Events

[ 0xe4, 0x45, 0xa5, 0x2e, 0x51, 0xcb, 0x9a, 0x1d ]   Anchor's event tag, sha256("anchor:event")[..8]
[ 8-byte event discriminator ]
[ Borsh-encoded fields ]

import { getBase58Encoder, type Signature } from "@solana/kit";
import { WAGER_SETTLED_EVENT_DISCRIMINATOR, getWagerSettledEventDecoder } from "./generated/fade";
import { PROGRAM, rpc } from "./fade";

const TAG = new Uint8Array([0xe4, 0x45, 0xa5, 0x2e, 0x51, 0xcb, 0x9a, 0x1d]);
const startsWith = (b: Uint8Array, p: ArrayLike<number>) =>
  b.length >= p.length && Array.from(p).every((x, i) => b[i] === x);

export async function settledEvents(signature: Signature) {
  const tx = await rpc
    .getTransaction(signature, { encoding: "json", maxSupportedTransactionVersion: 0, commitment: "confirmed" })
    .send();
  if (!tx?.meta) return [];
  const keys = [
    ...tx.transaction.message.accountKeys,
    ...(tx.meta.loadedAddresses?.writable ?? []),
    ...(tx.meta.loadedAddresses?.readonly ?? []),
  ];
  const out = [];
  for (const group of tx.meta.innerInstructions ?? []) {
    for (const ix of group.instructions) {
      if (keys[ix.programIdIndex] !== PROGRAM) continue;
      const data = new Uint8Array(getBase58Encoder().encode(ix.data));
      if (!startsWith(data, TAG)) continue;
      const body = data.subarray(8);
      if (startsWith(body, WAGER_SETTLED_EVENT_DISCRIMINATOR)) out.push(getWagerSettledEventDecoder().decode(body));
    }
  }
  return out;
}