/*
 *  Copyright (c) 2021 Neil Alexander
 *
 *  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 imapserver

import (
	"log"
	"net"
	"time"

	idle "github.com/emersion/go-imap-idle"
	move "github.com/emersion/go-imap-move"
	"github.com/emersion/go-imap/server"
	"github.com/emersion/go-sasl"
)

type IMAPServer struct {
	server  *server.Server
	backend *Backend
}

type tcpNoDelayListener struct {
	net.Listener
}

func (l *tcpNoDelayListener) Accept() (net.Conn, error) {
	conn, err := l.Listener.Accept()
	if err != nil {
		return nil, err
	}
	if tcpConn, ok := conn.(*net.TCPConn); ok {
		tcpConn.SetNoDelay(true)
		tcpConn.SetKeepAlive(true)
		tcpConn.SetKeepAlivePeriod(time.Second * 5)
	}
	return conn, nil
}

func NewIMAPServer(backend *Backend, addr string, insecure bool) (*IMAPServer, error) {

	s := &IMAPServer{
		server:  server.New(backend),
		backend: backend,
	}

	s.server.Addr = addr
	s.server.AllowInsecureAuth = insecure

	// s.server.Debug = func() io.Writer {
	// 	return log.New(os.Stdout, "IMAP :", log.Default().Flags()).Writer()
	// }()
	s.server.Enable(idle.NewExtension())
	s.server.Enable(move.NewExtension())
	s.server.EnableAuth(sasl.Login, func(conn server.Conn) sasl.Server {
		return sasl.NewLoginServer(func(username, password string) error {
			_, err := s.backend.Login(nil, username, password)
			return err
		})
	})
	// go func() {
	// 	if err := s.server.ListenAndServe(); err != nil {
	// 		log.Fatal(err)
	// 	}
	// }()
	go func() {
		l, err := net.Listen("tcp", s.server.Addr)
		if err != nil {
			log.Fatal(err)
		}

		// Оборачиваем листенер в наш тюнингованный вариант
		if err := s.server.Serve(&tcpNoDelayListener{l}); err != nil {
			log.Fatal(err)
		}
	}()
	return s, nil
}