// BNS index host. Runs in its own process (Electron utilityProcess), started
// by main.js, so snapshot parsing, index builds, the Ariadne pipe and any
// electrum traffic never compete with the browser's main thread.
// Spec: DESIGN-bns-indexer-service.md ("Theseus").
//
// Ariadne's Thread owns BNS indexing on a machine; Theseus reads from it
// through the shared source chain (Argus/src/lib/bns-source-chain.js):
//   1. Ariadne's indexer over its pipe, server-checked (ariadne-helper.exe):
//      a snapshot, then pushes
//   2. local copies: Ariadne's two files (All users / Just me), Theseus's own
//      raw copy, the bundled snapshot (the one with the most evidence wins),
//      and Theseus's own index copy written from the pipe
//   3. (main.js) the quick single-name lookup on the gateway, provisional
// Theseus's own electrum indexer (the shared core, bns-index-core.js) is a
// standby, the last resort:
//   - started when Ariadne is unhealthy: no pipe a few seconds after launch,
//     a pipe that fails the server check, a pipe that went silent, or an
//     index that is not being confirmed while Ariadne says it is not paused.
//     Warm-started from the richest local copy (normally Ariadne's), so no
//     download and no cold sync.
//   - stopped again once Ariadne has been healthy for 90 s, so a flapping
//     service cannot start and stop it over and over.
//   Under Economy Ariadne is paused, not unhealthy: no takeover.
// With no Ariadne at all (portable, not installed, a pre-0.2 install) it is
// the 0.3.70 behaviour: the own indexer runs throughout.
//
// The only thing Theseus ever does to Ariadne: when "Launch at start" is off,
// it runs the indexer's task once at launch. It never writes Ariadne's files.
//
// Protocol (process.parentPort messages), unchanged for main.js:
//   main -> host  { type: "init", resolverPath, coreLib, chainLib, pipeLib,
//                   userData, bundledSnapshot, torPort }
//                 { type: "go" }                  network work may start
//                 { type: "tor", port }           electrum via Tor (null = direct)
//                 { type: "stop-polling" }
//                 { id, type: "poll" | "rebuild" | "ready" }   replies { type: "reply", id, ok }
//   host -> main  { type: "index", builtAt, names: [[key, entry]...], network, source }
//                 { type: "fresh", builtAt }      confirmed, nothing changed
//                 { type: "status", ... }         where the names come from (Settings)
//                 { type: "reply", id, ok, error? }
"use strict";
const fs = require("fs");
const path = require("path");
const { execFile } = require("child_process");
const { pathToFileURL } = require("url");
const WebSocket = require("ws");

const port = process.parentPort;
const log = (...a) => console.log("[bns]", ...a);

// Same guard as main.js: ws turns "closed while still connecting" into an
// uncaught error event. Electrum servers that reset mid-handshake are routine.
{
  const close = WebSocket.prototype.close;
  WebSocket.prototype.close = function (...args) {
    if (this.readyState === WebSocket.CONNECTING && this.listenerCount("error") === 0) this.once("error", () => {});
    return close.apply(this, args);
  };
}
process.on("uncaughtException", (err) => { try { console.error("[bns] uncaught:", (err && err.stack) || err); } catch {} });
process.on("unhandledRejection", (err) => { try { console.error("[bns] unhandled rejection:", (err && err.message) || err); } catch {} });

const LAUNCH_GRACE_MS = 4_000;     // the pipe gets this long before the own indexer starts
const STALE_MS = 10 * 60_000;      // unpaused Ariadne whose index is not confirmed this long: unhealthy
const HANDBACK_MS = 90_000;        // healthy this long before the own indexer is stopped
const CHECK_EVERY_MS = 10_000;

let cfg = null, R = null, core = null, chainLib = null, pipeLib = null;
const importEsm = (p) => import(pathToFileURL(p).href);

// ---- Tor ------------------------------------------------------------------
let torAgent = null;
async function setTor(torPort) {
  if (!torPort) { torAgent = null; return; }
  const { SocksProxyAgent } = await import("socks-proxy-agent");
  torAgent = new SocksProxyAgent(`socks5h://127.0.0.1:${torPort}`);
}
class TorWebSocket extends WebSocket { constructor(url, opts) { super(url, { agent: torAgent, ...opts }); } }
const currentWS = () => (torAgent ? TorWebSocket : WebSocket);

// ---- Ariadne's Thread on this machine ---------------------------------------
// Each scope it may be installed in: where its files are, its pipe, and how
// to check the pipe's server (Ariadne's helper; the server's image is
// Ariadne's own node.exe). The install folder comes from Ariadne's uninstall
// key. A pre-0.2 Ariadne has no helper and no pipe: only files (none either).
const ARIADNE_KEY = "Software\\Microsoft\\Windows\\CurrentVersion\\Uninstall\\{7E7A5F1C-3B4E-4C8A-9E1D-ARIADNERSLVR}_is1";
function execOut(file, args) {
  return new Promise((resolve) => execFile(file, args, { windowsHide: true, timeout: 10_000 }, (err, out) => resolve(err ? "" : String(out))));
}
async function installLocation(hive) {
  const out = await execOut("reg.exe", ["query", `${hive}\\${ARIADNE_KEY}`, "/v", "InstallLocation", "/reg:64"]);
  const m = /InstallLocation\s+REG_\w+\s+(.+)/.exec(out);
  return m ? m[1].trim() : null;
}
async function findAriadne() {
  // Tests point Theseus at a scratch Ariadne: {scope, pipe, stateDir, helper, imagePrefix}.
  if (process.env.THESEUS_ARIADNE_TEST) {
    try { return [JSON.parse(process.env.THESEUS_ARIADNE_TEST)]; } catch { return []; }
  }
  if (process.platform !== "win32") return [];
  const scopes = [];
  const programData = process.env.ProgramData || process.env.PROGRAMDATA || "C:\\ProgramData";
  const localAppData = process.env.LOCALAPPDATA || "";
  const machineLoc = await installLocation("HKLM");
  scopes.push({
    scope: "machine", pipe: "\\\\.\\pipe\\ariadne-bns", task: "Ariadne BNS Indexer",
    stateDir: path.join(programData, "Ariadne"), loc: machineLoc,
  });
  const userLoc = await installLocation("HKCU");
  if (userLoc || (localAppData && fs.existsSync(path.join(localAppData, "Ariadne", "index")))) {
    const sid = (/"(S-1-[\d-]+)"/.exec(await execOut("whoami", ["/user", "/fo", "csv", "/nh"])) || [])[1];
    scopes.push({
      scope: "user", pipe: sid ? `\\\\.\\pipe\\ariadne-bns-${sid}` : null, task: `Ariadne BNS Indexer (${process.env.USERNAME || ""})`,
      stateDir: path.join(localAppData, "Ariadne"), loc: userLoc,
    });
  }
  for (const s of scopes) {
    if (!s.loc) continue;
    const exe = path.join(s.loc, "tools", "ariadne-helper.exe");
    if (fs.existsSync(exe)) { s.helper = { exe }; s.imagePrefix = path.join(s.loc, "runtime") + path.sep; }
  }
  return scopes;
}
const ariadneCopies = (scopes) => scopes.flatMap((s) => [
  path.join(s.stateDir, "index", "bns-name-snapshot.json"),
  path.join(s.stateDir, "index", "bns-name-snapshot.prev.json"),
]);

// "Launch at start" off: the indexer runs on demand, i.e. now. The one thing
// Theseus starts on Ariadne's side; its task lets local users run it.
function runIndexerOnDemand(scopes) {
  for (const s of scopes) {
    if (!s.task || !s.loc) continue;
    let pol = null;
    try { pol = JSON.parse(fs.readFileSync(path.join(s.stateDir, "policy.json"), "utf8").replace(/^\uFEFF/, "")); } catch {}
    if (pol && pol.startAtBoot === false) {
      execFile("schtasks.exe", ["/Run", "/TN", s.task], { windowsHide: true }, (err) => {
        log(err ? `Ariadne's indexer (${s.scope}) could not be started on demand` : `Ariadne's indexer (${s.scope}) started on demand (Launch at start is off)`);
      });
    }
  }
}

// ---- state ------------------------------------------------------------------
let networkId = "chipnet";
const netSuffix = () => (networkId === "chipnet" ? "" : `.${networkId}`);
let scopes = [];
let chain = null;              // the source chain (Ariadne + local copies)
let own = null;                // Theseus's own indexer, while it runs
let ownReason = null;
let goReceived = false;
let launchedAt = Date.now();
let healthySince = 0;
let lastPublished = null;      // which index main has: "chain" | "own"

function active() { return own && own.index ? "own" : "chain"; }
function publish(reason) {
  const which = active();
  const idx = which === "own" ? own.index : chain && chain.index;
  if (!idx || !idx.size) return;
  lastPublished = which;
  const builtAt = which === "own" ? own.builtAt : chain.builtAt;
  port.postMessage({ type: "index", builtAt, names: [...idx], network: networkId, reason, source: which === "own" ? "theseus-indexer" : chain.source });
  sendStatus();
}
function sendStatus() {
  const cs = chain ? chain.status() : null;
  port.postMessage({
    type: "status",
    source: active() === "own" ? "theseus-indexer" : cs && cs.source,
    ariadne: {
      installed: scopes.filter((s) => s.loc).map((s) => s.scope),
      pipe: cs ? cs.pipe : null,
      paused: cs ? cs.paused : false,
      builtAt: cs ? cs.builtAt : 0,
      healthy: ariadneHealthy(),
    },
    ownIndexer: own ? { running: true, reason: ownReason, ...own.status() } : { running: false },
  });
}

// ---- health -----------------------------------------------------------------
function ariadneHealthy() {
  if (!chain || !chain.pipeConnected) return false;
  // Economy: Ariadne pauses its network work and stops confirming. That is a
  // setting, not a failure; taking over would undo it.
  if (chain.paused) return true;
  return Date.now() - chain.builtAt < STALE_MS;
}
function checkHealth() {
  const now = Date.now();
  if (ariadneHealthy()) {
    healthySince = healthySince || now;
    if (own && now - healthySince >= HANDBACK_MS) stopOwn();
  } else {
    healthySince = 0;
    if (!own && now - launchedAt >= LAUNCH_GRACE_MS) {
      const cs = chain && chain.status();
      const why = !scopes.some((s) => s.helper) ? "no Ariadne indexer installed"
        : cs && cs.pipe && cs.pipe.error ? `Ariadne pipe: ${cs.pipe.error}`
        : chain && chain.pipeConnected ? "Ariadne's index is not being confirmed"
        : "Ariadne's indexer is not answering";
      startOwn(why);
    }
  }
}

// ---- Theseus's own indexer (standby) ------------------------------------------
function startOwn(reason) {
  if (own) return own;
  ownReason = reason;
  log(`own indexer starting: ${reason}`);
  own = core.createIndexer({
    resolver: R,
    WebSocket: currentWS(),
    snapshotDir: cfg.userData,
    snapshotBase: `bns-name-snapshot${netSuffix()}`,
    // Ariadne's last snapshot first in line: no download, no cold sync.
    warmPaths: [...ariadneCopies(scopes), cfg.bundledSnapshot],
    electrumCacheFile: path.join(cfg.userData, `electrum-servers${netSuffix()}.json`),
    log: (...a) => log(...a),
  });
  own.on("change", () => { if (own) publish("own"); });
  own.on("fresh", ({ builtAt }) => { if (own && active() === "own") port.postMessage({ type: "fresh", builtAt }); });
  own.warm();
  if (own.index && lastPublished !== "own") publish("own-warm"); // its "change" normally did
  if (goReceived) own.start();
  sendStatus();
  return own;
}
function stopOwn() {
  if (!own) return;
  log("Ariadne healthy again: own indexer stopped");
  own.stop();
  own.removeAllListeners();
  own = null; ownReason = null;
  publish("handback");
}

// ---- boot -------------------------------------------------------------------
async function init(m) {
  cfg = m;
  await setTor(m.torPort);
  [R, core, chainLib, pipeLib] = await Promise.all([importEsm(m.resolverPath), importEsm(m.coreLib), importEsm(m.chainLib), importEsm(m.pipeLib)]);
  networkId = (R.NETWORK && R.NETWORK.id) || "chipnet";
  scopes = await findAriadne();
  launchedAt = Date.now();
  const checked = scopes.filter((s) => s.helper && s.pipe);
  chain = chainLib.createSourceChain({
    resolver: R,
    // Machine scope first: if both are installed, readers use the machine one.
    connectPipe: checked.length ? async () => {
      let last = null;
      for (const s of checked) {
        try { return await pipeLib.connectIndexerPipe({ pipeName: s.pipe, helper: s.helper, expect: { scope: s.scope, imagePrefix: s.imagePrefix } }); }
        catch (e) { last = e; }
      }
      throw last || new Error("no pipe");
    } : null,
    localPaths: [
      ...ariadneCopies(scopes),
      path.join(cfg.userData, `bns-name-snapshot${netSuffix()}.json`),
      path.join(cfg.userData, `bns-name-snapshot${netSuffix()}.prev.json`),
      cfg.bundledSnapshot,
    ],
    ownCopyPath: path.join(cfg.userData, `bns-name-index${netSuffix()}.json`),
    // The public sources are not the chain's job here: the own indexer
    // fetches the published snapshot when it runs, and main.js has the
    // quick single-name lookup (through Tor or the session proxy).
    publicSnapshotUrls: [],
    publicIndexerUrl: null,
    log: (...a) => log(...a),
  });
  chain.on("change", () => { if (active() === "chain") publish("chain"); });
  chain.on("fresh", ({ builtAt }) => { if (active() === "chain") port.postMessage({ type: "fresh", builtAt }); });
  chain.on("pipe", ({ connected, error }) => { log(connected ? "Ariadne's indexer connected" : `Ariadne's indexer unavailable (${error})`); checkHealth(); sendStatus(); });
  chain.on("paused", (p) => { log(p ? "Ariadne is in Economy: sync paused" : "Ariadne resumed syncing"); sendStatus(); });
  const t0 = Date.now();
  chain.start(); // local copies now (synchronous), the pipe in the background
  if (chain.index.size) log(`local copy: ${chain.index.size} names from ${chain.source} in ${Date.now() - t0} ms`);
  if (!lastPublished) publish("local"); // the chain's "change" has normally sent it already
  runIndexerOnDemand(scopes);
  // Nothing to wait for (portable Theseus, no Ariadne, or one older than the
  // pipe): the own indexer at once, as in 0.3.70.
  if (!checked.length) startOwn("no Ariadne indexer installed");
  setTimeout(checkHealth, LAUNCH_GRACE_MS);
  setInterval(checkHealth, CHECK_EVERY_MS);
}
let initP = null;

// "ready": resolves once there is any index. The pipe gets its grace period;
// then the own indexer (published snapshot, electrum as the last resort).
async function whenReady() {
  await initP;
  if (active() === "chain" && chain.index.size) return true;
  if (own && own.index) return true;
  const until = launchedAt + LAUNCH_GRACE_MS;
  while (Date.now() < until && !chain.index.size) await new Promise((r) => setTimeout(r, 200));
  if (chain.index.size && active() === "chain") return true;
  return startOwn(own ? ownReason : "no index yet").ready();
}
async function poll() {
  await initP;
  if (own) return own.poll({ force: true });
  if (chain.pipeConnected) return chain.requestPoll();
  return false; // no live source yet: the health check starts the own indexer
}

port.on("message", async (e) => {
  const m = e.data || {};
  const reply = (ok, error) => { if (m.id != null) port.postMessage({ type: "reply", id: m.id, ok: !!ok, error }); };
  try {
    switch (m.type) {
      case "init": initP = init(m); await initP; break;
      case "go": goReceived = true; await initP; if (own) own.start(); break;
      case "tor": await setTor(m.port); if (own) own.setWebSocket(currentWS()); break;
      case "stop-polling": if (own) own.stop(); if (chain) chain.stop(); break;
      case "ready": reply(await whenReady()); break;
      // On-demand poll (a tab's name is not in the index): Ariadne's indexer
      // when it is live, else the own one; allowed before "go".
      case "poll": reply(await poll()); break;
      case "rebuild": await initP; reply(await startOwn(ownReason || "rebuild requested").rebuild()); break;
      default: reply(false, "unknown request");
    }
  } catch (err) { reply(false, err?.message || String(err)); }
});