feat(js-api-client): pricesForUsageOnTier helper

Author: Plopix

package.json

@@ -1,7 +1,7 @@
 {
     "name": "@crystallize/js-api-client",
     "license": "MIT",
-    "version": "1.3.1",
+    "version": "1.4.0",
     "author": "Crystallize <[email protected]> (https://crystallize.com)",
     "contributors": [
         "Sébastien Morel <[email protected]>"

src/core/pricing.ts

@@ -0,0 +1,50 @@
+import { Prices, Tier } from '../types/pricing';
+
+export function pricesForUsageOnTier(usage: number, tiers: Tier[], tierType: 'volume' | 'graduated'): Prices {
+    const sortedTiers = [...tiers].sort((a: Tier, b: Tier) => a.threshold - b.threshold);
+
+    if (tierType === 'volume') {
+        return volumeBasedPriceFor(usage, sortedTiers);
+    }
+    return graduatedBasedPriceFor(usage, sortedTiers);
+}
+
+function volumeBasedPriceFor(usage: number, tiers: Tier[]): Prices {
+    const tiersLength = tiers.length;
+
+    for (let i = tiersLength - 1; i >= 0; i--) {
+        const tier: Tier = tiers[i];
+        if (usage < tier.threshold && i > 0) {
+            continue;
+        }
+        // manage also an inexistent tier (threshold = 0)
+        return { [tier.currency]: (usage >= tier.threshold ? tier.price : 0) * usage };
+    }
+    return { USD: 0.0 };
+}
+
+function graduatedBasedPriceFor(usage: number, tiers: Tier[]): Prices {
+    let rest = usage;
+
+    // manage also an inexistent tier (threshold = 0)
+    if (tiers[0].threshold > 0) {
+        rest = Math.max(0, rest - (tiers[0].threshold - 1));
+    }
+
+    const splitUsage: Array<Tier & { usage: number }> = tiers.map((tier: Tier, tierIndex: number) => {
+        const limit = tiers[tierIndex + 1]?.threshold || Infinity;
+        const tierUsage = rest > limit ? limit : rest;
+        rest -= tierUsage;
+        return {
+            ...tier,
+            usage: tierUsage,
+        };
+    });
+
+    return splitUsage.reduce((memo: Prices, tier: Tier & { usage: number }) => {
+        return {
+            ...memo,
+            [tier.currency]: (memo[tier.currency] || 0.0) + tier.usage * tier.price,
+        };
+    }, {});
+}

src/index.ts

@@ -7,6 +7,7 @@ export * from './core/order';
 export * from './core/search';
 export * from './core/subscription';
 export * from './core/customer';
+export * from './core/pricing';
 export * from './types/product';
 export * from './types/order';
 export * from './types/payment';
@@ -16,6 +17,7 @@ export * from './types/subscription';
 export * from './types/address';
 export * from './types/customer';
 export * from './types/signature';
+export * from './types/pricing';
 
 import { createClient } from './core/client';
 import { createNavigationFetcher } from './core/navigation';

src/types/pricing.ts

@@ -0,0 +1,7 @@
+export type Tier = {
+    threshold: number;
+    price: number;
+    currency: string;
+};
+
+export type Prices = Record<string, number>;

tests/pricesForUsageOnTier.test.js

@@ -0,0 +1,127 @@
+const { pricesForUsageOnTier } = require('../dist/index.js');
+
+const tiers1 = [
+    {
+        threshold: 0,
+        price: 0,
+        currency: 'EUR',
+    },
+    {
+        threshold: 2,
+        price: 250,
+        currency: 'EUR',
+    },
+    {
+        threshold: 20,
+        price: 20,
+        currency: 'EUR',
+    },
+];
+
+const tiers2 = [
+    {
+        threshold: 15,
+        price: 500,
+        currency: 'EUR',
+    },
+    {
+        threshold: 40,
+        price: 100,
+        currency: 'EUR',
+    },
+    {
+        threshold: 30,
+        price: 300,
+        currency: 'EUR',
+    },
+];
+
+const tiers3 = [
+    {
+        threshold: 0,
+        price: 5,
+        currency: 'EUR',
+    },
+    {
+        threshold: 3,
+        price: 4,
+        currency: 'EUR',
+    },
+    {
+        threshold: 15,
+        price: 3,
+        currency: 'EUR',
+    },
+    {
+        threshold: 25,
+        price: 2,
+        currency: 'EUR',
+    },
+    {
+        threshold: 50,
+        price: 1,
+        currency: 'EUR',
+    },
+];
+
+const tiers4 = [
+    {
+        threshold: 15,
+        price: 3,
+        currency: 'EUR',
+    },
+    {
+        threshold: 25,
+        price: 2,
+        currency: 'EUR',
+    },
+    {
+        threshold: 50,
+        price: 1,
+        currency: 'EUR',
+    },
+];
+
+const tiers5 = [
+    {
+        threshold: 75,
+        price: 3,
+        currency: 'EUR',
+    },
+    {
+        threshold: 25,
+        price: 2,
+        currency: 'EUR',
+    },
+    {
+        threshold: 50,
+        price: 1,
+        currency: 'EUR',
+    },
+];
+
+test('Price For Volume', () => {
+    expect(pricesForUsageOnTier(0, tiers1, 'volume')).toEqual({ EUR: 0 });
+    expect(pricesForUsageOnTier(2, tiers1, 'volume')).toEqual({ EUR: 500 });
+    expect(pricesForUsageOnTier(3, tiers1, 'volume')).toEqual({ EUR: 750 });
+    expect(pricesForUsageOnTier(20, tiers1, 'volume')).toEqual({ EUR: 400 });
+    expect(pricesForUsageOnTier(40, tiers1, 'volume')).toEqual({ EUR: 800 });
+
+    expect(pricesForUsageOnTier(3, tiers2, 'volume')).toEqual({ EUR: 0 });
+    expect(pricesForUsageOnTier(14, tiers2, 'volume')).toEqual({ EUR: 0 });
+    expect(pricesForUsageOnTier(15, tiers2, 'volume')).toEqual({ EUR: 7500 });
+    expect(pricesForUsageOnTier(16, tiers2, 'volume')).toEqual({ EUR: 8000 });
+    expect(pricesForUsageOnTier(30, tiers2, 'volume')).toEqual({ EUR: 9000 });
+    expect(pricesForUsageOnTier(31, tiers2, 'volume')).toEqual({ EUR: 9300 });
+    expect(pricesForUsageOnTier(40, tiers2, 'volume')).toEqual({ EUR: 4000 });
+    expect(pricesForUsageOnTier(41, tiers2, 'volume')).toEqual({ EUR: 4100 });
+    expect(pricesForUsageOnTier(131, tiers2, 'volume')).toEqual({ EUR: 13100 });
+});
+
+test('Price For Graduated', () => {
+    expect(pricesForUsageOnTier(4, tiers3, 'graduated')).toEqual({ EUR: 19 });
+    expect(pricesForUsageOnTier(211, tiers3, 'graduated')).toEqual({ EUR: 368 });
+    expect(pricesForUsageOnTier(14, tiers4, 'graduated')).toEqual({ EUR: 0 });
+    expect(pricesForUsageOnTier(15, tiers5, 'graduated')).toEqual({ EUR: 0 });
+    expect(pricesForUsageOnTier(25, tiers5, 'graduated')).toEqual({ EUR: 2 });
+});