package net

import (
	"fmt"
	"net"
	"sync/atomic"
	"time"

	"git.loafle.net/commons/logging-go"
	"git.loafle.net/commons/server-go"
)

type Server interface {
	server.Server
}

func NewServer(serverHandler ServerHandler) Server {
	s := &netServer{}
	s.ServerHandler = serverHandler

	return s
}

type netServer struct {
	server.Servers
}

func (s *netServer) ListenAndServe() error {
	if s.StopChan != nil {
		return fmt.Errorf(s.ServerMessage("already running. Stop it before starting it again"))
	}

	var (
		err      error
		listener net.Listener
	)
	if nil == s.ServerHandler {
		return fmt.Errorf("Server: server handler must be specified")
	}
	if err = s.ServerHandler.Validate(); nil != err {
		return err
	}

	s.ServerCtx = s.ServerHandler.ServerCtx()
	if nil == s.ServerCtx {
		return fmt.Errorf(s.ServerMessage("ServerCtx is nil"))
	}

	if err = s.ServerHandler.Init(s.ServerCtx); nil != err {
		return err
	}

	if listener, err = s.ServerHandler.Listener(s.ServerCtx); nil != err {
		return err
	}

	s.StopChan = make(chan struct{})
	s.StopWg.Add(1)
	return s.handleServer(listener)
}

func (s *netServer) handleServer(listener net.Listener) error {
	var (
		stopping atomic.Value
		netConn  net.Conn
		err      error
	)

	defer func() {
		if nil != listener {
			listener.Close()
		}

		s.ServerHandler.OnStop(s.ServerCtx)

		logging.Logger().Infof(s.ServerMessage("Stopped"))

		s.StopWg.Done()
	}()

	if err = s.ServerHandler.OnStart(s.ServerCtx); nil != err {
		return err
	}

	logging.Logger().Infof(s.ServerMessage("Started"))

	for {
		acceptChan := make(chan struct{})

		go func() {
			if netConn, err = listener.Accept(); err != nil {
				if nil == stopping.Load() {
					logging.Logger().Errorf(s.ServerMessage(fmt.Sprintf("%v", err)))
				}
			}
			close(acceptChan)
		}()

		select {
		case <-s.StopChan:
			stopping.Store(true)
			listener.Close()
			<-acceptChan
			listener = nil
			return nil
		case <-acceptChan:
		}

		if nil != err {
			select {
			case <-s.StopChan:
				return nil
			case <-time.After(time.Second):
			}
			continue
		}

		if 0 < s.ServerHandler.GetConcurrency() {
			sz := s.ConnectionSize()
			if sz >= s.ServerHandler.GetConcurrency() {
				logging.Logger().Warnf(s.ServerMessage(fmt.Sprintf("max connections size %d, refuse", sz)))
				netConn.Close()
				continue
			}
		}

		servlet := s.ServerHandler.(ServerHandler).Servlet()
		if nil == servlet {
			logging.Logger().Errorf(s.ServerMessage("Servlet is nil"))
			continue
		}

		servletCtx := servlet.ServletCtx(s.ServerCtx)
		if nil == servletCtx {
			logging.Logger().Errorf(s.ServerMessage("ServletCtx is nil"))
			continue
		}

		if err := servlet.Handshake(servletCtx, netConn); nil != err {
			logging.Logger().Infof(s.ServerMessage(fmt.Sprintf("Handshaking of Client[%s] has been failed %v", netConn.RemoteAddr(), err)))
			continue
		}

		conn := server.NewConn(netConn, true, s.ServerHandler.GetReadBufferSize(), s.ServerHandler.GetWriteBufferSize())

		s.StopWg.Add(1)
		go s.HandleConnection(servlet, servletCtx, conn)
	}
}