gridmap.set("columns", 22)
	gridmap.set("rows", 10)
	
	# Clear existing items on all layers
	gridmap.clear()

	# Dynamic Safe Zone: No static safe columns anymore
	# Safe zone spawns randomly during gameplay

	# Create bands based on X (Horizontal Progress)
	for x in range(gridmap.columns):
		var tile_id = TILE_WALKABLE
		if x == 0:
			tile_id = TILE_START
		elif x == gridmap.columns - 1:
			tile_id = TILE_FINISH
		
		for z in range(gridmap.rows):
			gridmap.set_cell_item(Vector3i(x, 0, z), tile_id)
			
	# Note: Specific obstacles removed as per user request to replace with random ones.
	# MISSION TILES: Moved to start_game_mode() to ensure they spawn AFTER walls.
	
	gridmap.update_grid_data()
	gridmap.initialize_astar()
	
func setup_mission_tiles():
	"""Public wrapper to trigger mission tile spawning before game start."""
	if multiplayer.is_server():
		_spawn_mission_tiles()

func _spawn_mission_tiles():
	var gridmap = get_parent().get_node_or_null("EnhancedGridMap")
	if not gridmap:
		gridmap = get_node_or_null("/root/Main/EnhancedGridMap")
	if not gridmap: return
	
	# Forbidden Zones (Start, Finish) - No items here
	var forbidden_x = [0, 21]
	
	# Goal items: Heart(7), Diamond(8), Star(9), Coin(10)
	var goal_items = [7, 8, 9, 10]
	
	for x in range(gridmap.columns):
		if x in forbidden_x:
			continue # Clear zone
			
		for z in range(gridmap.rows):
			# Ensure we don't spawn on obstacles
			var base_tile = gridmap.get_cell_item(Vector3i(x, 0, z))
			var current_item = gridmap.get_cell_item(Vector3i(x, 1, z))
			
			# PROTECTED FLOOR CHECK: Don't spawn on walls or void
			if base_tile in [TILE_OBSTACLE, -1] or current_item == TILE_OBSTACLE or current_item == 13:
				continue
				
			# Spawn tiles with 60% density
			if randf() > 0.6:
				gridmap.set_cell_item(Vector3i(x, 1, z), -1)
				continue
				
			var tile_type = goal_items[randi() % goal_items.size()]
			gridmap.set_cell_item(Vector3i(x, 1, z), tile_type)
			
			# Sync to clients
			var main = get_node("/root/Main")
			if main:
				main.rpc("sync_grid_item", x, 1, z, tile_type)

func _assign_missions():
	# NO-OP: Missions are now achievement-based (Complete 3 Goals)
	# which is tracked natively by GoalsCycleManager.
	pass

@rpc("authority", "call_local", "reliable")
func sync_missions(missions: Dictionary):
	player_missions = missions

func check_movement_violation(player_id: int, from: Vector2i, to: Vector2i) -> bool:
	"""Check if movement is illegal (during STOP phase and not in safe zone)."""
	if current_phase == Phase.STOP:
		# Use dynamic safe zone position check instead of static tile check
		if not _is_in_safe_zone(from):
			var gridmap = get_parent().get_node_or_null("EnhancedGridMap")
			if not gridmap:
				gridmap = get_node_or_null("/root/Main/EnhancedGridMap")
			if gridmap:
				var tile_from = gridmap.get_cell_item(Vector3i(from.x, 0, from.y))
				if tile_from != TILE_START and tile_from != TILE_FINISH:
					_penalize_player(player_id)
					return true
	return false

func _penalize_player(player_id: int):
	if not multiplayer.is_server(): return
	
	var main = get_node("/root/Main")
	if not main: return
	
	var player_node = main.get_node_or_null(str(player_id))
	if player_node:
		# We now use the 'on_stop_phase_violation' RPC which scatters tiles around the player
		# like they got attacked, instead of just dropping them in one pile.
		if can_rpc():
			player_node.rpc("on_stop_phase_violation")
		
		# Notification is also handled inside on_stop_phase_violation on the player node
		emit_signal("player_penalized", player_id)

func update_mission_progress(_player_id: int, _tile_id: int):
	# Redundant in Board-based mode, but kept for compatibility.
	# The board is synced separately via sync_playerboard in playerboard_manager.gd.
	pass

@rpc("any_peer", "call_local", "reliable")
func sync_mission_progress(_player_id: int, _mission_index: int, _current: int):
	# Deprecated
	pass

func is_mission_complete(player_id: int) -> bool:
	var main = get_node_or_null("/root/Main")
	if not main: return false
	
	var goals_cycle_manager = main.get_node_or_null("GoalsCycleManager")
	if not goals_cycle_manager: return false
	
	var completed_count = goals_cycle_manager.player_goal_counts.get(player_id, 0)
	return completed_count >= REQUIRED_GOALS

func check_win_condition(player_id: int, position: Vector2i) -> bool:
	# 1. Must reach the finish line (Column 21)
	if position.x < finish_line_x:
		return false
		
	# 2. Must have enough Goal Completions
	if is_mission_complete(player_id):
		print("[StopNGo] Player %d REACHED FINISH with goals complete!" % player_id)
		return true
	else:
		# Inform the player locally if they reach the end without goals
		var main = get_node_or_null("/root/Main")
		var player_node = main.get_node_or_null(str(player_id)) if main else null
		if player_node:
			NotificationManager.send_message(player_node, "Incomplete! Achieve %d goals to win!" % REQUIRED_GOALS, NotificationManager.MessageType.WARNING)
		
		print("[StopNGo] Player %d reached finish but goals incomplete." % player_id)
		return false

# =============================================================================
# Dynamic Safe Zone
# =============================================================================

func _spawn_safe_zone():
	"""Server: Pick a random walkable position and spawn the safe zone."""
	if not multiplayer.is_server(): return
	
	var gridmap = get_parent().get_node_or_null("EnhancedGridMap")
	if not gridmap:
		gridmap = get_node_or_null("/root/Main/EnhancedGridMap")
	if not gridmap: return
	
	# Collect valid center positions (not too close to edges so the zone fits)
	var valid_positions: Array[Vector2i] = []
	for x in range(SAFE_ZONE_RADIUS, gridmap.columns - SAFE_ZONE_RADIUS):
		for z in range(SAFE_ZONE_RADIUS, gridmap.rows - SAFE_ZONE_RADIUS):
			var tile = gridmap.get_cell_item(Vector3i(x, 0, z))
			# Only walkable tiles (not start/finish)
			if tile == TILE_WALKABLE:
				valid_positions.append(Vector2i(x, z))
	
	if valid_positions.is_empty():
		print("[StopNGo] WARNING: No valid position for safe zone!")
		return
	
	# Pick random center
	var rng = RandomNumberGenerator.new()
	rng.randomize()
	safe_zone_center = valid_positions[rng.randi() % valid_positions.size()]
	safe_zone_spawned = true
	
	print("[StopNGo] Safe Zone spawned at %s (radius %d)" % [safe_zone_center, SAFE_ZONE_RADIUS])
	
	# Sync to all peers
	if can_rpc():
		rpc("sync_safe_zone", safe_zone_center, SAFE_ZONE_RADIUS)

func _clear_safe_zone():
	"""Server: Clear the safe zone overlay and reset state."""
	if not multiplayer.is_server(): return
	
	if safe_zone_spawned:
		safe_zone_spawned = false
		safe_zone_center = Vector2i(-1, -1)
		
		if can_rpc():
			rpc("sync_clear_safe_zone")

func _is_in_safe_zone(pos: Vector2i) -> bool:
	"""Check if a position is within the dynamic safe zone."""
	if not safe_zone_spawned or safe_zone_center == Vector2i(-1, -1):
		return false
	# Chebyshev distance (square area)
	var dx = abs(pos.x - safe_zone_center.x)
	var dz = abs(pos.y - safe_zone_center.y)
	return dx <= SAFE_ZONE_RADIUS and dz <= SAFE_ZONE_RADIUS

func _scatter_player_tiles(player_node: Node):
	"""Server: Take all tiles from player's playerboard and scatter them onto nearby grid cells."""
	if not multiplayer.is_server(): return
	
	var main = get_node_or_null("/root/Main")
	if not main: return
	
	var gridmap = main.get_node_or_null("EnhancedGridMap")
	if not gridmap: return
	
	var peer_id = player_node.name.to_int()
	var playerboard = player_node.playerboard
	var tiles_to_scatter: Array[int] = []
	
	# Collect all non-empty tiles from playerboard
	for i in range(playerboard.size()):
		if playerboard[i] != -1:
			tiles_to_scatter.append(playerboard[i])
			playerboard[i] = -1
	
	if tiles_to_scatter.is_empty():
		return # Nothing to scatter
	
	# Find valid nearby positions to drop tiles (within radius 3 of player)
	var center = player_node.current_position
	var valid_drop_positions: Array[Vector2i] = []
	for dx in range(-3, 4):
		for dz in range(-3, 4):
			var pos = Vector2i(center.x + dx, center.y + dz)
			# Bounds check
			if pos.x < 0 or pos.x >= gridmap.columns or pos.y < 0 or pos.y >= gridmap.rows:
				continue
			# Check floor is walkable (not void, not obstacle)
			var floor_tile = gridmap.get_cell_item(Vector3i(pos.x, 0, pos.y))
			if floor_tile == -1 or floor_tile == TILE_OBSTACLE:
				continue
			# Check floor 1 is empty (no existing item)
			var existing_item = gridmap.get_cell_item(Vector3i(pos.x, 1, pos.y))
			if existing_item != -1:
				continue
			valid_drop_positions.append(pos)
	
	# Scatter tiles onto valid positions
	var rng = RandomNumberGenerator.new()
	rng.randomize()
	
	for tile in tiles_to_scatter:
		if valid_drop_positions.is_empty():
			break # No more space
		
		var idx = rng.randi() % valid_drop_positions.size()
		var drop_pos = valid_drop_positions[idx]
		valid_drop_positions.remove_at(idx)
		
		# Place tile on grid Floor 1
		gridmap.set_cell_item(Vector3i(drop_pos.x, 1, drop_pos.y), tile)
		# Sync to all clients
		main.rpc("sync_grid_item", drop_pos.x, 1, drop_pos.y, tile)
	
	# Sync cleared playerboard to all clients
	main.rpc("sync_playerboard", peer_id, playerboard)
	
	# Notify the player
	NotificationManager.send_message(player_node, "Not in Safe Zone! Tiles scattered!", NotificationManager.MessageType.WARNING)
	
	# Screen shake
	if player_node.has_method("trigger_screen_shake") and can_rpc():
		player_node.rpc("trigger_screen_shake", "heavy")
	
	print("[StopNGo] Scattered %d tiles from Player %d" % [tiles_to_scatter.size(), peer_id])

@rpc("authority", "call_local", "reliable")
func sync_safe_zone(center: Vector2i, radius: int):
	"""Client: Show the safe zone overlay on the grid."""
	safe_zone_center = center
	safe_zone_spawned = true
	
	var gridmap = get_parent().get_node_or_null("EnhancedGridMap")
	if not gridmap:
		gridmap = get_node_or_null("/root/Main/EnhancedGridMap")
	if not gridmap: return
	
	# Paint safe zone on Floor 2 (overlay layer) with TILE_SAFE visual
	for dx in range(-radius, radius + 1):
		for dz in range(-radius, radius + 1):
			var x = center.x + dx
			var z = center.y + dz
			if x >= 0 and x < gridmap.columns and z >= 0 and z < gridmap.rows:
				gridmap.set_cell_item(Vector3i(x, 2, z), TILE_SAFE)
	
	# Notify local player
	var my_id = multiplayer.get_unique_id()
	var main = get_node_or_null("/root/Main")
	var player_node = main.get_node_or_null(str(my_id)) if main else null
	if player_node:
		NotificationManager.send_message(player_node, "⚠ Safe Zone spawned! Get inside!", NotificationManager.MessageType.WARNING)

@rpc("authority", "call_local", "reliable")
func sync_clear_safe_zone():
	"""Client: Clear the safe zone overlay."""
	var gridmap = get_parent().get_node_or_null("EnhancedGridMap")
	if not gridmap:
		gridmap = get_node_or_null("/root/Main/EnhancedGridMap")
	if not gridmap: return
	
	if safe_zone_center != Vector2i(-1, -1):
		for dx in range(-SAFE_ZONE_RADIUS, SAFE_ZONE_RADIUS + 1):
			for dz in range(-SAFE_ZONE_RADIUS, SAFE_ZONE_RADIUS + 1):
				var x = safe_zone_center.x + dx
				var z = safe_zone_center.y + dz
				if x >= 0 and x < gridmap.columns and z >= 0 and z < gridmap.rows:
					gridmap.set_cell_item(Vector3i(x, 2, z), -1)
	
	safe_zone_center = Vector2i(-1, -1)
	safe_zone_spawned = false

# =============================================================================
# Power-Up Tile Spawning (Speed & Ghost)
# =============================================================================

func _spawn_powerup_tiles():
	"""Server: Spawn 5 Speed & Ghost power-up tiles at random walkable positions."""
	if not multiplayer.is_server(): return
	
	var main = get_node_or_null("/root/Main")
	if not main: return
	
	var gridmap = main.get_node_or_null("EnhancedGridMap")
	if not gridmap: return
	
	# Collect valid positions (walkable floor, no existing item on Floor 1)
	var valid_positions: Array[Vector2i] = []
	for x in range(gridmap.columns):
		for z in range(gridmap.rows):
			var floor_tile = gridmap.get_cell_item(Vector3i(x, 0, z))
			# Skip void, obstacles, start, finish
			if floor_tile == -1 or floor_tile == TILE_OBSTACLE:
				continue
			# Skip cells that already have items on Floor 1
			var existing_item = gridmap.get_cell_item(Vector3i(x, 1, z))
			if existing_item != -1:
				continue
			valid_positions.append(Vector2i(x, z))
	
	if valid_positions.is_empty():
		print("[StopNGo] WARNING: No valid positions for power-up tiles!")
		return
	
	# Shuffle and pick up to POWERUP_SPAWN_COUNT positions
	var rng = RandomNumberGenerator.new()
	rng.randomize()
	valid_positions.shuffle()
	
	var spawn_count = min(POWERUP_SPAWN_COUNT, valid_positions.size())
	
	for i in range(spawn_count):
		var pos = valid_positions[i]
		var tile_id = POWERUP_TILES[rng.randi() % POWERUP_TILES.size()]
		
		# Place on Floor 1
		gridmap.set_cell_item(Vector3i(pos.x, 1, pos.y), tile_id)
		
		# Sync to all clients
		if can_rpc():
			main.rpc("sync_grid_item", pos.x, 1, pos.y, tile_id)
	
	print("[StopNGo] Spawned %d power-up tiles (Speed & Ghost)" % spawn_count)