import "./sentry.server";

import { createRequestHandler } from "@remix-run/express";
import { broadcastDevReady, logDevReady } from "@remix-run/server-runtime";
import compression from "compression";
import type { Server as EngineServer } from "engine.io";
import express from "express";
import morgan from "morgan";
import { nanoid } from "nanoid";
import path from "path";
import type { Server as IoServer } from "socket.io";
import { WebSocketServer } from "ws";
import { RateLimitMiddleware } from "~/services/apiRateLimit.server";
import { type RunWithHttpContextFunction } from "~/services/httpAsyncStorage.server";
import cluster from "node:cluster";
import os from "node:os";

const ENABLE_CLUSTER = process.env.ENABLE_CLUSTER === "1";
const cpuCount = os.availableParallelism();
const WORKERS =
  Number.parseInt(process.env.WEB_CONCURRENCY || process.env.CLUSTER_WORKERS || "", 10) || cpuCount;

function forkWorkers() {
  for (let i = 0; i < WORKERS; i++) {
    cluster.fork();
  }
}

function installPrimarySignalHandlers() {
  let didHandleSigterm = false;
  let didHandleSigint = false;
  let didGracefulExit = false;

  const forward = (signal: NodeJS.Signals) => {
    for (const id in cluster.workers) {
      const w = cluster.workers[id];
      if (w?.process?.pid) {
        try {
          process.kill(w.process.pid, signal);
        } catch {}
      }
    }
  };

  const gracefulExit = () => {
    if (didGracefulExit) return;
    didGracefulExit = true;

    const timeoutMs = Number(process.env.GRACEFUL_SHUTDOWN_TIMEOUT || 30_000);
    // wait for workers to exit, then exit the primary too
    const maybeExit = () => {
      const alive = Object.values(cluster.workers || {}).some((w) => w && !w.isDead());
      if (!alive) process.exit(0);
    };
    setInterval(maybeExit, 1000);
    setTimeout(() => process.exit(0), timeoutMs);
  };

  process.on("SIGTERM", () => {
    if (didHandleSigterm) return;
    didHandleSigterm = true;
    forward("SIGTERM");
    gracefulExit();
  });
  process.on("SIGINT", () => {
    if (didHandleSigint) return;
    didHandleSigint = true;
    forward("SIGINT");
    gracefulExit();
  });
}

if (ENABLE_CLUSTER && cluster.isPrimary) {
  process.title = `node webapp-server primary`;
  console.log(`[cluster] Primary ${process.pid} is starting with ${WORKERS} workers`);
  forkWorkers();

  cluster.on("exit", (worker, code, signal) => {
    const intentional =
      // If we sent "shutdown", the worker will exit with code 0 after closing.
      code === 0 || worker.exitedAfterDisconnect;
    console.log(
      `[cluster] worker ${worker.process.pid} exited (code=${code}, signal=${signal}, intentional=${intentional})`
    );
    // If it wasn't during a shutdown, replace the worker.
    if (!intentional) cluster.fork();
  });

  installPrimarySignalHandlers();
} else {
  const app = express();

  if (process.env.DISABLE_COMPRESSION !== "1") {
    app.use(compression());
  }

  // http://expressjs.com/en/advanced/best-practice-security.html#at-a-minimum-disable-x-powered-by-header
  app.disable("x-powered-by");

  // Remix fingerprints its assets so we can cache forever.
  app.use("/build", express.static("public/build", { immutable: true, maxAge: "1y" }));

  // Everything else (like favicon.ico) is cached for an hour. You may want to be
  // more aggressive with this caching.
  app.use(express.static("public", { maxAge: "1h" }));

  app.use(morgan("tiny"));

  process.title = ENABLE_CLUSTER
    ? `node webapp-worker-${cluster.isWorker ? cluster.worker?.id : "solo"}`
    : "node webapp-server";

  const MODE = process.env.NODE_ENV;
  const BUILD_DIR = path.join(process.cwd(), "build");
  const build = require(BUILD_DIR);

  const port = process.env.REMIX_APP_PORT || process.env.PORT || 3000;

  if (process.env.HTTP_SERVER_DISABLED !== "true") {
    const socketIo: { io: IoServer } | undefined = build.entry.module.socketIo;
    const wss: WebSocketServer | undefined = build.entry.module.wss;
    const apiRateLimiter: RateLimitMiddleware = build.entry.module.apiRateLimiter;
    const engineRateLimiter: RateLimitMiddleware = build.entry.module.engineRateLimiter;
    const runWithHttpContext: RunWithHttpContextFunction = build.entry.module.runWithHttpContext;

    app.use((req, res, next) => {
      // helpful headers:
      res.set("Strict-Transport-Security", `max-age=${60 * 60 * 24 * 365 * 100}`);

      // Add X-Robots-Tag header for test-cloud.trigger.dev
      if (req.hostname !== "cloud.trigger.dev") {
        res.set("X-Robots-Tag", "noindex, nofollow");
      }

      // /clean-urls/ -> /clean-urls
      if (req.path.endsWith("/") && req.path.length > 1) {
        const query = req.url.slice(req.path.length);
        const safepath = req.path.slice(0, -1).replace(/\/+/g, "/");
        res.redirect(301, safepath + query);
        return;
      }
      next();
    });

    app.use((req, res, next) => {
      // Generate a unique request ID for each request
      const requestId = nanoid();

      runWithHttpContext(
        { requestId, path: req.url, host: req.hostname, method: req.method },
        next
      );
    });

    if (process.env.DASHBOARD_AND_API_DISABLED !== "true") {
      if (process.env.ALLOW_ONLY_REALTIME_API === "true") {
        // Block all requests that do not start with /realtime
        app.use((req, res, next) => {
          // Make sure /healthcheck is still accessible
          if (!req.url.startsWith("/realtime") && req.url !== "/healthcheck") {
            res.status(404).send("Not Found");
            return;
          }

          next();
        });
      }

      app.use(apiRateLimiter);
      app.use(engineRateLimiter);

      app.all(
        "*",
        // @ts-ignore
        createRequestHandler({
          build,
          mode: MODE,
        })
      );
    } else {
      // we need to do the health check here at /healthcheck
      app.get("/healthcheck", (req, res) => {
        res.status(200).send("OK");
      });
    }

    const server = app.listen(port, () => {
      console.log(
        `✅ server ready: http://localhost:${port} [NODE_ENV: ${MODE}]${
          ENABLE_CLUSTER && cluster.isWorker ? ` [worker ${cluster.worker?.id}/${process.pid}]` : ""
        }`
      );

      if (MODE === "development") {
        broadcastDevReady(build)
          .then(() => logDevReady(build))
          .catch(console.error);
      }
    });

    server.keepAliveTimeout = 65 * 1000;
    // Mitigate against https://github.com/triggerdotdev/trigger.dev/security/dependabot/128
    // by not allowing 2000+ headers to be sent and causing a DoS
    // headers will instead be limited by the maxHeaderSize
    server.maxHeadersCount = 0;

    let didCloseServer = false;

    function closeServer(signal: NodeJS.Signals) {
      if (didCloseServer) return;
      didCloseServer = true;

      server.close((err) => {
        if (err) {
          console.error("Error closing express server:", err);
        } else {
          console.log("Express server closed gracefully.");
        }
      });
    }

    process.on("SIGTERM", closeServer);
    process.on("SIGINT", closeServer);

    socketIo?.io.attach(server);
    server.removeAllListeners("upgrade"); // prevent duplicate upgrades from listeners created by io.attach()

    server.on("upgrade", async (req, socket, head) => {
      console.log(`Attemping to upgrade connection at url ${req.url}`);

      socket.on("error", (err) => {
        console.error("Connection upgrade error:", err);
      });

      const url = new URL(req.url ?? "", "http://localhost");

      // Upgrade socket.io connection
      if (url.pathname.startsWith("/socket.io/")) {
        console.log(`Socket.io client connected, upgrading their connection...`);

        // https://github.com/socketio/socket.io/issues/4693
        (socketIo?.io.engine as EngineServer).handleUpgrade(req, socket, head);
        return;
      }

      // Only upgrade the connecting if the path is `/ws`
      if (url.pathname !== "/ws") {
        // Setting the socket.destroy() error param causes an error event to be emitted which needs to be handled with socket.on("error") to prevent uncaught exceptions.
        socket.destroy(
          new Error(
            "Cannot connect because of invalid path: Please include `/ws` in the path of your upgrade request."
          )
        );
        return;
      }

      console.log(`Client connected, upgrading their connection...`);

      // Handle the WebSocket connection
      wss?.handleUpgrade(req, socket, head, (ws) => {
        wss?.emit("connection", ws, req);
      });
    });
  } else {
    require(BUILD_DIR);
    console.log(`✅ app ready (skipping http server)`);
  }
}
