adding 502 error

games/space-invaders404/js/ai.js

@@ -0,0 +1,41 @@
+var updateEnemies = function(){
+
+  if (hasReachedEnd()) {
+    changeEnemyDirection();
+    return;
+  }
+  var enemyMovement;
+  if (enemyDirection == LEFT) enemyMovement = -10;
+  else enemyMovement = 10;
+
+  for (var i = 0 ; i < enemies.length; i++){
+    var enemy = enemies[i];
+    enemy.x = enemy.x + enemyMovement ;
+  }
+}
+
+var hasReachedEnd = function(){
+  var threshold = 32;
+
+  for (var i = 0 ; i < enemies.length; i++){
+    var enemy = enemies[i];
+    if (enemyDirection == RIGHT && enemy.x > canvas.width - threshold - 32) return true;
+    else if (enemyDirection == LEFT && enemy.x < threshold) return true;
+  }
+  return false;
+}
+
+var changeEnemyDirection = function(){
+  if (enemyDirection == LEFT) enemyDirection = RIGHT;
+  else enemyDirection = LEFT;
+
+  for (var i = 0 ; i < enemies.length; i++){
+    var enemy = enemies[i];
+    enemy.y = enemy.y + 30 ;
+  }
+}
+
+var enemyShot = function(){
+  var enemy = enemies[Math.floor(Math.random()*enemies.length)];
+  enemyShots.push({x:enemy.x, y: enemy.y});
+}