OrderBuilder

An Order builder API makes business-logic development more easier.

Features

• Arbitrary-precision order-calculating based on decimal.js.
• Common Pipe pattern API.

Core API

1. OrderBuilder

   • config
     • PolicyPickStrategy
       • ItemBasedPolicyPickStrategy
       • OrderBasedPolicyPickStrategy
     • DiscountMethod
       • PriceWeightedAverageDiscountMethod
       • QuantityWeightedAverageDiscountMethod
     • RoundStrategy
       • EveryCalculationRoundStrategy
       • FinalPriceRoundStrategy
       • NoRoundRoundStrategy

2. Policy

   • discount
     • ValueDiscount
     • PercentageDiscount
     • StepValueDiscount
     • StepPercentageDiscount
     • ItemGiveawayDiscount

3. Condition

   • threshold
     • PriceThreshold
     • QuantityThreshold
   • requirement
     • ItemIncluded
     • ItemRequired
     • QuantityRequired
     • ItemExcluded
   • validator
     • CouponValidator

Documents

OrderBuilder

| Arguments | index | Type | Required | | -------------------- | ------- | ------------------------------- | -------- | | overload1 | | | | | builder | 0 | OrderBuilder | false | | overload2 | | | | | options | 0 | OrderBuilderConstructor | false |

OrderBuilderConstructor

| Properties | Type | Required | | -------------------- | ------------------------ | -------- | | policies | Policy[] | true | | discountMethod | "price-weighted-average" | "quantity-weighted-average" | false | | roundStrategy | "every-calculation" | "final-price-only" | "no-round" | false | | logistics | OrderLogistics | false |

| OrderBuilder | Return | Description | | ---------------------------------------- | ----------------- | ----------- | | Properties | | | | config | OrderConfig | Get the configuration of current builder. | | policies | Policies[] | Get all the policies of the builder. (activated + none-activated) | | hasBuiltOrders | boolean | Checks whether this builder has already built any instance of order. | | Methods | | | | build | Order | Create an order instance, and lock the access of mutations on policy. | | clone | OrderBuilder | Create a new OrderBuilder instance based on current instance. | | addPolicy(policy: Policies) | this | Push policy instance(s) into builder.policies (can active as builder.hasBuiltOrders is false). | | addPolicy(policies: Policies[]) | | | | removePolicy(policy: Policy) | this | Remove policy instance(s) from builder.policies based on instance reference or policy.id (can active as builder.hasBuiltOrders is false) | | removePolicy(policy: string) | | | | removePolicy(policies: Policy[]) | | | | removePolicy(policies: string[]) | | | | getPolicy(policyId: string) | Policy | undefined | Get the specified policy instance by policy.id | | setLogistics(logistics: OrderLogistics)| this | Set the logistics of the order. |

Order

OrderConstructor

| Properties | Type | Required | | -------------------- | ------------- | -------- | | items | OrderItem[] | true | | coupons | string[] | false |

| Order | Return | Description | | ---------------------------------------- | ----------------- | ----------- | | Properties | | | | builder | OrderBuilder | Get the the owner of current order. | | config | OrderConfig | Get the configuration from its builder. | | policies | Policies[] | Get all the policies from its builder. | | coupons | string[] | Get all the coupons from current order. | | items | OrderItem[] | Get all the items from current order. | | itemManager | OrderItemManager | Get the item manager. | | itemRecords | OrderItemRecord[] | Get all the detail-records of item based on policies. | | discounts | PolicyDiscountDescription[] | Get the descriptions of discount based on applied-policies. | | discountValue | number | Get total discount in this order. | | itemValue | number | Get total value of items in this order. | | itemQuantity | number | Get total quantity of items in this order. | | price | number | Get final price of order. | | logistics | OrderLogistics | Get logistics config of current order. | | logisticsRecord | OrderItemRecord | Get logistics in the type of order-item-record. | | Methods | | | | subOrder(subCondition: SubOrderCondition)| Order | Create a new instance of Order based on the sub-condition on items and coupons. | | addCoupon(coupon: string) | this | Push coupon(s) into order.coupons. | | addCoupon(coupons: string[]) | | | | removeCoupon(coupon: string) | this | Remove coupons(s) from order.coupons | | removeCoupon(coupons: string[]) | | | | addItem(item: OrderItem) | this | Push item(s) into order.items. | | addItem(items: OrderItem[]) | | | | removeItem(id: string, quantity: number) | this | Remove item(s) from order.items. | | removeItem(item: OrderItem) | | | | removeItem(item: string) | | | | removeItem(items: OrderItem[]) | | | | removeItem(items: string[]) | | |

Discount

| Arguments | index | Type | Required | | -------------------- | ------- | --------------- | -------- | | overload1 | | | | | value | 0 | number | true | | condition | 1 | Condition | false | | options | 2 | DiscountOptions | false | | overload2 | | | | | value | 0 | number | true | | conditions | 1 | Condition[] | false | | options | 2 | DiscountOptions | false | | overload3 | | | | | value | 0 | number | true | | options | 1 | DiscountOptions | false |

Interfaces Remark

| Interface | Type | | -------------- | ---------------------- | | Policies | Policy | Policy[] | | RemovePolicy | Policy | string |

Basic Usage

import { OrderBuilder, ValueDiscount, PercentageDiscount } from '@rytass/order-builder';

const policy1 = new ValueDiscount(100, { id: 'DISCOUNT_1' });
const policy2 = new PercentageDiscount(0.8, { id: 'DISCOUNT_2' });

// Initialize an order-builder.
const builder = new OrderBuilder({
  policyPickStrategy: 'item-based',
  discountMethod: 'price-weighted-average',
  roundStrategy: 'every-calculation',
  policies: [policy1],
});

// Allowing conditional business-logic to determinate whether to mutate policies.
const order = builder
  .addPolicy(policy2) // 20% off
  .removePolicy('DISCOUNT_1') // or .removePolicy(policy1)
  .build({
    items: [
      {
        id: 'ItemA',
        name: 'Foo',
        unitPrice: 100,
        quantity: 2,
      },
      {
        id: 'ItemB',
        name: 'Bar',
        unitPrice: 50,
        quantity: 1,
      },
    ],
  });

builder.getPolicy('DISCOUNT_1'); // undefined
builder.getPolicy('DISCOUNT_2'); // reference to `policy2`
order.price // 250 * 0.8 = 200
order.itemRecords
// [
//   {
//     itemId: 'ItemA-1',
//     originItem: { id: 'ItemA', name: 'Foo', unitPrice: 100 },
//     initialValue: 100,
//     discountValue: 20,
//     finalPrice: 80,
//     discountRecords: [{ policyId: 'DISCOUNT_2', discountValue: 20 }],
//     appliedPolicies: [policy2]
//   },
//   {
//     itemId: 'ItemA-2',
//     originItem: { id: 'ItemA', name: 'Foo', unitPrice: 100 },
//     initialValue: 100,
//     discountValue: 20,
//     finalPrice: 80,
//     discountRecords: [{ policyId: 'DISCOUNT_2', discountValue: 20 }],
//     appliedPolicies: [policy2]
//   },
//   {
//     itemId: 'ItemB-1',
//     originItem: { id: 'ItemB', name: 'Bar', unitPrice: 50 },
//     initialValue: 50,
//     discountValue: 10,
//     finalPrice: 40,
//     discountRecords: [{ policyId: 'DISCOUNT_2', discountValue: 10 }],
//     appliedPolicies: [policy2]
//   }
// ]

Examples

Custom OrderItem Dto

import {
  /** Core */
  OrderItem,
  OrderBuilder,
  /** Conditions */
  ItemIncluded,
  PriceThreshold,
  QuantityThreshold,
  /** Discount policies */
  ValueDiscount,
  StepValueDiscount,
  PercentageDiscount,
  ItemGiveawayDiscount,
  StepPercentageDiscount,
} from '@rytass/order-builder';

// Allow custom order-item dto.
type TestOrderItem = OrderItem<{
  category: string,
  brand: string,
}>;

const items: TestOrderItem[] = [
  {
    id: 'A',
    name: '外套A',
    unitPrice: 1000,
    quantity: 1,
    category: 'jacket',
    brand: 'AJE',
  },
  {
    id: 'B',
    name: '外套B',
    unitPrice: 1500,
    quantity: 1,
    category: 'jacket',
    brand: 'N21',
  },
  {
    id: 'C',
    name: '鞋子C',
    unitPrice: 2000,
    quantity: 1,
    category: 'shoes',
    brand: 'N21',
  },
  {
    id: 'D',
    name: '鞋子D',
    unitPrice: 2500,
    quantity: 1,
    category: 'shoes',
    brand: 'Preen',
  },
  {
    id: 'E',
    name: '鞋子E',
    unitPrice: 3000,
    quantity: 1,
    category: 'shoes',
    brand: 'Preen',
  },
  {
    id: 'F',
    name: '飾品F',
    unitPrice: 4000,
    quantity: 1,
    category: 'accessory',
    brand: 'Swell',
  },
  {
    id: 'G',
    name: '飾品G',
    unitPrice: 5000,
    quantity: 1,
    category: 'accessory',
    brand: 'Swell',
  },
  {
    id: 'H',
    name: '飾品H',
    unitPrice: 6000,
    quantity: 1,
    category: 'accessory',
    brand: 'Swell',
  },
  {
    id: 'I',
    name: '飾品I',
    unitPrice: 6500,
    quantity: 1,
    category: 'accessory',
    brand: 'Boyy',
  },
];

Scenario 1 - 1

/**
 * 情境編號：甲
 * 
 * 決策法：擇優取一 (order-based)
 *
 * 情境敘述：
 * 1. 指定商品（Ａ～Ｆ）滿3件 打9折
 * 2. 指定商品（Ｃ～Ｉ）每5000元 折600元
 * 3. 指定分類（鞋子）滿4000元 送最低價商品
 * 4. 指定分類（Swell）每1件 打9折
 *
 * 輸入：(1|2) & (3|4)
 * 預期結果：2 + 4
 * 購物車顯示金額 24856
 */

// 1. 指定商品（Ａ～Ｆ）滿3件 打9折
const policy1 = new PercentageDiscount(
  0.9,
  new ItemIncluded({
    items: ['A', 'B', 'C', 'D', 'E', 'F'],
    threshold: 3,
  }),
  { onlyMatched: true },
);

// 2. 指定商品（Ｃ～Ｉ）每5000元 折600元
const policy2 = new StepValueDiscount(
  5000,
  600,
  new ItemIncluded<TestOrderItem>({
    items: ['C', 'D', 'E', 'F', 'G', 'H', 'I'],
  }),
  { stepUnit: 'price', onlyMatched: true },
);

// 3. 指定分類（鞋子）滿4000元 送最低價商品
const policy3 = new ItemGiveawayDiscount(
  1,
  new ItemIncluded<TestOrderItem>({
    scope: 'category',
    items: ['shoes'],
    conditions: [new PriceThreshold(4000)],
  }),
  { onlyMatched: true },
);

// 4. 指定分類（Swell）每1件 打9折
const policy4 = new StepPercentageDiscount(
  1,
  0.9,
  new ItemIncluded<TestOrderItem>({
    scope: 'brand',
    items: ['Swell'],
  }),
  {
    stepUnit: 'quantity',
    onlyMatched: true,
  }
);

// 擇優 (1|2) & (3|4)
const builder = new OrderBuilder({
  policyPickStrategy: 'order-based',
  policies: [
    [policy1, policy2],
    [policy3, policy4],
  ],
});

const order = builder.build({ items });

order.price // 24856

Scenario 2

/**
 * 情境編號：乙
 * 
 * 決策法：擇優取一 (order-based)
 *
 * 情境敘述：
 * 1. 指定商品（Ｂ～Ｅ）無條件 送最低價商品
 * 2. 指定商品（Ｃ～Ｉ）每3000元 折200元
 * 3. 指定分類（N21）滿2件 折100元
 * 4. 指定分類（飾品）每2件 打9折
 * 5. 指定分類（Boyy）滿5000元 打9折
 * 6. 全館 滿6件 送最低價商品
 *
 * 輸入：(1|2) & (3|4|5) & 6
 * 輸出：2 + 4 + 6
 * 購物車顯示金額 24868
 */

// 1. 指定商品（Ｂ～Ｅ）無條件 送最低價商品
const policy1 = new ItemGiveawayDiscount(
  1,
  new ItemIncluded<TestOrderItem>({
    items: ['B', 'C', 'D', 'E'],
  }),
  { onlyMatched: true }
);

// 2. 指定商品（Ｃ～Ｉ）每3000元 折200元
const policy2 = new StepValueDiscount(
  3000,
  200,
  new ItemIncluded<TestOrderItem>({
    items: ['C', 'D', 'E', 'F', 'G', 'H', 'I'],
    scope: 'id',
  }),
  { stepUnit: 'price', onlyMatched: true }
);

// 3. 指定分類（N21）滿2件 折100元
const policy3 = new ValueDiscount(
  100,
  new ItemIncluded<TestOrderItem>({
    items: ['N21'],
    scope: 'brand',
    threshold: 2,
  }),
  { onlyMatched: true }
);

// 4. 指定分類（飾品）每2件 打9折
const policy4 = new StepPercentageDiscount(
  2,
  0.9,
  new ItemIncluded<TestOrderItem>({
    items: ['accessory'],
    scope: 'category',
  }),
  { stepUnit: 'quantity', onlyMatched: true }
);

// 5. 指定分類（Boyy）滿5000元 打9折
const policy5 = new PercentageDiscount(
  0.9,
  new ItemIncluded<TestOrderItem>({
    items: ['Boyy'],
    scope: 'brand',
    conditions: [new PriceThreshold(5000)],
  }),
  { id: 'P5', onlyMatched: true }
);

// 6. 全館 滿6件 送最低價商品
const policy6 = new ItemGiveawayDiscount(1, new QuantityThreshold(6));

// 擇優 (1|2) & (3|4|5) & 6
const builder = new OrderBuilder({
  policyPickStrategy: 'order-based',
  policies: [
    [policy1, policy2],
    [policy3, policy4, policy5],
    policy6,
  ],
});

const order = builder.build({ items });

order.price // 24868

Scenario 3

/**
 * 情境編號：丙 - 1
 * 
 * 決策法：擇優取一 (order-based)
 *
 * 情境敘述：
 * 1. 全館 滿6件 送最低價商品
 * 2. 指定分類（Boyy）滿5000元 打9折
 * 3. 指定商品（Ｂ～Ｅ）無條件 送最低價商品
 * 4. 指定商品（Ｃ～Ｉ）每3000元 折200元
 * 5. 指定分類（鞋子）滿4000元 送最低價商品
 *
 * 輸入：1 & 2 & 3 & 4 & 5
 * 輸出：1 + 2 + 3 + 4 + 5
 * 購物車顯示金額 24677
 */

// 1. 全館 滿6件 送最低價商品
const policy1 = new ItemGiveawayDiscount(
  1,
  new QuantityThreshold(6),
);

// 2. 指定分類（Boyy）滿5000元 打9折
const policy2 = new PercentageDiscount(
  0.9,
  new ItemIncluded<TestOrderItem>({
    items: ['Boyy'],
    scope: 'brand',
    conditions: [new PriceThreshold(5000)],
  }),
  { onlyMatched: true }
);

// 3. 指定商品（Ｂ～Ｅ）無條件 送最低價商品
const policy3 = new ItemGiveawayDiscount(
  1,
  new ItemIncluded<TestOrderItem>({
    items: ['B''C', 'D', 'E'],
  }),
  { onlyMatched: true }
);

// 4. 指定商品（Ｃ～Ｉ）每3000元 折200元
const policy4 = new StepValueDiscount(
  3000,
  200,
  new ItemIncluded<TestOrderItem>({
    items: ['C', 'D', 'E', 'F', 'G', 'H', 'I'],
  }),
  { stepUnit: 'price', onlyMatched: true }
);

// 5. 指定分類（鞋子）滿4000元 送最低價商品
const policy5 = new ItemGiveawayDiscount(
  1,
  new ItemIncluded<TestOrderItem>({
    items: ['shoes'],
    scope: 'category',
    conditions: [new PriceThreshold(4000)],
  }),
  { onlyMatched: true }
);

const builder = new OrderBuilder({
  policyPickStrategy: 'order-based',
  policies: [
    policy1,
    policy2,
    policy3,
    policy4,
    policy5,
  ],
});

const order = builder.build({ items });

order.price // 24677

Scenario 3 - 2

/**
 * 情境編號：丙 - 2
 * 
 * 決策法：擇優取一 (order-based)
 *
 * 情境敘述：
 * 1. 全館 滿14000元 贈最低價品
 * 2. 指定商品（Ｃ～Ｅ）無條件 送最低價商品
 * 3. 指定分類（鞋子）滿6000元 送最低價商品
 * 4. 指定分類（Boyy）滿5000元 打9折
 * 5. 全館 滿9件 送最低價商品
 * 6. 指定商品（Ｃ～Ｉ）每3000元 折200元
 *
 * 輸入：1 & 2 & 3 & 4 & 5 & 6
 * 輸出：1 + 2 + 3 + 4 + 5 + 6
 * 購物車顯示金額 26250
 */

// 1. 全館 滿14000元 送最低價商品
const policy1 = new ItemGiveawayDiscount(
  1,
  new PriceThreshold(14000),
);

// 2. 指定商品（Ｃ～Ｅ）無條件 送最低價商品
const policy2 = new ItemGiveawayDiscount(
  1,
  new ItemIncluded<TestOrderItem>({
    items: ['C', 'D', 'E', 'F', 'G', 'H', 'I'],
  }),
  { onlyMatched: true }
);

// 3. 指定分類（鞋子）滿6000元 送最低價商品
const policy3 = new ItemGiveawayDiscount(
  1,
  new ItemIncluded<TestOrderItem>({
    items: ['shoes'],
    scope: 'category',
    conditions: [new PriceThreshold(6000)],
  }),
  { onlyMatched: true }
);

// 4. 指定分類（Boyy）滿5000元 打9折
const policy4 = new PercentageDiscount(
  0.9,
  new ItemIncluded<TestOrderItem>({
    scope: 'brand',
    items: ['Boyy'],
    conditions: [new PriceThreshold(5000)],
  }),
  { onlyMatched: true }
);

// 5. 全館 滿9件 送最低價商品
const policy5 = new ItemGiveawayDiscount(
  1,
  new QuantityThreshold(9),
);

// 6. 指定商品（Ｃ～Ｉ）每3000元 折200元
const policy6 = new StepValueDiscount(
  3000,
  200,
  new ItemIncluded({
    items: ['C', 'D', 'E', 'F''G', 'H', 'I'],
  }),
  { stepUnit: 'price', onlyMatched: true }
);

const builder = new OrderBuilder({
  policyPickStrategy: 'order-based',
  discountMethod: 'price-weighted-average',
  policies: [
    policy1,
    policy2,
    policy3,
    policy4,
    policy5,
    policy6,
  ],
});

const order = builder.build({ items });

order.price // 26250

Scenario 4

/**
  * 情境編號：丁
  * 
  * 決策法：擇優取一 (order-based)
  *
  * 情境敘述：
  * 1. 指定分類（飾品）無條件 折1,000 元
  * 2. 指定分類（Swell）滿10,000元 打9折
  * 3. 全館 滿15,000元 送最低價品
  * 4. 指定商品（Ｆ～Ｉ）無條件 打9折
  * 5. 指定分類（Boyy）滿5000 打9折
  *
  * 預期結果：(1&2&3) | (4&5)
  * 購物車顯示金額 28070
  */

// 1. 指定分類（飾品）無條件 折1,000 元
const policy1 = new ValueDiscount(
  1000,
  new ItemIncluded<TestOrderItem>({
    scope: 'category',
    items: ['accessory'],
  }),
  { onlyMatched: true }
);

// 2. 指定分類（Swell）滿10,000元 打9折
const policy2 = new PercentageDiscount(
  0.9,
  new ItemIncluded<TestOrderItem>({
    scope: 'brand',
    items: ['Swell'],
    conditions: [new PriceThreshold(10000)],
  }),
  { onlyMatched: true }
);

// 3. 全館 滿15,000元 送最低價品
const policy3 = new ItemGiveawayDiscount(
  1,
  new PriceThreshold(15000),
);

// 4. 指定商品（Ｆ～Ｉ）無條件 打9折
const policy4 = new PercentageDiscount(
  0.9,
  new ItemIncluded<TestOrderItem>({
    items: ['F', 'G', 'H', 'I'],
  }),
  { onlyMatched: true }
);

// 5. 指定分類（Boyy）滿5000 打9折
const policy5 = new PercentageDiscount(
  0.9,
  new ItemIncluded<TestOrderItem>({
    scope: 'brand',
    items: ['Boyy'],
    conditions: [new PriceThreshold(5000)],
  }),
  { onlyMatched: true }
);

const builder1 = new OrderBuilder({
  policyPickStrategy: 'order-based',
  policies: [
    policy1,
    policy2,
    policy3,
  ],
});

const builder2 = new OrderBuilder({
  policyPickStrategy: 'order-based',
  policies: [
    policy4,
    policy5,
  ],
});

const order1 = builder1.build({ items });
const order2 = builder2.build({ items });

order1.price // 28070
order2.price // 28765

Scenario 5

/**
 * 情境編號：戊
 *
 * 決策法：擇優取一 (order-based)
 *
 * 情境敘述：
 * 1. 指定商品（Ｂ～Ｅ）無條件 送最低價商品
 * 2. 全館 滿6件 送最低價商品
 * 3. 指定分類（飾品）每2件 打9折
 * 4. 指定分類（鞋子）滿4000元 送最低價商品
 * 5. 指定分類（Boyy）滿5000元 打9折
 * 6. 全館 滿15,000元 送最低價品
 *
 * 預期結果：(1&2&3) | (4&5&6)
 * 購物車顯示金額 24915
 */

// 1. 指定商品（Ｂ～Ｅ）無條件 送最低價商品
const policy1 = new ItemGiveawayDiscount(
  1,
  new ItemIncluded<TestOrderItem>({
    items: ['B', 'C', 'D', 'E'],
  }),
  { onlyMatched: true }
);

// 2.全館 滿6件 送最低價商品
const policy2 = new ItemGiveawayDiscount(
  1,
  new QuantityThreshold(6),
);

// 3. 指定分類（飾品）每2件 打9折
const policy3 = new StepPercentageDiscount(
  2,
  0.9,
  new ItemIncluded<TestOrderItem>({
    scope: 'category',
    items: ['accessory'],
  }),
  { stepUnit: 'quantity', onlyMatched: true }
);

// 4. 指定分類（鞋子）滿4000元 送最低價商品
const policy4 = new ItemGiveawayDiscount(
  1,
  new ItemIncluded<TestOrderItem>({
    scope: 'category',
    items: ['shoes'],
    conditions: [new PriceThreshold(4000)],
  }),
  { onlyMatched: true }
);

// 5. 指定分類（Boyy）滿5000元 打9折
const policy5 = new PercentageDiscount(
  0.9,
  new ItemIncluded<TestOrderItem>({
    scope: 'brand',
    items: ['Boyy'],
    conditions: [new PriceThreshold(5000)],
  }),
  { onlyMatched: true }
);

// 6. 全館 滿15,000元 送最低價品
const policy6 = new ItemGiveawayDiscount(
  1,
  new PriceThreshold(15000),
);

const builder1 = new OrderBuilder({
  policyPickStrategy: 'order-based',
  policies: [
    policy1,
    policy2,
    policy3,
  ],
});

const builder2 = new OrderBuilder({
  policyPickStrategy: 'order-based',
  policies: [
    policy4,
    policy5,
    policy6,
  ],
});

const order1 = builder1.build({ items });
const order2 = builder2.build({ items });

order1.price // 24915
order2.price // 27850

Scenario 1 - 2

/**
 * 情境編號：甲 - 2
 *
 * 決策法：最適組合 (item-based)
 *
 * 情境敘述：
 * 1. 指定商品（Ａ～Ｆ）滿3件 打9折
 * 2. 指定商品（Ｃ～Ｉ）每5000元 折600元
 * 3. 指定分類（鞋子）滿4000元 送最低價商品
 * 4. 指定分類（Swell）每1件 打9折
 * 5. 全館 滿6件 贈紅利點數1000點
 * 6. 全館 滿6000元 免運
 *
 * 預期結果：
 * 取最優排列組合：2+4
 * 購物車顯示金額 24856
 */

// 指定商品（Ａ～Ｆ）滿3件 打9折
const policy1 = new PercentageDiscount(
  0.9,
  new ItemIncluded({
    items: ['A', 'B', 'C', 'D', 'E', 'F'],
    threshold: 3,
  }),
  { id: 'SPECIFIED_A_F', onlyMatched: true }
);

// 2. 指定商品（Ｃ～Ｉ）每5000元 折600元
const policy2 = new StepValueDiscount(
  5000,
  600,
  new ItemIncluded<TestOrderItem>({
    items: ['C', 'D', 'E', 'F', 'G', 'H', 'I'],
  }),
  { id: 'SPECIFIED_C_I', stepUnit: 'price', onlyMatched: true }
);

// 3. 指定分類（鞋子）滿4000元 送最低價商品
const policy3 = new ItemGiveawayDiscount(
  1,
  new ItemIncluded<TestOrderItem>({
    scope: 'category',
    items: ['shoes'],
    conditions: [new PriceThreshold(4000)],
  }),
  { id: 'GIVEAWAY_BY_SHOES_1', onlyMatched: true }
);

// * 4. 指定分類（Swell）每1件 打9折
const policy4 = new StepPercentageDiscount(
  1,
  0.9,
  new ItemIncluded<TestOrderItem>({
    scope: 'brand',
    items: ['Swell'],
  }),
  {
    id: 'SPECIFIED_BRAND_BY_Swell_1',
    stepUnit: 'quantity',
    onlyMatched: true,
  }
);

// (1|2)&(3|4)
const builder1 = new OrderBuilder<TestOrderItem>({
  policyPickStrategy: 'item-based',
  policies: [
    [policy1, policy2],
    [policy3, policy4],
  ],
});

const order1 = builder1.build({ items });

const builder2 = new OrderBuilder<TestOrderItem>({
  policyPickStrategy: 'item-based',
  policies: [
    [policy1, policy2],
    policy3,
    policy4,
  ],
});

const order2 = builder2.build({ items });

order1.price === order2.price // true
order1.price // 22491
order2.price // 22491

order1.itemRecords
// [ 
//   {
//     itemId: 'A-1',
//     originItem: {
//       id: 'A',
//       name: '外套A',
//       unitPrice: 1000,
//       category: 'jacket',
//       brand: 'AJE',
//     },
//     initialValue: 1000,
//     discountValue: 100,
//     finalPrice: 900,
//     discountRecords: [
//       {
//         policyId: 'SPECIFIED_A_F',
//         discountValue: 100,
//       },
//     ],
//     appliedPolicies: [
//       {
//         prefix: 'DISCOUNT',
//         type: 'PERCENTAGE',
//         id: 'SPECIFIED_A_F',
//         value: 0.9,
//         conditions: [
//           {
//             type: 'QUANTITY',
//             items: ['A', 'B', 'C', 'D', 'E', 'F'],
//             threshold: 3,
//             conditions: [],
//             scope: 'id',
//           },
//         ],
//         options: {
//           id: 'SPECIFIED_A_F',
//           onlyMatched: true,
//         },
//       },
//     ],
//   },
//   ...

Logistics Fee

/**
 * 情境編號：總額滿 2000元 免運
 *
 * 情境敘述：
 * 1. 指定商品（B～E）滿2件 送最低價品
 * 2. 整筆訂單 滿 2000 元免運
 *
 * 預期結果： 4500 + 200 - 1500 - 200 = 3000
 * 購物車顯示金額 3000
 */
const originItems: TestOrderItem[] = [
  {
    id: 'A',
    name: '外套A',
    unitPrice: 1000,
    quantity: 1,
    category: 'jacket',
    brand: 'AJE',
  },
  {
    id: 'B',
    name: '外套B',
    unitPrice: 1500,
    quantity: 1,
    category: 'jacket',
    brand: 'N21',
  },
  {
    id: 'C',
    name: '鞋子C',
    unitPrice: 2000,
    quantity: 1,
    category: 'shoes',
    brand: 'N21',
  },
];

const order = new OrderBuilder()
  // 滿 2000 免運
  .setLogistics({
    price: 200,
    threshold: 2000,
    name: '運費',
  })
  // 指定商品 B, C, D, E 滿兩件送最低價品
  .addPolicy(
    new ItemGiveawayDiscount(
      1,
      new ItemIncluded<TestOrderItem>({
        items: ['B', 'C', 'D', 'E'],
        threshold: 2,
      }),
      { onlyMatched: true }
    )
  )
  .build({ items: originItems });

order.price // 4500 + 200 - 1500 - 200 = 3000

Matched Times & Excluded Calculating Policy

/**
 * 情境敘述：
 * 滿足條件贈送紅利點數、滿足條件可加購商品
 * 需要能單純判斷是否滿足特定條件、滿足幾次，不影響訂單計算的 policy 功能
 */
const items: TestOrderItem[] = [
  {
    id: 'A',
    name: '外套A',
    unitPrice: 1000,
    quantity: 1,
    category: 'jacket',
    brand: 'AJE',
  },
  {
    id: 'B',
    name: '外套B',
    unitPrice: 1500,
    quantity: 1,
    category: 'jacket',
    brand: 'N21',
  },
  {
    id: 'C',
    name: '鞋子C',
    unitPrice: 2000,
    quantity: 1,
    category: 'shoes',
    brand: 'N21',
  },
];

// Policy1: 每 2000 元折 200 元
const policy1 = new StepValueDiscount(
  2000,
  200,
  { stepUnit: 'price' },
);

// Policy1 滿足次數
new OrderBuilder()
  .addPolicy(policy1)
  .build({ items })
  .discounts
  .find(discount => discount.id === policy1.id)
  ?.matchedTimes; // step(4500, 2000) = 2

// Policy2: 每 1499 元打 8折 (Matched only Policy, will not participant in discounting)
const policy2 = new StepPercentageDiscount(
  1499,
  0.8,
  { stepUnit: 'price', excludedInCalculation: true }
);

const order = new OrderBuilder()
  .addPolicy(policy2)
  .build({ items });

// Policy2: 滿足次數
order
.discounts
.find(discount => discount.id === policy2id)
?.matchedTimes; // step(4500, 1499) = 3

// Policy2: Excluded in calculation.
order.discountValue // 0