solana intent event parsing

solana.ts

// src/intentEventParser.ts
import { Connection, PublicKey } from '@solana/web3.js';

/* -------------------------------------------------------------------------- */
/*                               Types & helpers                              */
/* -------------------------------------------------------------------------- */

export interface ParsedIntentEvent {
  intentId:        string;
  messageId:       string;
  initiator:       string;
  receiver:        string;
  inputAsset:      string;
  outputAsset:     string;
  normalizedAmount: bigint;
  maxFee:           number;
  originDomain:     number;
  nonce:            bigint;
  ttl:              bigint;
  timestamp:        bigint;
  destinationCount: number;
  destinations:     number[];
  data:             string;   // 0x-prefixed
}

/** Reverse little-endian hex -> big-endian hex (deadbeef ➜ efbeadde). */
const reverseBytes = (hex: string) => hex.match(/.{2}/g)!.reverse().join('');
const leHexToBigInt = (hex: string) => BigInt('0x' + reverseBytes(hex));
const leHexToNumber = (hex: string) => Number(leHexToBigInt(hex));

const strip0x = (h: string) => h.replace(/^0x/i, '').toLowerCase();

/* Slice helper that advances an internal cursor. Starts after 32-byte discriminator. */
const slicer = (hex: string) => {
  let offset = 64;
  return (chars: number) => {
    const part = hex.slice(offset, offset + chars);
    offset += chars;
    return part;
  };
};

/* -------------------------------------------------------------------------- */
/*                            Pure parsing function                           */
/* -------------------------------------------------------------------------- */
export function parseIntentEvent(hexData: string): ParsedIntentEvent {
  const raw = strip0x(hexData);
  const next = slicer(raw);

  const intentId         = '0x' + next(64);
  const messageId        = '0x' + next(64);
  const initiator        = '0x' + next(64);
  const receiver         = '0x' + next(64);
  const inputAsset       = '0x' + next(64);
  const outputAsset      = '0x' + next(64);
  const normalizedAmount = leHexToBigInt(next(32));
  const maxFee           = leHexToNumber(next(8));
  const originDomain     = leHexToNumber(next(8));
  const nonce            = leHexToBigInt(next(16));
  const ttl              = leHexToBigInt(next(16));
  const timestamp        = leHexToBigInt(next(16));
  const destinationCount = leHexToNumber(next(8));

  const destinations: number[] = [];
  for (let i = 0; i < destinationCount; i++) {
    destinations.push(leHexToNumber(next(8)));
  }

  const dataLength = leHexToNumber(next(8));
  const data       = '0x' + next(dataLength);

  return {
    intentId,
    messageId,
    initiator,
    receiver,
    inputAsset,
    outputAsset,
    normalizedAmount,
    maxFee,
    originDomain,
    nonce,
    ttl,
    timestamp,
    destinationCount,
    destinations,
    data,
  };
}

/* -------------------------------------------------------------------------- */
/*                      Fetch-and-parse convenience helper                    */
/* -------------------------------------------------------------------------- */

/**
 * Fetches a Solana transaction, extracts all Anchor `emit!` blobs from the
 * program logs of `programId`, parses them, and returns an array of events.
 */
export async function fetchParsedIntentEvents(
  connection: Connection,
  txSignature: string,
  programId: PublicKey,
): Promise<ParsedIntentEvent[]> {
  const tx = await connection.getTransaction(txSignature, {
    maxSupportedTransactionVersion: 0,
    commitment: 'confirmed',
  });
  if (!tx) return [];

  // Anchor encodes events as base64 after the prefix `Program data: `
  const EV_PREFIX = 'Program data: ';
  const blobs = tx.meta?.logMessages
    ?.filter((l) => l.startsWith(EV_PREFIX) && l.includes(programId.toBase58()))
    .map((l) => l.slice(EV_PREFIX.length).trim()) ?? [];

  return blobs.map((b64) => {
    const hex = Buffer.from(b64, 'base64').toString('hex');
    return parseIntentEvent(hex);
  });
}

/* -------------------------------------------------------------------------- */
/*                               Example usage                                */
/* -------------------------------------------------------------------------- */
/*
import { Connection, PublicKey } from '@solana/web3.js';

(async () => {
  const connection = new Connection('https://api.mainnet-beta.solana.com');
  const PROGRAM_ID = new PublicKey('YourProgram111111111111111111111111111111111');
  const SIG        = '5cD3…<tx signature>';

  const events = await fetchParsedIntentEvents(connection, SIG, PROGRAM_ID);
  console.log(events);
})();
*/