const http = require("node:http");
const { Server: SocketServer } = require("socket.io");
const { createApp } = require("./app");
const { openDatabase } = require("./database");
const { runMigrations } = require("./database/migrate");

function listen(httpServer, port, host) {
  return new Promise((resolve, reject) => {
    function onError(error) {
      httpServer.off("listening", onListening);
      reject(error);
    }
    function onListening() {
      httpServer.off("error", onError);
      resolve(httpServer.address());
    }
    httpServer.once("error", onError);
    httpServer.once("listening", onListening);
    httpServer.listen(port, host);
  });
}

function createRuntime({ config, logger = console }) {
  const database = openDatabase(config.database);
  let migrations;
  try {
    migrations = runMigrations(database);
  } catch (error) {
    database.close();
    throw error;
  }

  const lifecycle = {
    ready: false,
    stopping: false,
  };
  const app = createApp({ config, database, lifecycle, migrations });
  const httpServer = http.createServer(app);
  const io = new SocketServer(httpServer, {
    serveClient: false,
  });

  io.on("connection", (socket) => {
    logger.info?.(`Socket.IO client connected: ${socket.id}`);
    socket.on("disconnect", () => {
      logger.info?.(`Socket.IO client disconnected: ${socket.id}`);
    });
  });

  let address = null;
  let startPromise = null;
  let stopPromise = null;

  async function start() {
    if (stopPromise) {
      throw new Error("Cannot start a runtime after shutdown has begun");
    }
    if (startPromise) {
      return startPromise;
    }

    startPromise = listen(httpServer, config.port, config.host)
      .then((listeningAddress) => {
        address = listeningAddress;
        lifecycle.ready = true;
        return listeningAddress;
      })
      .catch((error) => {
        database.close();
        throw error;
      });
    return startPromise;
  }

  async function stop(reason = "shutdown") {
    if (stopPromise) {
      return stopPromise;
    }

    lifecycle.ready = false;
    lifecycle.stopping = true;
    stopPromise = new Promise((resolve) => {
      let settled = false;
      const finish = () => {
        if (settled) return;
        settled = true;
        clearTimeout(timeout);
        if (database.open) {
          database.close();
        }
        resolve();
      };
      const timeout = setTimeout(() => {
        logger.warn?.(
          `Graceful shutdown timed out after ${config.shutdownTimeoutMs}ms`,
        );
        httpServer.closeAllConnections?.();
        finish();
      }, config.shutdownTimeoutMs);
      timeout.unref?.();

      if (!httpServer.listening) {
        io.close();
        finish();
        return;
      }

      logger.info?.(`Stopping Announcements API (${reason})`);
      io.close(finish);
    });
    return stopPromise;
  }

  return {
    app,
    config,
    database,
    httpServer,
    io,
    lifecycle,
    migrations,
    get address() {
      return address;
    },
    start,
    stop,
  };
}

module.exports = {
  createRuntime,
};