'use strict';

const net = require('node:net');
const assert = require('node:assert');
const util = require('./util');
const { InvalidArgumentError, ConnectTimeoutError } = require('./errors');
const timers = require('../util/timers');

function noop() {}

let tls; // include tls conditionally since it is not always available

// TODO: session re-use does not wait for the first
// connection to resolve the session and might therefore
// resolve the same servername multiple times even when
// re-use is enabled.

let SessionCache;
// FIXME: remove workaround when the Node bug is fixed
// https://github.com/nodejs/node/issues/49344#issuecomment-1741776308
if (
  global.FinalizationRegistry &&
  !(process.env.NODE_V8_COVERAGE || process.env.UNDICI_NO_FG)
) {
  SessionCache = class WeakSessionCache {
    constructor(maxCachedSessions) {
      this._maxCachedSessions = maxCachedSessions;
      this._sessionCache = new Map();
      this._sessionRegistry = new global.FinalizationRegistry((key) => {
        if (this._sessionCache.size < this._maxCachedSessions) {
          return;
        }

        const ref = this._sessionCache.get(key);
        if (ref !== undefined && ref.deref() === undefined) {
          this._sessionCache.delete(key);
        }
      });
    }

    get(sessionKey) {
      const ref = this._sessionCache.get(sessionKey);
      return ref ? ref.deref() : null;
    }

    set(sessionKey, session) {
      if (this._maxCachedSessions === 0) {
        return;
      }

      this._sessionCache.set(sessionKey, new WeakRef(session));
      this._sessionRegistry.register(session, sessionKey);
    }
  };
} else {
  SessionCache = class SimpleSessionCache {
    constructor(maxCachedSessions) {
      this._maxCachedSessions = maxCachedSessions;
      this._sessionCache = new Map();
    }

    get(sessionKey) {
      return this._sessionCache.get(sessionKey);
    }

    set(sessionKey, session) {
      if (this._maxCachedSessions === 0) {
        return;
      }

      if (this._sessionCache.size >= this._maxCachedSessions) {
        // remove the oldest session
        const { value: oldestKey } = this._sessionCache.keys().next();
        this._sessionCache.delete(oldestKey);
      }

      this._sessionCache.set(sessionKey, session);
    }
  };
}

function buildConnector({
  allowH2,
  maxCachedSessions,
  socketPath,
  timeout,
  session: customSession,
  ...opts
}) {
  if (
    maxCachedSessions != null &&
    (!Number.isInteger(maxCachedSessions) || maxCachedSessions < 0)
  ) {
    throw new InvalidArgumentError(
      'maxCachedSessions must be a positive integer or zero'
    );
  }

  const options = { path: socketPath, ...opts };
  const sessionCache = new SessionCache(
    maxCachedSessions == null ? 100 : maxCachedSessions
  );
  timeout = timeout == null ? 10e3 : timeout;
  allowH2 = allowH2 != null ? allowH2 : false;
  return function connect(
    { hostname, host, protocol, port, servername, localAddress, httpSocket },
    callback
  ) {
    let socket;
    if (protocol === 'https:') {
      if (!tls) {
        tls = require('node:tls');
      }
      servername =
        servername || options.servername || util.getServerName(host) || null;

      const sessionKey = servername || hostname;
      assert(sessionKey);

      const session = customSession || sessionCache.get(sessionKey) || null;

      port = port || 443;

      socket = tls.connect({
        highWaterMark: 16384, // TLS in node can't have bigger HWM anyway...
        ...options,
        servername,
        session,
        localAddress,
        // TODO(HTTP/2): Add support for h2c
        ALPNProtocols: allowH2 ? ['http/1.1', 'h2'] : ['http/1.1'],
        socket: httpSocket, // upgrade socket connection
        port,
        host: hostname,
      });

      socket.on('session', function (session) {
        // TODO (fix): Can a session become invalid once established? Don't think so?
        sessionCache.set(sessionKey, session);
      });
    } else {
      assert(!httpSocket, 'httpSocket can only be sent on TLS update');

      port = port || 80;

      socket = net.connect({
        highWaterMark: 64 * 1024, // Same as nodejs fs streams.
        ...options,
        localAddress,
        port,
        host: hostname,
      });
    }

    // Set TCP keep alive options on the socket here instead of in connect() for the case of assigning the socket
    if (options.keepAlive == null || options.keepAlive) {
      const keepAliveInitialDelay =
        options.keepAliveInitialDelay === undefined ?
          60e3
        : options.keepAliveInitialDelay;
      socket.setKeepAlive(true, keepAliveInitialDelay);
    }

    const clearConnectTimeout = setupConnectTimeout(new WeakRef(socket), {
      timeout,
      hostname,
      port,
    });

    socket
      .setNoDelay(true)
      .once(protocol === 'https:' ? 'secureConnect' : 'connect', function () {
        queueMicrotask(clearConnectTimeout);

        if (callback) {
          const cb = callback;
          callback = null;
          cb(null, this);
        }
      })
      .on('error', function (err) {
        queueMicrotask(clearConnectTimeout);

        if (callback) {
          const cb = callback;
          callback = null;
          cb(err);
        }
      });

    return socket;
  };
}

/**
 * @param {WeakRef<net.Socket>} socketWeakRef
 * @param {object} opts
 * @param {number} opts.timeout
 * @param {string} opts.hostname
 * @param {number} opts.port
 * @returns {() => void}
 */
const setupConnectTimeout =
  process.platform === 'win32' ?
    (socketWeakRef, opts) => {
      if (!opts.timeout) {
        return noop;
      }

      let s1 = null;
      let s2 = null;
      const fastTimer = timers.setFastTimeout(() => {
        // setImmediate is added to make sure that we prioritize socket error events over timeouts
        s1 = setImmediate(() => {
          // Windows needs an extra setImmediate probably due to implementation differences in the socket logic
          s2 = setImmediate(() =>
            onConnectTimeout(socketWeakRef.deref(), opts)
          );
        });
      }, opts.timeout);
      return () => {
        timers.clearFastTimeout(fastTimer);
        clearImmediate(s1);
        clearImmediate(s2);
      };
    }
  : (socketWeakRef, opts) => {
      if (!opts.timeout) {
        return noop;
      }

      let s1 = null;
      const fastTimer = timers.setFastTimeout(() => {
        // setImmediate is added to make sure that we prioritize socket error events over timeouts
        s1 = setImmediate(() => {
          onConnectTimeout(socketWeakRef.deref(), opts);
        });
      }, opts.timeout);
      return () => {
        timers.clearFastTimeout(fastTimer);
        clearImmediate(s1);
      };
    };

/**
 * @param {net.Socket} socket
 * @param {object} opts
 * @param {number} opts.timeout
 * @param {string} opts.hostname
 * @param {number} opts.port
 */
function onConnectTimeout(socket, opts) {
  // The socket could be already garbage collected
  if (socket == null) {
    return;
  }

  let message = 'Connect Timeout Error';
  if (Array.isArray(socket.autoSelectFamilyAttemptedAddresses)) {
    message += ` (attempted addresses: ${socket.autoSelectFamilyAttemptedAddresses.join(', ')},`;
  } else {
    message += ` (attempted address: ${opts.hostname}:${opts.port},`;
  }

  message += ` timeout: ${opts.timeout}ms)`;

  util.destroy(socket, new ConnectTimeoutError(message));
}

module.exports = buildConnector;