feat: three nuxt frontends, demo seed, rounding + money-exponent + rate-cast fixes, archived specs

apps/mall/composables/usePrice.ts

@@ -0,0 +1,60 @@
+import { formatMoney } from "@vmall/shared";
+import type { Currency } from "@vmall/shared";
+
+export function usePrice() {
+  const { currency } = usePrefs();
+  const { locale } = useI18n();
+  const { $api } = useNuxtApp();
+  const currencies = useState<Currency[]>("mall-currencies", () => []);
+  const cache = useState<Map<string, number>>("mall-price-cache", () => new Map());
+  const currencyRequest = useState<Promise<Currency[]> | null>("mall-currency-request", () => null);
+
+  async function ensureCurrencies(): Promise<Currency[]> {
+    if (currencies.value.length > 0) return currencies.value;
+    if (!currencyRequest.value) {
+      currencyRequest.value = $api.listCurrencies().then((list) => {
+        currencies.value = list;
+        return list;
+      }).finally(() => {
+        currencyRequest.value = null;
+      });
+    }
+    return currencyRequest.value;
+  }
+
+  function exponentFor(code: string): number {
+    return currencies.value.find((item) => item.code === code)?.exponent ?? 2;
+  }
+
+  async function convertAmount(amountMinor: number, from: string, to = currency.value): Promise<number> {
+    if (from === to) return amountMinor;
+    const key = `${amountMinor}:${from}:${to}`;
+    const cached = cache.value.get(key);
+    if (cached !== undefined) return cached;
+    const converted = await $api.convert(amountMinor, from, to);
+    cache.value.set(key, converted.amount_minor);
+    return converted.amount_minor;
+  }
+
+  async function formatPrice(amountMinor: number, from: string, to = currency.value): Promise<string> {
+    await ensureCurrencies();
+    const amount = await convertAmount(amountMinor, from, to);
+    return formatMoney(amount, to, exponentFor(to), locale.value);
+  }
+
+  async function formatAmount(amountMinor: number, code: string): Promise<string> {
+    await ensureCurrencies();
+    return formatMoney(amountMinor, code, exponentFor(code), locale.value);
+  }
+
+  return {
+    currency,
+    currencies,
+    cache,
+    ensureCurrencies,
+    exponentFor,
+    convertAmount,
+    formatPrice,
+    formatAmount,
+  };
+}