package xboard

import (
	"net"
	"sort"
	"strconv"
	"time"

	"github.com/sagernet/sing-box/adapter"
	"github.com/sagernet/sing-box/service/ssmapi"
	N "github.com/sagernet/sing/common/network"
)

const aliveIPRetention = 5 * time.Minute

var _ adapter.SSMTracker = (*xboardTracker)(nil)

type xboardTracker struct {
	service *Service
	traffic *ssmapi.TrafficManager
}

func newXboardTracker(service *Service) *xboardTracker {
	return &xboardTracker{
		service: service,
		traffic: ssmapi.NewTrafficManager(),
	}
}

func (t *xboardTracker) TrafficManager() *ssmapi.TrafficManager {
	return t.traffic
}

func (t *xboardTracker) TrackConnection(conn net.Conn, metadata adapter.InboundContext) net.Conn {
	t.service.recordAliveIP(metadata)
	return t.traffic.TrackConnection(conn, metadata)
}

func (t *xboardTracker) TrackPacketConnection(conn N.PacketConn, metadata adapter.InboundContext) N.PacketConn {
	t.service.recordAliveIP(metadata)
	return t.traffic.TrackPacketConnection(conn, metadata)
}

func (s *Service) recordAliveIP(metadata adapter.InboundContext) {
	if metadata.User == "" || !metadata.Source.IsValid() || !metadata.Source.Addr.IsValid() {
		return
	}

	clientIP := metadata.Source.Addr.Unmap().String()
	if clientIP == "" {
		return
	}

	s.access.Lock()
	defer s.access.Unlock()

	ipSet, exists := s.aliveUsers[metadata.User]
	if !exists {
		ipSet = make(map[string]time.Time)
		s.aliveUsers[metadata.User] = ipSet
	}
	ipSet[clientIP] = time.Now()
}

func (s *Service) buildAlivePayload() map[string][]string {
	now := time.Now()

	s.access.Lock()
	defer s.access.Unlock()

	payload := make(map[string][]string)
	for userName, ipSet := range s.aliveUsers {
		userMeta, exists := s.localUsers[userName]
		if !exists || userMeta.ID == 0 {
			delete(s.aliveUsers, userName)
			continue
		}

		activeIPs := make([]string, 0, len(ipSet))
		for ip, lastSeen := range ipSet {
			if now.Sub(lastSeen) > aliveIPRetention {
				delete(ipSet, ip)
				continue
			}
			activeIPs = append(activeIPs, ip)
		}
		if len(ipSet) == 0 {
			delete(s.aliveUsers, userName)
		}
		if len(activeIPs) == 0 {
			continue
		}

		sort.Strings(activeIPs)
		payload[strconv.Itoa(userMeta.ID)] = activeIPs
	}

	return payload
}