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

/**** 
* Classes
****/ 
// Enemy Shell Class
var EnemyShell = Container.expand(function () {
	var self = Container.call(this);
	var shell = self.attachAsset('enemyShell', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.width = shell.width;
	self.height = shell.height;
	self.vx = 0;
	self.vy = 8; // Reduced speed
	self.update = function () {
		self.x += self.vx;
		self.y += self.vy;
	};
	return self;
});
// Enemy Tank Class
var EnemyTank = Container.expand(function () {
	var self = Container.call(this);
	var tank = self.attachAsset('enemyTank', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.width = tank.width;
	self.height = tank.height;
	// Movement
	self.speed = 6 + Math.random() * 2 + Math.floor(LK.getScore() / 10); // Escalate with score
	// Firing
	self.fireInterval = 120; // 2 seconds at 60fps
	self.fireCounter = 0;
	self.update = function () {
		self.y += self.speed;
		self.fireCounter++;
		if (self.fireCounter >= self.fireInterval) {
			self.fireCounter = 0;
			self.fire();
		}
	};
	self.fire = function () {
		var shell = new EnemyShell();
		shell.x = self.x;
		shell.y = self.y + self.height / 2 + shell.height / 2;
		// Aim at player
		var dx = player.x - shell.x;
		var dy = player.y - shell.y;
		var mag = Math.sqrt(dx * dx + dy * dy);
		// Lowered speed for enemy shells
		var shellSpeed = 7 + Math.floor(LK.getScore() / 20);
		shell.vx = dx / mag * shellSpeed;
		shell.vy = dy / mag * shellSpeed;
		enemyShells.push(shell);
		game.addChild(shell);
		LK.getSound('enemyFire').play();
	};
	return self;
});
// Explosion effect (for destroyed tanks)
var Explosion = Container.expand(function () {
	var self = Container.call(this);
	var exp = self.attachAsset('explosion', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	exp.alpha = 0.7;
	// Animate fade out and destroy
	tween(exp, {
		alpha: 0
	}, {
		duration: 350,
		easing: tween.linear,
		onFinish: function onFinish() {
			self.destroy();
		}
	});
	return self;
});
// Heart Drop Class (powerup)
var HeartDrop = Container.expand(function () {
	var self = Container.call(this);
	var heart = self.attachAsset('heart', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.width = heart.width;
	self.height = heart.height;
	self.speed = 7 + Math.random() * 2;
	self.update = function () {
		self.y += self.speed;
	};
	return self;
});
// Player Shell Class
var PlayerShell = Container.expand(function () {
	var self = Container.call(this);
	var shell = self.attachAsset('playerShell', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.width = shell.width;
	self.height = shell.height;
	self.speed = -32; // Upwards
	self.update = function () {
		self.y += self.speed;
	};
	return self;
});
// Player Tank Class
var PlayerTank = Container.expand(function () {
	var self = Container.call(this);
	var tank = self.attachAsset('playerTank', {
		anchorX: 0.5,
		anchorY: 0.5
	});
	self.width = tank.width;
	self.height = tank.height;
	// Fire cooldown
	self.canFire = true;
	self.fireCooldown = 18; // frames (0.3s)
	self.cooldownCounter = 0;
	self.update = function () {
		if (!self.canFire) {
			self.cooldownCounter++;
			if (self.cooldownCounter >= self.fireCooldown) {
				self.canFire = true;
				self.cooldownCounter = 0;
			}
		}
	};
	// Fire a shell
	self.fire = function () {
		if (self.canFire) {
			var shell = new PlayerShell();
			shell.x = self.x;
			shell.y = self.y - self.height / 2 - shell.height / 2;
			playerShells.push(shell);
			game.addChild(shell);
			LK.getSound('fire').play();
			self.canFire = false;
		}
	};
	return self;
});

/**** 
* Initialize Game
****/ 
var game = new LK.Game({
	backgroundColor: 0x22272b
});

/**** 
* Game Code
****/ 
// Sound effects
// Explosion: white ellipse (for flash effect)
// Enemy shell: orange ellipse
// Enemy tank: red box
// Player shell: yellow ellipse
// Player tank: green box
// Game area
var GAME_W = 2048;
var GAME_H = 2732;
// Player
var player = new PlayerTank();
player.x = GAME_W / 2;
player.y = GAME_H - 350;
game.addChild(player);
// Arrays for game objects
var playerShells = [];
var enemyTanks = [];
var enemyShells = [];
var heartDrops = []; // Array for heart drops
// Score display
var scoreTxt = new Text2('0', {
	size: 120,
	fill: "#fff"
});
scoreTxt.anchor.set(0.5, 0);
LK.gui.top.addChild(scoreTxt);
// Player health
var playerHealth = 5;
var healthTxt = new Text2('❤❤❤❤❤', {
	size: 100,
	fill: 0xFF4444
});
healthTxt.anchor.set(0.5, 0);
LK.gui.top.addChild(healthTxt);
healthTxt.x = 300;
healthTxt.y = 0;
// Dragging
var dragNode = null;
// Spawn enemy timer
var enemySpawnInterval = 90; // frames (1.5s)
var enemySpawnCounter = 0;
// Difficulty escalation
function getEnemySpawnInterval() {
	var s = LK.getScore();
	if (s < 10) return 90;
	if (s < 25) return 70;
	if (s < 50) return 55;
	return 40;
}
// Move handler (drag player tank)
function handleMove(x, y, obj) {
	if (dragNode) {
		// Clamp to game area, avoid top 100px (menu)
		var minX = dragNode.width / 2;
		var maxX = GAME_W - dragNode.width / 2;
		var minY = 100 + dragNode.height / 2;
		var maxY = GAME_H - dragNode.height / 2;
		dragNode.x = Math.max(minX, Math.min(maxX, x));
		dragNode.y = Math.max(minY, Math.min(maxY, y));
	}
}
game.move = handleMove;
game.down = function (x, y, obj) {
	// Only drag if touch is on player tank
	var local = player.toLocal(game.toGlobal({
		x: x,
		y: y
	}));
	if (local.x > -player.width / 2 && local.x < player.width / 2 && local.y > -player.height / 2 && local.y < player.height / 2) {
		dragNode = player;
	}
};
game.up = function (x, y, obj) {
	dragNode = null;
};
// Tap to fire (anywhere)
game.tap = function (x, y, obj) {
	player.fire();
};
// For compatibility, also fire on down if not dragging
game.down = function (x, y, obj) {
	var local = player.toLocal(game.toGlobal({
		x: x,
		y: y
	}));
	if (local.x > -player.width / 2 && local.x < player.width / 2 && local.y > -player.height / 2 && local.y < player.height / 2) {
		dragNode = player;
	} else {
		player.fire();
	}
};
// Main update loop
game.update = function () {
	// Update player
	player.update();
	// Update player shells
	for (var i = playerShells.length - 1; i >= 0; i--) {
		var shell = playerShells[i];
		shell.update();
		// Remove if off screen
		if (shell.y < -shell.height / 2) {
			shell.destroy();
			playerShells.splice(i, 1);
			continue;
		}
		// Check collision with enemy tanks
		for (var j = enemyTanks.length - 1; j >= 0; j--) {
			var enemy = enemyTanks[j];
			if (shell.intersects(enemy)) {
				// Explosion
				var exp = new Explosion();
				exp.x = enemy.x;
				exp.y = enemy.y;
				game.addChild(exp);
				LK.getSound('explode').play();
				// Remove both
				shell.destroy();
				playerShells.splice(i, 1);
				enemy.destroy();
				enemyTanks.splice(j, 1);
				// Score
				LK.setScore(LK.getScore() + 1);
				scoreTxt.setText(LK.getScore());
				break;
			}
		}
	}
	// Update enemy tanks
	for (var i = enemyTanks.length - 1; i >= 0; i--) {
		var enemy = enemyTanks[i];
		enemy.update();
		// Remove if off screen
		if (enemy.y > GAME_H + enemy.height / 2) {
			enemy.destroy();
			enemyTanks.splice(i, 1);
			continue;
		}
		// Check collision with player
		if (enemy.intersects(player)) {
			// Explosion
			var exp = new Explosion();
			exp.x = player.x;
			exp.y = player.y;
			game.addChild(exp);
			LK.getSound('explode').play();
			LK.effects.flashScreen(0xff0000, 800);
			// Decrease health
			playerHealth--;
			// Update health display
			var hearts = '';
			for (var h = 0; h < playerHealth; h++) hearts += '❤';
			healthTxt.setText(hearts);
			if (playerHealth <= 0) {
				LK.showGameOver();
				return;
			}
			// Remove enemy tank
			enemy.destroy();
			enemyTanks.splice(i, 1);
			continue;
		}
	}
	// Update enemy shells
	for (var i = enemyShells.length - 1; i >= 0; i--) {
		var shell = enemyShells[i];
		shell.update();
		// Remove if off screen
		if (shell.y > GAME_H + shell.height / 2 || shell.x < -shell.width / 2 || shell.x > GAME_W + shell.width / 2) {
			shell.destroy();
			enemyShells.splice(i, 1);
			continue;
		}
		// Check collision with player
		if (shell.intersects(player)) {
			// Explosion
			var exp = new Explosion();
			exp.x = player.x;
			exp.y = player.y;
			game.addChild(exp);
			LK.getSound('explode').play();
			LK.effects.flashScreen(0xff0000, 800);
			// Decrease health
			playerHealth--;
			// Update health display
			var hearts = '';
			for (var h = 0; h < playerHealth; h++) hearts += '❤';
			healthTxt.setText(hearts);
			if (playerHealth <= 0) {
				LK.showGameOver();
				return;
			}
			// Remove shell
			shell.destroy();
			enemyShells.splice(i, 1);
			continue;
		}
	}
	// Spawn enemies
	enemySpawnCounter++;
	if (enemySpawnCounter >= getEnemySpawnInterval()) {
		enemySpawnCounter = 0;
		var enemy = new EnemyTank();
		// Random x, avoid edges
		var margin = 200;
		enemy.x = margin + Math.random() * (GAME_W - 2 * margin);
		enemy.y = -enemy.height / 2;
		enemyTanks.push(enemy);
		game.addChild(enemy);
	}
	// Rarely spawn heart drops (about 1 in 400 frames, ~every 6-7 seconds)
	if (Math.random() < 1 / 400) {
		var heart = new HeartDrop();
		var margin = 200;
		heart.x = margin + Math.random() * (GAME_W - 2 * margin);
		heart.y = -heart.height / 2;
		heartDrops.push(heart);
		game.addChild(heart);
	}
	// Update heart drops
	for (var i = heartDrops.length - 1; i >= 0; i--) {
		var heart = heartDrops[i];
		heart.update();
		// Remove if off screen
		if (heart.y > GAME_H + heart.height / 2) {
			heart.destroy();
			heartDrops.splice(i, 1);
			continue;
		}
		// Check collision with player
		if (heart.intersects(player)) {
			// Only heal if not at max health
			if (playerHealth < 5) {
				playerHealth++;
				var hearts = '';
				for (var h = 0; h < playerHealth; h++) hearts += '❤';
				healthTxt.setText(hearts);
			}
			heart.destroy();
			heartDrops.splice(i, 1);
			continue;
		}
	}
};
// Set initial score
LK.setScore(0);
scoreTxt.setText('0');
;
// Set initial health
playerHealth = 5;
var hearts = '';
for (var h = 0; h < playerHealth; h++) hearts += '❤';
healthTxt.setText(hearts);

===================================================================
--- original.js
+++ change.js
@@ -82,8 +82,23 @@
 		}
 	});
 	return self;
 });
+// Heart Drop Class (powerup)
+var HeartDrop = Container.expand(function () {
+	var self = Container.call(this);
+	var heart = self.attachAsset('heart', {
+		anchorX: 0.5,
+		anchorY: 0.5
+	});
+	self.width = heart.width;
+	self.height = heart.height;
+	self.speed = 7 + Math.random() * 2;
+	self.update = function () {
+		self.y += self.speed;
+	};
+	return self;
+});
 // Player Shell Class
 var PlayerShell = Container.expand(function () {
 	var self = Container.call(this);
 	var shell = self.attachAsset('playerShell', {
@@ -144,15 +159,15 @@
 
 /**** 
 * Game Code
 ****/ 
-// Game area
-// Player tank: green box
-// Player shell: yellow ellipse
-// Enemy tank: red box
-// Enemy shell: orange ellipse
-// Explosion: white ellipse (for flash effect)
 // Sound effects
+// Explosion: white ellipse (for flash effect)
+// Enemy shell: orange ellipse
+// Enemy tank: red box
+// Player shell: yellow ellipse
+// Player tank: green box
+// Game area
 var GAME_W = 2048;
 var GAME_H = 2732;
 // Player
 var player = new PlayerTank();
@@ -162,8 +177,9 @@
 // Arrays for game objects
 var playerShells = [];
 var enemyTanks = [];
 var enemyShells = [];
+var heartDrops = []; // Array for heart drops
 // Score display
 var scoreTxt = new Text2('0', {
 	size: 120,
 	fill: "#fff"
@@ -352,8 +368,41 @@
 		enemy.y = -enemy.height / 2;
 		enemyTanks.push(enemy);
 		game.addChild(enemy);
 	}
+	// Rarely spawn heart drops (about 1 in 400 frames, ~every 6-7 seconds)
+	if (Math.random() < 1 / 400) {
+		var heart = new HeartDrop();
+		var margin = 200;
+		heart.x = margin + Math.random() * (GAME_W - 2 * margin);
+		heart.y = -heart.height / 2;
+		heartDrops.push(heart);
+		game.addChild(heart);
+	}
+	// Update heart drops
+	for (var i = heartDrops.length - 1; i >= 0; i--) {
+		var heart = heartDrops[i];
+		heart.update();
+		// Remove if off screen
+		if (heart.y > GAME_H + heart.height / 2) {
+			heart.destroy();
+			heartDrops.splice(i, 1);
+			continue;
+		}
+		// Check collision with player
+		if (heart.intersects(player)) {
+			// Only heal if not at max health
+			if (playerHealth < 5) {
+				playerHealth++;
+				var hearts = '';
+				for (var h = 0; h < playerHealth; h++) hearts += '❤';
+				healthTxt.setText(hearts);
+			}
+			heart.destroy();
+			heartDrops.splice(i, 1);
+			continue;
+		}
+	}
 };
 // Set initial score
 LK.setScore(0);
 scoreTxt.setText('0');