/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package protocol

import (
	"sync"
	"sync/atomic"
	"time"
)

import (
	uberAtomic "go.uber.org/atomic"
)

import (
	"dubbo.apache.org/dubbo-go/v3/common"
	"dubbo.apache.org/dubbo-go/v3/common/constant"
	"dubbo.apache.org/dubbo-go/v3/common/logger"
)

var (
	methodStatistics    sync.Map        // url -> { methodName : RPCStatus}
	serviceStatistic    sync.Map        // url -> RPCStatus
	invokerBlackList    sync.Map        // store unhealthy url blackList
	blackListCacheDirty uberAtomic.Bool // store if the cache in chain is not refreshed by blacklist
	blackListRefreshing int32           // store if the refresing method is processing
)

func init() {
	blackListCacheDirty.Store(false)
}

// RPCStatus is URL statistics.
type RPCStatus struct {
	active                        int32
	failed                        int32
	total                         int32
	totalElapsed                  int64
	failedElapsed                 int64
	maxElapsed                    int64
	failedMaxElapsed              int64
	succeededMaxElapsed           int64
	successiveRequestFailureCount int32
	lastRequestFailedTimestamp    int64
}

// GetActive gets active.
func (rpc *RPCStatus) GetActive() int32 {
	return atomic.LoadInt32(&rpc.active)
}

// GetFailed gets failed.
func (rpc *RPCStatus) GetFailed() int32 {
	return atomic.LoadInt32(&rpc.failed)
}

// GetTotal gets total.
func (rpc *RPCStatus) GetTotal() int32 {
	return atomic.LoadInt32(&rpc.total)
}

// GetTotalElapsed gets total elapsed.
func (rpc *RPCStatus) GetTotalElapsed() int64 {
	return atomic.LoadInt64(&rpc.totalElapsed)
}

// GetFailedElapsed gets failed elapsed.
func (rpc *RPCStatus) GetFailedElapsed() int64 {
	return atomic.LoadInt64(&rpc.failedElapsed)
}

// GetMaxElapsed gets max elapsed.
func (rpc *RPCStatus) GetMaxElapsed() int64 {
	return atomic.LoadInt64(&rpc.maxElapsed)
}

// GetFailedMaxElapsed gets failed max elapsed.
func (rpc *RPCStatus) GetFailedMaxElapsed() int64 {
	return atomic.LoadInt64(&rpc.failedMaxElapsed)
}

// GetSucceededMaxElapsed gets succeeded max elapsed.
func (rpc *RPCStatus) GetSucceededMaxElapsed() int64 {
	return atomic.LoadInt64(&rpc.succeededMaxElapsed)
}

// GetLastRequestFailedTimestamp gets last request failed timestamp.
func (rpc *RPCStatus) GetLastRequestFailedTimestamp() int64 {
	return atomic.LoadInt64(&rpc.lastRequestFailedTimestamp)
}

// GetSuccessiveRequestFailureCount gets successive request failure count.
func (rpc *RPCStatus) GetSuccessiveRequestFailureCount() int32 {
	return atomic.LoadInt32(&rpc.successiveRequestFailureCount)
}

// GetURLStatus get URL RPC status.
func GetURLStatus(url *common.URL) *RPCStatus {
	rpcStatus, found := serviceStatistic.Load(url.Key())
	if !found {
		rpcStatus, _ = serviceStatistic.LoadOrStore(url.Key(), &RPCStatus{})
	}
	return rpcStatus.(*RPCStatus)
}

// GetMethodStatus get method RPC status.
func GetMethodStatus(url *common.URL, methodName string) *RPCStatus {
	identifier := url.Key()
	methodMap, found := methodStatistics.Load(identifier)
	if !found {
		methodMap, _ = methodStatistics.LoadOrStore(identifier, &sync.Map{})
	}

	methodActive := methodMap.(*sync.Map)
	rpcStatus, found := methodActive.Load(methodName)
	if !found {
		rpcStatus, _ = methodActive.LoadOrStore(methodName, &RPCStatus{})
	}

	status := rpcStatus.(*RPCStatus)
	return status
}

// BeginCount gets begin count.
func BeginCount(url *common.URL, methodName string) {
	beginCount0(GetURLStatus(url))
	beginCount0(GetMethodStatus(url, methodName))
}

// EndCount gets end count.
func EndCount(url *common.URL, methodName string, elapsed int64, succeeded bool) {
	endCount0(GetURLStatus(url), elapsed, succeeded)
	endCount0(GetMethodStatus(url, methodName), elapsed, succeeded)
}

// private methods
func beginCount0(rpcStatus *RPCStatus) {
	atomic.AddInt32(&rpcStatus.active, 1)
}

func endCount0(rpcStatus *RPCStatus, elapsed int64, succeeded bool) {
	atomic.AddInt32(&rpcStatus.active, -1)
	atomic.AddInt32(&rpcStatus.total, 1)
	atomic.AddInt64(&rpcStatus.totalElapsed, elapsed)

	if rpcStatus.maxElapsed < elapsed {
		atomic.StoreInt64(&rpcStatus.maxElapsed, elapsed)
	}
	if succeeded {
		if rpcStatus.succeededMaxElapsed < elapsed {
			atomic.StoreInt64(&rpcStatus.succeededMaxElapsed, elapsed)
		}
		atomic.StoreInt32(&rpcStatus.successiveRequestFailureCount, 0)
	} else {
		atomic.StoreInt64(&rpcStatus.lastRequestFailedTimestamp, CurrentTimeMillis())
		atomic.AddInt32(&rpcStatus.successiveRequestFailureCount, 1)
		atomic.AddInt32(&rpcStatus.failed, 1)
		atomic.AddInt64(&rpcStatus.failedElapsed, elapsed)
		if rpcStatus.failedMaxElapsed < elapsed {
			atomic.StoreInt64(&rpcStatus.failedMaxElapsed, elapsed)
		}
	}
}

// CurrentTimeMillis get current timestamp
func CurrentTimeMillis() int64 {
	return time.Now().UnixNano() / int64(time.Millisecond)
}

// Destroy is used to clean all status
func CleanAllStatus() {
	delete1 := func(key, _ interface{}) bool {
		methodStatistics.Delete(key)
		return true
	}
	methodStatistics.Range(delete1)
	delete2 := func(key, _ interface{}) bool {
		serviceStatistic.Delete(key)
		return true
	}
	serviceStatistic.Range(delete2)
	delete3 := func(key, _ interface{}) bool {
		invokerBlackList.Delete(key)
		return true
	}
	invokerBlackList.Range(delete3)
}

// GetInvokerHealthyStatus get invoker's conn healthy status
func GetInvokerHealthyStatus(invoker Invoker) bool {
	_, found := invokerBlackList.Load(invoker.GetURL().Key())
	return !found
}

// SetInvokerUnhealthyStatus add target invoker to black list
func SetInvokerUnhealthyStatus(invoker Invoker) {
	invokerBlackList.Store(invoker.GetURL().Key(), invoker)
	logger.Info("Add invoker ip = ", invoker.GetURL().Location, " to black list")
	blackListCacheDirty.Store(true)
}

// RemoveInvokerUnhealthyStatus remove unhealthy status of target invoker from blacklist
func RemoveInvokerUnhealthyStatus(invoker Invoker) {
	invokerBlackList.Delete(invoker.GetURL().Key())
	logger.Info("Remove invoker ip = ", invoker.GetURL().Location, " from black list")
	blackListCacheDirty.Store(true)
}

// GetBlackListInvokers get at most size of blockSize invokers from black list
func GetBlackListInvokers(blockSize int) []Invoker {
	resultIvks := make([]Invoker, 0, 16)
	invokerBlackList.Range(func(k, v interface{}) bool {
		resultIvks = append(resultIvks, v.(Invoker))
		return true
	})
	if blockSize > len(resultIvks) {
		return resultIvks
	}
	return resultIvks[:blockSize]
}

// RemoveUrlKeyUnhealthyStatus called when event of provider unregister, delete from black list
func RemoveUrlKeyUnhealthyStatus(key string) {
	invokerBlackList.Delete(key)
	logger.Info("Remove invoker key = ", key, " from black list")
	blackListCacheDirty.Store(true)
}

func GetAndRefreshState() bool {
	state := blackListCacheDirty.Load()
	blackListCacheDirty.Store(false)
	return state
}

// TryRefreshBlackList start 3 gr to check at most block=16 invokers in black list
// if target invoker is available, then remove it from black list
func TryRefreshBlackList() {
	if atomic.CompareAndSwapInt32(&blackListRefreshing, 0, 1) {
		wg := sync.WaitGroup{}
		defer func() {
			atomic.CompareAndSwapInt32(&blackListRefreshing, 1, 0)
		}()

		ivks := GetBlackListInvokers(constant.DEFAULT_BLACK_LIST_RECOVER_BLOCK)
		logger.Debug("blackList len = ", len(ivks))

		for i := 0; i < 3; i++ {
			wg.Add(1)
			go func(ivks []Invoker, i int) {
				defer wg.Done()
				for j := range ivks {
					if j%3-i == 0 && ivks[j].(Invoker).IsAvailable() {
						RemoveInvokerUnhealthyStatus(ivks[i])
					}
				}
			}(ivks, i)
		}
		wg.Wait()
	}
}