packages/discount-loyalty/
├── src/
│   ├── types/
│   │   └── schemas.ts          # Zod schemas for Voucher, OrderContext, LoyaltyAccount, MemberTier
│   ├── voucher/
│   │   └── voucher-engine.ts   # VoucherEngine, validateVoucher, calculateVoucherDiscount, TIER_RANKS
│   ├── loyalty/
│   │   └── loyalty-engine.ts   # LoyaltyEngine, determineMemberTier, calculatePointsToEarn, calculateRedeemDiscount
│   └── index.ts                # SSoT Unified Barrel

import {
  VoucherEngine,
  calculateVoucherDiscount,
  determineMemberTier,
  calculatePointsToEarn,
  calculateRedeemDiscount,
  DEFAULT_LOYALTY_CONFIG,
  type OrderContextInput,
  type VoucherInput,
  type LoyaltyAccountInput,
} from '@kido/discount-loyalty';

// 1. Define customer order context
const orderContext: OrderContextInput = {
  orderId: 'ORD-2026-9921',
  userTier: 'GOLD',
  items: [
    { id: 'SKU-COFFEE-01', name: 'Arabica Cold Brew', price: 65_000, quantity: 2, categoryId: 'BEVERAGE' },
    { id: 'SKU-CAKE-02', name: 'Matcha Tiramisu', price: 85_000, quantity: 1, categoryId: 'BAKERY' },
  ],
  subtotal: 215_000,
  currentDate: new Date('2026-11-20T10:00:00Z'),
};

// 2. Configure voucher with category restriction & cap
const summerVoucher: VoucherInput = {
  id: 'vouch-sum-2026',
  code: 'SUMMER20',
  name: 'Giảm 20% đồ uống tối đa 30,000₫',
  type: 'PERCENTAGE',
  value: 20,
  maxDiscountAmount: 30_000,
  minOrderValue: 100_000,
  minTier: 'SILVER',
  applicableCategories: ['BEVERAGE'], // Only applied to 130,000₫ of coffee
  isActive: true,
  validFrom: new Date('2026-06-01T00:00:00Z'),
  validTo: new Date('2026-12-31T23:59:59Z'),
  usedCount: 14,
  usageLimit: 1000,
};

// 3. Evaluate voucher discount
const voucherResult = calculateVoucherDiscount(summerVoucher, orderContext);
console.log('Voucher Applied:', {
  isValid: voucherResult.isValid,
  eligibleAmount: voucherResult.eligibleAmount, // 130,000₫
  discountAmount: voucherResult.discountAmount, // 26,000₫ (20% of 130k)
  payableSubtotal: voucherResult.finalTotal,    // 189,000₫
});

// 4. Evaluate Loyalty Points Redemption (Gold Tier)
const userAccount: LoyaltyAccountInput = {
  id: 'loyalty-usr-441',
  userId: 'usr-8819',
  balance: 150, // 150 points = 150,000₫ max
  tier: 'GOLD',
  totalSpend: 7_500_000,
  updatedAt: new Date(),
};

// Customer wants to redeem 100 points (100,000₫)
// Guard: Max 50% of payable subtotal (50% of 189,000₫ = 94,500₫ = 94 points max)
const redeemResult = calculateRedeemDiscount(
  userAccount,
  100,
  voucherResult.finalTotal,
  DEFAULT_LOYALTY_CONFIG
);

console.log('Loyalty Redemption Result:', {
  success: redeemResult.success,
  redeemedPoints: redeemResult.pointsRedeemed, // 94 points capped
  discount: redeemResult.discountAmount,       // 94,000₫
  finalTotal: voucherResult.finalTotal - redeemResult.discountAmount, // 95,000₫
});

// 5. Calculate Points Earned from Cash Portion
const pointsEarned = calculatePointsToEarn(95_000, 'GOLD', DEFAULT_LOYALTY_CONFIG);
console.log(`Earned ${pointsEarned} loyalty points on post-discount cash spend.`);