Build with
DrawEngine.

// Independent verification — no trust required
const proof = await engine.getResult(txHash);

// 1. Check VRF output is authentic
const valid = await oracle.verify(proof.vrfProof, proof.roundSeed, proof.vrfOutput);

// 2. Check winner arithmetic
const winningTicket = BigInt(proof.vrfOutput.slice(0, 8)) % proof.totalTickets;
assert(winningTicket === proof.winningTicket);

// 3. Check ticket maps to winner address
assert(proof.ticketOwner[winningTicket] === proof.winner);

const past = await engine.getResult("TX_HASH_HERE");

// past.winner         — winning Stellar address
// past.vrfProof       — verifiable proof bytes
// past.vrfOutput      — 32-byte random seed used
// past.winningTicket  — which ticket number won
// past.totalTickets   — total tickets in draw
// past.timestamp      — Unix timestamp of draw
// past.entrants       — total number of entrants
// past.prize          — USDC amount paid to winner (if LuckyPool draw)

import { DrawEngineError } from "@luckypool/draw-engine";

try {
  await engine.draw();
} catch (err) {
  if (err instanceof DrawEngineError) {
    switch (err.code) {
      case 6: console.error("Prize pool is empty — fund it first"); break;
      case 8: console.error("No depositors registered for this draw"); break;
      default: console.error("Contract error:", err.code, err.name);
    }
  }
}

// Subscribe to draw completions
engine.on("DrawCompleted", (event) => {
  console.log(`Round ${event.round}: ${event.winner} won ${event.prize} USDC`);
});

// Or query past events from Horizon
const events = await engine.getEvents({
  type: "DrawCompleted",
  fromLedger: 50000000,
});