複雑・炎上システムを根本脱却
システムレスキュープロ

// 🤢 Spaghetti Code (Before)
function processOrder(order) {
  let isOk = false;
  let t = 0;
  for(let i=0; i<order.items.length; i++) {
    if(order.items[i].price > 0) {
       t = t + (order.items[i].price * order.items[i].qty);
    }
  }
  if (t > 1000) {
    if (order.user.isVip == true) {
      t = t - (t * 0.2); // 20% off
    } else {
      if (order.user.isPremium == true) {
         t = t - (t * 0.1); // 10% off
      }
    }
  }
  setTimeout(function() {
    apiCall('save', order, function(res) {
      if(res.status == 200) {
         isOk = true;
         console.log('done');
      }
    });
  }, 1000);
  return isOk; // ALWAYS RETURNS FALSE due to async!
}

// ✨ Refactored Modern Code (After)
const calculateDiscount = (total: number, user: User) => {
  if (total <= 1000) return 0;
  if (user.isVip) return total * 0.2;
  if (user.isPremium) return total * 0.1;
  return 0;
};

export const processOrder = async (order: Order): Promise<boolean> => {
  try {
    const subtotal = order.items.reduce((sum, item) => 
      sum + Math.max(0, item.price) * item.qty, 0
    );
    
    const discount = calculateDiscount(subtotal, order.user);
    const finalTotal = subtotal - discount;

    const res = await apiCall('save', { ...order, finalTotal });
    return res.status === 200;

  } catch (error) {
    console.error('Order processing failed:', error);
    return false;
  }
};