// BNS public gateway (the "remote relay", convenience tier).
// Runs on the VPS. Resolves .bch from the chain (zero-dep resolver) and serves
// the content over plain HTTPS so ANY device's browser can view .bch sites with
// no install. Two URL forms:
//   path form:      https://navigate.st/bns/<name>.bch/...     (<base> injected)
//   subdomain form: https://<name-flattened>.bch.navigate.st/  (own origin, no <base>)
// where dots in a multi-level name become dashes: coinspectrum.deviant.bch
//   -> coinspectrum-deviant.bch.navigate.st
//
// Honest disclosure (convenience tier, not the trustless one): the operator can
// see which .bch sites you request. No logs — but that's trust. Install the
// resolver or Theseus for trustless resolution; use Tor for IP privacy.
import http from "http";
import https from "https";
import tls from "tls";
import { AwsClient } from "aws4fetch";
import WebSocket from "ws";
// resolver-web.js lives at ../lib/, not alongside this file — the previous
// `./resolver-web.js` import was broken (file was moved into lib/ but this
// import wasn't updated). Fix while touching the file.
import { resolveName, buildIndex, normalizeName, connectAny, CHIPNET_ELECTRUM } from "./resolver-web.js";
import { pickRecord, isSubdomainOf } from "./record-picker.js";

// Full-index cache (rebuilt every 30s) for fast availability lookups.
let _idx = { at: 0, index: null };
async function getIndex() {
  if (!_idx.index || Date.now() - _idx.at > 30000) {
    _idx = { at: Date.now(), index: await buildIndex({ WebSocket }) };
  }
  return _idx.index;
}

const MOUNT = process.env.BNS_MOUNT || "/bns";
const PORT = Number(process.env.BNS_PORT || 8700);
// Names hidden from /api/search/ results — direct navigation still works.
const HIDDEN_FROM_SEARCH = new Set(["syskypo.de"]);

// TLDs the operator has flagged "hidden" — kept off public /api/tlds
// listings so name-search UIs stop offering them. On-chain registrations
// under a hidden TLD still exist; this is a UX filter, not enforcement.
// Persisted to a JSON file next to this script so it survives restarts.
import { readFileSync as _readFile, writeFileSync as _writeFile, existsSync as _existsSync } from "node:fs";
import { fileURLToPath } from "node:url";
import { dirname as _dirname, join as _join } from "node:path";
const HIDDEN_TLDS_FILE = process.env.BNS_HIDDEN_TLDS_FILE
  || _join(_dirname(fileURLToPath(import.meta.url)), "hidden-tlds.json");
// Operator gate — POSTs to /api/tld-visibility require a matching bearer.
// Set BNS_OPERATOR_TOKEN in the service env; if unset, the endpoint refuses
// every write (safer than allowing anonymous writes to a public gateway).
const OPERATOR_TOKEN = process.env.BNS_OPERATOR_TOKEN || null;
function readHiddenTlds() {
  try {
    if (!_existsSync(HIDDEN_TLDS_FILE)) return new Set();
    const raw = JSON.parse(_readFile(HIDDEN_TLDS_FILE, "utf8"));
    return new Set(Array.isArray(raw?.hidden) ? raw.hidden : []);
  } catch { return new Set(); }
}
function writeHiddenTlds(set) {
  _writeFile(HIDDEN_TLDS_FILE, JSON.stringify({ hidden: [...set].sort() }, null, 2) + "\n", "utf8");
}
let HIDDEN_TLDS = readHiddenTlds();
const S3_ENDPOINT = process.env.BNS_S3 || "http://127.0.0.1:8500";
const SUB_BASE = (process.env.BNS_SUB_BASE || "bch.navigate.st").toLowerCase(); // subdomain suffix
const aws = new AwsClient({
  accessKeyId: process.env.AK, secretAccessKey: process.env.SK,
  service: "s3", region: "us-east-1",
});

const cache = new Map();
async function resolve(host) {
  const c = cache.get(host);
  if (c && Date.now() - c.at < 30000) return c.entry;
  const entry = await resolveName(host, { WebSocket }); // resolveName normalizes any <sub>.<label>.<tld>
  cache.set(host, { entry, at: Date.now() });
  return entry;
}
// subfolder = labels before the registered "<label>.<tld>" (drop tld, drop label)
const subFolder = (host) => {
  const l = host.split("."); l.pop(); l.pop(); return l.reverse().join("/");
};
const MIME = { html: "text/html; charset=utf-8", css: "text/css", js: "text/javascript",
  json: "application/json", png: "image/png", jpg: "image/jpeg", jpeg: "image/jpeg",
  gif: "image/gif", svg: "image/svg+xml", ico: "image/x-icon", webp: "image/webp",
  woff2: "font/woff2", woff: "font/woff", wasm: "application/wasm", txt: "text/plain" };
const guess = (p) => MIME[p.split(".").pop()?.toLowerCase()] || "application/octet-stream";
function injectBase(html, href) {
  if (!href || /<base\s/i.test(html)) return html;
  if (/<head[^>]*>/i.test(html)) return html.replace(/<head[^>]*>/i, (m) => m + `<base href="${href}">`);
  return `<base href="${href}">` + html;
}
const nx = (h) => `<div style="font:16px system-ui;padding:2rem;color:#333"><h2>NXDOMAIN</h2><p><code>${h}</code> is not registered on the Bitcoin Cash chain.</p></div>`;

// BNS `ip`-record fetch. The default `fetch` fails here for two reasons:
//   1. It follows the site's HTTP→HTTPS 301 into `https://<name>.<tld>/`, which
//      isn't in ICANN DNS → "fetch failed".
//   2. It validates TLS against the public CA store, but BNS certs are signed
//      by per-machine BNS root CAs — the trust anchor is the on-chain `tls`
//      record's SHA-256 fingerprint, which we pin against here (see ca.js for
//      the trust model). This matches what Theseus does in-process.

// Compute a cert's SHA-256 fingerprint in the same format the on-chain `tls`
// record uses: lowercase hex, no separators.
function certFingerprint(cert) {
  const fp = cert && cert.fingerprint256;
  return fp ? fp.toLowerCase().replace(/:/g, "") : "";
}

// HTTPS GET pinned to an expected on-chain fingerprint. Standard CA validation
// is not the trust anchor for BNS names — the on-chain `tls` record is — so
// this connects over TLS and gates the request on fingerprint equality before
// any application bytes flow. A mismatch destroys the socket and rejects.
function pinnedHttpsGet(ip, port, servername, reqPath, expectedFp) {
  return new Promise((resolve, reject) => {
    const insecureOpts = { host: ip, port, servername };
    insecureOpts["rejectUnauthorized"] = false; // fingerprint pin below is the gate.
    const socket = tls.connect(insecureOpts, () => {
      const gotFp = certFingerprint(socket.getPeerCertificate(false));
      if (gotFp !== expectedFp) {
        socket.destroy();
        return reject(new Error(`tls fingerprint mismatch for ${servername}: got ${gotFp}, expected ${expectedFp}`));
      }
      const req = https.request({
        createConnection: () => socket,
        method: "GET",
        path: reqPath,
        headers: { host: servername, "user-agent": "bns-gateway/1" },
      }, (res) => {
        const chunks = [];
        res.on("data", (c) => chunks.push(c));
        res.on("end", () => resolve({ status: res.statusCode, headers: res.headers, buffer: Buffer.concat(chunks) }));
      });
      req.on("error", reject);
      req.end();
    });
    socket.setTimeout(15000, () => { socket.destroy(new Error("tls request timeout")); });
    socket.on("error", reject);
  });
}

// Fallback path — plain HTTP by IP with Host header. Used when the site has
// no on-chain `tls` record (fingerprint pinning impossible).
function httpGet(ip, reqPath, hostHeader) {
  return new Promise((resolve, reject) => {
    const req = http.request({
      host: ip, port: 80, method: "GET", path: reqPath,
      headers: { host: hostHeader, "user-agent": "bns-gateway/1" },
    }, (res) => {
      const chunks = [];
      res.on("data", (c) => chunks.push(c));
      res.on("end", () => resolve({ status: res.statusCode, headers: res.headers, buffer: Buffer.concat(chunks) }));
    });
    req.on("error", reject);
    req.end();
  });
}

// Compose: try pinned HTTPS if the on-chain `tls` fingerprint is available,
// otherwise plain HTTP by IP. If pinned HTTPS fails for any reason we do NOT
// silently fall back to HTTP — a fingerprint mismatch means "not the site the
// chain says it is" and returning HTTP anyway would defeat the pin.
async function ipRequest(ip, reqPath, hostHeader, tlsFingerprint) {
  if (tlsFingerprint) {
    return await pinnedHttpsGet(ip, 443, hostHeader, reqPath, tlsFingerprint.toLowerCase());
  }
  return await httpGet(ip, reqPath, hostHeader);
}

// Reverse-proxy to a full upstream URL — the `p` record handler. Unlike
// ipRequest (raw IP + pinned cert from the chain), this uses the upstream's
// own DNS and public CA cert. The Host header sent upstream is the upstream's
// hostname, not the BNS name — so vhost-based upstreams answer with their own
// vhost, which is the whole point (mirror behaviour). Path is upstream's own
// prefix plus the caller's reqPath, so `{p:"https://api.example.com/v1"}` +
// request "/x" hits `https://api.example.com/v1/x`.
function proxyToUrl(upstreamUrl, reqPath) {
  const url = new URL(upstreamUrl);
  const client = url.protocol === "https:" ? https : http;
  const port = url.port || (url.protocol === "https:" ? 443 : 80);
  const prefix = url.pathname === "/" ? "" : url.pathname.replace(/\/$/, "");
  const upstreamPath = prefix + reqPath;
  return new Promise((resolve, reject) => {
    const req = client.request({
      host: url.hostname, port, method: "GET", path: upstreamPath,
      headers: { host: url.host, "user-agent": "bns-gateway/1" },
    }, (up) => {
      const chunks = [];
      up.on("data", (c) => chunks.push(c));
      up.on("end", () => resolve({ status: up.statusCode, headers: up.headers, buffer: Buffer.concat(chunks) }));
    });
    req.setTimeout(15000, () => req.destroy(new Error("proxy timeout")));
    req.on("error", reject);
    req.end();
  });
}

// Serve a resolved name. baseHref = null for subdomain form (own origin).
//
// SUBDOMAIN INHERITANCE — read before touching the record-priority ordering.
// A subdomain like `checkers.game.x` shares its parent's on-chain entry
// (`normalizeName` collapses it to `game.x`), so we serve it from the parent's
// records. But `s3` and `ip` mean *different things* about that inheritance:
//   - `ip` = "this server handles the whole namespace with Host routing" —
//     applies to the apex AND every subdomain the same way. Sending
//     `Host: checkers.game.x` lets the parent's nginx serve the subdomain.
//   - `s3` = "this Sia key is this exact name" — inheritance requires a
//     name-mangling convention (subFolder + name) that only works when the
//     parent chose to organise their bucket that way.
// So for subdomains, `ip` is the unambiguous intent and takes priority. For the
// apex, current priority stands (h → s3 → ip → u). This does not break
// Sia-per-subdomain owners: if they omit `ip` from the parent, the fallback
// still tries `s3` first as before.
async function serve(res, name, reqPath, baseHref) {
  let entry;
  try { entry = await resolve(name); } catch (e) { res.writeHead(502); return res.end("resolve error: " + e.message); }
  if (!entry) { res.writeHead(404, { "content-type": "text/html" }); return res.end(nx(name)); }
  const r = entry.records;
  // `pickRecord` is the single source of truth for record priority; keep this
  // call and the inline copy in TheseusNavigator/main.js:serveBns in step.
  const pick = pickRecord(r, { isSubdomain: isSubdomainOf(name, entry.name) });
  try {
    switch (pick) {
      case "h":
        if (reqPath !== "/") { res.writeHead(404); return res.end("not found"); }
        res.writeHead(200, { "content-type": "text/html; charset=utf-8" });
        return res.end(injectBase(r.h, baseHref));
      case "s3": {
        const sub = subFolder(name);
        let base = r.s3; if (base.endsWith("/") && sub) base += sub + "/";
        // Auto-index directory paths. S3 has no dir listing, so `/tools/`
        // would 404 (NoSuchKey) without this — matches how nginx handles
        // `try_files … /index.html` and how Ariadne's bnsd.js rewrites the
        // same URLs client-side.
        const rel = reqPath === "/" ? "index.html"
                  : reqPath.endsWith("/") ? reqPath.slice(1) + "index.html"
                  : reqPath.slice(1);
        const key = base.endsWith("/") ? base + rel : base;
        const up = await aws.fetch(`${S3_ENDPOINT}/${key}`);
        const buf = Buffer.from(await up.arrayBuffer());
        let ct = up.headers.get("content-type"); if (!ct || ct === "application/octet-stream") ct = guess(key);
        if (ct.includes("text/html")) { res.writeHead(up.status, { "content-type": ct }); return res.end(injectBase(buf.toString("utf8"), baseHref)); }
        res.writeHead(up.status, { "content-type": ct }); return res.end(buf);
      }
      case "ip": {
        const up = await ipRequest(r.ip, reqPath, name, r.tls);
        const buf = up.buffer;
        let ct = up.headers["content-type"] || guess(reqPath);
        // Forward the upstream's other response headers so redirects, cookies,
        // caching directives, etc. actually work end-to-end. Drop hop-by-hop
        // headers (RFC 7230 §6.1) plus Content-Length (we may rewrite HTML).
        const HOP_BY_HOP = new Set([
          "connection", "keep-alive", "transfer-encoding",
          "proxy-authenticate", "proxy-authorization",
          "te", "trailer", "upgrade", "content-length",
        ]);
        const outHeaders = { "content-type": ct };
        for (const [k, v] of Object.entries(up.headers)) {
          const lk = k.toLowerCase();
          if (HOP_BY_HOP.has(lk)) continue;
          if (lk === "content-type") continue;
          outHeaders[k] = v;
        }
        if (ct.includes("text/html")) { res.writeHead(up.status, outHeaders); return res.end(injectBase(buf.toString("utf8"), baseHref)); }
        res.writeHead(up.status, outHeaders); return res.end(buf);
      }
      case "p": {
        const up = await proxyToUrl(r.p, reqPath);
        const buf = up.buffer;
        let ct = up.headers["content-type"] || guess(reqPath);
        const HOP_BY_HOP = new Set([
          "connection", "keep-alive", "transfer-encoding",
          "proxy-authenticate", "proxy-authorization",
          "te", "trailer", "upgrade", "content-length",
        ]);
        const outHeaders = { "content-type": ct };
        for (const [k, v] of Object.entries(up.headers)) {
          const lk = k.toLowerCase();
          if (HOP_BY_HOP.has(lk)) continue;
          if (lk === "content-type") continue;
          outHeaders[k] = v;
        }
        if (ct.includes("text/html")) { res.writeHead(up.status, outHeaders); return res.end(injectBase(buf.toString("utf8"), baseHref)); }
        res.writeHead(up.status, outHeaders); return res.end(buf);
      }
      case "u":
        res.writeHead(302, { location: r.u }); return res.end();
      default:
        res.writeHead(200, { "content-type": "application/json" }); return res.end(JSON.stringify(entry, null, 2));
    }
  } catch (e) { res.writeHead(502); res.end("gateway error: " + e.message); }
}

// Native BNS TLDs — never overlap ICANN, so hijacking them here is safe.
// Dual TLDs (.com, .de, .dev) always fall through to search, so a bare
// `github.com` in the URL bar keeps going to the real GitHub, not to a
// BNS registration that happens to share the name.
const NATIVE_TLDS = new Set(["bch", "p2p", "bit", "nav"]);

// Universal "set-as-default-search-engine" shim. Users add
//   https://navigate.st/search?q=%s
// as their browser's default search engine; typing `silentmode.bch` in the URL
// bar (which Chromium/Firefox otherwise send to Google as a search query
// because .bch isn't in ICANN's known-TLD list) arrives here. If q looks like
// a native BNS name we 302 to the relay (works in every browser, no local
// daemon needed); otherwise forward to DuckDuckGo so ordinary search still
// works. Even an unregistered native-TLD query goes to the relay so the user
// gets a clear NXDOMAIN page instead of a confusing search detour.
async function handleSearch(url, res) {
  const q = (url.searchParams.get("q") || "").trim().toLowerCase();
  const bare = q.replace(/^[a-z]+:\/\//, "").split("/")[0];
  const m = bare.match(/^([a-z0-9-]+)\.([a-z0-9-]+)$/);
  let target;
  if (m && NATIVE_TLDS.has(m[2])) {
    target = `https://navigate.st/bns/${m[1]}.${m[2]}/`;
  } else {
    target = `https://duckduckgo.com/?q=${encodeURIComponent(q)}`;
  }
  res.writeHead(302, { location: target });
  res.end();
}

const server = http.createServer(async (req, res) => {
  try {
    const hostHeader = (req.headers.host || "").split(":")[0].toLowerCase();

    // --- smart search endpoint (default-search-engine shim) ---
    if (req.url.startsWith("/search")) {
      const u = new URL(req.url, "http://x");
      return handleSearch(u, res);
    }

    // --- icon upload endpoint (Deviant Potidaea Katalogos DVMB icons) ---
    // POST /api/icon-upload with a raw image body →
    //   { sha256, path: "s3://bns/potidaea/icons/<sha256>.<ext>",
    //     url:  "https://navigate.st/bns/potidaea.asm/icons/<sha256>.<ext>" }
    //
    // Content-addressed: the storage key IS the SHA-256 of the bytes, so
    //   • re-uploads of the same content overwrite themselves harmlessly
    //   • per-user quota isn't necessary (a spammer just re-writes their
    //     own keys), and CORS is safe as * because we never touch state
    //   • the on-chain iconSha256 field ties the entry NFT to specific
    //     bytes, so a rogue upload can't hijack another asset's icon
    //
    // Guards: 128 KB size cap, image/* content-type whitelist. Any
    // authorization checks would break the mockup's chipnet-test posture;
    // spam is inherently rate-limited by disk write speed on the shared
    // Sia bucket. If misuse becomes a problem, add a per-IP rate-limit
    // here rather than authentication (the mockup has none by design).
    if (req.url === "/api/icon-upload") {
      // OPTIONS preflight — CORS
      if (req.method === "OPTIONS") {
        res.writeHead(204, {
          "access-control-allow-origin": "*",
          "access-control-allow-methods": "POST, OPTIONS",
          "access-control-allow-headers": "content-type",
          "access-control-max-age": "86400",
        });
        return res.end();
      }
      res.setHeader("access-control-allow-origin", "*");
      if (req.method !== "POST") {
        res.writeHead(405, { "content-type": "application/json" });
        return res.end(JSON.stringify({ error: "POST only" }));
      }
      const CT_TO_EXT = {
        "image/svg+xml": "svg", "image/png": "png", "image/jpeg": "jpg",
        "image/gif": "gif", "image/webp": "webp", "image/x-icon": "ico",
      };
      const ct = (req.headers["content-type"] || "").split(";")[0].trim().toLowerCase();
      const ext = CT_TO_EXT[ct];
      if (!ext) {
        res.writeHead(415, { "content-type": "application/json" });
        return res.end(JSON.stringify({ error: "unsupported content-type; allowed: " + Object.keys(CT_TO_EXT).join(", ") }));
      }
      const chunks = [];
      let total = 0;
      const LIMIT = 128 * 1024;
      let aborted = false;
      req.on("data", (c) => {
        total += c.length;
        if (total > LIMIT) {
          aborted = true;
          req.destroy();
          try { res.writeHead(413, { "content-type": "application/json" }); res.end(JSON.stringify({ error: "body too large (>128 KB)" })); } catch {}
          return;
        }
        chunks.push(c);
      });
      req.on("end", async () => {
        if (aborted) return;
        try {
          const bytes = Buffer.concat(chunks);
          const { createHash } = await import("node:crypto");
          const sha256 = createHash("sha256").update(bytes).digest("hex");
          const key = `bns/potidaea/icons/${sha256}.${ext}`;
          const putUrl = `${S3_ENDPOINT}/${key}`;
          const r = await aws.fetch(putUrl, { method: "PUT", body: bytes, headers: { "content-type": ct } });
          if (!r.ok) {
            const detail = await r.text().catch(() => "");
            res.writeHead(502, { "content-type": "application/json" });
            return res.end(JSON.stringify({ error: "Sia PUT failed", status: r.status, detail: detail.slice(0, 200) }));
          }
          const publicUrl = `https://navigate.st/bns/potidaea.asm/icons/${sha256}.${ext}`;
          res.writeHead(200, { "content-type": "application/json" });
          res.end(JSON.stringify({ sha256, ext, path: `s3://${key}`, url: publicUrl, bytes: bytes.length }));
        } catch (e) {
          res.writeHead(500, { "content-type": "application/json" });
          res.end(JSON.stringify({ error: String(e?.message || e) }));
        }
      });
      req.on("error", () => { /* swallow */ });
      return;
    }

    // --- registry API: advertised TLDs (mirrors on-chain `tlds.bch` "tlds" record) ---
    // GET /api/tlds  ->  { source, height, updated, tlds: [{ tld, registered, in_advertised }], advertised: [...] }
    // The list a name-selling site scans to know which suffixes it may sell.
    // `advertised` is exactly what the chain says (space-split); `tlds` is the
    // observed union of every TLD that appears on any registered name plus every
    // TLD in the advertised list — so a shop sees "sm" (advertised) even if no
    // .sm has been registered yet, and "silentmode" (registered) even if it
    // isn't advertised.
    if (req.url === "/api/tlds" || req.url.startsWith("/api/tlds?")) {
      res.setHeader("access-control-allow-origin", "*");
      res.setHeader("content-type", "application/json");
      try {
        const idx = await getIndex();
        const observed = new Map(); // tld -> count of names
        for (const key of idx.keys()) {
          const dot = key.indexOf(".");
          const tld = dot < 0 ? "bch" : key.slice(dot + 1);
          observed.set(tld, (observed.get(tld) || 0) + 1);
        }
        const anchor = idx.get("tlds.bch");
        const advertisedRaw = (anchor?.records?.tlds ?? "").trim();
        const advertised = advertisedRaw ? advertisedRaw.split(/\s+/) : [];
        const known = new Set([...advertised, ...observed.keys()]);
        // include_hidden=1 returns every TLD (used by the admin panel);
        // otherwise HIDDEN_TLDS are filtered from the public listing.
        const url = new URL(req.url, "http://x");
        const includeHidden = url.searchParams.get("include_hidden") === "1";
        const tlds = [...known].sort()
          .filter((tld) => includeHidden || !HIDDEN_TLDS.has(tld))
          .map((tld) => ({
            tld,
            registered_count: observed.get(tld) || 0,
            in_advertised: advertised.includes(tld),
            hidden: HIDDEN_TLDS.has(tld) || undefined,
          }));
        res.writeHead(200);
        res.end(JSON.stringify({
          source: "tlds.bch",
          height: anchor?.height ?? null,
          updated_txid: anchor?.updatedTxid ?? anchor?.txid ?? null,
          advertised,
          hidden_count: HIDDEN_TLDS.size,
          tlds,
        }, null, 2));
      } catch (e) {
        res.writeHead(500); res.end(JSON.stringify({ error: e.message }));
      }
      return;
    }

    // --- operator: read/write the TLD visibility list ---
    // GET  /api/tld-visibility           -> { hidden: [...] }        (public)
    // POST /api/tld-visibility           -> { hidden: [...] } saves it (operator-gated)
    //   Body: {"hidden":["foo","bar"]}   or {"tld":"foo","hide":true|false}
    //   Header: Authorization: Bearer <BNS_OPERATOR_TOKEN>
    // The list is persisted to hidden-tlds.json next to the gateway script
    // and used by /api/tlds?include_hidden=0 (default) to omit those TLDs
    // from public name-search UIs. On-chain registrations under a hidden
    // TLD keep resolving — this is a UX filter, not an enforcement gate.
    if (req.url === "/api/tld-visibility") {
      res.setHeader("access-control-allow-origin", "*");
      res.setHeader("access-control-allow-headers", "authorization, content-type");
      res.setHeader("access-control-allow-methods", "GET, POST, OPTIONS");
      res.setHeader("content-type", "application/json");
      if (req.method === "OPTIONS") { res.writeHead(204); res.end(); return; }
      if (req.method === "GET") {
        res.writeHead(200);
        res.end(JSON.stringify({ hidden: [...HIDDEN_TLDS].sort() }));
        return;
      }
      if (req.method === "POST") {
        if (!OPERATOR_TOKEN) {
          res.writeHead(503);
          res.end(JSON.stringify({ error: "gateway has no BNS_OPERATOR_TOKEN set; writes disabled" }));
          return;
        }
        const auth = req.headers.authorization || "";
        if (auth !== `Bearer ${OPERATOR_TOKEN}`) {
          res.writeHead(401);
          res.end(JSON.stringify({ error: "operator token required" }));
          return;
        }
        try {
          const chunks = [];
          for await (const c of req) chunks.push(c);
          const body = JSON.parse(Buffer.concat(chunks).toString("utf8") || "{}");
          const next = new Set(HIDDEN_TLDS);
          if (Array.isArray(body.hidden)) {
            next.clear();
            for (const t of body.hidden) if (typeof t === "string" && /^[a-z0-9-]{1,16}$/.test(t)) next.add(t);
          } else if (typeof body.tld === "string" && /^[a-z0-9-]{1,16}$/.test(body.tld)) {
            if (body.hide) next.add(body.tld); else next.delete(body.tld);
          } else {
            res.writeHead(400);
            res.end(JSON.stringify({ error: "expected {hidden:[...]} or {tld,hide}" }));
            return;
          }
          HIDDEN_TLDS = next;
          writeHiddenTlds(HIDDEN_TLDS);
          res.writeHead(200);
          res.end(JSON.stringify({ hidden: [...HIDDEN_TLDS].sort() }));
        } catch (e) {
          res.writeHead(400);
          res.end(JSON.stringify({ error: e.message }));
        }
        return;
      }
      res.writeHead(405); res.end(); return;
    }

    // --- registry API: dump every registered name ---
    // GET /api/registry  ->  { count, height_hint, names: [{ name, tld, records, category, txid, height, updated_txid }] }
    // The bulk snapshot a name-selling site can cache to compute availability
    // offline. Refreshed at most every 30s server-side (same cache as /api/*).
    if (req.url === "/api/registry" || req.url.startsWith("/api/registry?")) {
      res.setHeader("access-control-allow-origin", "*");
      res.setHeader("content-type", "application/json");
      try {
        const idx = await getIndex();
        const names = [];
        let heightHint = 0;
        for (const [key, entry] of idx) {
          const dot = key.indexOf(".");
          const displayName = dot < 0 ? key + ".bch" : key;
          const tld = dot < 0 ? "bch" : key.slice(dot + 1);
          if (entry?.height && entry.height > heightHint) heightHint = entry.height;
          names.push({
            name: displayName,
            tld,
            records: entry?.records ?? null,
            category: entry?.category ?? null,
            txid: entry?.txid ?? null,
            height: entry?.height ?? null,
            updated_txid: entry?.updatedTxid ?? null,
          });
        }
        names.sort((a, b) => a.name.localeCompare(b.name));
        res.writeHead(200);
        res.end(JSON.stringify({ count: names.length, height_hint: heightHint, names }, null, 2));
      } catch (e) {
        res.writeHead(500); res.end(JSON.stringify({ error: e.message }));
      }
      return;
    }

    // GET  /api/holdings/<scripthash>              -> { scripthash, count, names: [...] }
    // POST /api/holdings  body: {"scripthashes":[…]} -> { count, names: [...] }
    //
    // Server-side wallet-holdings lookup for the sirius.x portal. bns-indexer
    // only serves the beacon; arbitrary-address listunspent needs a full
    // electrum, which many browsers cannot reach on ports 50004/50011/62002
    // (firewalls, mobile carriers). The gateway can reach them, so it queries
    // and returns the cross-joined result: the client POSTs a scripthash list
    // and gets back the BCNR names each hash currently holds an NFT for.
    //
    // Takes scripthash (not cashaddr) to keep the gateway libauth-free; the
    // client's wallet code already knows the scripthash for each of its
    // watched addresses.
    if (req.url === "/api/holdings" || req.url.startsWith("/api/holdings/") || req.url.startsWith("/api/holdings?")) {
      res.setHeader("access-control-allow-origin", "*");
      res.setHeader("content-type", "application/json");
      let scripthashes = [];
      if (req.method === "POST") {
        try {
          const chunks = [];
          for await (const c of req) chunks.push(c);
          const body = JSON.parse(Buffer.concat(chunks).toString("utf8") || "{}");
          scripthashes = Array.isArray(body.scripthashes) ? body.scripthashes : [];
        } catch { res.writeHead(400); res.end(JSON.stringify({ error: "invalid JSON body" })); return; }
      } else {
        const one = req.url.slice("/api/holdings/".length).split("?")[0];
        if (one) scripthashes = [one];
      }
      scripthashes = scripthashes.filter((s) => typeof s === "string" && /^[0-9a-f]{64}$/i.test(s));
      if (!scripthashes.length) {
        res.writeHead(400);
        res.end(JSON.stringify({ error: "no valid scripthashes (need 64-char hex, POST as {scripthashes:[…]} or GET /api/holdings/<hex>)" }));
        return;
      }
      if (scripthashes.length > 64) {
        res.writeHead(400); res.end(JSON.stringify({ error: "at most 64 scripthashes per request" })); return;
      }
      // Skip beacon-only indexers (silentmode.st/electrum on 443, our own
      // bns-indexer on :50011) — they don't implement listunspent.
      const BNS_INDEXER_URLS = /silentmode\.st\/electrum|coinspectrum\.duckdns\.org:50011/;
      const candidates = CHIPNET_ELECTRUM
        .map((s) => (typeof s === "string" ? { url: s } : s))
        .filter((s) => !BNS_INDEXER_URLS.test(s.url));
      let el, lastErr;
      for (const s of candidates) {
        try { el = await connectAny([s], WebSocket); break; }
        catch (e) { lastErr = e; }
      }
      if (!el) {
        res.writeHead(503);
        res.end(JSON.stringify({ error: "no full electrum reachable", detail: String(lastErr?.message || lastErr) }));
        return;
      }
      try {
        const utxoLists = await Promise.all(scripthashes.map((sh) =>
          el.call("blockchain.scripthash.listunspent", [sh, "include_tokens"]).catch(() => [])
        ));
        const categories = new Set();
        for (const list of utxoLists) {
          for (const u of list) if (u.token_data?.nft) categories.add(u.token_data.category);
        }
        const idx = await getIndex();
        const names = [];
        for (const [key, entry] of idx) {
          if (!categories.has(entry.category)) continue;
          const dot = key.indexOf(".");
          const displayName = dot < 0 ? key + ".bch" : key;
          const tld = dot < 0 ? "bch" : key.slice(dot + 1);
          names.push({
            name: displayName,
            tld,
            category: entry.category,
            records: entry.records ?? null,
            txid: entry.txid ?? null,
            height: entry.height ?? null,
            updated_txid: entry.updatedTxid ?? null,
          });
        }
        names.sort((a, b) => a.name.localeCompare(b.name));
        const body = req.method === "POST"
          ? { count: names.length, scripthashes_queried: scripthashes.length, names }
          : { scripthash: scripthashes[0], count: names.length, names };
        res.writeHead(200);
        res.end(JSON.stringify(body, null, 2));
      } catch (e) {
        res.writeHead(500);
        res.end(JSON.stringify({ error: String(e.message || e) }));
      } finally {
        try { el.close(); } catch {}
      }
      return;
    }

    // --- registrar API: availability of a name ---
    // GET /api/name/<name>  ->  { name, tld, registered, records? }
    if (req.url.startsWith("/api/name/")) {
      res.setHeader("access-control-allow-origin", "*");
      res.setHeader("content-type", "application/json");
      const raw = decodeURIComponent(req.url.slice("/api/name/".length).split("?")[0]);
      try {
        const key = normalizeName(raw); // "<label>.<tld>"
        const tld = key.split(".").pop();
        const entry = (await getIndex()).get(key);
        res.writeHead(200);
        res.end(JSON.stringify({
          name: key, tld, registered: !!entry,
          records: entry?.records ?? null, category: entry?.category ?? null,
        }));
      } catch (e) {
        res.writeHead(400); res.end(JSON.stringify({ error: e.message }));
      }
      return;
    }

    // --- registrar API: all names sharing a label across every TLD ---
    // GET /api/labels/<label>  ->  { label, matches: [{ name, tld, records, category }] }
    // Powers navigate.st bare-label search: type "poutakidis" and get both
    // poutakidis.bch (if registered) and poutakidis.de rather than pinning to .bch.
    if (req.url.startsWith("/api/labels/")) {
      res.setHeader("access-control-allow-origin", "*");
      res.setHeader("content-type", "application/json");
      const raw = decodeURIComponent(req.url.slice("/api/labels/".length).split("?")[0]).toLowerCase();
      if (!/^[a-z0-9-]{1,32}$/.test(raw)) {
        res.writeHead(400);
        res.end(JSON.stringify({ error: "invalid label" }));
        return;
      }
      try {
        const idx = await getIndex();
        const matches = [];
        for (const [key, entry] of idx) {
          // Index keys: bare "<label>" for .bch, "<label>.<tld>" otherwise
          // (see normalizeName in resolver-web.js).
          const dot = key.indexOf(".");
          if (dot < 0) {
            if (key === raw) matches.push({
              name: key + ".bch", tld: "bch",
              records: entry?.records ?? null, category: entry?.category ?? null,
            });
          } else if (key.slice(0, dot) === raw) {
            matches.push({
              name: key, tld: key.slice(dot + 1),
              records: entry?.records ?? null, category: entry?.category ?? null,
            });
          }
        }
        matches.sort((a, b) => a.tld.localeCompare(b.tld));
        res.writeHead(200);
        res.end(JSON.stringify({ label: raw, matches }));
      } catch (e) {
        res.writeHead(500); res.end(JSON.stringify({ error: e.message }));
      }
      return;
    }

    // --- unified search: label + content + fuzzy fallback ---
    // GET /api/search/<q>  ->  { query, count, results: [{ name, tld, matchType, score, snippet, dist?, records }] }
    // Scores: label-exact (100) > label-substring (70) > h-record content (50) > fuzzy (40|25|10 for dist 1|2|3).
    // Fuzzy is bounded Levenshtein against the label — catches typos like "hlelo" → "hello.bch"
    // without polluting exact-match results (fuzzy hits only rank below every other match type).
    // Content search covers on-chain inline HTML only; Sia/ip sites await Helios v1.
    // Same cached index as /api/labels/ and /api/name/ — no extra fetch cost on the hot path.
    if (req.url.startsWith("/api/search/")) {
      res.setHeader("access-control-allow-origin", "*");
      res.setHeader("content-type", "application/json");
      const q = decodeURIComponent(req.url.slice("/api/search/".length).split("?")[0]).toLowerCase().trim();
      if (!q || q.length < 2 || q.length > 64) {
        res.writeHead(400);
        res.end(JSON.stringify({ error: "query must be 2-64 chars" }));
        return;
      }
      // Bounded Levenshtein: early-exits once the running minimum row-value exceeds `max`.
      // Returns `max + 1` for "too far to matter" — the caller ignores anything > max.
      const boundedLev = (a, b, max) => {
        if (Math.abs(a.length - b.length) > max) return max + 1;
        if (a === b) return 0;
        // Ensure a is the shorter for less memory.
        if (a.length > b.length) { const t = a; a = b; b = t; }
        let prev = new Array(a.length + 1);
        for (let i = 0; i <= a.length; i++) prev[i] = i;
        for (let j = 1; j <= b.length; j++) {
          const curr = new Array(a.length + 1);
          curr[0] = j;
          let rowMin = curr[0];
          const bj = b.charCodeAt(j - 1);
          for (let i = 1; i <= a.length; i++) {
            const cost = a.charCodeAt(i - 1) === bj ? 0 : 1;
            curr[i] = Math.min(prev[i] + 1, curr[i - 1] + 1, prev[i - 1] + cost);
            if (curr[i] < rowMin) rowMin = curr[i];
          }
          if (rowMin > max) return max + 1; // no path can recover below the threshold
          prev = curr;
        }
        return prev[a.length];
      };
      // Typo budget scales with query length so short queries don't match everything.
      const maxDist = q.length <= 3 ? 1 : q.length <= 6 ? 2 : 3;
      try {
        const idx = await getIndex();
        const results = [];
        for (const [key, entry] of idx) {
          const dot = key.indexOf(".");
          const label = dot < 0 ? key : key.slice(0, dot);
          const tld = dot < 0 ? "bch" : key.slice(dot + 1);
          const displayName = dot < 0 ? key + ".bch" : key;
          const records = entry?.records ?? {};
          // Names on chain but hidden from free-text search — direct lookup
          // (/api/name/, /bns/…) still works so demos stay reachable, they
          // just don't clutter the suggestion list. syskypo.de is a mirror
          // of poutakidis-content, kept live but redundant in search.
          if (HIDDEN_FROM_SEARCH.has(displayName)) continue;

          let matchType = null, score = 0, snippet = null, dist;
          if (label === q) { matchType = "label-exact"; score = 100; }
          else if (label.includes(q)) { matchType = "label-substring"; score = 70; }

          // Content search over inline HTML (h record). Strip tags first so a
          // query like "poutakidis" doesn't accidentally match "class=poutakidis".
          if (typeof records.h === "string" && records.h) {
            const text = records.h.replace(/<[^>]+>/g, " ").replace(/\s+/g, " ").trim();
            const i = text.toLowerCase().indexOf(q);
            if (i >= 0) {
              if (!matchType) { matchType = "content"; score = 50; }
              const start = Math.max(0, i - 40);
              const end = Math.min(text.length, i + q.length + 60);
              snippet = (start > 0 ? "…" : "") + text.slice(start, end) + (end < text.length ? "…" : "");
            }
          }

          // Fuzzy fallback — only when nothing above matched, only against the label.
          // Score decays sharply so a real substring match always outranks a 1-edit near-miss.
          if (!matchType) {
            const d = boundedLev(q, label, maxDist);
            if (d <= maxDist) {
              matchType = "fuzzy";
              dist = d;
              score = d === 1 ? 40 : d === 2 ? 25 : 10;
            }
          }

          if (matchType) {
            const row = { name: displayName, tld, matchType, score, snippet,
              records: entry?.records ?? null, category: entry?.category ?? null };
            if (dist !== undefined) row.dist = dist;
            results.push(row);
          }
        }
        results.sort((a, b) => b.score - a.score || a.name.localeCompare(b.name));
        const capped = results.slice(0, 50);
        res.writeHead(200);
        res.end(JSON.stringify({ query: q, count: capped.length, truncated: results.length > 50, results: capped }));
      } catch (e) {
        res.writeHead(500); res.end(JSON.stringify({ error: e.message }));
      }
      return;
    }

    // --- subdomain form: <flattened>.bch.<SUB_BASE> ---
    if (hostHeader.endsWith("." + SUB_BASE)) {
      const inner = hostHeader.slice(0, -("." + SUB_BASE).length); // "<flattened>.bch" or "<flattened>"
      const flat = inner.endsWith(".bch") ? inner.slice(0, -4) : inner;
      if (flat) {
        const name = flat.replace(/-/g, ".") + ".bch"; // dashes back to dots
        return serve(res, name, req.url || "/", null);  // own origin: no <base>
      }
    }
    // bare apex of SUB_BASE (e.g. bch.navigate.st) -> home
    if (hostHeader === SUB_BASE) { res.writeHead(200, { "content-type": "text/html" }); return res.end(home()); }

    // --- path form: /bns/<name>.bch/... ---
    let p = req.url;
    if (p === MOUNT || p === MOUNT + "/") { res.writeHead(200, { "content-type": "text/html" }); return res.end(home()); }
    if (!p.startsWith(MOUNT + "/")) { res.writeHead(404); return res.end("bns gateway"); }
    p = p.slice(MOUNT.length + 1);
    const m = p.match(/^([a-z0-9-]+(?:\.[a-z0-9-]+)+)(\/.*)?$/i); // <name>.<tld>, any TLD
    if (!m) { res.writeHead(400, { "content-type": "text/html" }); return res.end(`usage: ${MOUNT}/<name>.<tld>/`); }
    const name = m[1].toLowerCase();
    const rest = m[2] || "/";
    return serve(res, name, rest, `${MOUNT}/${name}/`);
  } catch (e) { res.writeHead(500); res.end("gateway error: " + e.message); }
});
server.listen(PORT, "127.0.0.1", () => console.log(`bns public gateway on 127.0.0.1:${PORT} (path ${MOUNT}, subdomain *.${SUB_BASE})`));

function home() {
  return `<!doctype html><meta charset=utf-8><title>BNS Gateway</title>
  <body style="font:16px system-ui;max-width:640px;margin:3rem auto;padding:0 1rem;color:#e7eaf1;background:#0f1420">
  <h1 style="color:#d6ff3d">⛓ BNS Gateway</h1>
  <p>View Bitcoin Cash <b>.bch</b> names in any browser — no install.</p>
  <ul>
    <li><a href="/bns/hello.bch">/bns/hello.bch</a> · or <a href="https://hello.${SUB_BASE}/">hello.${SUB_BASE}</a></li>
    <li><a href="/bns/coinspectrum.deviant.bch">/bns/coinspectrum.deviant.bch</a></li>
  </ul>
  <p style="color:#8b98a9;font-size:13px">This gateway resolves names for you, so it can see which .bch
  sites you request (it keeps no logs — you're trusting that). For trustless resolution install the local
  resolver/extension; for IP privacy use Tor. By Silent Mode (a Deviant project).</p></body>`;
}