package websocket_fasthttp

import (
	"fmt"
	"net"
	"net/http"
	"sync"

	"git.loafle.net/commons_go/logging"

	"git.loafle.net/commons_go/websocket_fasthttp/websocket"
	"github.com/valyala/fasthttp"
)

type Server interface {
	Start() error
	Stop()

	Context() ServerContext
}

func New(sh ServerHandler) Server {
	s := &server{
		sh: sh,
	}

	return s
}

type server struct {
	ctx ServerContext

	sh ServerHandler

	httpServer *fasthttp.Server
	upgrader   *websocket.Upgrader
	listener   net.Listener

	stopChan chan struct{}
	stopWg   sync.WaitGroup
}

func (s *server) Start() error {
	if nil == s.sh {
		logging.Logger().Panic("Server: server handler must be specified.")
	}
	s.sh.Validate()

	if s.stopChan != nil {
		return fmt.Errorf("Server: server is already running. Stop it before starting it again")
	}

	s.httpServer = &fasthttp.Server{
		Handler:         s.handleRequest,
		Name:            s.sh.GetName(),
		Concurrency:     s.sh.GetConcurrency(),
		ReadBufferSize:  s.sh.GetReadBufferSize(),
		WriteBufferSize: s.sh.GetWriteBufferSize(),
		ReadTimeout:     s.sh.GetReadTimeout(),
		WriteTimeout:    s.sh.GetWriteTimeout(),
	}

	s.upgrader = &websocket.Upgrader{
		HandshakeTimeout:  s.sh.GetHandshakeTimeout(),
		ReadBufferSize:    s.sh.GetReadBufferSize(),
		WriteBufferSize:   s.sh.GetWriteBufferSize(),
		CheckOrigin:       s.sh.CheckOrigin,
		Error:             s.handleError,
		EnableCompression: s.sh.IsEnableCompression(),
	}

	var err error
	s.ctx = s.sh.ServerContext()

	if err = s.sh.Init(s.ctx); nil != err {
		return fmt.Errorf("Server: Initialization of server has been failed %v", err)
	}

	var listener net.Listener
	if listener, err = s.sh.Listen(s.ctx); nil != err {
		return err
	}

	s.listener = newGracefulListener(listener, s.sh.GetMaxStopWaitTime())
	s.stopChan = make(chan struct{})

	s.stopWg.Add(1)
	go handleServer(s)

	return nil
}

func (s *server) Stop() {
	if s.stopChan == nil {
		logging.Logger().Warn("Server: server must be started before stopping it")
		return
	}
	close(s.stopChan)
	s.stopWg.Wait()
	s.stopChan = nil

	s.sh.OnStop(s.ctx)

	logging.Logger().Info(fmt.Sprintf("Server[%s] is stopped", s.sh.GetName()))
}

func (s *server) Context() ServerContext {
	return s.ctx
}

func handleServer(s *server) {

	go func() {
		defer s.stopWg.Done()

		if err := s.httpServer.Serve(s.listener); nil != err {
			logging.Logger().Error(fmt.Sprintf("Server: Server err - %v", err))
		}
	}()

	logging.Logger().Info(fmt.Sprintf("Server[%s] is started", s.sh.GetName()))
	s.sh.OnStart(s.ctx)

	select {
	case <-s.stopChan:
		s.listener.Close()
		return
	}

}

func (s *server) handleRequest(ctx *fasthttp.RequestCtx) {
	path := string(ctx.Path())
	var socketHandler SocketHandler
	var err error

	if socketHandler, err = s.sh.GetSocketHandler(path); nil != err {
		s.handleError(ctx, fasthttp.StatusNotFound, err)
		return
	}
	var responseHeader *fasthttp.ResponseHeader
	var socketID string
	socketCTX := socketHandler.SocketContext(s.ctx)

	if socketID, responseHeader = socketHandler.Handshake(socketCTX, ctx); "" == socketID {
		s.handleError(ctx, http.StatusNotAcceptable, fmt.Errorf("Server: Handshake err"))
		return
	}

	s.upgrader.Upgrade(ctx, responseHeader, func(conn *websocket.Conn, err error) {
		if err != nil {
			s.handleError(ctx, fasthttp.StatusInternalServerError, err)
			return
		}

		soc := newSocket(socketHandler, socketCTX, conn, socketID)
		logging.Logger().Debug(fmt.Sprintf("Server: Client[%s] is connected.", soc.RemoteAddr()))

		socketHandler.addSocket(soc)
		socketHandler.OnConnect(soc)

		s.stopWg.Add(1)
		handleConnection(s, soc, socketHandler)
	})
}

func (s *server) handleError(ctx *fasthttp.RequestCtx, status int, reason error) {
	ctx.Response.Header.Set("Sec-Websocket-Version", "13")
	ctx.Error(http.StatusText(status), status)

	s.sh.OnError(s.ctx, ctx, status, reason)
}

func handleConnection(s *server, soc Socket, socketHandler SocketHandler) {
	defer s.stopWg.Done()

	clientStopChan := make(chan struct{})
	handleDoneChan := make(chan error, 1)

	go socketHandler.Handle(soc, clientStopChan, handleDoneChan)

	select {
	case <-s.stopChan:
		close(clientStopChan)
		<-handleDoneChan
	case <-handleDoneChan:
		close(clientStopChan)
		socketHandler.OnDisconnect(soc)
		logging.Logger().Debug(fmt.Sprintf("Server: Client[%s] is disconnected.", soc.RemoteAddr()))
		socketHandler.removeSocket(soc)
		soc.Close()
	}
}