feat: 优化抽取实现

tonesc-red-packet/app/server/actions/draw-red-packet.ts

@@ -6,6 +6,7 @@ import { redPacketDraws } from "@/app/server/schema/red-packet-draws"
 import { eq, sql } from "drizzle-orm"
 import { randomUUID } from "crypto"
 import { formatAmount } from "@/lib/format-amount"
+import { formatAmountFromInt, parseAmountToInt, randomBigInt } from "@/lib/utils"
 
 type DrawResult =
     | { ok: true; amount: string }
@@ -65,26 +66,65 @@ export async function drawRedPacket(
 
         const precision = packet.currencyPrecision;
         const rule = packet.rule
+
         let amount: string
 
         /* 5️⃣ 金额计算（关键） */
         if (rule.type === "fixed") {
             amount = formatAmount(rule.singleAmount, precision)
         } else if (rule.type === "random") {
-            const min = Number(rule.min)
-            const max = Number(rule.max)
-            amount = randomByPrecision(min, max, precision)
+            const minInt = parseAmountToInt(rule.min, precision)
+            const maxInt = parseAmountToInt(rule.max, precision)
+
+            if (minInt < 0n || maxInt < 0n) {
+                throw new Error("Invalid min/max: negative amount")
+            }
+
+            if (minInt > maxInt) {
+                throw new Error("Invalid min/max: min > max")
+            }
+
+            const amountInt = randomBigInt(minInt, maxInt)
+
+            amount = formatAmountFromInt(amountInt, precision)
         } else {
             // 拼手气
-            const total = Number(rule.totalAmount)
-            const remain = total - Number(usedAmount)
+            const totalInt = parseAmountToInt(rule.totalAmount, precision)
+            const usedInt = parseAmountToInt(usedAmount, precision)
+
+            const remainInt = totalInt - usedInt
+            if (remainInt < 0n) {
+                throw new Error("Invalid state: remaining amount < 0")
+            }
+
+            let amountInt: bigint
 
             if (remainingCount === 1) {
-                amount = remain.toFixed(precision)
+                amountInt = remainInt
             } else {
-                const max = remain / remainingCount * 2
-                amount = randomByPrecision(0.01, max, precision)
+                const count = BigInt(remainingCount)
+                const MIN_UNIT = 1n // 1 分 / 1 sat / 1 最小单位
+
+                // max = (remain / remainingCount) * 2
+                const maxInt = (remainInt / count) * 2n
+
+                if (maxInt < MIN_UNIT) {
+                    // 剩余过小，防御性兜底
+                    amountInt = MIN_UNIT
+                } else {
+                    amountInt = randomBigInt(MIN_UNIT, maxInt)
+                }
             }
+
+            if (amountInt < 0n) {
+                throw new Error("Invalid amount: negative")
+            }
+
+            if (amountInt > remainInt) {
+                throw new Error("Invalid amount: exceeds remaining")
+            }
+
+            amount = formatAmountFromInt(amountInt, precision)
         }
 
         /* 6️⃣ 写入抽取记录 */
@@ -97,18 +137,4 @@ export async function drawRedPacket(
 
         return { ok: true, amount }
     })
-}
-
-function randomByPrecision(
-    min: number,
-    max: number,
-    precision: number
-) {
-    const factor = Math.pow(10, precision)
-    const value =
-        Math.floor(
-            (Math.random() * (max - min) + min) * factor
-        ) / factor
-
-    return value.toFixed(precision)
-}
+}

tonesc-red-packet/lib/utils.ts

@@ -4,3 +4,37 @@ import { twMerge } from "tailwind-merge"
 export function cn(...inputs: ClassValue[]) {
   return twMerge(clsx(inputs))
 }
+
+export function parseAmountToInt(amountStr: string, precision: number): bigint {
+  // 例："123.45", precision=2 → 12345n
+  // 例："0.00001234", precision=8 → 1234n
+
+  const [intPart, fracPart = ""] = amountStr.split(".")
+
+  if (fracPart.length > precision) {
+    throw new Error(`Amount ${amountStr} exceeds precision ${precision}`)
+  }
+
+  const paddedFrac = fracPart.padEnd(precision, "0")
+  const normalized = intPart + paddedFrac
+
+  return BigInt(normalized)
+}
+
+export function formatAmountFromInt(value: bigint, precision: number): string {
+  const s = value.toString().padStart(precision + 1, "0")
+
+  if (precision === 0) return s
+
+  const i = s.length - precision
+  return `${s.slice(0, i)}.${s.slice(i)}`
+}
+
+export function randomBigInt(min: bigint, max: bigint): bigint {
+  if (max < min) throw new Error("max < min")
+
+  const range = max - min + 1n
+  const rand = BigInt(Math.floor(Math.random() * Number(range)))
+
+  return min + rand
+}

tonesc-red-packet/tsconfig.json

@@ -1,6 +1,6 @@
 {
   "compilerOptions": {
-    "target": "ES2017",
+    "target": "ES2020",
     "lib": ["dom", "dom.iterable", "esnext"],
     "allowJs": true,
     "skipLibCheck": true,