#!/usr/bin/env node
/**
 * 自定义 Next dev server：
 * - 解决 ONLYOFFICE 在 `/onlyoffice-server/*` 下的 WebSocket Upgrade 需求（socket.io / coauthoring）。
 * - Next App Router 的 Route Handler 无法处理 Upgrade，因此必须在 Node http server 层做透传。
 *
 * 用法（保持与 next dev 类似）：
 * - pnpm dev -p 3000
 * - node scripts/dev-server.js -p 3000
 *
 * 依赖环境变量：
 * - ONLYOFFICE_INTERNAL_URL：默认 http://127.0.0.1:8081
 */

const http = require("http");
const net = require("net");
const path = require("path");
const next = require("next");
const { parse: parseUrl } = require("url");

const ONLYOFFICE_PREFIX = "/onlyoffice-server";

function readArgValue(flag) {
  const idx = process.argv.findIndex((x) => x === flag);
  if (idx === -1) return null;
  const v = process.argv[idx + 1];
  if (!v || v.startsWith("-")) return null;
  return v;
}

function resolvePort() {
  const fromArg = readArgValue("-p") || readArgValue("--port");
  const raw = fromArg || process.env.PORT || "3000";
  const n = Number(raw);
  return Number.isFinite(n) ? Math.max(1, Math.min(65535, Math.floor(n))) : 3000;
}

function resolveHostname() {
  return readArgValue("-H") || readArgValue("--hostname") || process.env.HOSTNAME || "0.0.0.0";
}

function isOnlyOfficePath(urlString) {
  try {
    const u = new URL(urlString, "http://localhost");
    return u.pathname === ONLYOFFICE_PREFIX || u.pathname.startsWith(`${ONLYOFFICE_PREFIX}/`);
  } catch {
    return false;
  }
}

function buildUpstreamRequestHead(req, targetUrl) {
  const incoming = new URL(req.url || "/", "http://localhost");
  const rawPath = incoming.pathname || "/";
  const stripped = rawPath === ONLYOFFICE_PREFIX ? "/" : rawPath.slice(ONLYOFFICE_PREFIX.length) || "/";

  const basePath = String(targetUrl.pathname || "/").replace(/\/+$/, "") || "";
  const upstreamPath = `${basePath}${stripped}`.replace(/\/{2,}/g, "/") + (incoming.search || "");

  const lines = [];
  lines.push(`${req.method || "GET"} ${upstreamPath} HTTP/1.1`);

  const headers = req.headers || {};
  for (const [k, v] of Object.entries(headers)) {
    if (!v) continue;
    const key = String(k);
    if (key.toLowerCase() === "host") continue;
    if (Array.isArray(v)) {
      lines.push(`${key}: ${v.join(", ")}`);
    } else {
      lines.push(`${key}: ${String(v)}`);
    }
  }

  // 说明：Host 必须指向 ONLYOFFICE_INTERNAL_URL，否则上游可能拒绝 Upgrade。
  lines.push(`Host: ${targetUrl.host}`);
  lines.push("");
  lines.push("");
  return lines.join("\r\n");
}

function proxyOnlyOfficeUpgrade(req, socket, head) {
  const target = new URL((process.env.ONLYOFFICE_INTERNAL_URL || "http://127.0.0.1:8081").replace(/\/+$/, "") + "/");
  const port = Number(target.port) || (target.protocol === "https:" ? 443 : 80);

  const upstream = net.connect({ host: target.hostname, port }, () => {
    try {
      const reqHead = buildUpstreamRequestHead(req, target);
      upstream.write(reqHead);
      if (head && head.length > 0) upstream.write(head);
      socket.pipe(upstream);
      upstream.pipe(socket);
    } catch (e) {
      try {
        socket.destroy();
      } catch {}
      try {
        upstream.destroy();
      } catch {}
    }
  });

  const onError = (err) => {
    try {
      const msg = err && err.message ? String(err.message) : String(err || "");
      // eslint-disable-next-line no-console
      console.log("[dev-server][onlyoffice-ws] proxy error", msg);
    } catch {}
    try {
      socket.destroy();
    } catch {}
    try {
      upstream.destroy();
    } catch {}
  };

  upstream.on("error", onError);
  socket.on("error", onError);
}

async function main() {
  const port = resolvePort();
  const hostname = resolveHostname();
  const dev = true;

  const app = next({ dev, dir: path.join(__dirname, "..") });
  const handle = app.getRequestHandler();

  await app.prepare();
  // 说明：Next dev 的 HMR 依赖 WebSocket（/_next/webpack-hmr），需要交给 Next 自己处理 upgrade。
  const handleUpgrade = typeof app.getUpgradeHandler === "function" ? app.getUpgradeHandler() : null;

  const server = http.createServer((req, res) => {
    try {
      res.setHeader("x-mnote-dev-server", "1");
      res.setHeader("x-mnote-onlyoffice-ws-proxy", "1");
    } catch {
      // ignore
    }
    const parsed = parseUrl(req.url || "/", true);
    handle(req, res, parsed);
  });

  server.on("upgrade", (req, socket, head) => {
    if (isOnlyOfficePath(req.url || "/")) {
      try {
        // eslint-disable-next-line no-console
        console.log("[dev-server][onlyoffice-ws] upgrade", req.url);
      } catch {}
      proxyOnlyOfficeUpgrade(req, socket, head);
      return;
    }
    if (handleUpgrade) {
      handleUpgrade(req, socket, head);
      return;
    }
    try {
      socket.destroy();
    } catch {
      // ignore
    }
  });

  server.listen(port, hostname, () => {
    // eslint-disable-next-line no-console
    console.log(`[dev-server] ready http://${hostname}:${port} (ONLYOFFICE ws via ${ONLYOFFICE_PREFIX} -> ${process.env.ONLYOFFICE_INTERNAL_URL || "http://127.0.0.1:8081"})`);
  });
}

main().catch((err) => {
  // eslint-disable-next-line no-console
  console.error(err instanceof Error ? err.stack : String(err));
  process.exit(1);
});