package limit

import (
	"gd_auth_check/apis"
	"gd_auth_check/common.in/cache"
	"gd_auth_check/common.in/config"
	"gd_auth_check/consts"
	"gd_auth_check/errors"
	"strings"
	"sync"
	"time"

	"github.com/astaxie/beego/orm"
	"github.com/go-redis/redis"
)

const (
	reloadScript   = `return redis.call('set', 'KEYS[1]', 1,'ex', ARGV[1], 'NX')`
	reloadInterval = time.Millisecond * 100
	eventKey       = "__keyevent@4__:expired"
)

type rateLimiter struct {
	routerLimiter   map[string]*TokenLimiter
	merchantLimiter map[string]*TokenLimiter
	mu              sync.Mutex
	reload          bool
}

type rateLimit struct {
	AppKey    string `json:"app_key"`
	Router    string `json:"router"`
	RateLimit int    `json:"rate_limit"`
}

var lim rateLimiter

func getRouterKey(router string) string {
	return router
}

func getMerchantKey(appKey, router string) string {
	return appKey + ":" + router
}

func constructLimiter(init bool, reloadAll bool) {
	routerLimiter := make(map[string]*TokenLimiter)
	merchantLimiter := make(map[string]*TokenLimiter)

	var list []rateLimit
	orm.NewOrm().Raw("SELECT router, rate_limit FROM t_gd_api WHERE rate_limit > 0").QueryRows(&list)

	for _, v := range list {
		key := getRouterKey(v.Router)
		if !init && !reloadAll {
			if l, ok := lim.routerLimiter[key]; ok {
				if v.RateLimit != l.burst {
					routerLimiter[key] = NewTokenLimiter(v.RateLimit, redisRouterKeyPre, key, true, cache.Redis)
					continue
				}
			}
		}
		routerLimiter[key] = NewTokenLimiter(v.RateLimit, redisRouterKeyPre, key, reloadAll, cache.Redis)
	}
	lim.routerLimiter = routerLimiter

	orm.NewOrm().Raw(`SELECT
		router,
		t1.rate_limit,
		app_key
	FROM
		t_gd_merchant_child_data_api t1
		LEFT JOIN t_gd_merchant_data_api t2 ON t1.merchant_data_api_id = t2.id
		LEFT JOIN t_gd_merchants t3 ON t2.merchant_id = t3.id
		LEFT JOIN t_gd_api t4 ON t1.api_id = t4.id
	WHERE
		t1.rate_limit > 0`).QueryRows(&list)

	for _, v := range list {
		key := getMerchantKey(v.AppKey, v.Router)
		if !init && !reloadAll {
			if l, ok := lim.merchantLimiter[key]; ok {
				if l.burst != v.RateLimit {
					merchantLimiter[key] = NewTokenLimiter(v.RateLimit, redisMerchantKeyPre, key, true, cache.Redis)
					continue
				}
			}
		}
		merchantLimiter[key] = NewTokenLimiter(v.RateLimit, redisMerchantKeyPre, key, reloadAll, cache.Redis)
	}
	lim.merchantLimiter = merchantLimiter
}

// 初始化限流器
func InitLimiter() {
	constructLimiter(true, false)
	go subscribe()
}

// 重载限流器
func reload(key string) {
	lim.mu.Lock()
	defer lim.mu.Unlock()

	// 重新构建新的限流数据
	if key == pingSuccess {
		constructLimiter(true, true)
	} else {
		constructLimiter(false, false)
	}

	if lim.reload {
		// 正在重载
		// 使用时间轮，直到上次重载成功以后在继续执行
		ticker := time.NewTicker(reloadInterval)
		defer func() {
			ticker.Stop()
		}()

		for range ticker.C {
			if !lim.reload {
				break
			}
		}
	}

	// 使用分布式锁抢占当前key重载
	resp, err := cache.Redis.Eval(reloadScript, []string{consts.LimiterReload + key}, []string{"10"})
	if err == redis.Nil {
		// 锁抢占失败
		return
	}

	v, ok := resp.(string)
	if !ok || v != "OK" {
		// 锁抢占失败
		return
	}

	lim.reload = true
	defer func() {
		lim.reload = false
	}()

	// 重载，重载时会清空全部已用的token
	for _, v := range lim.routerLimiter {
		if v.update {
			v.Reload()
		}
	}

	for _, v := range lim.merchantLimiter {
		if v.update {
			v.Reload()
		}
	}
}

// 消息订阅
func subscribe() {
	pubsub := cache.Redis.Subscribe(config.Conf.RateLimit.RateLimitChannel)
	defer pubsub.Close()

	for msg := range pubsub.Channel() {
		reload(msg.Payload)
	}
}

func routeLimitAllow(router string) (bool, bool, string) {
	if v, ok := lim.routerLimiter[getRouterKey(router)]; ok {
		allow, token := v.Allow()
		return ok, allow, token
	}

	return false, false, ""
}

func merchantLimitAllow(appKey, router string) (bool, bool, string) {
	if v, ok := lim.merchantLimiter[getMerchantKey(appKey, router)]; ok {
		allow, token := v.Allow()
		return ok, allow, token
	}

	return false, false, ""
}

func Allow(router, appKey string) (error, *apis.RateLimitToken) {
	if exist, allow, rToken := routeLimitAllow(router); exist {
		if allow {
			// 拿到token
			if exist, allow, mToken := merchantLimitAllow(appKey, router); exist {
				if allow {
					// 拿到商户token
					return nil, &apis.RateLimitToken{
						AppKey:        appKey,
						Router:        router,
						RouterToken:   rToken,
						MerchantToken: mToken,
					}
				} else {
					// 释放路由token
					ReleaseRouterLimiterToken(router, rToken)
					return errors.RateLimit, nil
				}
			} else {
				return nil, &apis.RateLimitToken{
					AppKey:        appKey,
					Router:        router,
					RouterToken:   rToken,
					MerchantToken: mToken,
				}
			}
		} else {
			// 报错
			return errors.RateLimit, nil

		}
	} else if exist, allow, mToken := merchantLimitAllow(appKey, router); exist {
		// 判断商户token是否存在
		if allow {
			// 拿到商户token
			return nil, &apis.RateLimitToken{
				AppKey:        appKey,
				Router:        router,
				MerchantToken: mToken,
			}
		} else {
			// throw error
			return errors.RateLimit, nil
		}
	}

	return nil, &apis.RateLimitToken{}
}

func ReleaseRouterLimiterToken(router, token string) {
	if v, ok := lim.routerLimiter[getRouterKey(router)]; ok {
		v.release(token)
	}
}

func ReleaseMerchantLimiterToken(router, appKey, token string) {
	if v, ok := lim.merchantLimiter[getMerchantKey(appKey, router)]; ok {
		v.release(token)
	}
}

func expireEvent() {
	pubsub := cache.Redis.Subscribe(eventKey)
	defer pubsub.Close()

	for msg := range pubsub.Channel() {
		if msg.Channel == eventKey {
			if msg.Payload != "" && strings.Index(msg.Payload, redisUsedTokenKey) == 0 {
				key := strings.Replace(msg.Payload, redisUsedTokenKey, "", 1)
				keyArr := strings.Split(key, ":")
				switch len(keyArr) {
				case 2:
					ReleaseRouterLimiterToken(keyArr[0], keyArr[1])
				case 3:
					ReleaseMerchantLimiterToken(keyArr[1], keyArr[0], keyArr[2])
				}
			}
		}
	}
}