/*
	Copyright NetFoundry, Inc.

	Licensed 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

	https://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 handler_ctrl

import (
	"time"

	"github.com/michaelquigley/pfxlog"
	"github.com/openziti/channel"
	"github.com/openziti/channel/latency"
	"github.com/openziti/fabric/controller/network"
	"github.com/openziti/fabric/controller/xctrl"
	metrics2 "github.com/openziti/fabric/router/metrics"
	"github.com/openziti/fabric/trace"
	"github.com/openziti/foundation/metrics"
	"github.com/openziti/foundation/util/concurrenz"
)

type bindHandler struct {
	router  *network.Router
	network *network.Network
	xctrls  []xctrl.Xctrl
}

func newBindHandler(router *network.Router, network *network.Network, xctrls []xctrl.Xctrl) channel.BindHandler {
	return &bindHandler{router: router, network: network, xctrls: xctrls}
}

func (self *bindHandler) BindChannel(binding channel.Binding) error {
	log := pfxlog.Logger().WithFields(map[string]interface{}{
		"routerId":      self.router.Id,
		"routerVersion": self.router.VersionInfo.Version,
	})

	traceDispatchWrapper := trace.NewDispatchWrapper(self.network.GetEventDispatcher().Dispatch)
	binding.AddTypedReceiveHandler(newCircuitRequestHandler(self.router, self.network))
	binding.AddTypedReceiveHandler(newRouteResultHandler(self.network, self.router))
	binding.AddTypedReceiveHandler(newCircuitConfirmationHandler(self.network, self.router))
	binding.AddTypedReceiveHandler(newCreateTerminatorHandler(self.network, self.router))
	binding.AddTypedReceiveHandler(newRemoveTerminatorHandler(self.network))
	binding.AddTypedReceiveHandler(newUpdateTerminatorHandler(self.network))
	binding.AddTypedReceiveHandler(newLinkConnectedHandler(self.router, self.network))
	binding.AddTypedReceiveHandler(newRouterLinkHandler(self.router, self.network))
	binding.AddTypedReceiveHandler(newVerifyLinkHandler(self.router, self.network))
	binding.AddTypedReceiveHandler(newFaultHandler(self.router, self.network))
	binding.AddTypedReceiveHandler(newMetricsHandler(self.network))
	binding.AddTypedReceiveHandler(newTraceHandler(traceDispatchWrapper))
	binding.AddTypedReceiveHandler(newInspectHandler(self.network))
	binding.AddTypedReceiveHandler(newPingHandler())
	binding.AddPeekHandler(trace.NewChannelPeekHandler(self.network.GetAppId(), binding.GetChannel(), self.network.GetTraceController(), traceDispatchWrapper))
	binding.AddPeekHandler(metrics2.NewCtrlChannelPeekHandler(self.router.Id, self.network.GetMetricsRegistry()))

	doHeartbeat := self.router.VersionInfo.HasMinimumVersion("0.25.5")

	roundTripHistogram := self.network.GetMetricsRegistry().Histogram("ctrl.latency:" + self.router.Id)
	queueTimeHistogram := self.network.GetMetricsRegistry().Histogram("ctrl.queue_time:" + self.router.Id)
	binding.AddCloseHandler(channel.CloseHandlerF(func(ch channel.Channel) {
		roundTripHistogram.Dispose()
		queueTimeHistogram.Dispose()
	}))

	if doHeartbeat {
		log.Info("router supports heartbeats")
		cb := &heartbeatCallback{
			latencyMetric:    roundTripHistogram,
			queueTimeMetric:  queueTimeHistogram,
			ch:               binding.GetChannel(),
			latencySemaphore: concurrenz.NewSemaphore(2),
		}
		channel.ConfigureHeartbeat(binding, 10*time.Second, time.Second, cb)
	} else if self.router.VersionInfo.HasMinimumVersion("0.18.7") {
		log.Info("router does not support heartbeats, using latency probe")
		latencyHandler := &ctrlChannelLatencyHandler{
			roundTripHistogram: roundTripHistogram,
			queueTimeHistogram: queueTimeHistogram,
		}
		latency.AddLatencyProbe(binding.GetChannel(), binding, self.network.GetOptions().CtrlChanLatencyInterval/time.Duration(10), 10, latencyHandler.HandleLatency)
	}

	xctrlDone := make(chan struct{})
	for _, x := range self.xctrls {
		if err := binding.Bind(x); err != nil {
			return err
		}
		if err := x.Run(binding.GetChannel(), self.network.GetDb(), xctrlDone); err != nil {
			return err
		}
	}
	if len(self.xctrls) > 0 {
		binding.AddCloseHandler(newXctrlCloseHandler(xctrlDone))
	}

	binding.AddCloseHandler(newCloseHandler(self.router, self.network))
	return nil
}

type ctrlChannelLatencyHandler struct {
	roundTripHistogram metrics.Histogram
	queueTimeHistogram metrics.Histogram
}

func (self *ctrlChannelLatencyHandler) HandleLatency(latencyType latency.Type, elapsed time.Duration) {
	if latencyType == latency.RoundTripType {
		self.roundTripHistogram.Update(elapsed.Nanoseconds())
	} else if latencyType == latency.BeforeSendType {
		self.queueTimeHistogram.Update(elapsed.Nanoseconds())
	}
}

type heartbeatCallback struct {
	latencyMetric    metrics.Histogram
	queueTimeMetric  metrics.Histogram
	firstSent        int64
	lastResponse     int64
	ch               channel.Channel
	latencySemaphore concurrenz.Semaphore
}

func (self *heartbeatCallback) HeartbeatTx(int64) {
	if self.firstSent == 0 {
		self.firstSent = time.Now().UnixMilli()
	}
}

func (self *heartbeatCallback) HeartbeatRx(int64) {}

func (self *heartbeatCallback) HeartbeatRespTx(int64) {}

func (self *heartbeatCallback) HeartbeatRespRx(ts int64) {
	now := time.Now()
	self.lastResponse = now.UnixMilli()
	self.latencyMetric.Update(now.UnixNano() - ts)
}

func (self *heartbeatCallback) CheckHeartBeat() {
	log := pfxlog.Logger().WithField("channelId", self.ch.Label())
	now := time.Now().UnixMilli()
	if self.firstSent != 0 && (now-self.firstSent > 30000) && (now-self.lastResponse > 30000) {
		log.Error("heartbeat not received in time, closing link")
		if err := self.ch.Close(); err != nil {
			log.WithError(err).Error("error while closing link")
		}
	}
	go self.checkQueueTime()
}

func (self *heartbeatCallback) checkQueueTime() {
	log := pfxlog.Logger().WithField("bindingId", self.ch.Id().Token)
	if !self.latencySemaphore.TryAcquire() {
		log.Warn("unable to check queue time, too many check already running")
		return
	}

	defer self.latencySemaphore.Release()

	sendTracker := &latency.SendTimeTracker{
		Handler: func(latencyType latency.Type, latency time.Duration) {
			self.queueTimeMetric.Update(latency.Nanoseconds())
		},
		StartTime: time.Now(),
	}
	if err := self.ch.Send(sendTracker); err != nil && !self.ch.IsClosed() {
		log.WithError(err).Error("unable to send queue time tracer")
	}
}