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

/**** 
* Classes
****/ 
// AISnake (AI snake that moves toward food and steals it)
var AISnake = Container.expand(function () {
	var self = Container.call(this);
	self.length = 3 + Math.floor(Math.random() * 2); // 3-4 segments
	self.segments = [];
	self.dir = 0;
	self.speed = Math.max(4, SNAKE_INIT_SPEED * 0.35); // AI snake moves much slower than player
	self.target = null;
	self.stealing = false;
	self.lastFood = null;
	// Create head
	var head = self.attachAsset('aiSnakeHead', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.asset = head;
	self.segments.push(self);
	// Create body segments
	for (var i = 1; i < self.length; ++i) {
		var seg = new Container();
		seg.asset = seg.attachAsset('aiSnakeBody', {
			anchorX: 0.5,
			anchorY: 0.5
		});
		seg.x = self.x - i * 60;
		seg.y = self.y;
		self.addChild(seg);
		self.segments.push(seg);
	}
	// Custom hitbox
	self.hitboxScale = 0.6;
	// Custom intersects for head
	self.intersects = function (other) {
		var scaleA = typeof self.hitboxScale === "number" ? self.hitboxScale : 1;
		var scaleB = typeof other.hitboxScale === "number" ? other.hitboxScale : 1;
		var ax = self.x,
			ay = self.y,
			aw = self.asset.width * scaleA,
			ah = self.asset.height * scaleA;
		var bx = other.x,
			by = other.y,
			bw = other.asset && other.asset.width ? other.asset.width * scaleB : 0,
			bh = other.asset && other.asset.height ? other.asset.height * scaleB : 0;
		var rA = Math.max(aw, ah) / 2;
		var rB = Math.max(bw, bh) / 2;
		var dx = ax - bx,
			dy = ay - by;
		return dx * dx + dy * dy < (rA + rB) * (rA + rB);
	};
	// Update method
	self.update = function () {
		// Save last position for event triggers
		if (self.lastX === undefined) self.lastX = self.x;
		if (self.lastY === undefined) self.lastY = self.y;
		// Find food if not already targeting
		if (!self.target || self.target.destroyed) {
			if (typeof food !== "undefined" && food && !food.destroyed) {
				self.target = food;
			} else {
				self.target = null;
			}
		}
		// Move toward food using player-like movement
		if (self.target) {
			// Calculate desired direction
			var dx = self.target.x - self.x;
			var dy = self.target.y - self.y;
			var desiredDir = Math.atan2(dy, dx);
			// Smoothly turn toward the target (like player)
			var d = desiredDir - self.dir;
			while (d > Math.PI) d -= 2 * Math.PI;
			while (d < -Math.PI) d += 2 * Math.PI;
			var turn = Math.sign(d) * Math.min(Math.abs(d), SNAKE_TURN_ANGLE);
			self.dir += turn;
			// Move head forward
			self.x += Math.cos(self.dir) * self.speed;
			self.y += Math.sin(self.dir) * self.speed;
			// Clamp to bounds
			self.x = Math.max(100 + self.asset.width / 2, Math.min(2048 - 100 - self.asset.width / 2, self.x));
			self.y = Math.max(100 + self.asset.height / 2, Math.min(2732 - 100 - self.asset.height / 2, self.y));
			// Move body segments to follow the previous segment, like player
			for (var i = 1; i < self.segments.length; ++i) {
				var seg = self.segments[i];
				var target = self.segments[i - 1];
				var sdx = target.x - seg.x;
				var sdy = target.y - seg.y;
				var sdist = Math.sqrt(sdx * sdx + sdy * sdy);
				var desired = self.speed * 0.9;
				if (sdist > desired) {
					var move = (sdist - desired) * 0.5;
					seg.x += sdx / sdist * move;
					seg.y += sdy / sdist * move;
				}
			}
			// Steal food if close enough
			if (self.target && self.intersects(self.target)) {
				self.stealing = true;
				// Remove food from game
				if (typeof food !== "undefined" && food === self.target) {
					food.destroy();
					food = null;
					// Always respawn food after AI steals it
					if (typeof spawnFood === "function") {
						spawnFood();
					}
				}
				self.target = null;
			}
		}
		// Despawn if off screen or after stealing
		if (self.stealing) {
			// Move off screen quickly
			self.x += Math.cos(self.dir) * self.speed * 2;
			self.y += Math.sin(self.dir) * self.speed * 2;
			if (self.x < -200 || self.x > 2048 + 200 || self.y < -200 || self.y > 2732 + 200) {
				self._despawn = true;
			}
		}
		self.lastX = self.x;
		self.lastY = self.y;
	};
	return self;
});
// Food
var Food = Container.expand(function () {
	var self = Container.call(this);
	self.asset = self.attachAsset('food', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.hitboxScale = 0.6;
	return self;
});
// FoodPurple
var FoodPurple = Container.expand(function () {
	var self = Container.call(this);
	self.asset = self.attachAsset('foodPurple', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.hitboxScale = 0.6;
	return self;
});
// FoodRainbow (rare, big bonus)
var FoodRainbow = Container.expand(function () {
	var self = Container.call(this);
	self.asset = self.attachAsset('food', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.hitboxScale = 0.6;
	// Animate color cycling
	// Animate color cycling using tween plugin API
	tween(self.asset, {
		tint: 0xff0000
	}, {
		duration: 400,
		easing: tween.linear,
		onFinish: function onFinish() {
			// No-op, will be repeated
		}
	});
	// Manually cycle through rainbow colors in update (since tween can't do this directly)
	self.update = function () {
		var t = LK.ticks % 60 / 60;
		var r = Math.floor(127 * (Math.sin(2 * Math.PI * t) + 1));
		var g = Math.floor(127 * (Math.sin(2 * Math.PI * t + 2) + 1));
		var b = Math.floor(127 * (Math.sin(2 * Math.PI * t + 4) + 1));
		self.asset.tint = r << 16 | g << 8 | b;
	};
	return self;
});
// MovingObstacle
var MovingObstacle = Container.expand(function () {
	var self = Container.call(this);
	self.asset = self.attachAsset('obstacleMoving', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.hitboxScale = 0.7;
	// Pick a random direction and speed
	var angle = Math.random() * Math.PI * 2;
	var speed = 4 + Math.random() * 4;
	self.vx = Math.cos(angle) * speed;
	self.vy = Math.sin(angle) * speed;
	self.update = function () {
		// Save last position for event triggers
		if (self.lastX === undefined) self.lastX = self.x;
		if (self.lastY === undefined) self.lastY = self.y;
		self.x += self.vx;
		self.y += self.vy;
		// Despawn if out of bounds (with 150px margin)
		if (self.x < -150 || self.x > 2048 + 150 || self.y < -150 || self.y > 2732 + 150) {
			// Mark for removal by setting a flag
			self._despawn = true;
			return;
		}
		// Bounce off walls (100px margin)
		if (self.x < 100 + self.asset.width / 2 && self.vx < 0) self.vx *= -1;
		if (self.x > 2048 - 100 - self.asset.width / 2 && self.vx > 0) self.vx *= -1;
		if (self.y < 100 + self.asset.height / 2 && self.vy < 0) self.vy *= -1;
		if (self.y > 2732 - 100 - self.asset.height / 2 && self.vy > 0) self.vy *= -1;
		self.lastX = self.x;
		self.lastY = self.y;
	};
	return self;
});
// Obstacle (static)
var Obstacle = Container.expand(function () {
	var self = Container.call(this);
	self.asset = self.attachAsset('obstacle', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.hitboxScale = 0.7;
	// Add despawn timer and update method for static obstacles
	self._despawnTimer = 0;
	self._despawnInterval = 60 * 60; // Try to despawn every 60 seconds (3600 ticks)
	self.update = function () {
		if (self._despawnTimer === undefined) self._despawnTimer = 0;
		self._despawnTimer++;
		// Only check every _despawnInterval ticks
		if (self._despawnTimer >= self._despawnInterval) {
			self._despawnTimer = 0;
			// 40% chance to despawn (less often than moving obstacles)
			if (Math.random() < 0.4) {
				self._despawn = true;
			}
		}
	};
	return self;
});
// PowerUp
var PowerUp = Container.expand(function () {
	var self = Container.call(this);
	self.type = 'invincible'; // or 'shrink'
	self.asset = null;
	self.hitboxScale = 0.6;
	self.setType = function (type) {
		if (self.asset) self.removeChild(self.asset);
		self.type = type;
		if (type === 'invincible') {
			self.asset = self.attachAsset('powerupInvincible', {
				anchorX: 0.5,
				anchorY: 0.5
			});
		} else if (type === 'shrink') {
			self.asset = self.attachAsset('powerupShrink', {
				anchorX: 0.5,
				anchorY: 0.5
			});
		}
	};
	self.setType('invincible');
	return self;
});
// Snake Segment (body or head)
var SnakeSegment = Container.expand(function () {
	var self = Container.call(this);
	self.isHead = false;
	self.asset = null;
	// Custom hitbox size (smaller than visual asset)
	self.hitboxScale = 0.6; // 60% of asset size for both head and body
	self.setType = function (type) {
		if (self.asset) self.removeChild(self.asset);
		if (type === 'head') {
			self.asset = self.attachAsset('snakeHead', {
				anchorX: 0.5,
				anchorY: 0.5
			});
			self.isHead = true;
		} else {
			self.asset = self.attachAsset('snakeBody', {
				anchorX: 0.5,
				anchorY: 0.5
			});
			self.isHead = false;
		}
	};
	self.setType('body');
	// Custom intersects method for smaller hitbox
	self.intersects = function (other) {
		// Use hitboxScale for both this and other if available, else default to 1
		var scaleA = typeof self.hitboxScale === "number" ? self.hitboxScale : 1;
		var scaleB = typeof other.hitboxScale === "number" ? other.hitboxScale : 1;
		var ax = self.x,
			ay = self.y,
			aw = self.asset.width * scaleA,
			ah = self.asset.height * scaleA;
		var bx = other.x,
			by = other.y,
			bw = other.asset && other.asset.width ? other.asset.width * scaleB : 0,
			bh = other.asset && other.asset.height ? other.asset.height * scaleB : 0;
		// Circle collision (since snake is ellipse/circle)
		var rA = Math.max(aw, ah) / 2;
		var rB = Math.max(bw, bh) / 2;
		var dx = ax - bx;
		var dy = ay - by;
		return dx * dx + dy * dy < (rA + rB) * (rA + rB);
	};
	return self;
});
// SpikeObstacle (destroys snake segments it touches, rare spawn)
var SpikeObstacle = Container.expand(function () {
	var self = Container.call(this);
	// Add spike obstacle asset first (so aura is in front)
	self.asset = self.attachAsset('spikeObstacle', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	// Add spike aura in front of the spike asset
	self.aura = self.attachAsset('spikeAura', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.aura.alpha = 0.35;
	self.hitboxScale = 0.7;
	// Add despawn timer and update method for static obstacles
	self._despawnTimer = 0;
	self._despawnInterval = 60 * 45; // Try to despawn every 45 seconds (less often than normal obstacles)
	self.update = function () {
		if (self._despawnTimer === undefined) self._despawnTimer = 0;
		self._despawnTimer++;
		// Only check every _despawnInterval ticks
		if (self._despawnTimer >= self._despawnInterval) {
			self._despawnTimer = 0;
			// 60% chance to despawn (spikes are rare, so despawn more often)
			if (Math.random() < 0.6) {
				self._despawn = true;
			}
		}
		// Animate aura pulse
		if (self.aura) {
			var t = LK.ticks % 60 / 60;
			self.aura.alpha = 0.25 + 0.15 * Math.sin(2 * Math.PI * t);
			var scale = 1.05 + 0.08 * Math.sin(2 * Math.PI * t);
			self.aura.scaleX = scale;
			self.aura.scaleY = scale;
		}
	};
	return self;
});

/**** 
* Initialize Game
****/ 
var game = new LK.Game({
	backgroundColor: 0x181818
});

/**** 
* Game Code
****/ 
// Music
// Sounds
// Obstacles
// Power-ups
// Food
// Snake head and body
// --- Game constants ---
var SNAKE_INIT_LENGTH = 5;
var SNAKE_INIT_SPEED = 16; // pixels per tick
var SNAKE_MIN_SPEED = 8;
var SNAKE_MAX_SPEED = 40;
var SNAKE_TURN_ANGLE = Math.PI / 18; // 10 degrees per input
var FOOD_SCORE = 10;
var POWERUP_SCORE = 25;
var POWERUP_DURATION = 300; // ticks (5 seconds)
var OBSTACLE_COUNT = 3;
var OBSTACLE_SPEED = 6;
// --- Game state ---
var snake = [];
var aiSnakes = []; // Array of AI snakes
var snakeDir = 0; // in radians, 0 = right
var snakeNextDir = 0;
var snakeSpeed = SNAKE_INIT_SPEED;
var snakeGrow = 0;
var food = null;
var powerup = null;
var powerupActive = false;
var powerupType = null;
var powerupTimer = 0;
var obstacles = [];
var score = 0;
var isInvincible = false;
var lastTouch = null;
var dragStart = null;
var dragAngle = null;
var dragActive = false;
var gameOver = false;
// --- GUI ---
var scoreTxt = new Text2('0', {
	size: 120,
	fill: 0xFFFFFF
});
scoreTxt.anchor.set(0.5, 0);
LK.gui.top.addChild(scoreTxt);
// --- Helper functions ---
function randomPos(margin, avoidList, avoidRadius) {
	margin = margin || 150;
	avoidList = avoidList || [];
	avoidRadius = avoidRadius || 120; // Default: avoid within 120px of any avoidList item
	var tries = 0;
	while (tries < 50) {
		var x = margin + Math.random() * (2048 - 2 * margin);
		var y = margin + Math.random() * (2732 - 2 * margin);
		var ok = true;
		for (var i = 0; i < avoidList.length; ++i) {
			var obj = avoidList[i];
			var dx = obj.x - x;
			var dy = obj.y - y;
			if (dx * dx + dy * dy < avoidRadius * avoidRadius) {
				ok = false;
				break;
			}
		}
		if (ok) {
			return {
				x: x,
				y: y
			};
		}
		tries++;
	}
	// Fallback: just return a random position if we can't find a good one
	return {
		x: margin + Math.random() * (2048 - 2 * margin),
		y: margin + Math.random() * (2732 - 2 * margin)
	};
}
function dist2(a, b) {
	var dx = a.x - b.x,
		dy = a.y - b.y;
	return dx * dx + dy * dy;
}
function angleBetween(a, b) {
	return Math.atan2(b.y - a.y, b.x - a.x);
}
function wrapPos(pos) {
	// Not used, but could be for wrap-around
	if (pos.x < 0) pos.x += 2048;
	if (pos.x > 2048) pos.x -= 2048;
	if (pos.y < 0) pos.y += 2732;
	if (pos.y > 2732) pos.y -= 2732;
}
function spawnFood() {
	if (food) food.destroy();
	// 5% chance for rainbow food, 20% for purple, else normal
	var r = Math.random();
	if (r < 0.05) {
		food = new FoodRainbow();
		food.isRainbow = true;
		food.isPurple = false;
	} else if (r < 0.25) {
		food = new FoodPurple();
		food.isPurple = true;
		food.isRainbow = false;
	} else {
		food = new Food();
		food.isPurple = false;
		food.isRainbow = false;
	}
	// Avoid spawning on the snake and obstacles
	var avoidList = [];
	for (var i = 0; i < snake.length; ++i) {
		avoidList.push(snake[i]);
	}
	// Also avoid obstacles
	for (var i = 0; i < obstacles.length; ++i) {
		avoidList.push(obstacles[i]);
	}
	var pos = randomPos(200, avoidList, 120);
	food.x = pos.x;
	food.y = pos.y;
	game.addChild(food);
}
function spawnPowerUp() {
	if (powerup) powerup.destroy();
	powerup = new PowerUp();
	// Avoid spawning on the snake
	var avoidList = [];
	for (var i = 0; i < snake.length; ++i) {
		avoidList.push(snake[i]);
	}
	var pos = randomPos(200, avoidList, 120);
	// 67% invincible, 33% shrink
	var r = Math.random();
	var t;
	if (r < 0.67) t = 'invincible';else t = 'shrink';
	powerup.setType(t);
	powerup.x = pos.x;
	powerup.y = pos.y;
	game.addChild(powerup);
}
function spawnObstacles() {
	for (var i = 0; i < obstacles.length; ++i) {
		obstacles[i].destroy();
	}
	obstacles = [];
	// Avoid spawning on the snake
	var avoidList = [];
	for (var j = 0; j < snake.length; ++j) {
		avoidList.push(snake[j]);
	}
	for (var i = 0; i < OBSTACLE_COUNT; ++i) {
		var obs = new Obstacle();
		var pos = randomPos(300, avoidList, 140);
		obs.x = pos.x;
		obs.y = pos.y;
		// Add this obstacle to avoidList so next ones don't overlap
		avoidList.push(obs);
		obstacles.push(obs);
		game.addChild(obs);
	}
}
function resetSnake() {
	for (var i = 0; i < snake.length; ++i) {
		snake[i].destroy();
	}
	snake = [];
	var startX = 2048 / 2,
		startY = 2732 / 2;
	for (var i = 0; i < SNAKE_INIT_LENGTH; ++i) {
		var seg = new SnakeSegment();
		if (i === 0) {
			seg.setType('head');
			// Head spawns in front of the body, not on top of the first body segment
			seg.x = startX;
			seg.y = startY;
		} else {
			seg.setType('body');
			// Each body segment spawns behind the previous one, extending left from the head
			seg.x = startX - i * snakeSpeed * 1.2;
			seg.y = startY;
		}
		game.addChild(seg);
		snake.push(seg);
	}
	snakeDir = 0;
	snakeNextDir = 0;
	snakeSpeed = SNAKE_INIT_SPEED;
	snakeGrow = 0;
	isInvincible = false;
	powerupActive = false;
	powerupType = null;
	powerupTimer = 0;
}
function updateScore(val) {
	score = val;
	scoreTxt.setText(score);
	LK.setScore(score);
}
function activatePowerUp(type) {
	powerupActive = true;
	powerupType = type;
	powerupTimer = POWERUP_DURATION;
	if (type === 'invincible') {
		isInvincible = true;
		// Flash snake
		for (var i = 0; i < snake.length; ++i) {
			LK.effects.flashObject(snake[i], 0xf1c40f, 500);
		}
	} else if (type === 'shrink') {
		// Remove 3 segments from the tail, but always keep at least 5
		var minLen = 5;
		var removeCount = Math.min(3, snake.length - minLen);
		for (var i = 0; i < removeCount; ++i) {
			var seg = snake.pop();
			seg.destroy();
		}
	}
}
function deactivatePowerUp() {
	powerupActive = false;
	powerupType = null;
	powerupTimer = 0;
	isInvincible = false;
}
function endGame() {
	if (gameOver) return;
	gameOver = true;
	LK.effects.flashScreen(0xff0000, 1000);
	LK.getSound('hit').play();
	LK.showGameOver();
}
// --- Input handling (touch/drag to steer) ---
game.down = function (x, y, obj) {
	// Only allow drag from outside top left 100x100
	if (x < 100 && y < 100) return;
	dragStart = {
		x: x,
		y: y
	};
	dragAngle = null;
	dragActive = true;
};
game.move = function (x, y, obj) {
	if (!dragActive) return;
	if (!dragStart) return;
	// Calculate angle from snake head to drag point
	var head = snake[0];
	var dx = x - head.x;
	var dy = y - head.y;
	if (dx * dx + dy * dy < 100) return; // Ignore tiny drags
	var angle = Math.atan2(dy, dx);
	snakeNextDir = angle;
	dragAngle = angle;
};
game.up = function (x, y, obj) {
	dragActive = false;
	dragStart = null;
	dragAngle = null;
};
// --- Main game update loop ---
game.update = function () {
	if (gameOver) return;
	// Power-up timer
	if (powerupActive) {
		powerupTimer--;
		if (powerupTimer <= 0) {
			deactivatePowerUp();
		}
	}
	// --- AI Snake logic ---
	// Update AI snakes
	for (var i = aiSnakes.length - 1; i >= 0; --i) {
		var ai = aiSnakes[i];
		if (ai.update) ai.update();
		// Check if AI snake collides with any player tail segment (not head)
		// Only if not already despawning
		if (!ai._despawn && snake.length > 4) {
			// Start from segment 4 (skip head and first 3 for leniency)
			for (var s = 4; s < snake.length; ++s) {
				var seg = snake[s];
				// Only check if segment exists and not destroyed
				if (seg && !seg.destroyed) {
					// Track last intersection state for this ai/segment pair
					if (!ai.lastTailIntersect) ai.lastTailIntersect = {};
					if (ai.lastTailIntersect[s] === undefined) ai.lastTailIntersect[s] = false;
					var nowIntersect = ai.intersects(seg);
					if (!ai.lastTailIntersect[s] && nowIntersect) {
						// AI snake dies!
						LK.effects.flashObject(ai, 0xff0000, 600);
						ai._despawn = true;
						// Optionally, give player a score bonus for killing AI
						updateScore(score + 30);
						break;
					}
					ai.lastTailIntersect[s] = nowIntersect;
				}
			}
		}
		// Remove if marked for despawn
		if (ai._despawn) {
			ai.destroy();
			aiSnakes.splice(i, 1);
		}
	}
	// Spawn a new AI snake less frequently (about every 14-18 seconds, only one at a time)
	if (aiSnakes.length === 0 && LK.ticks > 60 * 5 && LK.ticks % (60 * (14 + Math.floor(Math.random() * 5))) === 0 && food && !food.isRainbow) {
		// Only spawn if food exists and is not rainbow (AI doesn't steal rainbow food)
		var avoidList = [];
		for (var j = 0; j < snake.length; ++j) avoidList.push(snake[j]);
		for (var k = 0; k < obstacles.length; ++k) avoidList.push(obstacles[k]);
		// Spawn at random edge
		var edge = Math.floor(Math.random() * 4);
		var pos;
		if (edge === 0) {
			// left
			pos = {
				x: 120,
				y: 200 + Math.random() * (2732 - 400)
			};
		} else if (edge === 1) {
			// right
			pos = {
				x: 2048 - 120,
				y: 200 + Math.random() * (2732 - 400)
			};
		} else if (edge === 2) {
			// top
			pos = {
				x: 200 + Math.random() * (2048 - 400),
				y: 120
			};
		} else {
			// bottom
			pos = {
				x: 200 + Math.random() * (2048 - 400),
				y: 2732 - 120
			};
		}
		// Avoid spawning on snake or obstacles
		var ok = true;
		for (var i = 0; i < avoidList.length; ++i) {
			var obj = avoidList[i];
			var dx = obj.x - pos.x;
			var dy = obj.y - pos.y;
			if (dx * dx + dy * dy < 200 * 200) {
				ok = false;
				break;
			}
		}
		if (ok) {
			var ai = new AISnake();
			ai.x = pos.x;
			ai.y = pos.y;
			aiSnakes.push(ai);
			game.addChild(ai);
		}
	}
	// Update obstacles (moving, static, and spike)
	for (var i = obstacles.length - 1; i >= 0; --i) {
		if (obstacles[i].update) obstacles[i].update();
		// Remove moving obstacles that have been marked for despawn
		if (obstacles[i] instanceof MovingObstacle && obstacles[i]._despawn) {
			obstacles[i].destroy();
			obstacles.splice(i, 1);
			continue;
		}
		// Remove static obstacles that have been marked for despawn
		if (obstacles[i] instanceof Obstacle && obstacles[i]._despawn) {
			obstacles[i].destroy();
			obstacles.splice(i, 1);
			continue;
		}
		// Remove spike obstacles that have been marked for despawn
		if (typeof SpikeObstacle !== "undefined" && obstacles[i] instanceof SpikeObstacle && obstacles[i]._despawn) {
			obstacles[i].destroy();
			obstacles.splice(i, 1);
			continue;
		}
	}
	// Obstacles are static, no update needed
	// Snake direction: smooth turn toward nextDir
	var d = snakeNextDir - snakeDir;
	while (d > Math.PI) d -= 2 * Math.PI;
	while (d < -Math.PI) d += 2 * Math.PI;
	if (Math.abs(d) > 0.01) {
		var turn = Math.sign(d) * Math.min(Math.abs(d), SNAKE_TURN_ANGLE);
		snakeDir += turn;
	}
	// Move snake head
	var head = snake[0];
	var prevPos = {
		x: head.x,
		y: head.y
	};
	head.x += Math.cos(snakeDir) * snakeSpeed;
	head.y += Math.sin(snakeDir) * snakeSpeed;
	// Clamp to bounds (leave 100px margin for UI)
	head.x = Math.max(100 + head.asset.width / 2, Math.min(2048 - 100 - head.asset.width / 2, head.x));
	head.y = Math.max(100 + head.asset.height / 2, Math.min(2732 - 100 - head.asset.height / 2, head.y));
	// Move body segments to follow
	for (var i = 1; i < snake.length; ++i) {
		var seg = snake[i];
		var target = snake[i - 1];
		var dx = target.x - seg.x;
		var dy = target.y - seg.y;
		var dist = Math.sqrt(dx * dx + dy * dy);
		var desired = snakeSpeed * 0.9;
		if (dist > desired) {
			var move = (dist - desired) * 0.5;
			seg.x += dx / dist * move;
			seg.y += dy / dist * move;
		}
	}
	// Grow snake if needed
	if (snakeGrow > 0) {
		var tail = snake[snake.length - 1];
		var newSeg = new SnakeSegment();
		newSeg.setType('body');
		newSeg.x = tail.x;
		newSeg.y = tail.y;
		game.addChild(newSeg);
		snake.push(newSeg);
		snakeGrow--;
	}
	// Check collision with food
	if (food && head.intersects(food)) {
		LK.getSound('eat').play();
		if (food.isRainbow) {
			updateScore(score + FOOD_SCORE * 10);
			snakeGrow += 12;
			// Flash the whole snake rainbow
			for (var i = 0; i < snake.length; ++i) {
				LK.effects.flashObject(snake[i], 0xffffff, 800);
			}
		} else if (food.isPurple) {
			updateScore(score + FOOD_SCORE * 3);
			snakeGrow += 6;
		} else {
			updateScore(score + FOOD_SCORE);
			snakeGrow += 2;
		}
		food.destroy();
		food = null;
		// If an AI snake stole the food, don't respawn (AI snake update will handle it)
		// Only respawn food if it was NOT stolen by an AI snake this frame
		if (!aiSnakes.some(function (ai) {
			return ai.stealing;
		})) {
			spawnFood();
		}
		// Chance to spawn powerup
		if (!powerup && Math.random() < 0.2) {
			spawnPowerUp();
		}
	}
	// Check collision with powerup
	if (powerup && head.intersects(powerup)) {
		LK.getSound('powerup').play();
		updateScore(score + POWERUP_SCORE);
		activatePowerUp(powerup.type);
		// Flash the screen for feedback
		LK.effects.flashScreen(0xf1c40f, 400);
		powerup.destroy();
		powerup = null;
	}
	// Check collision with obstacles
	for (var i = 0; i < obstacles.length; ++i) {
		// SpikeObstacle: destroys segments it touches, reduces score
		if (typeof SpikeObstacle !== "undefined" && obstacles[i] instanceof SpikeObstacle) {
			// Check all segments (not just head)
			for (var s = 0; s < snake.length; ++s) {
				var seg = snake[s];
				if (seg.intersects(obstacles[i])) {
					// Only destroy if not invincible
					if (!isInvincible) {
						// Flash segment and obstacle
						LK.effects.flashObject(seg, 0xda2cff, 400);
						LK.effects.flashObject(obstacles[i], 0xda2cff, 400);
						// Remove segment (but always keep at least 2: head + 1)
						if (snake.length > 2) {
							seg.destroy();
							snake.splice(s, 1);
							// Reduce score, but not below zero
							updateScore(Math.max(0, score - 25));
							// Play hit sound
							LK.getSound('hit').play();
							// Do NOT remove spike after hit; spike stays infinitely until despawn
							break; // Only one segment hit per spike per frame
						} else {
							// If only 2 left, end game
							endGame();
							return;
						}
					} else {
						// Invincible: just destroy spike
						LK.effects.flashObject(obstacles[i], 0xffffff, 300);
						obstacles[i].destroy();
						obstacles.splice(i, 1);
						i--;
						break;
					}
				}
			}
			continue;
		}
		// Normal/moving obstacle logic
		if (head.intersects(obstacles[i])) {
			if (!isInvincible) {
				endGame();
				return;
			} else {
				// Flash obstacle and destroy it
				LK.effects.flashObject(obstacles[i], 0xffffff, 300);
				obstacles[i].destroy();
				obstacles.splice(i, 1);
				i--;
			}
		}
	}
	// Check collision with self (skip first 4 segments for leniency)
	if (!isInvincible) {
		for (var i = 4; i < snake.length; ++i) {
			if (head.intersects(snake[i])) {
				endGame();
				return;
			}
		}
	}
	// Evolving obstacles: every 30 seconds, add a new one (max 8)
	if (LK.ticks % (60 * 30) === 0 && obstacles.length < 8) {
		var obs;
		// 40% chance for spike, 30% moving, 30% static
		var r = Math.random();
		if (r < 0.40) {
			obs = new SpikeObstacle();
		} else if (r < 0.70) {
			obs = new MovingObstacle();
		} else {
			obs = new Obstacle();
		}
		// Avoid spawning on the snake and other obstacles
		var avoidList = [];
		for (var j = 0; j < snake.length; ++j) {
			avoidList.push(snake[j]);
		}
		for (var k = 0; k < obstacles.length; ++k) {
			avoidList.push(obstacles[k]);
		}
		var pos = randomPos(300, avoidList, 140);
		obs.x = pos.x;
		obs.y = pos.y;
		obstacles.push(obs);
		game.addChild(obs);
	}
	// After 2 minutes, every 20 seconds, add a new moving obstacle (max 12)
	if (LK.ticks > 60 * 120 && LK.ticks % (60 * 20) === 0 && obstacles.length < 12) {
		var obs2 = new MovingObstacle();
		// Avoid spawning on the snake and other obstacles
		var avoidList2 = [];
		for (var j = 0; j < snake.length; ++j) {
			avoidList2.push(snake[j]);
		}
		for (var k = 0; k < obstacles.length; ++k) {
			avoidList2.push(obstacles[k]);
		}
		var pos2 = randomPos(300, avoidList2, 140);
		obs2.x = pos2.x;
		obs2.y = pos2.y;
		obstacles.push(obs2);
		game.addChild(obs2);
	}
};
// --- Game start/reset ---
function startGame() {
	gameOver = false;
	updateScore(0);
	resetSnake();
	// Remove all AI snakes
	for (var i = 0; i < aiSnakes.length; ++i) {
		aiSnakes[i].destroy();
	}
	aiSnakes = [];
	spawnFood();
	if (powerup) {
		powerup.destroy();
		powerup = null;
	}
	spawnObstacles();
	deactivatePowerUp();
	LK.playMusic('snakebg', {
		fade: {
			start: 0,
			end: 1,
			duration: 1000
		}
	});
}
startGame();
// --- Game over/win handling is automatic by LK ---
// --- Music is started on game start ---