using Godot;
using System;
using System.Collections.Generic;
using System.Linq;
using Chessistics.Engine.Commands;
using Chessistics.Engine.Events;
using Chessistics.Engine.Loading;
using Chessistics.Engine.Model;
using Chessistics.Engine.Simulation;
using Chessistics.Scripts.Automation;
using Chessistics.Scripts.Board;
using Chessistics.Scripts.Input;
using Chessistics.Scripts.Pieces;
using Chessistics.Scripts.Presentation;
using Chessistics.Scripts.UI;

namespace Chessistics.Scripts;

public partial class Main : Node2D
{
	private GameSim? _sim;
	private CampaignDef? _campaignDef;

	// Views
	private BoardView _boardView = null!;
	private InputMapper _inputMapper = null!;
	private EventAnimator _eventAnimator = null!;

	// UI
	private CanvasLayer _uiLayer = null!;
	private ObjectivePanel _objectivePanel = null!;
	private PieceStockPanel _pieceStockPanel = null!;
	private DetailPanel _detailPanel = null!;
	private ControlBar _controlBar = null!;
	private MetricsOverlay _metricsOverlay = null!;
	private LevelSelectScreen _titleScreen = null!;
	private Label _levelTitle = null!;
	private PanelContainer _sidePanel = null!;
	private PanelContainer _controlBarWrapper = null!;
	private Camera2D _camera = null!;
	private ColorRect _fadeOverlay = null!;
	private FlavorBanner _flavorBanner = null!;
	private Label _collisionToast = null!;

	// Simulation timer
	private Godot.Timer _simTimer = null!;
	private float _simInterval = 1.0f;
	private bool _running;
	private bool _panning;
	private bool _rightDragged;
	private bool _collisionPauseOccurred;
	private const float CameraKeyboardSpeed = 400f;

	private const float SidePanelWidth = 280f;
	private const float ControlBarHeight = 48f;
	private const float TitleBarHeight = 40f;

	private static readonly Color BackgroundColor = new("#2D2D2D");

	// Automation harness (active only when --automation=<dir> CLI flag is given)
	private string? _automationDir;
	private AutomationHarness? _automationHarness;

	public override void _Ready()
	{
		RenderingServer.SetDefaultClearColor(BackgroundColor);

		_automationDir = ParseAutomationArg();

		BuildSceneTree();
		ConnectSignals();
		ShowTitleScreen();

		if (_automationDir != null)
		{
			// Skip the opening fade so the harness sees a stable frame immediately.
			_fadeOverlay.Color = new Color(0, 0, 0, 0);
			MountAutomationHarness(_automationDir);
		}
		else
		{
			FadeIn(0.5f);
		}
	}

	private static string? ParseAutomationArg()
	{
		foreach (var arg in OS.GetCmdlineArgs())
		{
			if (arg.StartsWith("--automation=", StringComparison.Ordinal))
				return arg.Substring("--automation=".Length);
		}
		return null;
	}

	private void MountAutomationHarness(string dir)
	{
		var facade = new AutomationFacade(
			sim: () => _sim,
			input: _inputMapper,
			animator: _eventAnimator,
			stock: _pieceStockPanel,
			controlBar: _controlBar,
			loadMission: HarnessLoadMission,
			play: OnPlay,
			pause: OnPause,
			step: OnStep,
			togglePlayPause: TogglePlayPause,
			backToMenu: HarnessBackToMenu,
			setSpeed: HarnessSetSpeed,
			quit: () => GetTree().Quit(),
			quickSave: OnQuickSave,
			quickLoad: OnQuickLoad,
			undo: OnUndo);

		_automationHarness = new AutomationHarness(dir, facade);
		AddChild(_automationHarness);
	}

	private void HarnessLoadMission(string campaignName, int missionIndex)
	{
		var path = $"res://Data/campaigns/{campaignName}.json";
		LoadCampaignDirect(path);

		// Fast-forward to the requested mission by completing prior ones synthetically.
		while (_sim != null && _campaignDef != null
			&& _sim.GetSnapshot().Campaign is { } campSnap
			&& campSnap.CurrentMissionIndex < missionIndex)
		{
			_sim.ProcessCommand(new PauseSimulationCommand()); // no-op if already paused
			// Cheat the phase to MissionComplete then Advance — only valid in automation.
			// Simpler: refuse non-zero missionIndex for now and require AdvanceMission
			// via gameplay. Breaking the break keeps harness predictable.
			GD.PrintErr($"[Automation] missionIndex > 0 not supported yet; staying at mission {campSnap.CurrentMissionIndex}");
			break;
		}
	}

	private void HarnessBackToMenu()
	{
		_running = false;
		_simTimer.Stop();
		_eventAnimator.ClearAll();
		ShowTitleScreen();
	}

	private void HarnessSetSpeed(float interval)
	{
		_simInterval = interval;
		OnSpeedChanged(interval);
	}

	public override void _UnhandledInput(InputEvent @event)
	{
		if (@event is InputEventMouseButton mb)
		{
			if (mb.ButtonIndex == MouseButton.Middle)
			{
				_panning = mb.Pressed;
			}
			else if (mb.ButtonIndex == MouseButton.Right)
			{
				if (mb.Pressed)
				{
					_panning = true;
					_rightDragged = false;
				}
				else
				{
					_panning = false;
					if (!_rightDragged)
					{
						_inputMapper.Cancel();
						_pieceStockPanel.ClearSelection();
					}
				}
			}
			else if (mb.Pressed && mb.ButtonIndex == MouseButton.WheelUp)
				ZoomCamera(1.1f);
			else if (mb.Pressed && mb.ButtonIndex == MouseButton.WheelDown)
				ZoomCamera(0.9f);
		}
		else if (@event is InputEventMouseMotion motion && _panning)
		{
			_rightDragged = true;
			_camera.Position -= motion.Relative / _camera.Zoom;
		}
		else if (@event is InputEventKey key && key.Pressed && !key.Echo)
		{
			if (key.Keycode == Key.Space)
			{
				TogglePlayPause();
				GetViewport().SetInputAsHandled();
			}
			else if (key.Keycode == Key.F5)
			{
				OnQuickSave();
				GetViewport().SetInputAsHandled();
			}
			else if (key.Keycode == Key.F9)
			{
				OnQuickLoad();
				GetViewport().SetInputAsHandled();
			}
			else if (key.Keycode == Key.Z && key.CtrlPressed)
			{
				OnUndo();
				GetViewport().SetInputAsHandled();
			}
		}
	}

	public override void _Process(double delta)
	{
		var dir = Vector2.Zero;
		if (Godot.Input.IsKeyPressed(Key.Z) || Godot.Input.IsKeyPressed(Key.W))
			dir.Y -= 1;
		if (Godot.Input.IsKeyPressed(Key.S))
			dir.Y += 1;
		if (Godot.Input.IsKeyPressed(Key.Q) || Godot.Input.IsKeyPressed(Key.A))
			dir.X -= 1;
		if (Godot.Input.IsKeyPressed(Key.D))
			dir.X += 1;

		if (dir != Vector2.Zero)
			_camera.Position += dir.Normalized() * CameraKeyboardSpeed * (float)delta / _camera.Zoom.X;
	}

	private void ZoomCamera(float factor)
	{
		var newZoom = _camera.Zoom * factor;
		newZoom = newZoom.Clamp(new Vector2(0.3f, 0.3f), new Vector2(3f, 3f));
		_camera.Zoom = newZoom;
	}

	private void FadeIn(float duration)
	{
		_fadeOverlay.Color = new Color(0, 0, 0, 1);
		var tween = CreateTween();
		tween.TweenProperty(_fadeOverlay, "color:a", 0f, duration)
			.SetEase(Tween.EaseType.Out);
	}

	private void FadeOut(float duration, Action onComplete)
	{
		_fadeOverlay.Color = new Color(0, 0, 0, 0);
		var tween = CreateTween();
		tween.TweenProperty(_fadeOverlay, "color:a", 1f, duration)
			.SetEase(Tween.EaseType.In);
		tween.TweenCallback(Callable.From(onComplete));
	}

	private void BuildSceneTree()
	{
		_camera = new Camera2D { Enabled = true };
		AddChild(_camera);

		var sfx = new SfxManager();
		AddChild(sfx);

		_boardView = new BoardView();
		AddChild(_boardView);

		_inputMapper = new InputMapper();
		_inputMapper.Initialize(_boardView);
		AddChild(_inputMapper);

		_eventAnimator = new EventAnimator();
		AddChild(_eventAnimator);

		_simTimer = new Godot.Timer { OneShot = false, WaitTime = _simInterval };
		_simTimer.Timeout += OnSimTimerTick;
		AddChild(_simTimer);

		// --- UI Layer ---
		_uiLayer = new CanvasLayer();
		AddChild(_uiLayer);

		var uiRoot = new Control();
		uiRoot.SetAnchorsPreset(Control.LayoutPreset.FullRect);
		uiRoot.MouseFilter = Control.MouseFilterEnum.Ignore;
		_uiLayer.AddChild(uiRoot);

		// Title bar
		var titleBar = new HBoxContainer();
		titleBar.SetAnchorsPreset(Control.LayoutPreset.TopLeft);
		titleBar.OffsetLeft = 12;
		titleBar.OffsetTop = 8;
		titleBar.AddThemeConstantOverride("separation", 12);

		var backButton = new Button { Text = "← Menu", CustomMinimumSize = new Vector2(70, 28) };
		backButton.AddThemeFontSizeOverride("font_size", 11);
		var backStyle = new StyleBoxFlat
		{
			BgColor = new Color("#2A2A2E"),
			BorderColor = new Color("#444448"),
			BorderWidthBottom = 1, BorderWidthTop = 1, BorderWidthLeft = 1, BorderWidthRight = 1,
			CornerRadiusTopLeft = 4, CornerRadiusTopRight = 4,
			CornerRadiusBottomLeft = 4, CornerRadiusBottomRight = 4,
			ContentMarginLeft = 8, ContentMarginRight = 8,
			ContentMarginTop = 2, ContentMarginBottom = 2
		};
		backButton.AddThemeStyleboxOverride("normal", backStyle);
		backButton.Pressed += OnBackToMenu;
		titleBar.AddChild(backButton);

		_levelTitle = new Label { Text = "CHESSISTICS" };
		_levelTitle.AddThemeFontSizeOverride("font_size", 20);
		_levelTitle.MouseFilter = Control.MouseFilterEnum.Ignore;
		titleBar.AddChild(_levelTitle);

		uiRoot.AddChild(titleBar);

		// --- Side Panel ---
		_sidePanel = new PanelContainer();
		_sidePanel.AnchorLeft = 1.0f;
		_sidePanel.AnchorRight = 1.0f;
		_sidePanel.AnchorTop = 0.0f;
		_sidePanel.AnchorBottom = 1.0f;
		_sidePanel.OffsetLeft = -SidePanelWidth;
		_sidePanel.OffsetRight = 0;
		_sidePanel.OffsetTop = 0;
		_sidePanel.OffsetBottom = -ControlBarHeight;

		var sidePanelStyle = new StyleBoxFlat
		{
			BgColor = new Color(0.14f, 0.14f, 0.16f, 0.97f),
			BorderColor = new Color(0.25f, 0.25f, 0.28f),
			BorderWidthLeft = 1,
			ContentMarginLeft = 16, ContentMarginRight = 16,
			ContentMarginTop = 16, ContentMarginBottom = 16
		};
		_sidePanel.AddThemeStyleboxOverride("panel", sidePanelStyle);

		var sideScroll = new ScrollContainer
		{
			HorizontalScrollMode = ScrollContainer.ScrollMode.Disabled,
			SizeFlagsVertical = Control.SizeFlags.ExpandFill
		};

		var sideVBox = new VBoxContainer();
		sideVBox.AddThemeConstantOverride("separation", 12);

		_objectivePanel = new ObjectivePanel();
		sideVBox.AddChild(_objectivePanel);
		sideVBox.AddChild(new HSeparator());

		_pieceStockPanel = new PieceStockPanel();
		sideVBox.AddChild(_pieceStockPanel);

		_detailPanel = new DetailPanel();
		sideVBox.AddChild(_detailPanel);

		sideScroll.AddChild(sideVBox);
		_sidePanel.AddChild(sideScroll);
		uiRoot.AddChild(_sidePanel);

		// --- Control Bar ---
		_controlBarWrapper = new PanelContainer();
		_controlBarWrapper.AnchorLeft = 0.0f;
		_controlBarWrapper.AnchorRight = 1.0f;
		_controlBarWrapper.AnchorTop = 1.0f;
		_controlBarWrapper.AnchorBottom = 1.0f;
		_controlBarWrapper.OffsetTop = -ControlBarHeight;
		_controlBarWrapper.OffsetRight = -SidePanelWidth;

		var controlBarStyle = new StyleBoxFlat
		{
			BgColor = new Color(0.11f, 0.11f, 0.13f, 0.97f),
			BorderColor = new Color(0.25f, 0.25f, 0.28f),
			BorderWidthTop = 1,
			ContentMarginLeft = 12, ContentMarginRight = 12,
			ContentMarginTop = 4, ContentMarginBottom = 4
		};
		_controlBarWrapper.AddThemeStyleboxOverride("panel", controlBarStyle);

		_controlBar = new ControlBar();
		_controlBarWrapper.AddChild(_controlBar);
		uiRoot.AddChild(_controlBarWrapper);

		// --- Metrics Overlay ---
		var metricsCenter = new CenterContainer();
		metricsCenter.SetAnchorsPreset(Control.LayoutPreset.FullRect);
		metricsCenter.OffsetRight = -SidePanelWidth;
		metricsCenter.OffsetBottom = -ControlBarHeight;
		metricsCenter.MouseFilter = Control.MouseFilterEnum.Ignore;

		_metricsOverlay = new MetricsOverlay();
		_metricsOverlay.CustomMinimumSize = new Vector2(340, 260);
		metricsCenter.AddChild(_metricsOverlay);
		uiRoot.AddChild(metricsCenter);

		// --- Title Screen ---
		_titleScreen = new LevelSelectScreen();
		_titleScreen.SetAnchorsPreset(Control.LayoutPreset.FullRect);
		uiRoot.AddChild(_titleScreen);

		// --- Collision toast (hidden by default, shown on collision) ---
		_collisionToast = new Label
		{
			Text = "",
			Visible = false,
			MouseFilter = Control.MouseFilterEnum.Ignore
		};
		_collisionToast.AddThemeFontSizeOverride("font_size", 14);
		_collisionToast.AddThemeColorOverride("font_color", new Color("#FFE8D0"));
		_collisionToast.AddThemeColorOverride("font_outline_color", new Color(0, 0, 0, 0.8f));
		_collisionToast.AddThemeConstantOverride("outline_size", 4);
		_collisionToast.AnchorLeft = 0.0f;
		_collisionToast.AnchorRight = 0.0f;
		_collisionToast.AnchorTop = 1.0f;
		_collisionToast.AnchorBottom = 1.0f;
		_collisionToast.OffsetLeft = 20;
		_collisionToast.OffsetRight = 400;
		_collisionToast.OffsetTop = -ControlBarHeight - 60;
		_collisionToast.OffsetBottom = -ControlBarHeight - 20;
		uiRoot.AddChild(_collisionToast);

		// --- Flavor Banner (narrative text) ---
		_flavorBanner = new FlavorBanner();
		_flavorBanner.AnchorLeft = 0.1f;
		_flavorBanner.AnchorRight = 0.7f;
		_flavorBanner.AnchorTop = 0.0f;
		_flavorBanner.AnchorBottom = 0.0f;
		_flavorBanner.OffsetTop = 44; // Below title bar
		_flavorBanner.OffsetBottom = 100;
		uiRoot.AddChild(_flavorBanner);

		// --- Fade overlay ---
		_fadeOverlay = new ColorRect
		{
			Color = new Color(0, 0, 0, 1),
			MouseFilter = Control.MouseFilterEnum.Ignore
		};
		_fadeOverlay.SetAnchorsPreset(Control.LayoutPreset.FullRect);
		uiRoot.AddChild(_fadeOverlay);

		_eventAnimator.Initialize(_boardView, _objectivePanel, _controlBar, _metricsOverlay);
	}

	private void ConnectSignals()
	{
		_titleScreen.StartCampaignPressed += OnStartCampaign;
		_pieceStockPanel.PieceSelected += OnPieceKindSelected;
		_inputMapper.PlacementRequested += OnPlacementRequested;
		_inputMapper.Cancelled += OnPlacementCancelled;
		_inputMapper.RelocateRequested += OnRelocateRequested;
		_controlBar.PlayPressed += OnPlay;
		_controlBar.PausePressed += OnPause;
		_controlBar.StepPressed += OnStep;
		_controlBar.SpeedChanged += OnSpeedChanged;
		_eventAnimator.TurnAnimationCompleted += OnTurnAnimationCompleted;
		_eventAnimator.VictoryReached += OnCampaignComplete;
		_eventAnimator.MissionAdvanced += OnMissionAdvanced;
		_eventAnimator.CollisionOccurred += OnCollisionOccurred;
		_metricsOverlay.NextLevelPressed += OnBackToMenu;
		_detailPanel.RemoveRequested += OnRemoveRequested;
		_inputMapper.CellClicked += OnCellClicked;
	}

	private void OnCellClicked(int col, int row)
	{
		if (_sim == null) return;
		var snap = _sim.GetSnapshot();

		_boardView.ClearHighlights();

		var coords = new Coords(col, row);
		var piece = snap.Pieces.FirstOrDefault(p => p.StartCell == coords || p.EndCell == coords);
		if (piece != null)
		{
			_detailPanel.ShowPiece(piece);
			var pieceColor = PieceView.GetPieceColor(piece.Kind);
			var highlightColor = new Color(pieceColor, 0.3f);
			_boardView.HighlightCells([piece.StartCell, piece.EndCell], highlightColor);
		}
		else
		{
			_detailPanel.Hide();
		}
	}

	// --- Campaign Management ---

	private void ShowTitleScreen()
	{
		_titleScreen.Visible = true;
		_boardView.Visible = false;
		_sidePanel.Visible = false;
		_controlBarWrapper.Visible = false;
		_levelTitle.Visible = false;
	}

	private void OnStartCampaign()
	{
		SfxManager.Instance?.PlayClick();

		FadeOut(0.25f, () =>
		{
			LoadCampaign();
			FadeIn(0.3f);
		});
	}

	private void LoadCampaign() => LoadCampaignDirect("res://Data/campaigns/campaign_01.json");

	private void LoadCampaignDirect(string path)
	{
		var file = Godot.FileAccess.Open(path, Godot.FileAccess.ModeFlags.Read);
		if (file == null)
		{
			GD.PrintErr($"Cannot open campaign file: {path}");
			return;
		}

		var json = file.GetAsText();
		file.Close();

		_campaignDef = CampaignLoader.Load(json);
		_sim = new GameSim(_campaignDef);

		// Load campaign: applies mission 0 terrain, stock, unlocked pieces
		var loadEvents = _sim.ProcessCommand(new LoadCampaignCommand());
		foreach (var evt in loadEvents)
		{
			if (evt is CommandRejectedEvent r)
			{
				GD.PrintErr($"Cannot load campaign: {r.Reason}");
				return;
			}
		}

		_titleScreen.Visible = false;
		_boardView.Visible = true;
		_sidePanel.Visible = true;
		_controlBarWrapper.Visible = true;
		_levelTitle.Visible = true;

		var snap = _sim.GetSnapshot();
		var mission = _campaignDef.Missions[snap.Campaign!.CurrentMissionIndex];

		BuildBoardFromSnapshot(snap);
		SetupUIForMission(snap, mission);

		CenterCameraOnBoard(snap.Width, snap.Height);
		_inputMapper.SetSnapshot(snap);
	}

	private void BuildBoardFromSnapshot(BoardSnapshot snap)
	{
		_eventAnimator.ClearAll();
		_boardView.BuildBoardFromSnapshot(snap);

		// Recreate piece visuals if any exist
		foreach (var ps in snap.Pieces)
		{
			var pieceView = new PieceView();
			pieceView.Setup(ps.Id, ps.Kind, ps.StartCell, ps.EndCell, _boardView);
			_boardView.AddChild(pieceView);

			var color = PieceView.GetPieceColor(ps.Kind);
			var trajectView = new TrajectView();
			trajectView.Setup(ps.Id,
				_boardView.CoordsToPixel(ps.StartCell),
				_boardView.CoordsToPixel(ps.EndCell),
				color);
			_boardView.AddChild(trajectView);

			_eventAnimator.RegisterPiece(ps.Id, pieceView, trajectView);
		}
	}

	private void SetupUIForMission(BoardSnapshot snap, MissionDef mission)
	{
		// Show all demands (current + previous missions)
		var allDemands = snap.Demands
			.Select(d => new DemandDef(d.Position, d.Name, d.Cargo, d.Required))
			.ToList();

		_objectivePanel.Setup(allDemands);

		// Setup stock panel with only unlocked piece kinds
		var availableStock = new List<PieceStock>();
		foreach (var (kind, remaining) in snap.RemainingStock)
		{
			if (snap.Campaign != null && !snap.Campaign.AvailablePieceKinds.Contains(kind))
				continue;
			availableStock.Add(new PieceStock(kind, remaining));
		}
		_pieceStockPanel.Setup(availableStock);

		_controlBar.UpdateForPhase(snap.Phase);
		_controlBar.ResetTurn();
		_metricsOverlay.Hide();
		_detailPanel.Hide();

		var missionNum = snap.Campaign!.CurrentMissionIndex + 1;
		var totalMissions = _campaignDef!.Missions.Count;
		_levelTitle.Text = $"CHESSISTICS — Mission {missionNum}/{totalMissions}: {mission.Name}";

		// Show narrative flavor text
		_flavorBanner.ShowFlavor(mission.Flavor);
	}

	private void CenterCameraOnBoard(int width, int height)
	{
		_camera.Position = new Vector2(
			width * BoardView.CellSize / 2f,
			-height * BoardView.CellSize / 2f + BoardView.CellSize
		);
		// Offset: shift view to account for side panel (right) and title/control bars
		// Positive X → camera looks right → board appears left (compensates right panel)
		// Positive Y → camera looks down → board appears up (compensates bottom bar)
		_camera.Offset = new Vector2(SidePanelWidth / 2f, (ControlBarHeight - TitleBarHeight) / 2f);
	}

	// --- Placement ---

	private void OnPieceKindSelected(int kindIndex)
	{
		_inputMapper.SelectPieceKind((PieceKind)kindIndex);
	}

	private void OnPlacementRequested(int kindIndex, int startCol, int startRow, int endCol, int endRow)
	{
		if (_sim == null) return;

		var kind = (PieceKind)kindIndex;
		var start = new Coords(startCol, startRow);
		var end = new Coords(endCol, endRow);

		var events = _sim.ProcessCommand(new PlacePieceCommand(kind, start, end));
		HandleEditEvents(events);
		_inputMapper.SetSnapshot(_sim.GetSnapshot());
		_pieceStockPanel.ClearSelection();
	}

	private void OnPlacementCancelled()
	{
		_pieceStockPanel.ClearSelection();
	}

	private void OnRelocateRequested(int pieceId, int newStartCol, int newStartRow, int newEndCol, int newEndRow)
	{
		if (_sim == null) return;
		var newStart = new Coords(newStartCol, newStartRow);
		var newEnd = new Coords(newEndCol, newEndRow);
		var events = _sim.ProcessCommand(new MovePieceCommand(pieceId, newStart, newEnd));
		foreach (var evt in events)
		{
			switch (evt)
			{
				case PieceMovedByPlayerEvent moved:
					UpdatePieceVisualPosition(moved);
					_detailPanel.Hide();
					break;
				case CommandRejectedEvent rejected:
					GD.Print($"Move rejected: {rejected.Reason}");
					break;
			}
		}
		_inputMapper.SetSnapshot(_sim.GetSnapshot());
	}

	private void UpdatePieceVisualPosition(PieceMovedByPlayerEvent moved)
	{
		// Refresh from snapshot — the cleanest path is a full rebuild of this piece's visuals
		if (_sim == null) return;
		_eventAnimator.UnregisterPiece(moved.PieceId);

		var snap = _sim.GetSnapshot();
		var ps = snap.Pieces.FirstOrDefault(p => p.Id == moved.PieceId);
		if (ps == null) return;

		var pieceView = new PieceView();
		pieceView.Setup(ps.Id, ps.Kind, ps.StartCell, ps.EndCell, _boardView);
		_boardView.AddChild(pieceView);

		var color = PieceView.GetPieceColor(ps.Kind);
		var trajectView = new TrajectView();
		trajectView.Setup(ps.Id,
			_boardView.CoordsToPixel(ps.StartCell),
			_boardView.CoordsToPixel(ps.EndCell),
			color);
		_boardView.AddChild(trajectView);

		_eventAnimator.RegisterPiece(ps.Id, pieceView, trajectView);
	}

	private void OnRemoveRequested(int pieceId)
	{
		if (_sim == null) return;

		var events = _sim.ProcessCommand(new RemovePieceCommand(pieceId));
		HandleEditEvents(events);
		_inputMapper.SetSnapshot(_sim.GetSnapshot());
	}

	private void HandleEditEvents(IReadOnlyList<IWorldEvent> events)
	{
		foreach (var evt in events)
		{
			switch (evt)
			{
				case PiecePlacedEvent placed:
					CreatePieceVisual(placed);
					UpdateStockFromSnapshot();
					break;

				case PieceRemovedEvent removed:
					_eventAnimator.UnregisterPiece(removed.PieceId);
					UpdateStockFromSnapshot();
					_detailPanel.Hide();
					break;

				case PlacementRejectedEvent rejected:
					GD.Print($"Placement rejected: {rejected.Reason}");
					break;

				case CommandRejectedEvent rejected:
					GD.Print($"Command rejected: {rejected.Reason}");
					break;
			}
		}
	}

	private void CreatePieceVisual(PiecePlacedEvent placed)
	{
		SfxManager.Instance?.PlayPlace();

		var pieceView = new PieceView();
		pieceView.Setup(placed.PieceId, placed.Kind, placed.Start, placed.End, _boardView);
		_boardView.AddChild(pieceView);

		var color = PieceView.GetPieceColor(placed.Kind);
		var trajectView = new TrajectView();
		trajectView.Setup(placed.PieceId,
			_boardView.CoordsToPixel(placed.Start),
			_boardView.CoordsToPixel(placed.End),
			color);
		_boardView.AddChild(trajectView);

		_eventAnimator.RegisterPiece(placed.PieceId, pieceView, trajectView);
	}

	private void UpdateStockFromSnapshot()
	{
		if (_sim == null) return;
		var snap = _sim.GetSnapshot();
		foreach (var (kind, remaining) in snap.RemainingStock)
			_pieceStockPanel.UpdateCount(kind, remaining);
	}

	// --- Simulation Control ---

	private void TogglePlayPause()
	{
		if (_sim == null) return;
		var phase = _sim.GetSnapshot().Phase;
		if (phase == SimPhase.Running)
			OnPause();
		else if (phase == SimPhase.Paused)
			OnPlay();
	}

	private void OnPlay()
	{
		if (_sim == null) return;

		var snap = _sim.GetSnapshot();
		if (snap.Phase == SimPhase.Paused || snap.Phase == SimPhase.MissionComplete)
		{
			_sim.ProcessCommand(new ResumeSimulationCommand());
		}

		_running = true;
		_controlBar.UpdateForPhase(SimPhase.Running);
		_simTimer.WaitTime = _simInterval;
		_simTimer.Start();
	}

	private void OnPause()
	{
		if (_sim == null) return;
		_sim.ProcessCommand(new PauseSimulationCommand());
		_running = false;
		_simTimer.Stop();
		_controlBar.UpdateForPhase(SimPhase.Paused);
	}

	private void OnStep()
	{
		if (_sim == null || _eventAnimator.IsAnimating) return;

		_collisionPauseOccurred = false;
		var events = _sim.ProcessCommand(new StepSimulationCommand());

		// Detect if a collision auto-pause happened this step
		_collisionPauseOccurred = events.Any(e => e is PieceReturnedToStockEvent);

		_eventAnimator.ProcessEvents(events);
		_controlBar.UpdateForPhase(_sim.GetSnapshot().Phase);
	}

	private void OnSpeedChanged(float interval)
	{
		_simInterval = interval;
		if (_simTimer.TimeLeft > 0)
			_simTimer.WaitTime = interval;
	}

	private void OnSimTimerTick()
	{
		if (_sim == null || _eventAnimator.IsAnimating) return;

		_collisionPauseOccurred = false;
		var events = _sim.ProcessCommand(new StepSimulationCommand());

		_collisionPauseOccurred = events.Any(e => e is PieceReturnedToStockEvent);

		_eventAnimator.ProcessEvents(events);
	}

	private void OnTurnAnimationCompleted()
	{
		if (_sim == null) return;
		var phase = _sim.GetSnapshot().Phase;
		_controlBar.UpdateForPhase(phase);

		if (phase == SimPhase.MissionComplete)
		{
			// Stop auto-running, show mission complete overlay
			_running = false;
			_simTimer.Stop();
		}
		else if (_collisionPauseOccurred && _running)
		{
			// Collision caused auto-pause — stop the timer
			_running = false;
			_simTimer.Stop();
			_collisionPauseOccurred = false;
		}
		// Otherwise: if _running, the timer will fire next step automatically
	}

	private void OnCampaignComplete()
	{
		// Last mission complete — show victory overlay
		_running = false;
		_simTimer.Stop();

		if (_sim == null || _campaignDef == null) return;

		var snap = _sim.GetSnapshot();
		_metricsOverlay.ShowMissionComplete(
			snap.Campaign!.CurrentMissionIndex + 1,
			snap.TurnNumber,
			true
		);
	}

	private void OnQuickSave()
	{
		if (_sim == null) return;
		var events = _sim.QuickSave();
		foreach (var evt in events)
		{
			if (evt is StateSavedEvent saved)
				GD.Print($"[QuickSave] Slot {saved.SlotId} — turn {saved.TurnNumber}");
		}
	}

	private void OnQuickLoad()
	{
		if (_sim == null || _campaignDef == null) return;
		if (!_sim.HasSave())
		{
			GD.Print("[QuickLoad] No save available");
			return;
		}

		// Halt any running simulation loop before rebuilding visuals
		_running = false;
		_simTimer.Stop();

		var events = _sim.QuickLoad();
		foreach (var evt in events)
		{
			if (evt is StateRestoredEvent restored)
			{
				GD.Print($"[QuickLoad] Slot {restored.SlotId} — turn {restored.Snapshot.TurnNumber}");
				ApplyRestoredSnapshot(restored.Snapshot);
			}
		}
	}

	private void OnCollisionOccurred(int col, int row, string victimKind, int destroyerId)
	{
		if (_sim == null) return;

		// Pan + slight zoom to the collision cell
		var cellPixel = _boardView.CoordsToPixel(new Coords(col, row));
		var originalZoom = _camera.Zoom;
		var targetZoom = originalZoom * 1.4f;
		var tween = CreateTween();
		tween.SetParallel(true);
		tween.TweenProperty(_camera, "position", cellPixel, 0.45f)
			.SetEase(Tween.EaseType.Out).SetTrans(Tween.TransitionType.Cubic);
		tween.TweenProperty(_camera, "zoom", targetZoom, 0.45f)
			.SetEase(Tween.EaseType.Out).SetTrans(Tween.TransitionType.Cubic);

		// Compose toast message
		string message;
		if (destroyerId < 0)
		{
			message = $"{victimKind} détruit (collision mutuelle) — retourné au stock";
		}
		else
		{
			var snap = _sim.GetSnapshot();
			var dp = snap.Pieces.FirstOrDefault(p => p.Id == destroyerId);
			var destroyer = dp?.Kind.ToString() ?? "?";
			message = $"{victimKind} détruit par {destroyer} — retourné au stock";
		}
		_collisionToast.Text = message;
		_collisionToast.Modulate = new Color(1, 1, 1, 0);
		_collisionToast.Visible = true;
		var fadeIn = _collisionToast.CreateTween();
		fadeIn.TweenProperty(_collisionToast, "modulate:a", 1f, 0.2f);
		fadeIn.TweenInterval(3.0f);
		fadeIn.TweenProperty(_collisionToast, "modulate:a", 0f, 0.5f);
		fadeIn.TweenCallback(Callable.From(() => _collisionToast.Visible = false));
	}

	private void OnUndo()
	{
		if (_sim == null) return;
		if (!_sim.CanUndo)
		{
			GD.Print("[Undo] Nothing to undo");
			return;
		}

		_running = false;
		_simTimer.Stop();

		var events = _sim.Undo();
		foreach (var evt in events)
		{
			if (evt is StateRestoredEvent restored)
			{
				GD.Print($"[Undo] Reverted to turn {restored.Snapshot.TurnNumber}");
				ApplyRestoredSnapshot(restored.Snapshot);
			}
		}
	}

	private void ApplyRestoredSnapshot(BoardSnapshot snap)
	{
		if (_campaignDef == null) return;

		var mission = _campaignDef.Missions[snap.Campaign!.CurrentMissionIndex];

		BuildBoardFromSnapshot(snap);
		SetupUIForMission(snap, mission);

		CenterCameraOnBoard(snap.Width, snap.Height);
		_inputMapper.SetSnapshot(snap);
		_controlBar.UpdateTurn(snap.TurnNumber);
		_controlBar.UpdateForPhase(snap.Phase);
	}

	private void OnMissionAdvanced()
	{
		// Auto-advance happened during simulation — rebuild board seamlessly
		if (_sim == null || _campaignDef == null) return;

		var snap = _sim.GetSnapshot();
		var mission = _campaignDef.Missions[snap.Campaign!.CurrentMissionIndex];

		BuildBoardFromSnapshot(snap);
		SetupUIForMission(snap, mission);

		CenterCameraOnBoard(snap.Width, snap.Height);
		_inputMapper.SetSnapshot(snap);
	}

	// --- Navigation ---

	private void OnBackToMenu()
	{
		SfxManager.Instance?.PlayClick();
		_running = false;
		_simTimer.Stop();
		_eventAnimator.ClearAll();

		FadeOut(0.2f, () =>
		{
			ShowTitleScreen();
			FadeIn(0.3f);
		});
	}
}