package tpapi

import (
	"context"
	"fmt"
	"sync"
	"time"
)

type ThirdPartyApiServiceState uint32

const (
	// 服务未启动
	ThirdPartyState_Closed ThirdPartyApiServiceState = iota
	// 服务正常
	ThirdPartyState_Normal
	// 服务异常
	ThirdPartyState_Broken
)

// 第三方对接接口服务
type ThirdPartyApiService interface {
	Name() string
	// 服务状态
	State() ThirdPartyApiServiceState
}

// func NewThirdPartyApiService() ThirdPartyApiService {
// 	return &thirdPartyApiService{
// 		state: ThirdPartyState_Closed,
// 	}
// }

// type thirdPartyApiService struct {
// 	state ThirdPartyApiServiceState
// }

// func (s *thirdPartyApiService) UpdateState(state ThirdPartyApiServiceState) {
// 	s.state = state
// }

// func (s *thirdPartyApiService) State() ThirdPartyApiServiceState {
// 	return s.state
// }

// UDP通信延时记录
type UdpDelayRecorder struct {
	mu sync.Mutex

	// 接收消息间隔，单位毫秒
	interval int
	// 上一次收到消息时刻
	lastReceiedTime int64
	// 近期收到消息时间间隔
	intervals []int64
	// 是否发生异常
	err error
	// 长时间未收到消息或恢复处理回调
	handler func(err error)

	cancelFunc context.CancelFunc
	done       chan struct{} // 服务协程退出信号
}

func NewUdpDelayRecorder(interval int, handler func(err error)) *UdpDelayRecorder {
	return &UdpDelayRecorder{
		interval:        interval,
		lastReceiedTime: 0,
		handler:         handler,
	}
}

func (r *UdpDelayRecorder) Start() {
	r.mu.Lock()
	defer r.mu.Unlock()
	r.lastReceiedTime = 0
	r.err = nil
	r.done = make(chan struct{})
	ctx, cf := context.WithCancel(context.Background())
	r.cancelFunc = cf
	go r.checkTimeout(ctx)
}

func (r *UdpDelayRecorder) checkTimeout(ctx context.Context) {
	defer close(r.done)
	for {
		select {
		case <-ctx.Done():
			return
		default:
		}
		time.Sleep(time.Millisecond * time.Duration(r.interval*2))
		lastReceiedTime := r.lastReceiedTime
		interval := int(time.Now().UnixMilli() - lastReceiedTime)
		if r.err == nil && interval > calUdpTimeout(r.interval) { // 超时故障回调
			r.err = fmt.Errorf("UDP通信超时未收到消息,可能网络异常")
			if r.handler != nil {
				r.handler(r.err)
			}
		} else if r.err != nil && interval <= r.interval*3 { // 恢复正常回调
			r.err = nil
			if r.handler != nil {
				r.handler(r.err)
			}
		}
	}
}

func (r *UdpDelayRecorder) Stop() {
	r.mu.Lock()
	defer r.mu.Unlock()
	if r.cancelFunc == nil {
		return
	}
	r.cancelFunc()
	<-r.done
	r.lastReceiedTime = 0
	r.err = nil
}

// 记录时间间隔
func (r *UdpDelayRecorder) RecordInterval() {
	r.mu.Lock()
	defer r.mu.Unlock()
	// 记录时间及间隔
	ts := time.Now().UnixMilli()
	if r.lastReceiedTime > 0 {
		r.intervals = append(r.intervals, ts-r.lastReceiedTime)
		if len(r.intervals) > 10 {
			r.intervals = r.intervals[1:]
		}
	}
	r.lastReceiedTime = ts
}

func (r *UdpDelayRecorder) GetIntervals() []int64 {
	return r.intervals
}

func calUdpTimeout(interval int) int {
	if interval <= 50 {
		return interval * 10
	} else {
		return interval * 5
	}
}