/*
 * Copyright 2018-present Open Networking Foundation

 * 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

 * 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 devices

import (
	"context"
	"errors"
	"fmt"
	"github.com/google/gopacket"
	"github.com/google/gopacket/layers"
	"github.com/looplab/fsm"
	bbsim "github.com/opencord/bbsim/internal/bbsim/types"
	"github.com/opencord/voltha-protos/go/openolt"
	"github.com/opencord/voltha-protos/go/tech_profile"
	log "github.com/sirupsen/logrus"
	"google.golang.org/grpc"
	"net"
	"sync"
)

var oltLogger = log.WithFields(log.Fields{
	"module": "OLT",
})

func init() {
	//log.SetReportCaller(true)
	log.SetLevel(log.DebugLevel)
}

var olt = OltDevice{}

func GetOLT() OltDevice {
	return olt
}

func CreateOLT(seq int, nni int, pon int, onuPerPon int, sTag int, cTagInit int, oltDoneChannel *chan bool, apiDoneChannel *chan bool, group *sync.WaitGroup) OltDevice {
	oltLogger.WithFields(log.Fields{
		"ID":           seq,
		"NumNni":       nni,
		"NumPon":       pon,
		"NumOnuPerPon": onuPerPon,
	}).Debug("CreateOLT")

	olt = OltDevice{
		ID:           seq,
		SerialNumber: fmt.Sprintf("BBSIM_OLT_%d", seq),
		OperState: getOperStateFSM(func(e *fsm.Event) {
			oltLogger.Debugf("Changing OLT OperState from %s to %s", e.Src, e.Dst)
		}),
		NumNni:          nni,
		NumPon:          pon,
		NumOnuPerPon:    onuPerPon,
		Pons:            []PonPort{},
		Nnis:            []NniPort{},
		channel:         make(chan Message),
		oltDoneChannel:  oltDoneChannel,
		apiDoneChannel:  apiDoneChannel,
		nniPktInChannel: make(chan *bbsim.PacketMsg, 1024), // packets coming in from the NNI and going to VOLTHA
	}

	// OLT State machine
	// NOTE do we need 2 state machines for the OLT? (InternalState and OperState)
	olt.InternalState = fsm.NewFSM(
		"created",
		fsm.Events{
			{Name: "enable", Src: []string{"created"}, Dst: "enabled"},
			{Name: "disable", Src: []string{"enabled"}, Dst: "disabled"},
		},
		fsm.Callbacks{
			"enter_state": func(e *fsm.Event) {
				oltLogger.Debugf("Changing OLT InternalState from %s to %s", e.Src, e.Dst)
			},
		},
	)

	// create NNI Port
	nniPort, err := CreateNNI(&olt)

	if err != nil {
		oltLogger.Fatalf("Couldn't create NNI Port: %v", err)
	}

	olt.Nnis = append(olt.Nnis, nniPort)

	// create PON ports
	availableCTag := cTagInit
	for i := 0; i < pon; i++ {
		p := PonPort{
			NumOnu: olt.NumOnuPerPon,
			ID:     uint32(i),
			Type:   "pon",
			Olt:    olt,
		}
		p.OperState = getOperStateFSM(func(e *fsm.Event) {
			oltLogger.WithFields(log.Fields{
				"ID": p.ID,
			}).Debugf("Changing PON Port OperState from %s to %s", e.Src, e.Dst)
		})

		// create ONU devices
		for j := 0; j < onuPerPon; j++ {
			//o := CreateONU(olt, p, uint32(onuId))
			o := CreateONU(olt, p, uint32(j+1), sTag, availableCTag)
			p.Onus = append(p.Onus, o)
			availableCTag = availableCTag + 1
		}

		olt.Pons = append(olt.Pons, p)
	}

	newOltServer(olt)

	group.Done()
	return olt
}

func newOltServer(o OltDevice) error {
	// TODO make configurable
	address := "0.0.0.0:50060"
	lis, err := net.Listen("tcp", address)
	if err != nil {
		oltLogger.Fatalf("OLT failed to listen: %v", err)
	}
	grpcServer := grpc.NewServer()
	openolt.RegisterOpenoltServer(grpcServer, o)

	wg := sync.WaitGroup{}
	wg.Add(1)

	go grpcServer.Serve(lis)
	oltLogger.Debugf("OLT Listening on: %v", address)

	for {
		_, ok := <-*o.oltDoneChannel
		if !ok {
			// if the olt Channel is closed, stop the gRPC server
			log.Warnf("Stopping OLT gRPC server")
			grpcServer.Stop()
			wg.Done()
			break
		}
	}

	wg.Wait()

	return nil
}

// Device Methods

func (o OltDevice) Enable(stream openolt.Openolt_EnableIndicationServer) error {

	oltLogger.Debug("Enable OLT called")

	wg := sync.WaitGroup{}
	wg.Add(2)

	// create a Channel for all the OLT events
	go o.processOltMessages(stream)
	go o.processNniPacketIns(stream)

	// enable the OLT
	olt_msg := Message{
		Type: OltIndication,
		Data: OltIndicationMessage{
			OperState: UP,
		},
	}
	o.channel <- olt_msg

	// send NNI Port Indications
	for _, nni := range o.Nnis {
		msg := Message{
			Type: NniIndication,
			Data: NniIndicationMessage{
				OperState: UP,
				NniPortID: nni.ID,
			},
		}
		o.channel <- msg
	}

	// send PON Port indications
	for _, pon := range o.Pons {
		msg := Message{
			Type: PonIndication,
			Data: PonIndicationMessage{
				OperState: UP,
				PonPortID: pon.ID,
			},
		}
		o.channel <- msg

		for _, onu := range pon.Onus {
			go onu.processOnuMessages(stream)
			go onu.processOmciMessages(stream)
			// FIXME move the message generation in the state transition
			// from here only invoke the state transition
			msg := Message{
				Type: OnuDiscIndication,
				Data: OnuDiscIndicationMessage{
					Onu:       onu,
					OperState: UP,
				},
			}
			onu.Channel <- msg
		}
	}

	wg.Wait()
	return nil
}

// Helpers method

func (o OltDevice) getPonById(id uint32) (*PonPort, error) {
	for _, pon := range o.Pons {
		if pon.ID == id {
			return &pon, nil
		}
	}
	return nil, errors.New(fmt.Sprintf("Cannot find PonPort with id %d in OLT %d", id, o.ID))
}

func (o OltDevice) getNniById(id uint32) (*NniPort, error) {
	for _, nni := range o.Nnis {
		if nni.ID == id {
			return &nni, nil
		}
	}
	return nil, errors.New(fmt.Sprintf("Cannot find NniPort with id %d in OLT %d", id, o.ID))
}

func (o OltDevice) sendOltIndication(msg OltIndicationMessage, stream openolt.Openolt_EnableIndicationServer) {
	data := &openolt.Indication_OltInd{OltInd: &openolt.OltIndication{OperState: msg.OperState.String()}}
	if err := stream.Send(&openolt.Indication{Data: data}); err != nil {
		oltLogger.Errorf("Failed to send Indication_OltInd: %v", err)
	}

	oltLogger.WithFields(log.Fields{
		"OperState": msg.OperState,
	}).Debug("Sent Indication_OltInd")
}

func (o OltDevice) sendNniIndication(msg NniIndicationMessage, stream openolt.Openolt_EnableIndicationServer) {
	nni, _ := o.getNniById(msg.NniPortID)
	nni.OperState.Event("enable")
	// NOTE Operstate may need to be an integer
	operData := &openolt.Indication_IntfOperInd{IntfOperInd: &openolt.IntfOperIndication{
		Type:      nni.Type,
		IntfId:    nni.ID,
		OperState: nni.OperState.Current(),
	}}

	if err := stream.Send(&openolt.Indication{Data: operData}); err != nil {
		oltLogger.Errorf("Failed to send Indication_IntfOperInd for NNI: %v", err)
	}

	oltLogger.WithFields(log.Fields{
		"Type":      nni.Type,
		"IntfId":    nni.ID,
		"OperState": nni.OperState.Current(),
	}).Debug("Sent Indication_IntfOperInd for NNI")
}

func (o OltDevice) sendPonIndication(msg PonIndicationMessage, stream openolt.Openolt_EnableIndicationServer) {
	pon, _ := o.getPonById(msg.PonPortID)
	pon.OperState.Event("enable")
	discoverData := &openolt.Indication_IntfInd{IntfInd: &openolt.IntfIndication{
		IntfId:    pon.ID,
		OperState: pon.OperState.Current(),
	}}

	if err := stream.Send(&openolt.Indication{Data: discoverData}); err != nil {
		oltLogger.Errorf("Failed to send Indication_IntfInd: %v", err)
	}

	oltLogger.WithFields(log.Fields{
		"IntfId":    pon.ID,
		"OperState": pon.OperState.Current(),
	}).Debug("Sent Indication_IntfInd")

	operData := &openolt.Indication_IntfOperInd{IntfOperInd: &openolt.IntfOperIndication{
		Type:      pon.Type,
		IntfId:    pon.ID,
		OperState: pon.OperState.Current(),
	}}

	if err := stream.Send(&openolt.Indication{Data: operData}); err != nil {
		oltLogger.Errorf("Failed to send Indication_IntfOperInd for PON: %v", err)
	}

	oltLogger.WithFields(log.Fields{
		"Type":      pon.Type,
		"IntfId":    pon.ID,
		"OperState": pon.OperState.Current(),
	}).Debug("Sent Indication_IntfOperInd for PON")
}

func (o OltDevice) processOltMessages(stream openolt.Openolt_EnableIndicationServer) {
	oltLogger.Debug("Started OLT Indication Channel")
	for message := range o.channel {

		oltLogger.WithFields(log.Fields{
			"oltId":       o.ID,
			"messageType": message.Type,
		}).Trace("Received message")

		switch message.Type {
		case OltIndication:
			msg, _ := message.Data.(OltIndicationMessage)
			if msg.OperState == UP {
				o.InternalState.Event("enable")
				o.OperState.Event("enable")
			} else if msg.OperState == DOWN {
				o.InternalState.Event("disable")
				o.OperState.Event("disable")
			}
			o.sendOltIndication(msg, stream)
		case NniIndication:
			msg, _ := message.Data.(NniIndicationMessage)
			o.sendNniIndication(msg, stream)
		case PonIndication:
			msg, _ := message.Data.(PonIndicationMessage)
			o.sendPonIndication(msg, stream)
		default:
			oltLogger.Warnf("Received unknown message data %v for type %v in OLT Channel", message.Data, message.Type)
		}

	}
}

func (o OltDevice) processNniPacketIns(stream openolt.Openolt_EnableIndicationServer) {
	oltLogger.WithFields(log.Fields{
		"nniChannel": o.nniPktInChannel,
	}).Debug("Started NNI Channel")
	nniId := o.Nnis[0].ID // FIXME we are assuming we have only one NNI
	for message := range o.nniPktInChannel {
		oltLogger.Debug("Received packets on NNI Channel")
		data := &openolt.Indication_PktInd{PktInd: &openolt.PacketIndication{
			IntfType: "nni",
			IntfId:   nniId,
			Pkt:      message.Pkt.Data()}}
		if err := stream.Send(&openolt.Indication{Data: data}); err != nil {
			oltLogger.WithFields(log.Fields{
				"IntfType": data.PktInd.IntfType,
				"IntfId":   nniId,
				"Pkt":      message.Pkt.Data(),
			}).Errorf("Fail to send PktInd indication: %v", err)
		}
	}
}

func (o OltDevice) FindOnu(serialNumber string) (*Onu, error) {

	for _, pon := range o.Pons {
		for _, onu := range pon.Onus {
			if onu.Sn() == serialNumber {
				return &onu, nil
			}
		}
	}

	return &Onu{}, errors.New(fmt.Sprintf("cannot-find-onu-%s", serialNumber))
}

// GRPC Endpoints

func (o OltDevice) ActivateOnu(context context.Context, onu *openolt.Onu) (*openolt.Empty, error) {
	oltLogger.WithFields(log.Fields{
		"OnuSn": onuSnToString(onu.SerialNumber),
	}).Info("Received ActivateOnu call from VOLTHA")

	pon, _ := o.getPonById(onu.IntfId)
	_onu, _ := pon.getOnuBySn(onu.SerialNumber)

	if err := _onu.OperState.Event("enable"); err != nil {
		oltLogger.WithFields(log.Fields{
			"IntfId": _onu.PonPortID,
			"OnuSn":  _onu.Sn(),
			"OnuId":  _onu.ID,
		}).Infof("Failed to transition ONU.OperState to enabled state: %s", err.Error())
	}
	if err := _onu.InternalState.Event("enable"); err != nil {
		oltLogger.WithFields(log.Fields{
			"IntfId": _onu.PonPortID,
			"OnuSn":  _onu.Sn(),
			"OnuId":  _onu.ID,
		}).Infof("Failed to transition ONU to enabled state: %s", err.Error())
	}

	// NOTE we need to immediately activate the ONU or the OMCI state machine won't start

	return new(openolt.Empty), nil
}

func (o OltDevice) DeactivateOnu(context.Context, *openolt.Onu) (*openolt.Empty, error) {
	oltLogger.Error("DeactivateOnu not implemented")
	return new(openolt.Empty), nil
}

func (o OltDevice) DeleteOnu(context.Context, *openolt.Onu) (*openolt.Empty, error) {
	oltLogger.Error("DeleteOnu not implemented")
	return new(openolt.Empty), nil
}

func (o OltDevice) DisableOlt(context.Context, *openolt.Empty) (*openolt.Empty, error) {
	// NOTE when we disable the OLT should we disable NNI, PONs and ONUs altogether?
	olt_msg := Message{
		Type: OltIndication,
		Data: OltIndicationMessage{
			OperState: DOWN,
		},
	}
	o.channel <- olt_msg
	return new(openolt.Empty), nil
}

func (o OltDevice) DisablePonIf(context.Context, *openolt.Interface) (*openolt.Empty, error) {
	oltLogger.Error("DisablePonIf not implemented")
	return new(openolt.Empty), nil
}

func (o OltDevice) EnableIndication(_ *openolt.Empty, stream openolt.Openolt_EnableIndicationServer) error {
	oltLogger.WithField("oltId", o.ID).Info("OLT receives EnableIndication call from VOLTHA")
	o.Enable(stream)
	return nil
}

func (o OltDevice) EnablePonIf(context.Context, *openolt.Interface) (*openolt.Empty, error) {
	oltLogger.Error("EnablePonIf not implemented")
	return new(openolt.Empty), nil
}

func (o OltDevice) FlowAdd(ctx context.Context, flow *openolt.Flow) (*openolt.Empty, error) {
	oltLogger.WithFields(log.Fields{
		"IntfId":    flow.AccessIntfId,
		"OnuId":     flow.OnuId,
		"EthType":   fmt.Sprintf("%x", flow.Classifier.EthType),
		"InnerVlan": flow.Classifier.IVid,
		"OuterVlan": flow.Classifier.OVid,
		"FlowType":  flow.FlowType,
		"FlowId":    flow.FlowId,
		"UniID":     flow.UniId,
		"PortNo":    flow.PortNo,
	}).Tracef("OLT receives Flow")
	// TODO optionally store flows somewhere

	if flow.AccessIntfId == -1 {
		oltLogger.WithFields(log.Fields{
			"FlowId": flow.FlowId,
		}).Debugf("This is an OLT flow")
	} else {
		pon, _ := o.getPonById(uint32(flow.AccessIntfId))
		onu, _ := pon.getOnuById(uint32(flow.OnuId))

		msg := Message{
			Type: FlowUpdate,
			Data: OnuFlowUpdateMessage{
				PonPortID: pon.ID,
				OnuID:     onu.ID,
				Flow:      flow,
			},
		}
		onu.Channel <- msg
	}

	return new(openolt.Empty), nil
}

func (o OltDevice) FlowRemove(context.Context, *openolt.Flow) (*openolt.Empty, error) {
	oltLogger.Tracef("received FlowRemove")
	// TODO store flows somewhere
	return new(openolt.Empty), nil
}

func (o OltDevice) HeartbeatCheck(context.Context, *openolt.Empty) (*openolt.Heartbeat, error) {
	oltLogger.Error("HeartbeatCheck not implemented")
	return new(openolt.Heartbeat), nil
}

func (o OltDevice) GetDeviceInfo(context.Context, *openolt.Empty) (*openolt.DeviceInfo, error) {

	oltLogger.WithFields(log.Fields{
		"oltId":    o.ID,
		"PonPorts": o.NumPon,
	}).Info("OLT receives GetDeviceInfo call from VOLTHA")
	devinfo := new(openolt.DeviceInfo)
	devinfo.Vendor = "BBSim"
	devinfo.Model = "asfvolt16"
	devinfo.HardwareVersion = "emulated"
	devinfo.FirmwareVersion = ""
	devinfo.Technology = "xgspon"
	devinfo.PonPorts = uint32(o.NumPon)
	devinfo.OnuIdStart = 1
	devinfo.OnuIdEnd = 255
	devinfo.AllocIdStart = 1024
	devinfo.AllocIdEnd = 16383
	devinfo.GemportIdStart = 1024
	devinfo.GemportIdEnd = 65535
	devinfo.FlowIdStart = 1
	devinfo.FlowIdEnd = 16383
	devinfo.DeviceSerialNumber = o.SerialNumber

	return devinfo, nil
}

func (o OltDevice) OmciMsgOut(ctx context.Context, omci_msg *openolt.OmciMsg) (*openolt.Empty, error) {
	pon, _ := o.getPonById(omci_msg.IntfId)
	onu, _ := pon.getOnuById(omci_msg.OnuId)
	oltLogger.WithFields(log.Fields{
		"IntfId": onu.PonPortID,
		"OnuId":  onu.ID,
		"OnuSn":  onu.Sn(),
	}).Tracef("Received OmciMsgOut")
	msg := Message{
		Type: OMCI,
		Data: OmciMessage{
			OnuSN:   onu.SerialNumber,
			OnuID:   onu.ID,
			omciMsg: omci_msg,
		},
	}
	onu.Channel <- msg
	return new(openolt.Empty), nil
}

func (o OltDevice) OnuPacketOut(ctx context.Context, onuPkt *openolt.OnuPacket) (*openolt.Empty, error) {
	pon, _ := o.getPonById(onuPkt.IntfId)
	onu, _ := pon.getOnuById(onuPkt.OnuId)

	rawpkt := gopacket.NewPacket(onuPkt.Pkt, layers.LayerTypeEthernet, gopacket.Default)

	etherType := rawpkt.Layer(layers.LayerTypeEthernet).(*layers.Ethernet).EthernetType

	if etherType == layers.EthernetTypeEAPOL {
		eapolPkt := bbsim.ByteMsg{IntfId: onuPkt.IntfId, OnuId: onuPkt.OnuId, Bytes: rawpkt.Data()}
		onu.eapolPktOutCh <- &eapolPkt
	} else if layerDHCP := rawpkt.Layer(layers.LayerTypeDHCPv4); layerDHCP != nil {
		// TODO use IsDhcpPacket
		// TODO we need to untag the packets
		// NOTE here we receive packets going from the DHCP Server to the ONU
		// for now we expect them to be double-tagged, but ideally the should be single tagged
		dhcpPkt := bbsim.ByteMsg{IntfId: onuPkt.IntfId, OnuId: onuPkt.OnuId, Bytes: rawpkt.Data()}
		onu.dhcpPktOutCh <- &dhcpPkt
	}
	return new(openolt.Empty), nil
}

func (o OltDevice) Reboot(context.Context, *openolt.Empty) (*openolt.Empty, error) {
	oltLogger.Info("Shutting Down")
	close(*o.oltDoneChannel)
	close(*o.apiDoneChannel)
	return new(openolt.Empty), nil
}

func (o OltDevice) ReenableOlt(context.Context, *openolt.Empty) (*openolt.Empty, error) {
	oltLogger.Error("ReenableOlt not implemented")
	return new(openolt.Empty), nil
}

func (o OltDevice) UplinkPacketOut(context context.Context, packet *openolt.UplinkPacket) (*openolt.Empty, error) {
	pkt := gopacket.NewPacket(packet.Pkt, layers.LayerTypeEthernet, gopacket.Default)

	sendNniPacket(pkt)
	// NOTE should we return an error if sendNniPakcet fails?
	return new(openolt.Empty), nil
}

func (o OltDevice) CollectStatistics(context.Context, *openolt.Empty) (*openolt.Empty, error) {
	oltLogger.Error("CollectStatistics not implemented")
	return new(openolt.Empty), nil
}

func (o OltDevice) GetOnuInfo(context context.Context, packet *openolt.Onu) (*openolt.OnuIndication, error) {
	oltLogger.Error("GetOnuInfo not implemented")
	return new(openolt.OnuIndication), nil
}

func (o OltDevice) GetPonIf(context context.Context, packet *openolt.Interface) (*openolt.IntfIndication, error) {
	oltLogger.Error("GetPonIf not implemented")
	return new(openolt.IntfIndication), nil
}

func (s OltDevice) CreateTrafficQueues(context.Context, *tech_profile.TrafficQueues) (*openolt.Empty, error) {
	oltLogger.Info("received CreateTrafficQueues")
	return new(openolt.Empty), nil
}

func (s OltDevice) RemoveTrafficQueues(context.Context, *tech_profile.TrafficQueues) (*openolt.Empty, error) {
	oltLogger.Info("received RemoveTrafficQueues")
	return new(openolt.Empty), nil
}

func (s OltDevice) CreateTrafficSchedulers(context.Context, *tech_profile.TrafficSchedulers) (*openolt.Empty, error) {
	oltLogger.Info("received CreateTrafficSchedulers")
	return new(openolt.Empty), nil
}

func (s OltDevice) RemoveTrafficSchedulers(context.Context, *tech_profile.TrafficSchedulers) (*openolt.Empty, error) {
	oltLogger.Info("received RemoveTrafficSchedulers")
	return new(openolt.Empty), nil
}