package libbox

import (
	std_bufio "bufio"
	"encoding/binary"
	"net"
	"runtime"
	"time"

	"github.com/sagernet/sing-box/common/conntrack"
	"github.com/sagernet/sing-box/experimental/clashapi"
	E "github.com/sagernet/sing/common/exceptions"
	F "github.com/sagernet/sing/common/format"
	"github.com/sagernet/sing/common/memory"
)

const (
	eventTypeEmpty byte = iota
	eventTypeOpenURL
)

type StatusMessage struct {
	Memory           int64
	Goroutines       int32
	ConnectionsIn    int32
	ConnectionsOut   int32
	TrafficAvailable bool
	Uplink           int64
	Downlink         int64
	UplinkTotal      int64
	DownlinkTotal    int64
}

func (s *CommandServer) readStatus() StatusMessage {
	var message StatusMessage
	message.Memory = int64(memory.Inuse())
	message.Goroutines = int32(runtime.NumGoroutine())
	message.ConnectionsOut = int32(conntrack.Count())

	if s.service != nil {
		if clashServer := s.service.instance.Router().ClashServer(); clashServer != nil {
			message.TrafficAvailable = true
			trafficManager := clashServer.(*clashapi.Server).TrafficManager()
			message.Uplink, message.Downlink = trafficManager.Now()
			message.UplinkTotal, message.DownlinkTotal = trafficManager.Total()
			message.ConnectionsIn = int32(trafficManager.ConnectionsLen())
		}
	}

	return message
}

func (s *CommandServer) handleStatusConn(conn net.Conn) error {
	var isMainClient bool
	err := binary.Read(conn, binary.BigEndian, &isMainClient)
	if err != nil {
		return E.Cause(err, "read is main client")
	}
	var interval int64
	err = binary.Read(conn, binary.BigEndian, &interval)
	if err != nil {
		return E.Cause(err, "read interval")
	}
	ticker := time.NewTicker(time.Duration(interval))
	defer ticker.Stop()
	ctx := connKeepAlive(conn)
	writer := std_bufio.NewWriter(conn)
	if isMainClient {
		for {
			writer.WriteByte(eventTypeEmpty)
			err = binary.Write(conn, binary.BigEndian, s.readStatus())
			if err != nil {
				return err
			}
			writer.Flush()
			select {
			case <-ctx.Done():
				return ctx.Err()
			case <-ticker.C:
			case event := <-s.events:
				event.writeTo(writer)
				writer.Flush()
			}
		}
	} else {
		for {
			err = binary.Write(conn, binary.BigEndian, s.readStatus())
			if err != nil {
				return err
			}
			writer.Flush()
			select {
			case <-ctx.Done():
				return ctx.Err()
			case <-ticker.C:
			}
		}
	}
}

func (c *CommandClient) handleStatusConn(conn net.Conn) {
	reader := std_bufio.NewReader(conn)
	for {
		if c.options.IsMainClient {
			rawEvent, err := readEvent(reader)
			if err != nil {
				c.handler.Disconnected(err.Error())
				return
			}
			switch event := rawEvent.(type) {
			case *eventOpenURL:
				c.handler.OpenURL(event.URL)
				continue
			case nil:
			default:
				panic(F.ToString("unexpected event type: ", event))
			}
		}
		var message StatusMessage
		err := binary.Read(reader, binary.BigEndian, &message)
		if err != nil {
			c.handler.Disconnected(err.Error())
			return
		}
		c.handler.WriteStatus(&message)
	}
}