argus/src/lib/bns.js

// BNS1 core: payload codec, chain indexer/resolver, and tx builders.
import { OpReturnData, TokenSendRequest, NFTCapability } from "mainnet-js";
import { BEACON, PREFIX, BEACON_DUST_SAT, NAME_RE } from "../config.js";

// ---------- payload codec ----------

const LABEL_RE = /^[a-z0-9-]{1,32}$/;
const TLD_RE = /^[a-z0-9-]{1,16}$/;
const RAWNAME_RE = /^[a-z0-9-]{1,32}(\.[a-z0-9-]{1,16})?$/;
// On-chain name for a registration: bare "<label>" for .bch (backward compat),
// or "<label>.<tld>" for any other TLD. The rightmost label is the registry.
export function normalizeName(input) {
  const parts = String(input).toLowerCase().trim().replace(/\.$/, "").split(".").filter(Boolean);
  let label, tld;
  if (parts.length === 1) { label = parts[0]; tld = "bch"; }
  else { tld = parts[parts.length - 1]; label = parts[parts.length - 2]; }
  if (!LABEL_RE.test(label) || !TLD_RE.test(tld)) {
    throw new Error(`invalid name "${input}" (allowed: <label>.<tld>, [a-z0-9-])`);
  }
  return tld === "bch" ? label : `${label}.${tld}`;
}

export function encodePayload(op, name, records) {
  const json = JSON.stringify({ o: op, n: name, r: records });
  const buf = Buffer.from(PREFIX + json, "utf8");
  if (buf.length > 200) throw new Error(`records too large (${buf.length} > 200 bytes)`);
  return buf;
}

// Parse a raw output script hex; return payload object or null.
export function parseOpReturn(scriptHex) {
  if (!scriptHex?.startsWith("6a")) return null; // OP_RETURN
  let i = 2;
  const pushes = [];
  while (i < scriptHex.length) {
    let op = parseInt(scriptHex.slice(i, i + 2), 16);
    i += 2;
    let len;
    if (op <= 0x4b) len = op;
    else if (op === 0x4c) { len = parseInt(scriptHex.slice(i, i + 2), 16); i += 2; }
    else if (op === 0x4d) { len = parseInt(scriptHex.slice(i + 2, i + 4) + scriptHex.slice(i, i + 2), 16); i += 4; }
    else return null;
    pushes.push(Buffer.from(scriptHex.slice(i, i + len * 2), "hex"));
    i += len * 2;
  }
  const data = pushes[0]?.toString("utf8") ?? "";
  if (!data.startsWith(PREFIX)) return null;
  try {
    const p = JSON.parse(data.slice(PREFIX.length));
    if ((p.o === "REG" || p.o === "UPD") && typeof p.n === "string") return p;
  } catch { /* not ours */ }
  return null;
}

// ---------- indexer / resolver ----------

// (height, txid) order; unconfirmed (height<=0) last.
function byHeightThenTxid(a, b) {
  const ha = a.height > 0 ? a.height : Infinity;
  const hb = b.height > 0 ? b.height : Infinity;
  return ha - hb || a.tx_hash.localeCompare(b.tx_hash);
}

// Never index a transaction before one it spends from — otherwise an UPD that
// happens to sort below its own REG is evaluated against an index that does not
// yet contain the name, and is dropped. Keeps the txid tiebreak for independent
// transactions. Mirrors resolver-web.js `orderByDependency` — change both.
function orderByDependency(history, txs) {
  const inSet = new Set(history.map((h) => h.tx_hash));
  const deps = new Map(
    history.map((h) => {
      const spent = new Set();
      for (const vin of txs.get(h.tx_hash)?.vin ?? []) {
        if (vin.txid && vin.txid !== h.tx_hash && inSet.has(vin.txid)) spent.add(vin.txid);
      }
      return [h.tx_hash, spent];
    }),
  );
  const emitted = new Set();
  const ordered = [];
  const pending = [...history];
  while (pending.length) {
    let i = pending.findIndex((h) => [...deps.get(h.tx_hash)].every((d) => emitted.has(d)));
    if (i < 0) i = 0; // unreachable on a real chain; guarantees termination
    const [next] = pending.splice(i, 1);
    emitted.add(next.tx_hash);
    ordered.push(next);
  }
  return ordered;
}

// Builds { name -> { name, category, records, txid, height, updatedTxid } }
export async function buildIndex(provider) {
  const history = await provider.getHistory(BEACON);
  history.sort(byHeightThenTxid);

  const txs = new Map();
  for (const { tx_hash } of history) {
    try { txs.set(tx_hash, await provider.getRawTransactionObject(tx_hash)); }
    catch { /* unreadable tx — skip it entirely */ }
  }

  const names = new Map();
  const byCategory = new Map();

  for (const { tx_hash, height } of orderByDependency(history.filter((h) => txs.has(h.tx_hash)), txs)) {
    const tx = txs.get(tx_hash);

    let payload = null;
    for (const vout of tx.vout) {
      payload = parseOpReturn(vout.scriptPubKey?.hex) ?? payload;
    }
    if (!payload) continue;

    const name = payload.n;
    if (!RAWNAME_RE.test(name)) continue;

    if (payload.o === "REG") {
      if (names.has(name)) continue; // first valid REG wins
      // the same tx must mint a certificate whose commitment is the name
      const commitment = Buffer.from(name, "utf8").toString("hex");
      const mint = tx.vout.find((v) => v.tokenData?.nft?.commitment === commitment);
      if (!mint) continue;
      const entry = {
        name, category: mint.tokenData.category, records: payload.r ?? {},
        txid: tx_hash, height, updatedTxid: null,
      };
      names.set(name, entry);
      byCategory.set(entry.category, entry);
    } else if (payload.o === "UPD") {
      const entry = names.get(name);
      if (!entry) continue;
      // ownership proof: some output carries the name's category
      // (consensus: impossible unless an input held that category)
      const proves = tx.vout.some((v) => v.tokenData?.category === entry.category);
      if (!proves) continue;
      entry.records = payload.r ?? {};
      entry.updatedTxid = tx_hash;
    }
  }
  return names;
}

export async function resolveName(provider, input) {
  const name = normalizeName(input);
  const index = await buildIndex(provider);
  return index.get(name) ?? null;
}

// ---------- tx builders ----------

// CashTokens genesis must spend an outpoint with index 0; self-send to make one if needed.
async function ensureGenesisInput(wallet) {
  const utxos = await wallet.getUtxos();
  if (utxos.some((u) => u.vout === 0 && !u.token)) return;
  await wallet.send([{ cashaddr: wallet.cashaddr, value: 10000n, unit: "sat" }]);
}

export async function registerName(wallet, input, records) {
  const name = normalizeName(input);
  const index = await buildIndex(wallet.provider);
  if (index.has(name)) throw new Error(`"${name}${'.bch'}" is already registered`);
  await ensureGenesisInput(wallet);
  const payload = encodePayload("REG", name, records);
  const result = await wallet.tokenGenesis(
    {
      cashaddr: wallet.tokenaddr,
      nft: {
        capability: NFTCapability.none,
        commitment: Buffer.from(name, "utf8").toString("hex"),
      },
      value: 1000n,
    },
    [
      OpReturnData.fromUint8Array(payload),
      { cashaddr: BEACON, value: BEACON_DUST_SAT, unit: "sat" },
    ],
  );
  return { name, txid: result.txId, category: result.tokenIds?.[0] };
}

export async function updateName(wallet, input, records) {
  const name = normalizeName(input);
  const index = await buildIndex(wallet.provider);
  const entry = index.get(name);
  if (!entry) throw new Error(`"${name}.bch" is not registered`);
  const payload = encodePayload("UPD", name, records);
  const result = await wallet.send([
    new TokenSendRequest({
      cashaddr: wallet.tokenaddr,
      category: entry.category,
      nft: {
        capability: NFTCapability.none,
        commitment: Buffer.from(name, "utf8").toString("hex"),
      },
    }),
    OpReturnData.fromUint8Array(payload),
    { cashaddr: BEACON, value: BEACON_DUST_SAT, unit: "sat" },
  ]);
  return { name, txid: result.txId, category: entry.category };
}