// Copyright (C) 2015 The Syncthing Authors.
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this file,
// You can obtain one at http://mozilla.org/MPL/2.0/.

package connections

import (
	"crypto/tls"
	"net"
	"net/url"
	"strings"

	"github.com/syncthing/syncthing/lib/dialer"
	"github.com/syncthing/syncthing/lib/model"
	"github.com/syncthing/syncthing/lib/osutil"
)

func init() {
	dialers["tcp"] = tcpDialer
	listeners["tcp"] = tcpListener
}

func tcpDialer(uri *url.URL, tlsCfg *tls.Config) (*tls.Conn, error) {
	// Check that there is a port number in uri.Host, otherwise add one.
	host, port, err := net.SplitHostPort(uri.Host)
	if err != nil && strings.HasPrefix(err.Error(), "missing port") {
		// addr is on the form "1.2.3.4"
		uri.Host = net.JoinHostPort(uri.Host, "22000")
	} else if err == nil && port == "" {
		// addr is on the form "1.2.3.4:"
		uri.Host = net.JoinHostPort(host, "22000")
	}

	// Don't try to resolve the address before dialing. The dialer may be a
	// proxy, and we should let the proxy do the resolving in that case.
	conn, err := dialer.Dial("tcp", uri.Host)
	if err != nil {
		l.Debugln(err)
		return nil, err
	}

	tc := tls.Client(conn, tlsCfg)
	err = tc.Handshake()
	if err != nil {
		tc.Close()
		return nil, err
	}

	return tc, nil
}

func tcpListener(uri *url.URL, tlsCfg *tls.Config, conns chan<- model.IntermediateConnection) {
	tcaddr, err := net.ResolveTCPAddr("tcp", uri.Host)
	if err != nil {
		l.Fatalln("listen (BEP/tcp):", err)
		return
	}
	listener, err := net.ListenTCP("tcp", tcaddr)
	if err != nil {
		l.Fatalln("listen (BEP/tcp):", err)
		return
	}

	for {
		conn, err := listener.Accept()
		if err != nil {
			l.Warnln("Accepting connection (BEP/tcp):", err)
			continue
		}

		l.Debugln("connect from", conn.RemoteAddr())

		err = osutil.SetTCPOptions(conn.(*net.TCPConn))
		if err != nil {
			l.Infoln(err)
		}

		tc := tls.Server(conn, tlsCfg)
		err = tc.Handshake()
		if err != nil {
			l.Infoln("TLS handshake (BEP/tcp):", err)
			tc.Close()
			continue
		}

		conns <- model.IntermediateConnection{
			tc, model.ConnectionTypeDirectAccept,
		}
	}
}