package server

import (
	"errors"
	"io"
	"net"
	"time"
)

const (
	// DefaultConcurrency is the default number of concurrent rpc calls
	// the server can process.
	DefaultConcurrency = 8 * 1024

	// DefaultRequestTimeout is the default timeout for client request.
	DefaultRequestTimeout = 20 * time.Second

	// DefaultPendingMessages is the default number of pending messages
	// handled by Client and Server.
	DefaultPendingMessages = 32 * 1024

	// DefaultFlushDelay is the default delay between message flushes
	// on Client and Server.
	DefaultFlushDelay = -1

	// DefaultBufferSize is the default size for Client and Server buffers.
	DefaultBufferSize = 64 * 1024

	// DefaultKeepAlivePeriod is the default time for KeepAlivePeriod of connection.
	DefaultKeepAlivePeriod = 0
)

type ServerHandlers struct {
	// Address to listen to for incoming connections.
	//
	// The address format depends on the underlying transport provided
	// by Server.Listener. The following transports are provided
	// out of the box:
	//   * TCP - see NewTCPServer() and NewTCPClient().
	//   * TLS (aka SSL) - see NewTLSServer() and NewTLSClient().
	//   * Unix sockets - see NewUnixServer() and NewUnixClient().
	//
	// By default TCP transport is used.
	Addr string

	KeepAlivePeriod time.Duration
}

func (sh *ServerHandlers) Listen() (net.Listener, error) {
	return nil, errors.New("Server: Handler method[Listen] of Server is not implement")
}

func (sh *ServerHandlers) Handle(remoteAddr string, rwc io.ReadWriteCloser, stopChan chan struct{}) {

}

func (sh *ServerHandlers) IsClientDisconnect(err error) bool {
	return err == io.ErrUnexpectedEOF || err == io.EOF
}

func (sh *ServerHandlers) OnStopped() {

}

func (sh *ServerHandlers) GetAddr() string {
	return sh.Addr
}

// func (sh *ServerHandlers)  {

// }
// func (sh *ServerHandlers)  {

// }
// func (sh *ServerHandlers)  {

// }
// func (sh *ServerHandlers)  {

// }
// func (sh *ServerHandlers)  {

// }
// func (sh *ServerHandlers)  {

// }
// func (sh *ServerHandlers)  {

// }
// func (sh *ServerHandlers)  {

// }

func (sh *ServerHandlers) accept(l net.Listener) (io.ReadWriteCloser, string, error) {
	conn, err := l.Accept()
	if nil != err {
		return nil, "", err
	}

	if 0 < sh.KeepAlivePeriod {
		if err = setupKeepalive(conn, sh.KeepAlivePeriod); nil != err {
			conn.Close()
			return nil, "", err
		}
	}

	return conn, conn.RemoteAddr().String(), nil
}

func (sh *ServerHandlers) Validate() {
	if sh.KeepAlivePeriod <= 0 {
		sh.KeepAlivePeriod = DefaultKeepAlivePeriod
	}

}

func setupKeepalive(conn net.Conn, keepAlivePeriod time.Duration) error {
	tcpConn, ok := conn.(*net.TCPConn)
	if !ok {
		return errors.New("Server: Keepalive is valid when connection is net.TCPConn")
	}

	if err := tcpConn.SetKeepAlive(true); err != nil {
		return err
	}
	if err := tcpConn.SetKeepAlivePeriod(keepAlivePeriod * time.Second); err != nil {
		return err
	}
	return nil
}