/*
   Copyright 2020 the original author or authors.

   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 openflow

import (
	"context"
	"encoding/json"
	"net"

	"github.com/opencord/goloxi"
	ofp "github.com/opencord/goloxi/of13"
	"github.com/opencord/voltha-lib-go/v4/pkg/log"
	"github.com/opencord/voltha-protos/v4/go/common"
	"github.com/opencord/voltha-protos/v4/go/openflow_13"
)

func (ofc *OFConnection) handleStatsRequest(ctx context.Context, request ofp.IHeader, statType uint16) error {
	span, ctx := log.CreateChildSpan(ctx, "openflow-stats")
	defer span.Finish()

	if logger.V(log.DebugLevel) {
		js, _ := json.Marshal(request)
		logger.Debugw(ctx, "handleStatsRequest called",
			log.Fields{
				"device-id": ofc.DeviceID,
				"stat-type": statType,
				"request":   js})
	}

	switch statType {
	case ofp.OFPSTDesc:
		statsReq := request.(*ofp.DescStatsRequest)
		response, err := ofc.handleDescStatsRequest(ctx, statsReq)
		if err != nil {
			return err
		}
		if logger.V(log.DebugLevel) {
			reqJs, _ := json.Marshal(statsReq)
			resJs, _ := json.Marshal(response)
			logger.Debugw(ctx, "handle-stats-request-desc",
				log.Fields{
					"device-id": ofc.DeviceID,
					"request":   reqJs,
					"response":  resJs})
		}
		return ofc.SendMessage(ctx, response)
	case ofp.OFPSTFlow:
		statsReq := request.(*ofp.FlowStatsRequest)
		responses, err := ofc.handleFlowStatsRequest(ctx, statsReq)
		if err != nil {
			return err
		}
		if logger.V(log.DebugLevel) {
			reqJs, _ := json.Marshal(statsReq)
			resJs, _ := json.Marshal(responses)
			logger.Debugw(ctx, "handle-stats-request-flow",
				log.Fields{
					"device-id":        ofc.DeviceID,
					"request":          reqJs,
					"responses-object": responses,
					"response":         resJs})
		}
		for _, response := range responses {
			err := ofc.SendMessage(ctx, response)
			if err != nil {
				return err
			}
		}
		return nil

	case ofp.OFPSTAggregate:
		statsReq := request.(*ofp.AggregateStatsRequest)
		response, err := ofc.handleAggregateStatsRequest(statsReq)
		if err != nil {
			return err
		}
		if logger.V(log.DebugLevel) {
			reqJs, _ := json.Marshal(statsReq)
			resJs, _ := json.Marshal(response)
			logger.Debugw(ctx, "handle-stats-request-aggregate",
				log.Fields{
					"device-id": ofc.DeviceID,
					"request":   reqJs,
					"response":  resJs})
		}
		return ofc.SendMessage(ctx, response)
	case ofp.OFPSTTable:
		statsReq := request.(*ofp.TableStatsRequest)
		response, e := ofc.handleTableStatsRequest(statsReq)
		if logger.V(log.DebugLevel) {
			reqJs, _ := json.Marshal(statsReq)
			resJs, _ := json.Marshal(response)
			logger.Debugw(ctx, "handle-stats-request-table",
				log.Fields{
					"device-id": ofc.DeviceID,
					"request":   reqJs,
					"response":  resJs})
		}
		if e != nil {
			return e
		}
		return ofc.SendMessage(ctx, response)
	case ofp.OFPSTPort:
		statsReq := request.(*ofp.PortStatsRequest)
		responses, err := ofc.handlePortStatsRequest(ctx, statsReq)
		if err != nil {
			return err
		}
		if logger.V(log.DebugLevel) {
			reqJs, _ := json.Marshal(statsReq)
			resJs, _ := json.Marshal(responses)
			logger.Debugw(ctx, "handle-stats-request-port",
				log.Fields{
					"device-id": ofc.DeviceID,
					"request":   reqJs,
					"response":  resJs})
		}
		for _, response := range responses {
			err := ofc.SendMessage(ctx, response)
			if err != nil {
				return err
			}
		}
		return nil
	case ofp.OFPSTQueue:
		statsReq := request.(*ofp.QueueStatsRequest)
		response, err := ofc.handleQueueStatsRequest(statsReq)
		if err != nil {
			return err
		}
		if logger.V(log.DebugLevel) {
			reqJs, _ := json.Marshal(statsReq)
			resJs, _ := json.Marshal(response)
			logger.Debugw(ctx, "handle-stats-request-queue",
				log.Fields{
					"device-id": ofc.DeviceID,
					"request":   reqJs,
					"response":  resJs})
		}
		return ofc.SendMessage(ctx, response)
	case ofp.OFPSTGroup:
		statsReq := request.(*ofp.GroupStatsRequest)
		response, err := ofc.handleGroupStatsRequest(ctx, statsReq)
		if err != nil {
			return err
		}
		if logger.V(log.DebugLevel) {
			reqJs, _ := json.Marshal(statsReq)
			resJs, _ := json.Marshal(response)
			logger.Debugw(ctx, "handle-stats-request-group",
				log.Fields{
					"device-id": ofc.DeviceID,
					"request":   reqJs,
					"response":  resJs})
		}
		return ofc.SendMessage(ctx, response)
	case ofp.OFPSTGroupDesc:
		statsReq := request.(*ofp.GroupDescStatsRequest)
		response, err := ofc.handleGroupStatsDescRequest(ctx, statsReq)
		if err != nil {
			return err
		}
		if logger.V(log.DebugLevel) {
			reqJs, _ := json.Marshal(statsReq)
			resJs, _ := json.Marshal(response)
			logger.Debugw(ctx, "handle-stats-request-group-desc",
				log.Fields{
					"device-id": ofc.DeviceID,
					"request":   reqJs,
					"response":  resJs})
		}
		return ofc.SendMessage(ctx, response)

	case ofp.OFPSTGroupFeatures:
		statsReq := request.(*ofp.GroupFeaturesStatsRequest)
		response, err := ofc.handleGroupFeatureStatsRequest(statsReq)
		if err != nil {
			return err
		}
		if logger.V(log.DebugLevel) {
			reqJs, _ := json.Marshal(statsReq)
			resJs, _ := json.Marshal(response)
			logger.Debugw(ctx, "handle-stats-request-group-features",
				log.Fields{
					"device-id": ofc.DeviceID,
					"request":   reqJs,
					"response":  resJs})
		}
		return ofc.SendMessage(ctx, response)
	case ofp.OFPSTMeter:
		statsReq := request.(*ofp.MeterStatsRequest)
		response, err := ofc.handleMeterStatsRequest(ctx, statsReq)
		if err != nil {
			return err
		}
		if logger.V(log.DebugLevel) {
			reqJs, _ := json.Marshal(statsReq)
			resJs, _ := json.Marshal(response)
			logger.Debugw(ctx, "handle-stats-request-meter",
				log.Fields{
					"device-id": ofc.DeviceID,
					"request":   reqJs,
					"response":  resJs})
		}
		return ofc.SendMessage(ctx, response)
	case ofp.OFPSTMeterConfig:
		statsReq := request.(*ofp.MeterConfigStatsRequest)
		response, err := ofc.handleMeterConfigStatsRequest(statsReq)
		if err != nil {
			return err
		}
		if logger.V(log.DebugLevel) {
			reqJs, _ := json.Marshal(statsReq)
			resJs, _ := json.Marshal(response)
			logger.Debugw(ctx, "handle-stats-request-meter-config",
				log.Fields{
					"device-id": ofc.DeviceID,
					"request":   reqJs,
					"response":  resJs})
		}
		return ofc.SendMessage(ctx, response)
	case ofp.OFPSTMeterFeatures:
		statsReq := request.(*ofp.MeterFeaturesStatsRequest)
		response, err := ofc.handleMeterFeatureStatsRequest(statsReq)
		if err != nil {
			return err
		}
		if logger.V(log.DebugLevel) {
			reqJs, _ := json.Marshal(statsReq)
			resJs, _ := json.Marshal(response)
			logger.Debugw(ctx, "handle-stats-request-meter-features",
				log.Fields{
					"device-id": ofc.DeviceID,
					"request":   reqJs,
					"response":  resJs})
		}
		return ofc.SendMessage(ctx, response)
	case ofp.OFPSTTableFeatures:
		statsReq := request.(*ofp.TableFeaturesStatsRequest)
		response, err := ofc.handleTableFeaturesStatsRequest(statsReq)
		if err != nil {
			return err
		}
		if logger.V(log.DebugLevel) {
			reqJs, _ := json.Marshal(statsReq)
			resJs, _ := json.Marshal(response)
			logger.Debugw(ctx, "handle-stats-request-table-features",
				log.Fields{
					"device-id": ofc.DeviceID,
					"request":   reqJs,
					"response":  resJs})
		}
		return ofc.SendMessage(ctx, response)
	case ofp.OFPSTPortDesc:
		statsReq := request.(*ofp.PortDescStatsRequest)
		responses, err := ofc.handlePortDescStatsRequest(ctx, statsReq)
		if err != nil {
			return err
		}
		if logger.V(log.DebugLevel) {
			reqJs, _ := json.Marshal(statsReq)
			resJs, _ := json.Marshal(responses)
			logger.Debugw(ctx, "handle-stats-request-port-desc",
				log.Fields{
					"device-id": ofc.DeviceID,
					"request":   reqJs,
					"response":  resJs})
		}
		for _, response := range responses {
			err := ofc.SendMessage(ctx, response)
			if err != nil {
				return err
			}
		}
		return nil

	case ofp.OFPSTExperimenter:
		statsReq := request.(*ofp.ExperimenterStatsRequest)
		response, err := ofc.handleExperimenterStatsRequest(statsReq)
		if err != nil {
			return err
		}
		if logger.V(log.DebugLevel) {
			reqJs, _ := json.Marshal(statsReq)
			resJs, _ := json.Marshal(response)
			logger.Debugw(ctx, "handle-stats-request-experimenter",
				log.Fields{
					"device-id": ofc.DeviceID,
					"request":   reqJs,
					"response":  resJs})
		}
		return ofc.SendMessage(ctx, response)
	}
	return nil
}

func (ofc *OFConnection) handleDescStatsRequest(ctx context.Context, request *ofp.DescStatsRequest) (*ofp.DescStatsReply, error) {
	volthaClient := ofc.VolthaClient.Get()
	if volthaClient == nil {
		return nil, NoVolthaConnectionError
	}
	response := ofp.NewDescStatsReply()
	response.SetXid(request.GetXid())
	response.SetVersion(request.GetVersion())
	response.SetFlags(ofp.StatsReplyFlags(request.GetFlags()))

	resp, err := volthaClient.GetLogicalDevice(log.WithSpanFromContext(context.Background(), ctx),
		&common.ID{Id: ofc.DeviceID})
	if err != nil {
		return nil, err
	}
	desc := resp.GetDesc()

	response.SetMfrDesc(PadString(desc.GetMfrDesc(), 256))
	response.SetHwDesc(PadString(desc.GetHwDesc(), 256))
	response.SetSwDesc(PadString(desc.GetSwDesc(), 256))
	response.SetSerialNum(PadString(desc.GetSerialNum(), 32))
	response.SetDpDesc(PadString(desc.GetDpDesc(), 256))
	return response, nil
}

func (ofc *OFConnection) handleFlowStatsRequest(ctx context.Context, request *ofp.FlowStatsRequest) ([]*ofp.FlowStatsReply, error) {
	volthaClient := ofc.VolthaClient.Get()
	if volthaClient == nil {
		return nil, NoVolthaConnectionError
	}
	resp, err := volthaClient.ListLogicalDeviceFlows(log.WithSpanFromContext(context.Background(), ctx),
		&common.ID{Id: ofc.DeviceID})
	if err != nil {
		return nil, err
	}
	logger.Debugw(ctx, "logicalDeviceFlows", log.Fields{"logical-device-id": ofc.DeviceID, "num-flows": len(resp.Items)})
	var flows []*ofp.FlowStatsEntry
	for _, item := range resp.GetItems() {
		entry := ofp.NewFlowStatsEntry()
		entry.SetTableId(uint8(item.GetTableId()))
		entry.SetDurationSec(item.GetDurationSec())
		entry.SetDurationNsec(item.GetDurationNsec())
		entry.SetPriority(uint16(item.GetPriority()))
		entry.SetIdleTimeout(uint16(item.GetIdleTimeout()))
		entry.SetHardTimeout(uint16(item.GetHardTimeout()))
		entry.SetFlags(ofp.FlowModFlags(item.GetFlags()))
		entry.SetCookie(item.GetCookie())
		entry.SetPacketCount(item.GetPacketCount())
		entry.SetByteCount(item.GetByteCount())
		match := ofp.NewMatchV3()
		pbMatch := item.GetMatch()
		match.SetType(uint16(pbMatch.GetType()))
		var fields []goloxi.IOxm
		for _, oxmField := range pbMatch.GetOxmFields() {
			field := oxmField.GetField()
			ofbField := field.(*openflow_13.OfpOxmField_OfbField).OfbField
			iOxm, err := parseOxm(ctx, ofbField)
			if err == nil {
				fields = append(fields, iOxm)
			} else {
				logger.Errorw(ctx, "error-parsing-oxm", log.Fields{"err": err})
			}
		}

		match.OxmList = fields
		entry.SetMatch(*match)
		var instructions []ofp.IInstruction
		for _, ofpInstruction := range item.Instructions {
			instruction, err := parseInstructions(ctx, ofpInstruction)
			if err == nil {
				instructions = append(instructions, instruction)
			} else {
				logger.Errorw(ctx, "error-parsing-instruction", log.Fields{"err": err})
			}
		}
		entry.Instructions = instructions
		flows = append(flows, entry)
	}
	var responses []*ofp.FlowStatsReply

	chunkSize := ofc.flowsChunkSize
	total := len(flows) / chunkSize
	n := 0
	for n <= total {
		response := ofp.NewFlowStatsReply()
		response.SetXid(request.GetXid())
		response.SetVersion(request.GetVersion())
		response.SetFlags(ofp.StatsReplyFlags(request.GetFlags()))

		limit := (n * chunkSize) + chunkSize
		chunk := flows[n*chunkSize : min(limit, len(flows))]

		if len(chunk) == 0 {
			// Special case - no flows
			if len(flows) == 0 {
				logger.Debugw(ctx, "no-flows-present", log.Fields{"logical-device-id": ofc.DeviceID})
				response.SetEntries(chunk)
				responses = append(responses, response)
			}
			break
		}

		if limit < len(flows) {
			response.SetFlags(ofp.StatsReplyFlags(ofp.OFPSFReplyMore))
		}
		response.SetEntries(chunk)
		responses = append(responses, response)
		n++
	}
	return responses, nil
}

func (ofc *OFConnection) handleAggregateStatsRequest(request *ofp.AggregateStatsRequest) (*ofp.AggregateStatsReply, error) {
	response := ofp.NewAggregateStatsReply()
	response.SetVersion(request.GetVersion())
	response.SetXid(request.GetXid())
	response.SetFlags(ofp.StatsReplyFlags(request.GetFlags()))
	response.SetFlowCount(0)
	//TODO wire this to voltha core when it implements
	return response, nil
}

func (ofc *OFConnection) handleGroupStatsRequest(ctx context.Context, request *ofp.GroupStatsRequest) (*ofp.GroupStatsReply, error) {
	volthaClient := ofc.VolthaClient.Get()
	if volthaClient == nil {
		return nil, NoVolthaConnectionError
	}
	response := ofp.NewGroupStatsReply()
	response.SetVersion(request.GetVersion())
	response.SetXid(request.GetXid())
	response.SetFlags(ofp.StatsReplyFlags(request.GetFlags()))
	reply, err := volthaClient.ListLogicalDeviceFlowGroups(log.WithSpanFromContext(context.Background(), ctx),
		&common.ID{Id: ofc.DeviceID})
	if err != nil {
		return nil, err
	}

	var groupStatsEntries []*ofp.GroupStatsEntry
	for _, item := range reply.GetItems() {
		stats := item.GetStats()
		var entry ofp.GroupStatsEntry
		entry.SetByteCount(stats.GetByteCount())
		entry.SetPacketCount(stats.GetPacketCount())
		entry.SetDurationNsec(stats.GetDurationNsec())
		entry.SetDurationSec(stats.GetDurationSec())
		entry.SetRefCount(stats.GetRefCount())
		entry.SetGroupId(stats.GetGroupId())
		var bucketStatsList []*ofp.BucketCounter
		// TODO fix this when API handler is fixed in the core
		// Core doesn't return any buckets in the Stats object, so just
		// fill out an empty BucketCounter for each bucket in the group Desc for now.
		for range item.GetDesc().GetBuckets() {
			bucketCounter := ofp.BucketCounter{}
			bucketCounter.SetPacketCount(0)
			bucketCounter.SetByteCount(0)
			bucketStatsList = append(bucketStatsList, &bucketCounter)
		}
		entry.SetBucketStats(bucketStatsList)
		groupStatsEntries = append(groupStatsEntries, &entry)
	}
	response.SetEntries(groupStatsEntries)
	return response, nil
}

func (ofc *OFConnection) handleGroupStatsDescRequest(ctx context.Context, request *ofp.GroupDescStatsRequest) (*ofp.GroupDescStatsReply, error) {
	volthaClient := ofc.VolthaClient.Get()
	if volthaClient == nil {
		return nil, NoVolthaConnectionError
	}
	response := ofp.NewGroupDescStatsReply()
	response.SetVersion(request.GetVersion())
	response.SetXid(request.GetXid())
	response.SetFlags(ofp.StatsReplyFlags(request.GetFlags()))
	reply, err := volthaClient.ListLogicalDeviceFlowGroups(log.WithSpanFromContext(context.Background(), ctx),
		&common.ID{Id: ofc.DeviceID})
	if err != nil {
		return nil, err
	}
	var groupDescStatsEntries []*ofp.GroupDescStatsEntry
	for _, item := range reply.GetItems() {
		desc := item.GetDesc()

		buckets, err := volthaBucketsToOpenflow(ctx, desc.Buckets)
		if err != nil {
			return nil, err
		}

		groupDesc := &ofp.GroupDescStatsEntry{
			GroupType: volthaGroupTypeToOpenflow(ctx, desc.Type),
			GroupId:   desc.GroupId,
			Buckets:   buckets,
		}
		groupDescStatsEntries = append(groupDescStatsEntries, groupDesc)
	}
	response.SetEntries(groupDescStatsEntries)
	return response, nil
}

func (ofc *OFConnection) handleGroupFeatureStatsRequest(request *ofp.GroupFeaturesStatsRequest) (*ofp.GroupFeaturesStatsReply, error) {
	response := ofp.NewGroupFeaturesStatsReply()
	response.SetVersion(request.GetVersion())
	response.SetXid(request.GetXid())
	response.SetFlags(ofp.StatsReplyFlags(request.GetFlags()))
	//TODO wire this to voltha core when it implements
	return response, nil
}

func (ofc *OFConnection) handleMeterStatsRequest(ctx context.Context, request *ofp.MeterStatsRequest) (*ofp.MeterStatsReply, error) {
	volthaClient := ofc.VolthaClient.Get()
	if volthaClient == nil {
		return nil, NoVolthaConnectionError
	}
	response := ofp.NewMeterStatsReply()
	response.SetVersion(request.GetVersion())
	response.SetXid(request.GetXid())
	response.SetFlags(ofp.StatsReplyFlags(request.GetFlags()))
	resp, err := volthaClient.ListLogicalDeviceMeters(log.WithSpanFromContext(context.Background(), ctx),
		&common.ID{Id: ofc.DeviceID})
	if err != nil {
		return nil, err
	}
	var meterStats []*ofp.MeterStats
	for _, item := range resp.Items {
		meterStat := ofp.NewMeterStats()
		stats := item.Stats
		meterStat.DurationNsec = stats.DurationNsec
		meterStat.DurationSec = stats.DurationSec
		meterStat.ByteInCount = stats.ByteInCount
		meterStat.FlowCount = stats.FlowCount
		meterStat.MeterId = stats.MeterId
		var bandStats []*ofp.MeterBandStats
		for _, bStat := range stats.BandStats {
			bandStat := ofp.NewMeterBandStats()
			bandStat.ByteBandCount = bStat.ByteBandCount
			bandStat.PacketBandCount = bStat.PacketBandCount
			bandStats = append(bandStats, bandStat)
		}
		meterStat.SetBandStats(bandStats)
		meterStats = append(meterStats, meterStat)
	}
	response.SetEntries(meterStats)
	return response, nil
}

func (ofc *OFConnection) handleMeterConfigStatsRequest(request *ofp.MeterConfigStatsRequest) (*ofp.MeterConfigStatsReply, error) {
	response := ofp.NewMeterConfigStatsReply()
	response.SetVersion(request.GetVersion())
	response.SetXid(request.GetXid())
	response.SetFlags(ofp.StatsReplyFlags(request.GetFlags()))
	//TODO wire this to voltha core when it implements
	return response, nil
}

func (ofc *OFConnection) handleTableFeaturesStatsRequest(request *ofp.TableFeaturesStatsRequest) (*ofp.TableFeaturesStatsReply, error) {
	response := ofp.NewTableFeaturesStatsReply()
	response.SetVersion(request.GetVersion())
	response.SetXid(request.GetXid())
	response.SetFlags(ofp.StatsReplyFlags(request.GetFlags()))
	//TODO wire this to voltha core when it implements
	return response, nil
}

func (ofc *OFConnection) handleTableStatsRequest(request *ofp.TableStatsRequest) (*ofp.TableStatsReply, error) {
	var response = ofp.NewTableStatsReply()
	response.SetFlags(ofp.StatsReplyFlags(request.GetFlags()))
	response.SetVersion(request.GetVersion())
	response.SetXid(request.GetXid())
	response.SetFlags(ofp.StatsReplyFlags(request.GetFlags()))
	return response, nil
}

func (ofc *OFConnection) handleQueueStatsRequest(request *ofp.QueueStatsRequest) (*ofp.QueueStatsReply, error) {
	response := ofp.NewQueueStatsReply()
	response.SetVersion(request.GetVersion())
	response.SetXid(request.GetXid())
	response.SetFlags(ofp.StatsReplyFlags(request.GetFlags()))
	//TODO wire this to voltha core when it implements
	return response, nil
}

func (ofc *OFConnection) handlePortStatsRequest(ctx context.Context, request *ofp.PortStatsRequest) ([]*ofp.PortStatsReply, error) {
	volthaClient := ofc.VolthaClient.Get()
	if volthaClient == nil {
		return nil, NoVolthaConnectionError
	}

	reply, err := volthaClient.ListLogicalDevicePorts(log.WithSpanFromContext(context.Background(), ctx),
		&common.ID{Id: ofc.DeviceID})
	if err != nil {
		return nil, err
	}
	var entries []*ofp.PortStatsEntry
	if request.GetPortNo() == 0xffffffff { //all ports
		for _, port := range reply.GetItems() {
			entries = append(entries, parsePortStats(port))
		}
	} else { //find right port that is requested
		for _, port := range reply.GetItems() {
			if port.GetOfpPortStats().GetPortNo() == uint32(request.GetPortNo()) {
				entries = append(entries, parsePortStats(port))
			}
		}
	}

	var responses []*ofp.PortStatsReply

	chunkSize := ofc.portsChunkSize
	total := len(entries) / chunkSize
	n := 0
	for n <= total {
		response := ofp.NewPortStatsReply()
		response.SetXid(request.GetXid())
		response.SetVersion(request.GetVersion())
		response.SetFlags(ofp.StatsReplyFlags(request.GetFlags()))

		chunk := entries[n*chunkSize : min((n*chunkSize)+chunkSize, len(entries))]

		if len(chunk) == 0 {
			// handle the case of no ports
			if len(entries) == 0 {
				logger.Debugw(ctx, "no-ports-present", log.Fields{"logical-device-id": ofc.DeviceID})
				response.SetEntries(chunk)
				responses = append(responses, response)
			}
			break
		}

		if total != n {
			response.SetFlags(ofp.StatsReplyFlags(ofp.OFPSFReplyMore))
		}
		response.SetEntries(chunk)
		responses = append(responses, response)
		n++
	}
	return responses, nil
}

func (ofc *OFConnection) handlePortDescStatsRequest(ctx context.Context, request *ofp.PortDescStatsRequest) ([]*ofp.PortDescStatsReply, error) {
	volthaClient := ofc.VolthaClient.Get()
	if volthaClient == nil {
		return nil, NoVolthaConnectionError
	}

	ports, err := volthaClient.ListLogicalDevicePorts(log.WithSpanFromContext(context.Background(), ctx), &common.ID{Id: ofc.DeviceID})
	if err != nil {
		return nil, err
	}
	var entries []*ofp.PortDesc
	for _, port := range ports.Items {
		ofpPort := port.GetOfpPort()
		var entry ofp.PortDesc
		entry.SetPortNo(ofp.Port(ofpPort.GetPortNo()))

		var octets []byte
		for _, val := range ofpPort.GetHwAddr() {
			octets = append(octets, byte(val))
		}
		hwAddr := net.HardwareAddr(octets)
		entry.SetHwAddr(hwAddr)
		entry.SetName(PadString(ofpPort.GetName(), 16))
		entry.SetConfig(ofp.PortConfig(ofpPort.GetConfig()))
		entry.SetState(ofp.PortState(ofpPort.GetState()))
		entry.SetCurr(ofp.PortFeatures(ofpPort.GetCurr()))
		entry.SetAdvertised(ofp.PortFeatures(ofpPort.GetAdvertised()))
		entry.SetSupported(ofp.PortFeatures(ofpPort.GetSupported()))
		entry.SetPeer(ofp.PortFeatures(ofpPort.GetPeer()))
		entry.SetCurrSpeed(ofpPort.GetCurrSpeed())
		entry.SetMaxSpeed(ofpPort.GetMaxSpeed())

		entries = append(entries, &entry)
	}

	var responses []*ofp.PortDescStatsReply

	chunkSize := ofc.portsDescChunkSize
	total := len(entries) / chunkSize
	n := 0
	for n <= total {
		response := ofp.NewPortDescStatsReply()
		response.SetVersion(request.GetVersion())
		response.SetXid(request.GetXid())
		response.SetFlags(ofp.StatsReplyFlags(request.GetFlags()))

		chunk := entries[n*chunkSize : min((n*chunkSize)+chunkSize, len(entries))]

		if len(chunk) == 0 {
			if len(entries) == 0 {
				logger.Debugw(ctx, "no-ports-desc-present", log.Fields{"logical-device-id": ofc.DeviceID})
				response.SetEntries(chunk)
				responses = append(responses, response)
			}
			break
		}

		if total != n {
			response.SetFlags(ofp.StatsReplyFlags(ofp.OFPSFReplyMore))
		}
		response.SetEntries(chunk)
		responses = append(responses, response)
		n++
	}
	return responses, nil

}

// Interestingly enough there is no min function fot two integers
func min(a, b int) int {
	if a < b {
		return a
	}
	return b
}

func (ofc *OFConnection) handleMeterFeatureStatsRequest(request *ofp.MeterFeaturesStatsRequest) (*ofp.MeterFeaturesStatsReply, error) {
	response := ofp.NewMeterFeaturesStatsReply()
	response.SetXid(request.GetXid())
	response.SetVersion(request.GetVersion())
	response.SetFlags(ofp.StatsReplyFlags(request.GetFlags()))
	meterFeatures := ofp.NewMeterFeatures()
	meterFeatures.Capabilities = ofp.OFPMFKbps
	meterFeatures.BandTypes = ofp.OFPMBTDrop
	meterFeatures.MaxMeter = 0xffffffff
	meterFeatures.MaxBands = 0xff
	meterFeatures.MaxColor = 0xff
	response.Features = *meterFeatures
	return response, nil
}

func (ofc *OFConnection) handleExperimenterStatsRequest(request *ofp.ExperimenterStatsRequest) (*ofp.ExperimenterStatsReply, error) {
	response := ofp.NewExperimenterStatsReply(request.GetExperimenter())
	response.SetVersion(request.GetVersion())
	response.SetXid(request.GetXid())
	response.SetFlags(ofp.StatsReplyFlags(request.GetFlags()))
	//TODO wire this to voltha core when it implements
	return response, nil
}