/**** 
* Plugins
****/ 
var tween = LK.import("@upit/tween.v1");

/**** 
* Classes
****/ 
// BuildTile class (for tower placement)
var BuildTile = Container.expand(function () {
	var self = Container.call(this);
	// Attach tile asset (box, light gray)
	var tileAsset = self.attachAsset('buildTile', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.occupied = false;
	self.tower = null;
	// For highlighting
	self.highlight = function (on) {
		tileAsset.tint = on ? 0x2ecc40 : 0xbdc3c7;
	};
	return self;
});
// Bullet class
var Bullet = Container.expand(function () {
	var self = Container.call(this);
	// Attach bullet asset (small yellow box)
	var bulletAsset = self.attachAsset('bullet', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.target = null;
	self.damage = 5;
	self.speed = 24;
	self.update = function () {
		if (!self.target || self.target.health <= 0 || self.target.reachedBase) {
			self.destroyed = true;
			return;
		}
		var dx = self.target.x - self.x;
		var dy = self.target.y - self.y;
		var dist = Math.sqrt(dx * dx + dy * dy);
		if (dist < 32) {
			// Hit
			self.target.takeDamage(self.damage);
			self.destroyed = true;
			return;
		}
		var moveDist = Math.min(self.speed, dist);
		self.x += dx / dist * moveDist;
		self.y += dy / dist * moveDist;
	};
	return self;
});
// Enemy (Creep) class
var Enemy = Container.expand(function () {
	var self = Container.call(this);
	// Attach enemy asset (ellipse, purple)
	var enemyAsset = self.attachAsset('enemy', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	// Enemy stats
	self.maxHealth = 10 + (currentWave - 1) * 5;
	self.health = self.maxHealth;
	self.speed = 2 + (currentWave - 1) * 0.2; // Slightly faster each wave
	self.reward = 5 + (currentWave - 1) * 2;
	// Path progress
	self.pathIndex = 0;
	self.pathProgress = 0;
	// For hit flash
	self.isFlashing = false;
	// Move along path
	self.update = function () {
		if (self.pathIndex >= path.length - 1) return;
		var from = path[self.pathIndex];
		var to = path[self.pathIndex + 1];
		var dx = to.x - from.x;
		var dy = to.y - from.y;
		var dist = Math.sqrt(dx * dx + dy * dy);
		if (dist === 0) {
			self.pathIndex++;
			self.pathProgress = 0;
			return;
		}
		var moveDist = self.speed;
		self.pathProgress += moveDist;
		if (self.pathProgress >= dist) {
			self.pathIndex++;
			self.pathProgress = 0;
			if (self.pathIndex >= path.length - 1) {
				// Reached end
				self.x = to.x;
				self.y = to.y;
				self.reachedBase = true;
				return;
			}
		}
		var t = self.pathProgress / dist;
		self.x = from.x + dx * t;
		self.y = from.y + dy * t;
	};
	// Take damage
	self.takeDamage = function (dmg) {
		self.health -= dmg;
		if (!self.isFlashing) {
			self.isFlashing = true;
			tween(enemyAsset, {
				tint: 0xffffff
			}, {
				duration: 80,
				onFinish: function onFinish() {
					tween(enemyAsset, {
						tint: 0x8e44ad
					}, {
						duration: 120,
						onFinish: function onFinish() {
							self.isFlashing = false;
						}
					});
				}
			});
		}
	};
	return self;
});
// Tower class
var Tower = Container.expand(function () {
	var self = Container.call(this);
	// Attach tower asset (box, blue)
	var towerAsset = self.attachAsset('tower', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	// Tower stats
	self.level = 1;
	self.range = 320;
	self.damage = 5;
	self.fireRate = 60; // frames per shot
	self.cooldown = 0;
	// For upgrade flash
	self.isFlashing = false;
	// Show range circle (for placement)
	self.rangeCircle = self.attachAsset('rangeCircle', {
		anchorX: 0.5,
		anchorY: 0.5,
		alpha: 0.15
	});
	self.rangeCircle.width = self.range * 2;
	self.rangeCircle.height = self.range * 2;
	self.rangeCircle.visible = false;
	// Upgrade tower
	self.upgrade = function () {
		if (self.level >= 3) return false;
		self.level++;
		self.damage += 5;
		self.range += 40;
		self.fireRate = Math.max(30, self.fireRate - 10);
		self.rangeCircle.width = self.range * 2;
		self.rangeCircle.height = self.range * 2;
		// Flash for upgrade
		if (!self.isFlashing) {
			self.isFlashing = true;
			tween(towerAsset, {
				tint: 0xffff00
			}, {
				duration: 120,
				onFinish: function onFinish() {
					tween(towerAsset, {
						tint: 0x3498db
					}, {
						duration: 180,
						onFinish: function onFinish() {
							self.isFlashing = false;
						}
					});
				}
			});
		}
		return true;
	};
	// Tower attack logic
	self.update = function () {
		if (self.cooldown > 0) {
			self.cooldown--;
			return;
		}
		// Find nearest enemy in range
		var nearest = null;
		var minDist = 99999;
		for (var i = 0; i < enemies.length; i++) {
			var e = enemies[i];
			var dx = e.x - self.x;
			var dy = e.y - self.y;
			var dist = Math.sqrt(dx * dx + dy * dy);
			if (dist <= self.range && dist < minDist) {
				nearest = e;
				minDist = dist;
			}
		}
		if (nearest) {
			// Shoot
			var b = new Bullet();
			b.x = self.x;
			b.y = self.y;
			b.target = nearest;
			b.damage = self.damage;
			b.speed = 24;
			b.lastX = b.x;
			b.lastY = b.y;
			bullets.push(b);
			game.addChild(b);
			self.cooldown = self.fireRate;
		}
	};
	return self;
});

/**** 
* Initialize Game
****/ 
var game = new LK.Game({
	backgroundColor: 0x000000
});

/**** 
* Game Code
****/ 
// --- Grid system ---
// Set grid to 10x12 with margins, leave 1 row margin at bottom, and add 5 tower selection squares below grid
var GRID_COLS = 10;
var GRID_ROWS = 12;
var GRID_SIZE = 160;
// Calculate margins to center grid in 2048x2732, leaving 1 row margin at bottom for spacing
var GRID_TOTAL_WIDTH = GRID_COLS * GRID_SIZE;
var GRID_TOTAL_HEIGHT = GRID_ROWS * GRID_SIZE;
var GRID_MARGIN_X = Math.floor((2048 - GRID_TOTAL_WIDTH) / 2);
var GRID_MARGIN_Y = Math.floor((2732 - (GRID_TOTAL_HEIGHT + GRID_SIZE)) / 2); // +GRID_SIZE for 1 row margin at bottom
// Helper to snap to grid (with margin)
function snapToGrid(x, y) {
	return {
		x: GRID_MARGIN_X + Math.round((x - GRID_MARGIN_X) / GRID_SIZE) * GRID_SIZE,
		y: GRID_MARGIN_Y + Math.round((y - GRID_MARGIN_Y) / GRID_SIZE) * GRID_SIZE
	};
}
// Path definition (array of {x, y}), snapped to grid
// New rules: start/end not at corners, always start/end with 1 down, no path on grid edges, max 5 straight, only adjacent steps
function generateSimplePath() {
	var pathArr = [];
	// Start: pick a column from 1 to 8 (not 0 or 9)
	var startCols = [];
	for (var c = 1; c < GRID_COLS - 1; c++) {
		startCols.push(c);
	}
	var startCol = startCols[Math.floor(Math.random() * startCols.length)];
	var col = startCol;
	var row = 0;
	// First point: start cell (row 0, col)
	pathArr.push(snapToGrid(GRID_MARGIN_X + col * GRID_SIZE, GRID_MARGIN_Y + row * GRID_SIZE));
	// Always move 1 down to start
	row = 1;
	pathArr.push(snapToGrid(GRID_MARGIN_X + col * GRID_SIZE, GRID_MARGIN_Y + row * GRID_SIZE));
	// End: pick a column from 1 to 8 (not 0 or 9)
	var endCols = [];
	for (var c = 1; c < GRID_COLS - 1; c++) {
		endCols.push(c);
	}
	var endCol = endCols[Math.floor(Math.random() * endCols.length)];
	var endRow = GRID_ROWS - 1;
	// The cell before the end (must be adjacent to end, not on edge)
	var preEndRow = endRow - 1;
	// Path must stay within 1..8 for both col and row (never on edge)
	// Build path from (col, row) to (endCol, preEndRow)
	var curCol = col;
	var curRow = row;
	var lastDir = null; // "down", "left", "right", "up"
	var straightCount = 1;
	// Track visited cells to prevent self-crossing
	var visited = {};
	function cellKey(x, y) {
		return x + "," + y;
	}
	visited[cellKey(curCol, curRow)] = true;
	// We'll use a random walk with constraints, now allowing up, but never crossing itself
	while (!(curRow === preEndRow && curCol === endCol)) {
		var moves = [];
		// Can move down if not at preEndRow
		if (curRow < preEndRow) moves.push("down");
		// Can move up if not at row 1 and not reversing last move
		if (curRow > 1 && lastDir !== "down") moves.push("up");
		// Can move left if not at col 1
		if (curCol > 1) moves.push("left");
		// Can move right if not at col 8
		if (curCol < GRID_COLS - 2) moves.push("right");
		// Don't allow to go back to previous cell or cross itself
		var validMoves = [];
		for (var mi = 0; mi < moves.length; mi++) {
			var testCol = curCol;
			var testRow = curRow;
			if (moves[mi] === "down") testRow++;
			if (moves[mi] === "up") testRow--;
			if (moves[mi] === "left") testCol--;
			if (moves[mi] === "right") testCol++;
			// Don't allow to cross itself
			if (visited[cellKey(testCol, testRow)]) continue;
			// If moving down, don't allow to land on left/right edge (col 0 or 9)
			if (moves[mi] === "down" && (testCol === 0 || testCol === GRID_COLS - 1)) continue;
			// If moving up, don't allow to land on left/right edge (col 0 or 9)
			if (moves[mi] === "up" && (testCol === 0 || testCol === GRID_COLS - 1)) continue;
			// If moving up, must allow a future down (not get stuck at top)
			if (moves[mi] === "up" && testRow === 1 && (testCol === 0 || testCol === GRID_COLS - 1)) continue;
			validMoves.push(moves[mi]);
		}
		// Prefer to move toward endCol/endRow if possible
		var preferred = [];
		for (var mi = 0; mi < validMoves.length; mi++) {
			var testCol = curCol;
			var testRow = curRow;
			if (validMoves[mi] === "down") testRow++;
			if (validMoves[mi] === "up") testRow--;
			if (validMoves[mi] === "left") testCol--;
			if (validMoves[mi] === "right") testCol++;
			if (testCol === endCol && testRow === preEndRow) {
				preferred.push(validMoves[mi]);
			} else if (testCol === endCol) {
				preferred.push(validMoves[mi]);
			} else if (testRow === preEndRow) {
				preferred.push(validMoves[mi]);
			}
		}
		// If we've gone straight 5 times, must turn
		if (straightCount >= 5) {
			validMoves = validMoves.filter(function (m) {
				return m !== lastDir;
			});
		}
		// Pick move: prefer toward end, but randomize
		var move = null;
		if (preferred.length > 0 && Math.random() < 0.7) {
			move = preferred[Math.floor(Math.random() * preferred.length)];
		} else if (validMoves.length > 0) {
			move = validMoves[Math.floor(Math.random() * validMoves.length)];
		} else {
			// Should not happen, but fallback: try to go down if possible, else break
			if (moves.indexOf("down") !== -1) {
				move = "down";
			} else {
				break;
			}
		}
		// Apply move
		if (move === lastDir) {
			straightCount++;
		} else {
			straightCount = 1;
		}
		lastDir = move;
		if (move === "down") curRow++;
		if (move === "up") curRow--;
		if (move === "left") curCol--;
		if (move === "right") curCol++;
		visited[cellKey(curCol, curRow)] = true;
		pathArr.push(snapToGrid(GRID_MARGIN_X + curCol * GRID_SIZE, GRID_MARGIN_Y + curRow * GRID_SIZE));
	}
	// Now at (endCol, preEndRow). Always finish with 1 down to (endCol, endRow)
	pathArr.push(snapToGrid(GRID_MARGIN_X + endCol * GRID_SIZE, GRID_MARGIN_Y + endRow * GRID_SIZE));
	return pathArr;
}
var path = generateSimplePath();
// --- Start Game Button Logic ---
var gameStarted = false;
var startBtn = new Text2('▶ Start Game', {
	size: 120,
	fill: 0x27AE60
});
startBtn.anchor.set(0.5, 0.5);
LK.gui.center.addChild(startBtn);
function setStartBtnVisible(visible) {
	startBtn.visible = visible;
}
setStartBtnVisible(true);
startBtn.down = function (x, y, obj) {
	if (!gameStarted) {
		gameStarted = true;
		setStartBtnVisible(false);
		setNextWaveBtnVisible(true);
		startWave(); // Start the first wave immediately
	}
};
// Hide all gameplay UI until game starts
setNextWaveBtnVisible(false);
if (typeof kpTxt !== "undefined") kpTxt.visible = false;
if (typeof healthTxt !== "undefined") healthTxt.visible = false;
if (typeof waveTxt !== "undefined") waveTxt.visible = false;
if (typeof nextWaveBtn !== "undefined") nextWaveBtn.visible = false;
if (typeof autoNextWaveBtn !== "undefined") autoNextWaveBtn.visible = false;
// Show gameplay UI when game starts
function showGameplayUI() {
	kpTxt.visible = true;
	healthTxt.visible = true;
	waveTxt.visible = true;
	nextWaveBtn.visible = false;
	nextWaveBtn.x = 0;
	nextWaveBtn.y = kpTxt.y + kpTxt.height + 20;
	autoNextWaveBtn.x = 0;
	autoNextWaveBtn.y = nextWaveBtn.y + nextWaveBtn.height + 10;
	autoNextWaveBtn.visible = true;
	kpTxt.setText('Points: ' + knowledgePoints);
	healthTxt.setText('Base: ' + baseHealth);
	waveTxt.setText('Wave: ' + currentWave + '/' + maxWaves);
}
var _origStartWave = startWave;
startWave = function startWave() {
	if (!gameStarted) return;
	showGameplayUI();
	_origStartWave();
};
// Buildable tile logic removed for now
var buildTilePositions = [];
// Global game state
var enemies = [];
var towers = [];
var bullets = [];
// buildTiles removed for now
var baseHealth = 10;
var knowledgePoints = 30;
var currentWave = 1;
var maxWaves = 10;
var waveInProgress = false;
var waveTimer = null;
var spawnIndex = 0;
var spawnDelay = 40; // frames between spawns
var enemiesToSpawn = 0;
var selectedTile = null;
// Asset initialization
// Draw grid background (light gray squares) with margins and 10x12 grid area
for (var row = 0; row < GRID_ROWS; row++) {
	for (var col = 0; col < GRID_COLS; col++) {
		var gridNode = LK.getAsset('buildTile', {
			anchorX: 0.5,
			anchorY: 0.5,
			width: GRID_SIZE - 4,
			height: GRID_SIZE - 4,
			color: 0xf4f4f4,
			shape: 'box',
			alpha: 0.18
		});
		gridNode.x = GRID_MARGIN_X + col * GRID_SIZE;
		gridNode.y = GRID_MARGIN_Y + row * GRID_SIZE;
		game.addChild(gridNode);
	}
}
// Draw 5 colored tower selection squares below the grid, centered horizontally
var TOWER_SELECT_COUNT = 5;
var TOWER_SELECT_SIZE = 140;
var TOWER_SELECT_SPACING = 60;
var TOWER_SELECT_COLORS = [0x3498db, 0xe74c3c, 0x2ecc40, 0xf1c40f, 0x8e44ad];
var TOWER_SELECT_LABELS = ['Mavi', 'Kırmızı', 'Yeşil', 'Sarı', 'Mor'];
var towerSelectSquares = [];
var totalWidth = TOWER_SELECT_COUNT * TOWER_SELECT_SIZE + (TOWER_SELECT_COUNT - 1) * TOWER_SELECT_SPACING;
var startX = Math.floor((2048 - totalWidth) / 2) + TOWER_SELECT_SIZE / 2;
var selectY = GRID_MARGIN_Y + GRID_ROWS * GRID_SIZE + GRID_SIZE / 2;
for (var i = 0; i < TOWER_SELECT_COUNT; i++) {
	var square = LK.getAsset('buildTile', {
		anchorX: 0.5,
		anchorY: 0.5,
		width: TOWER_SELECT_SIZE,
		height: TOWER_SELECT_SIZE,
		color: TOWER_SELECT_COLORS[i],
		shape: 'box',
		alpha: 0.95
	});
	square.x = startX + i * (TOWER_SELECT_SIZE + TOWER_SELECT_SPACING);
	square.y = selectY;
	game.addChild(square);
	// Add label for each tower color
	var label = new Text2(TOWER_SELECT_LABELS[i], {
		size: 48,
		fill: "#fff"
	});
	label.anchor.set(0.5, 0);
	label.x = square.x;
	label.y = square.y + TOWER_SELECT_SIZE / 2 + 8;
	game.addChild(label);
	towerSelectSquares.push(square);
}
// Draw path (for visual reference)
for (var i = 0; i < path.length - 1; i++) {
	var from = path[i];
	var to = path[i + 1];
	var dx = to.x - from.x;
	var dy = to.y - from.y;
	var dist = Math.sqrt(dx * dx + dy * dy);
	var steps = Math.floor(dist / 40);
	for (var s = 0; s <= steps; s++) {
		var t = s / steps;
		var px = from.x + dx * t;
		var py = from.y + dy * t;
		var node = LK.getAsset('pathDot', {
			anchorX: 0.5,
			anchorY: 0.5,
			width: 32,
			height: 32,
			color: 0x7f8c8d,
			shape: 'ellipse'
		});
		node.x = px;
		node.y = py;
		game.addChild(node);
	}
}
// Buildable tile objects removed for now
// --- Tower Selection Bar ---
var towerTypes = [];
var selectedTowerType = null;
var towerButtons = [];
var towerBtnY = 2400;
var towerBtnSpacing = 260;
var towerBtnStartX = 400;
var draggingTowerType = null;
var draggingTowerGhost = null;
// No tower selection buttons since normal tower is removed
// --- Drag-and-drop tower placement from colored squares ---
for (var i = 0; i < towerSelectSquares.length; i++) {
	(function (colorIdx) {
		var square = towerSelectSquares[colorIdx];
		square.down = function (x, y, obj) {
			// Clean up any previous ghost
			if (draggingTowerGhost) {
				if (draggingTowerGhost.rangeCircle) draggingTowerGhost.rangeCircle.destroy();
				draggingTowerGhost.destroy();
				draggingTowerGhost = null;
				draggingTowerType = null;
			}
			draggingTowerType = colorIdx;
			draggingTowerGhost = new Tower();
			// Snap to grid for initial drag position
			var gridX = Math.round((x - GRID_MARGIN_X) / GRID_SIZE);
			var gridY = Math.round((y - GRID_MARGIN_Y) / GRID_SIZE);
			var snapX = GRID_MARGIN_X + gridX * GRID_SIZE;
			var snapY = GRID_MARGIN_Y + gridY * GRID_SIZE;
			draggingTowerGhost.x = snapX;
			draggingTowerGhost.y = snapY;
			// Set color of ghost tower
			if (draggingTowerGhost.children && draggingTowerGhost.children.length > 0) {
				draggingTowerGhost.children[0].tint = TOWER_SELECT_COLORS[colorIdx];
			}
			// Show range circle while dragging, and center it on the ghost
			if (draggingTowerGhost.rangeCircle) {
				draggingTowerGhost.rangeCircle.visible = true;
				draggingTowerGhost.rangeCircle.x = 0;
				draggingTowerGhost.rangeCircle.y = 0;
			}
			draggingTowerGhost.alpha = 0.7;
			game.addChild(draggingTowerGhost);
		};
	})(i);
}
// Helper: check if a grid cell is on the path
function isCellOnPath(gridX, gridY) {
	for (var i = 0; i < path.length; i++) {
		var px = path[i].x;
		var py = path[i].y;
		var cellX = Math.round((px - GRID_MARGIN_X) / GRID_SIZE);
		var cellY = Math.round((py - GRID_MARGIN_Y) / GRID_SIZE);
		if (cellX === gridX && cellY === gridY) return true;
	}
	return false;
}
// Helper: check if a tower already exists at grid cell
function isTowerAtCell(gridX, gridY) {
	for (var i = 0; i < towers.length; i++) {
		var t = towers[i];
		var tx = Math.round((t.x - GRID_MARGIN_X) / GRID_SIZE);
		var ty = Math.round((t.y - GRID_MARGIN_Y) / GRID_SIZE);
		if (tx === gridX && ty === gridY) return true;
	}
	return false;
}
// Dragging ghost tower with finger/mouse
game.move = function (x, y, obj) {
	if (draggingTowerGhost) {
		// Snap ghost to grid for feedback
		var gridX = Math.round((x - GRID_MARGIN_X) / GRID_SIZE);
		var gridY = Math.round((y - GRID_MARGIN_Y) / GRID_SIZE);
		var snapX = GRID_MARGIN_X + gridX * GRID_SIZE;
		var snapY = GRID_MARGIN_Y + gridY * GRID_SIZE;
		draggingTowerGhost.x = snapX;
		draggingTowerGhost.y = snapY;
		// Always center rangeCircle on the ghost (0,0 in local coordinates)
		if (draggingTowerGhost.rangeCircle) {
			draggingTowerGhost.rangeCircle.x = 0;
			draggingTowerGhost.rangeCircle.y = 0;
		}
		// Visual feedback: tint red if invalid, normal if valid
		var valid = true;
		// Only allow inside grid
		if (gridX < 0 || gridX >= GRID_COLS || gridY < 0 || gridY >= GRID_ROWS || isCellOnPath(gridX, gridY) || isTowerAtCell(gridX, gridY)) {
			valid = false;
		}
		if (draggingTowerGhost.children && draggingTowerGhost.children.length > 0) {
			draggingTowerGhost.children[0].tint = valid ? TOWER_SELECT_COLORS[draggingTowerType] : 0x888888;
		}
		draggingTowerGhost.alpha = valid ? 0.7 : 0.35;
	}
};
// Place tower on grid on up
game.up = function (x, y, obj) {
	if (draggingTowerGhost && draggingTowerType !== null) {
		var gridX = Math.round((draggingTowerGhost.x - GRID_MARGIN_X) / GRID_SIZE);
		var gridY = Math.round((draggingTowerGhost.y - GRID_MARGIN_Y) / GRID_SIZE);
		var valid = true;
		if (gridX < 0 || gridX >= GRID_COLS || gridY < 0 || gridY >= GRID_ROWS || isCellOnPath(gridX, gridY) || isTowerAtCell(gridX, gridY)) {
			valid = false;
		}
		if (valid) {
			// Place tower if enough points
			var buildCost = 20;
			if (knowledgePoints >= buildCost) {
				knowledgePoints -= buildCost;
				var tower = new Tower();
				tower.x = GRID_MARGIN_X + gridX * GRID_SIZE;
				tower.y = GRID_MARGIN_Y + gridY * GRID_SIZE;
				// Set color
				if (tower.children && tower.children.length > 0) {
					tower.children[0].tint = TOWER_SELECT_COLORS[draggingTowerType];
				}
				towers.push(tower);
				game.addChild(tower);
				kpTxt.setText('Points: ' + knowledgePoints);
			}
		}
		// Clean up ghost
		if (draggingTowerGhost.rangeCircle) draggingTowerGhost.rangeCircle.destroy();
		draggingTowerGhost.destroy();
		draggingTowerGhost = null;
		draggingTowerType = null;
		return;
	}
	// If not placing, just clear ghost
	if (draggingTowerGhost) {
		if (draggingTowerGhost.rangeCircle) draggingTowerGhost.rangeCircle.destroy();
		draggingTowerGhost.destroy();
		draggingTowerGhost = null;
		draggingTowerType = null;
	}
};
// Base indicator (ellipse, red)
var baseNode = LK.getAsset('base', {
	anchorX: 0.5,
	anchorY: 0.5,
	width: 160,
	height: 160,
	color: 0xe74c3c,
	shape: 'ellipse'
});
baseNode.x = path[path.length - 1].x;
baseNode.y = path[path.length - 1].y;
game.addChild(baseNode);
// GUI: Points (KP) - Center top, smaller size, renamed to Points
var kpTxt = new Text2('Points: ' + knowledgePoints, {
	size: 48,
	fill: 0x222222
});
kpTxt.anchor.set(0.5, 0); // center aligned, top
kpTxt.x = 0;
kpTxt.y = 10;
LK.gui.top.addChild(kpTxt);
// GUI: Base Health - Top right, smaller size
var healthTxt = new Text2('Base: ' + baseHealth, {
	size: 48,
	fill: 0xE74C3C
});
healthTxt.anchor.set(1, 0); // right aligned, top
healthTxt.x = -40; // right margin
healthTxt.y = 10;
LK.gui.topRight.addChild(healthTxt);
// GUI: Wave - Bottom left, smaller size
var waveTxt = new Text2('Wave: ' + currentWave + '/' + maxWaves, {
	size: 48,
	fill: 0x2980B9
});
waveTxt.anchor.set(0, 1); // left aligned, bottom
waveTxt.x = 40;
waveTxt.y = -40;
LK.gui.bottomLeft.addChild(waveTxt);
// GUI: Next Wave Button
var nextWaveBtn = new Text2('▶ Next Wave', {
	size: 90,
	fill: 0x27AE60
});
nextWaveBtn.anchor.set(0.5, 0);
// Place nextWaveBtn under Points (kpTxt) in gui.top, centered horizontally
nextWaveBtn.x = 0;
nextWaveBtn.y = kpTxt.y + kpTxt.height + 20;
LK.gui.top.addChild(nextWaveBtn);
// Auto-next wave toggle
var autoNextWave = false;
var autoNextWaveBtn = new Text2('Auto: OFF', {
	size: 54,
	fill: 0x2980B9
});
autoNextWaveBtn.anchor.set(0.5, 0);
autoNextWaveBtn.x = 0;
autoNextWaveBtn.y = nextWaveBtn.y + nextWaveBtn.height + 10;
LK.gui.top.addChild(autoNextWaveBtn);
autoNextWaveBtn.visible = false;
autoNextWaveBtn.down = function (x, y, obj) {
	autoNextWave = !autoNextWave;
	autoNextWaveBtn.setText('Auto: ' + (autoNextWave ? 'ON' : 'OFF'));
};
// Show/hide next wave button
function setNextWaveBtnVisible(visible) {
	// Defensive: Only set visible if nextWaveBtn is defined and has a visible property
	if (typeof nextWaveBtn !== "undefined" && nextWaveBtn && typeof nextWaveBtn.visible !== "undefined") {
		nextWaveBtn.visible = visible;
	}
}
setNextWaveBtnVisible(false);
// Start next wave
function startWave() {
	if (waveInProgress || currentWave > maxWaves) return;
	waveInProgress = true;
	setNextWaveBtnVisible(false);
	enemiesToSpawn = 6 + currentWave * 2;
	spawnIndex = 0;
}
// Next wave button event
nextWaveBtn.down = function (x, y, obj) {
	if (!waveInProgress && currentWave <= maxWaves) {
		startWave();
	}
};
// Build/upgrade tower on tile
function tryBuildOrUpgrade(tile) {
	if (tile.occupied) {
		// Try upgrade
		if (tile.tower.level < 3) {
			var upgradeCost = 20 + tile.tower.level * 15;
			if (knowledgePoints >= upgradeCost) {
				knowledgePoints -= upgradeCost;
				tile.tower.upgrade();
				kpTxt.setText('Points: ' + knowledgePoints);
			}
		}
	} else {
		// Build new tower
		var buildCost = 20;
		if (knowledgePoints >= buildCost) {
			knowledgePoints -= buildCost;
			var tower = new Tower();
			tower.x = tile.x;
			tower.y = tile.y;
			towers.push(tower);
			game.addChild(tower);
			tile.occupied = true;
			tile.tower = tower;
			kpTxt.setText('Points: ' + knowledgePoints);
		}
	}
}
// Highlight build tiles on touch
game.down = function (x, y, obj) {
	// No tap-to-place logic; only drag-and-drop is supported for tower placement
};
// Remove highlight/range on up
// (handled by drag-and-drop up logic above)
// Main game update
game.update = function () {
	// Spawn enemies for wave
	if (waveInProgress && enemiesToSpawn > 0 && LK.ticks % spawnDelay === 0) {
		var enemy = new Enemy();
		enemy.x = path[0].x;
		enemy.y = path[0].y;
		enemy.pathIndex = 0;
		enemy.pathProgress = 0;
		enemies.push(enemy);
		game.addChild(enemy);
		enemiesToSpawn--;
	}
	// Update enemies
	for (var i = enemies.length - 1; i >= 0; i--) {
		var e = enemies[i];
		e.update();
		if (e.health <= 0) {
			// Enemy defeated
			knowledgePoints += e.reward;
			kpTxt.setText('Points: ' + knowledgePoints);
			e.destroy();
			enemies.splice(i, 1);
			kpTxt.setText('Points: ' + knowledgePoints);
		} else if (e.reachedBase) {
			// Enemy reached base
			baseHealth--;
			healthTxt.setText('Base: ' + baseHealth);
			e.destroy();
			enemies.splice(i, 1);
			healthTxt.setText('Base: ' + baseHealth);
			LK.effects.flashScreen(0xe74c3c, 400);
			if (baseHealth <= 0) {
				LK.showGameOver();
				return;
			}
		}
	}
	// Update towers
	for (var i = 0; i < towers.length; i++) {
		towers[i].update();
	}
	// Update bullets
	for (var i = bullets.length - 1; i >= 0; i--) {
		var b = bullets[i];
		b.update();
		if (b.destroyed) {
			b.destroy();
			bullets.splice(i, 1);
		}
	}
	// End wave if all enemies defeated and none left to spawn
	if (waveInProgress && enemies.length === 0 && enemiesToSpawn === 0) {
		waveInProgress = false;
		currentWave++;
		if (currentWave > maxWaves) {
			LK.showYouWin();
			return;
		}
		waveTxt.setText('Wave: ' + currentWave + '/' + maxWaves);
		// Reposition nextWaveBtn and autoNextWaveBtn under Points (kpTxt) in case Points text size changes
		nextWaveBtn.x = 0;
		nextWaveBtn.y = kpTxt.y + kpTxt.height + 20;
		autoNextWaveBtn.x = 0;
		autoNextWaveBtn.y = nextWaveBtn.y + nextWaveBtn.height + 10;
		if (autoNextWave) {
			setNextWaveBtnVisible(false);
			// Start next wave automatically after a short delay for feedback
			LK.setTimeout(function () {
				if (!waveInProgress && currentWave <= maxWaves) {
					startWave();
				}
			}, 700);
		} else {
			setNextWaveBtnVisible(true);
		}
	}
};

===================================================================
--- original.js
+++ change.js
@@ -273,41 +273,82 @@
 	// Path must stay within 1..8 for both col and row (never on edge)
 	// Build path from (col, row) to (endCol, preEndRow)
 	var curCol = col;
 	var curRow = row;
-	var lastDir = null; // "down", "left", "right"
+	var lastDir = null; // "down", "left", "right", "up"
 	var straightCount = 1;
-	// We'll use a simple random walk with constraints
+	// Track visited cells to prevent self-crossing
+	var visited = {};
+	function cellKey(x, y) {
+		return x + "," + y;
+	}
+	visited[cellKey(curCol, curRow)] = true;
+	// We'll use a random walk with constraints, now allowing up, but never crossing itself
 	while (!(curRow === preEndRow && curCol === endCol)) {
 		var moves = [];
 		// Can move down if not at preEndRow
 		if (curRow < preEndRow) moves.push("down");
+		// Can move up if not at row 1 and not reversing last move
+		if (curRow > 1 && lastDir !== "down") moves.push("up");
 		// Can move left if not at col 1
 		if (curCol > 1) moves.push("left");
 		// Can move right if not at col 8
 		if (curCol < GRID_COLS - 2) moves.push("right");
-		// Don't allow to go back to previous cell
-		// Prefer to move toward endCol if possible
+		// Don't allow to go back to previous cell or cross itself
+		var validMoves = [];
+		for (var mi = 0; mi < moves.length; mi++) {
+			var testCol = curCol;
+			var testRow = curRow;
+			if (moves[mi] === "down") testRow++;
+			if (moves[mi] === "up") testRow--;
+			if (moves[mi] === "left") testCol--;
+			if (moves[mi] === "right") testCol++;
+			// Don't allow to cross itself
+			if (visited[cellKey(testCol, testRow)]) continue;
+			// If moving down, don't allow to land on left/right edge (col 0 or 9)
+			if (moves[mi] === "down" && (testCol === 0 || testCol === GRID_COLS - 1)) continue;
+			// If moving up, don't allow to land on left/right edge (col 0 or 9)
+			if (moves[mi] === "up" && (testCol === 0 || testCol === GRID_COLS - 1)) continue;
+			// If moving up, must allow a future down (not get stuck at top)
+			if (moves[mi] === "up" && testRow === 1 && (testCol === 0 || testCol === GRID_COLS - 1)) continue;
+			validMoves.push(moves[mi]);
+		}
+		// Prefer to move toward endCol/endRow if possible
 		var preferred = [];
-		if (curCol < endCol && moves.indexOf("right") !== -1) preferred.push("right");
-		if (curCol > endCol && moves.indexOf("left") !== -1) preferred.push("left");
-		if (curRow < preEndRow && moves.indexOf("down") !== -1) preferred.push("down");
+		for (var mi = 0; mi < validMoves.length; mi++) {
+			var testCol = curCol;
+			var testRow = curRow;
+			if (validMoves[mi] === "down") testRow++;
+			if (validMoves[mi] === "up") testRow--;
+			if (validMoves[mi] === "left") testCol--;
+			if (validMoves[mi] === "right") testCol++;
+			if (testCol === endCol && testRow === preEndRow) {
+				preferred.push(validMoves[mi]);
+			} else if (testCol === endCol) {
+				preferred.push(validMoves[mi]);
+			} else if (testRow === preEndRow) {
+				preferred.push(validMoves[mi]);
+			}
+		}
 		// If we've gone straight 5 times, must turn
 		if (straightCount >= 5) {
-			// Remove lastDir from moves if possible
-			moves = moves.filter(function (m) {
+			validMoves = validMoves.filter(function (m) {
 				return m !== lastDir;
 			});
 		}
 		// Pick move: prefer toward end, but randomize
 		var move = null;
 		if (preferred.length > 0 && Math.random() < 0.7) {
 			move = preferred[Math.floor(Math.random() * preferred.length)];
-		} else if (moves.length > 0) {
-			move = moves[Math.floor(Math.random() * moves.length)];
+		} else if (validMoves.length > 0) {
+			move = validMoves[Math.floor(Math.random() * validMoves.length)];
 		} else {
-			// Should not happen, but fallback
-			move = "down";
+			// Should not happen, but fallback: try to go down if possible, else break
+			if (moves.indexOf("down") !== -1) {
+				move = "down";
+			} else {
+				break;
+			}
 		}
 		// Apply move
 		if (move === lastDir) {
 			straightCount++;
@@ -315,10 +356,12 @@
 			straightCount = 1;
 		}
 		lastDir = move;
 		if (move === "down") curRow++;
+		if (move === "up") curRow--;
 		if (move === "left") curCol--;
 		if (move === "right") curCol++;
+		visited[cellKey(curCol, curRow)] = true;
 		pathArr.push(snapToGrid(GRID_MARGIN_X + curCol * GRID_SIZE, GRID_MARGIN_Y + curRow * GRID_SIZE));
 	}
 	// Now at (endCol, preEndRow). Always finish with 1 down to (endCol, endRow)
 	pathArr.push(snapToGrid(GRID_MARGIN_X + endCol * GRID_SIZE, GRID_MARGIN_Y + endRow * GRID_SIZE));