first commit

Made-with: Cursor

backend/src/services/quote.ts

@@ -0,0 +1,69 @@
+import { randomInt } from "crypto";
+import { v4 as uuidv4 } from "uuid";
+import { config } from "../config.js";
+import { getDb } from "../db/index.js";
+import { getWalletBalanceSats } from "./lnbits.js";
+
+const QUOTE_TTL_SECONDS = 60;
+
+interface PayoutBucket {
+  sats: number;
+  weight: number;
+}
+
+function getPayoutBuckets(): PayoutBucket[] {
+  return [
+    { sats: config.payoutSmallSats, weight: config.payoutWeightSmall },
+    { sats: config.payoutMediumSats, weight: config.payoutWeightMedium },
+    { sats: config.payoutLargeSats, weight: config.payoutWeightLarge },
+    { sats: config.payoutJackpotSats, weight: config.payoutWeightJackpot },
+  ];
+}
+
+/**
+ * Weighted random selection. Returns sats amount.
+ */
+export function selectWeightedPayout(): number {
+  const buckets = getPayoutBuckets();
+  const totalWeight = buckets.reduce((s, b) => s + b.weight, 0);
+  let r = randomInt(0, totalWeight);
+  for (const b of buckets) {
+    if (r < b.weight) return b.sats;
+    r -= b.weight;
+  }
+  return config.payoutSmallSats;
+}
+
+/**
+ * Compute payout for this claim: weighted selection, capped by daily budget remaining.
+ */
+export function computePayoutForClaim(todayPaidSats: number): number {
+  const remaining = Math.max(0, config.dailyBudgetSats - todayPaidSats);
+  if (remaining < config.faucetMinSats) return 0;
+  const selected = selectWeightedPayout();
+  return Math.min(selected, remaining, config.faucetMaxSats);
+}
+
+export interface CreateQuoteResult {
+  quoteId: string;
+  payoutSats: number;
+  expiresAt: number;
+}
+
+export async function createQuote(pubkey: string, lightningAddress: string): Promise<CreateQuoteResult | null> {
+  const db = getDb();
+  const now = Math.floor(Date.now() / 1000);
+  const dayStart = now - (now % 86400);
+  const todayPaid = await db.getPaidSatsSince(dayStart);
+  let payout = computePayoutForClaim(todayPaid);
+  if (payout <= 0) return null;
+
+  const walletBalance = await getWalletBalanceSats();
+  payout = Math.min(payout, Math.max(0, walletBalance));
+  if (payout < config.faucetMinSats) return null;
+
+  const quoteId = uuidv4();
+  const expiresAt = now + QUOTE_TTL_SECONDS;
+  await db.createQuote(quoteId, pubkey, payout, lightningAddress, expiresAt);
+  return { quoteId, payoutSats: payout, expiresAt };
+}