/*
* Copyright 2022-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 controller

import (
	"context"
	"errors"
	"time"

	"voltha-go-controller/internal/pkg/of"
	"voltha-go-controller/internal/pkg/tasks"
	"voltha-go-controller/internal/pkg/util"
	"voltha-go-controller/log"

	"github.com/opencord/voltha-protos/v5/go/common"
	ofp "github.com/opencord/voltha-protos/v5/go/openflow_13"
	"github.com/opencord/voltha-protos/v5/go/voltha"
)

var (
	rcvdGroups  map[uint32]*ofp.OfpGroupDesc
	groupsToAdd []*of.Group
	groupsToMod []*of.Group
)

// AuditTablesTask structure
type AuditTablesTask struct {
	ctx       context.Context
	device    *Device
	timestamp string
	taskID    uint8
	stop      bool
}

// NewAuditTablesTask is constructor for AuditTablesTask
func NewAuditTablesTask(device *Device) *AuditTablesTask {
	var att AuditTablesTask
	att.device = device
	att.stop = false
	tstamp := (time.Now()).Format(time.RFC3339Nano)
	att.timestamp = tstamp
	return &att
}

// Name returns name of the task
func (att *AuditTablesTask) Name() string {
	return "Audit Table Task"
}

// TaskID to return task id of the task
func (att *AuditTablesTask) TaskID() uint8 {
	return att.taskID
}

// Timestamp to return timestamp for the task
func (att *AuditTablesTask) Timestamp() string {
	return att.timestamp
}

// Stop to stop the task
func (att *AuditTablesTask) Stop() {
	att.stop = true
}

// Start is called by the framework and is responsible for implementing
// the actual task.
func (att *AuditTablesTask) Start(ctx context.Context, taskID uint8) error {
	logger.Debugw(ctx, "Audit Table Task Triggered", log.Fields{"Context": ctx, "taskId": taskID, "Device": att.device.ID})
	att.taskID = taskID
	att.ctx = ctx
	var errInfo error
	var err error

	// Audit ports
	if err = att.AuditPorts(); err != nil {
		logger.Errorw(ctx, "Audit Ports Failed", log.Fields{"Reason": err.Error()})
		errInfo = err
	}

	// Audit the meters
	if err = att.AuditMeters(); err != nil {
		logger.Errorw(ctx, "Audit Meters Failed", log.Fields{"Reason": err.Error()})
		errInfo = err
	}

	// Audit the Groups
	if rcvdGroups, err = att.AuditGroups(); err != nil {
		logger.Errorw(ctx, "Audit Groups Failed", log.Fields{"Reason": err.Error()})
		errInfo = err
	}

	// Audit the flows
	if err = att.AuditFlows(ctx); err != nil {
		logger.Errorw(ctx, "Audit Flows Failed", log.Fields{"Reason": err.Error()})
		errInfo = err
	}

	// Triggering deletion of excess groups from device after the corresponding flows are removed
	// to avoid flow dependency error during group deletion
	logger.Debugw(ctx, "Excess Groups", log.Fields{"Groups": rcvdGroups})
	att.DelExcessGroups(rcvdGroups)
	logger.Debugw(ctx, "Audit Table Task Completed", log.Fields{"Context": ctx, "taskId": taskID, "Device": att.device.ID})
	return errInfo
}

// AuditMeters : Audit the meters which includes fetching the existing meters at the
// voltha and identifying the delta between the ones held here and the
// ones held at VOLTHA. The delta must be cleaned up to keep both the
// components in sync
func (att *AuditTablesTask) AuditMeters() error {
	if att.stop {
		return tasks.ErrTaskCancelError
	}
	var vc voltha.VolthaServiceClient
	if vc = att.device.VolthaClient(); vc == nil {
		logger.Error(ctx, "Fetch Device Meters Failed: Voltha Client Unavailable")
		return nil
	}

	//-----------------------------
	// Perform the audit of meters
	// Fetch the meters
	ms, err := vc.ListLogicalDeviceMeters(att.ctx, &voltha.ID{Id: att.device.ID})
	if err != nil {
		logger.Warnw(ctx, "Audit of flows failed", log.Fields{"Reason": err.Error()})
		return err
	}

	// Build the map for easy and faster processing
	rcvdMeters := make(map[uint32]*ofp.OfpMeterStats)
	for _, m := range ms.Items {
		rcvdMeters[m.Stats.MeterId] = m.Stats
	}

	// Verify all meters that are in the controller but not in the device
	missingMeters := []*of.Meter{}
	for _, meter := range att.device.meters {
		if att.stop {
			break
		}
		logger.Debugw(ctx, "Auditing Meter", log.Fields{"Id": meter.ID})

		if _, ok := rcvdMeters[meter.ID]; ok {
			// The meter exists in the device too. Just remove it from
			// the received meters
			delete(rcvdMeters, meter.ID)
		} else {
			// The flow exists at the controller but not at the device
			// Push the flow to the device
			logger.Infow(ctx, "Adding Meter To Missing Meters", log.Fields{"Id": meter.ID})
			missingMeters = append(missingMeters, meter)
		}
	}
	if !att.stop {
		att.AddMissingMeters(missingMeters)
		att.DelExcessMeters(rcvdMeters)
	} else {
		err = tasks.ErrTaskCancelError
	}
	return err
}

// AddMissingMeters adds the missing meters detected by AuditMeters
func (att *AuditTablesTask) AddMissingMeters(meters []*of.Meter) {
	logger.Debugw(ctx, "Adding missing meters", log.Fields{"Number": len(meters)})
	for _, meter := range meters {
		meterMod, err := of.MeterUpdate(att.device.ID, of.MeterCommandAdd, meter)
		if err != nil {
			logger.Errorw(ctx, "Update Meter Table Failed", log.Fields{"Reason": err.Error()})
			continue
		}
		if vc := att.device.VolthaClient(); vc != nil {
			if _, err = vc.UpdateLogicalDeviceMeterTable(att.ctx, meterMod); err != nil {
				logger.Errorw(ctx, "Update Meter Table Failed", log.Fields{"Reason": err.Error()})
			}
		} else {
			logger.Error(ctx, "Update Meter Table Failed: Voltha Client Unavailable")
		}
	}
}

// DelExcessMeters to delete excess meters
func (att *AuditTablesTask) DelExcessMeters(meters map[uint32]*ofp.OfpMeterStats) {
	logger.Debugw(ctx, "Deleting Excess Meters", log.Fields{"Number": len(meters)})
	for _, meter := range meters {
		meterMod := &ofp.OfpMeterMod{}
		meterMod.Command = ofp.OfpMeterModCommand_OFPMC_DELETE
		meterMod.MeterId = meter.MeterId
		meterUpd := &ofp.MeterModUpdate{Id: att.device.ID, MeterMod: meterMod}
		if vc := att.device.VolthaClient(); vc != nil {
			if _, err := vc.UpdateLogicalDeviceMeterTable(att.ctx, meterUpd); err != nil {
				logger.Errorw(ctx, "Update Meter Table Failed", log.Fields{"Reason": err.Error()})
			}
		} else {
			logger.Error(ctx, "Update Meter Table Failed: Voltha Client Unavailable")
		}
	}
}

// AuditFlows audit the flows which includes fetching the existing meters at the
// voltha and identifying the delta between the ones held here and the
// ones held at VOLTHA. The delta must be cleaned up to keep both the
// components in sync
func (att *AuditTablesTask) AuditFlows(cntx context.Context) error {
	if att.stop {
		return tasks.ErrTaskCancelError
	}

	var vc voltha.VolthaServiceClient
	if vc = att.device.VolthaClient(); vc == nil {
		logger.Error(ctx, "Flow Audit Failed: Voltha Client Unavailable")
		return nil
	}

	// ---------------------------------
	// Perform the audit of flows first
	// Retrieve the flows from the device
	f, err := vc.ListLogicalDeviceFlows(att.ctx, &common.ID{Id: att.device.ID})
	if err != nil {
		logger.Warnw(ctx, "Audit of flows failed", log.Fields{"Reason": err.Error()})
		return err
	}

	// defaultSuccessFlowStatus := intf.FlowStatus{
	// 	Device:      att.device.ID,
	// 	FlowModType: of.CommandAdd,
	// 	Status:      0,
	// 	Reason:      "",
	// }

	// Build the map for easy and faster processing
	rcvdFlows := make(map[uint64]*ofp.OfpFlowStats)
	volthaFlows := make(map[uint64]*ofp.OfpFlowStats)
	flowsToAdd := &of.VoltFlow{}
	flowsToAdd.SubFlows = make(map[uint64]*of.VoltSubFlow)
	for _, flow := range f.Items {
		rcvdFlows[flow.Cookie] = flow
		volthaFlows[flow.Cookie] = flow
	}

	att.device.flowLock.Lock()
	// Verify all flows that are in the controller but not in the device
	for _, flow := range att.device.flows {
		if att.stop {
			break
		}

		logger.Debugw(ctx, "Auditing Flow", log.Fields{"Cookie": flow.Cookie, "State": flow.State})
		if _, ok := rcvdFlows[flow.Cookie]; ok {
			// The flow exists in the device too. Just remove it from
			// the received flows & trigger flow success indication unless
			// the flow in del failure/pending state

			if flow.State != of.FlowDelFailure && flow.State != of.FlowDelPending {
				delete(rcvdFlows, flow.Cookie)
			} else {
				// Update flow delete count since we are retrying the flow delete due to failure
				att.device.UpdateFlowCount(cntx, flow.Cookie)
			}
			// defaultSuccessFlowStatus.Cookie = strconv.FormatUint(flow.Cookie, 10)
		} else {
			// Do not add the flow to device whose state was marked as delete failure
			// Remove the flow from DB as it is no longer reported by voltha
			if flow.State == of.FlowDelFailure {
				delete(att.device.flows, flow.Cookie)
				att.device.DelFlowFromDb(cntx, flow.Cookie)
				logger.Warnw(ctx, "Found flow with state DelFailure while adding to device, will remove from DB", log.Fields{"Cookie": flow.Cookie})
				continue
			}
			// The flow exists at the controller but not at the device
			// Push the flow to the device

			// If UST0 flow is missing in voltha but the UST1 flow is present in voltha,
			// then delete the UST1 flow from voltha and add both US flows to voltha
			if att.device.IsUSTable0Flow(ctx, flow) {
				logger.Debugw(ctx, "UST0 flow found, checking for UST1 flow", log.Fields{"Cookie": flow.Cookie})
				ust1Flow := att.device.GetDeviceFlow(ctx, flow, att.device.SerialNum, att.device.ID, false)
				if ust1Flow != nil {
					flowToDelete, ok := volthaFlows[ust1Flow.Cookie]
					if ok {
						// Sometimes the audit would happen even before all flows are installed for a service.
						// If the UST0 flow is still missing in voltha on second retry attempt, then remove the UST1 flow from voltha.
						if flow.FlowCount == 0 {
							att.device.UpdateFlowCount(cntx, flow.Cookie)
							continue
						}
						logger.Infow(ctx, "UST1 flow already present in Voltha, delete and install US flows", log.Fields{"UST1Flow": ust1Flow.Cookie, "UST0Flow": flow.Cookie})
						err = att.DeleteDeviceFlow(ctx, flowToDelete)
						if err == nil {
							flowsToAdd.SubFlows[ust1Flow.Cookie] = ust1Flow
						} else {
							logger.Warnw(ctx, "UST1 flow delete failed", log.Fields{"Cookie": ust1Flow.Cookie, "Reason": err.Error()})
						}
					}
				}
			}

			// If DST0 flow is missing in voltha but the DST1 flow is present in voltha,
			// then delete the DST1 flow from voltha and add both DS flows to voltha
			if att.device.IsDSTable0Flow(ctx, flow) {
				logger.Debugw(ctx, "DST0 flow found, checking for DST1 flow", log.Fields{"Cookie": flow.Cookie})
				dst1Flow := att.device.GetDeviceFlow(ctx, flow, att.device.SerialNum, att.device.ID, true)
				if dst1Flow != nil {
					flowToDelete, ok := volthaFlows[dst1Flow.Cookie]
					if ok {
						// Sometimes the audit would happen even before all flows are installed for a service.
						// If the DST0 flow is still missing in voltha on second retry attempt, then remove the DST1 flow from voltha.
						if flow.FlowCount == 0 {
							att.device.UpdateFlowCount(cntx, flow.Cookie)
							continue
						}
						logger.Infow(ctx, "DST1 flow already present in Voltha, delete and install DS flows", log.Fields{"DST1Flow": dst1Flow.Cookie, "DST0Flow": flow.Cookie})
						err = att.DeleteDeviceFlow(ctx, flowToDelete)
						if err == nil {
							flowsToAdd.SubFlows[dst1Flow.Cookie] = dst1Flow
						} else {
							logger.Warnw(ctx, "DST1 flow delete failed", log.Fields{"Cookie": dst1Flow.Cookie, "Reason": err.Error()})
						}
					}
				}
			}
			logger.Debugw(ctx, "Adding Flow To Missing Flows", log.Fields{"Cookie": flow.Cookie})
			if !att.device.IsFlowAddThresholdReached(flow.FlowCount, flow.Cookie) {
				flowsToAdd.SubFlows[flow.Cookie] = flow
				att.device.UpdateFlowCount(cntx, flow.Cookie)
			} else if flow.State != of.FlowDelFailure {
				// Release the lock before deactivating service, as we acquire the same lock to delete flows
				att.device.flowLock.Unlock()
				// If flow add threshold has reached, deactivate the service corresponding to the UNI
				GetController().CheckAndDeactivateService(cntx, flow, att.device.SerialNum, att.device.ID)
				// Acquire the lock again for processing remaining flows
				att.device.flowLock.Lock()
			}
		}
	}
	att.device.flowLock.Unlock()

	if !att.stop {
		//  The flows remaining in the received flows are the excess flows at
		// the device. Delete those flows
		att.DelExcessFlows(cntx, rcvdFlows)
		// Add the flows missing at the device
		att.AddMissingFlows(cntx, flowsToAdd)
	} else {
		err = tasks.ErrTaskCancelError
	}
	return err
}

// AddMissingFlows : The flows missing from the device are reinstalled att the audit
// The flows are added into a VoltFlow structure.
func (att *AuditTablesTask) AddMissingFlows(cntx context.Context, mflow *of.VoltFlow) {
	logger.Debugw(ctx, "Add Missing Flows", log.Fields{"Number": len(mflow.SubFlows)})
	mflow.Command = of.CommandAdd
	ofFlows := of.ProcessVoltFlow(att.device.ID, mflow.Command, mflow.SubFlows)
	var vc voltha.VolthaServiceClient
	var bwConsumedInfo of.BwAvailDetails
	if vc = att.device.VolthaClient(); vc == nil {
		logger.Error(ctx, "Update Flow Table Failed: Voltha Client Unavailable")
		return
	}
	for _, flow := range ofFlows {
		if flow.FlowMod != nil {
			if _, present := att.device.GetFlow(flow.FlowMod.Cookie); !present {
				logger.Warnw(ctx, "Flow Removed from DB. Ignoring Add Missing Flow", log.Fields{"Device": att.device.ID, "Cookie": flow.FlowMod.Cookie})
				continue
			}
		}
		var err error
		if _, err = vc.UpdateLogicalDeviceFlowTable(att.ctx, flow); err != nil {
			logger.Errorw(ctx, "Update Flow Table Failed", log.Fields{"Reason": err.Error()})
		}
		att.device.triggerFlowNotification(cntx, flow.FlowMod.Cookie, of.CommandAdd, bwConsumedInfo, err)
	}
}

// DelExcessFlows delete the excess flows held at the VOLTHA
func (att *AuditTablesTask) DelExcessFlows(cntx context.Context, flows map[uint64]*ofp.OfpFlowStats) {
	logger.Debugw(ctx, "Deleting Excess Flows", log.Fields{"Number of Flows": len(flows)})

	var vc voltha.VolthaServiceClient
	if vc = att.device.VolthaClient(); vc == nil {
		logger.Error(ctx, "Delete Excess Flows Failed: Voltha Client Unavailable")
		return
	}

	// Let's cycle through the flows to delete the excess flows
	for _, flow := range flows {
		if dbFlow, present := att.device.GetFlow(flow.Cookie); present {
			if dbFlow.State != of.FlowDelFailure && dbFlow.State != of.FlowDelPending {
				logger.Warnw(ctx, "Flow Present in DB. Ignoring Delete Excess Flow", log.Fields{"Device": att.device.ID, "Cookie": flow.Cookie})
				continue
			}
		} else {
			logger.Debugw(ctx, "Flow removed from DB after delete threshold reached. Ignoring Delete Excess Flow", log.Fields{"Device": att.device.ID, "Cookie": flow.Cookie})
			continue
		}

		logger.Debugw(ctx, "Deleting Flow", log.Fields{"Cookie": flow.Cookie})
		// Create the flowMod structure and fill it out
		flowMod := &ofp.OfpFlowMod{}
		flowMod.Cookie = flow.Cookie
		flowMod.TableId = flow.TableId
		flowMod.Command = ofp.OfpFlowModCommand_OFPFC_DELETE_STRICT
		flowMod.IdleTimeout = flow.IdleTimeout
		flowMod.HardTimeout = flow.HardTimeout
		flowMod.Priority = flow.Priority
		flowMod.BufferId = of.DefaultBufferID
		flowMod.OutPort = of.DefaultOutPort
		flowMod.OutGroup = of.DefaultOutGroup
		flowMod.Flags = flow.Flags
		flowMod.Match = flow.Match
		flowMod.Instructions = flow.Instructions

		// Create FlowTableUpdate
		flowUpdate := &ofp.FlowTableUpdate{
			Id:      att.device.ID,
			FlowMod: flowMod,
		}

		var err error
		if _, err = vc.UpdateLogicalDeviceFlowTable(att.ctx, flowUpdate); err != nil {
			logger.Errorw(ctx, "Flow Audit Delete Failed", log.Fields{"Reason": err.Error()})
		}
		att.device.triggerFlowNotification(cntx, flow.Cookie, of.CommandDel, of.BwAvailDetails{}, err)
	}
}

func (att *AuditTablesTask) DeleteDeviceFlow(cntx context.Context, flow *ofp.OfpFlowStats) error {
	logger.Debugw(ctx, "Deleting Flow", log.Fields{"Cookie": flow.Cookie})

	// Create the flowMod structure and fill it out
	flowMod := &ofp.OfpFlowMod{}
	flowMod.Cookie = flow.Cookie
	flowMod.TableId = flow.TableId
	flowMod.Command = ofp.OfpFlowModCommand_OFPFC_DELETE_STRICT
	flowMod.IdleTimeout = flow.IdleTimeout
	flowMod.HardTimeout = flow.HardTimeout
	flowMod.Priority = flow.Priority
	flowMod.BufferId = of.DefaultBufferID
	flowMod.OutPort = of.DefaultOutPort
	flowMod.OutGroup = of.DefaultOutGroup
	flowMod.Flags = flow.Flags
	flowMod.Match = flow.Match
	flowMod.Instructions = flow.Instructions

	// Create FlowTableUpdate
	flowUpdate := &ofp.FlowTableUpdate{
		Id:      att.device.ID,
		FlowMod: flowMod,
	}

	var err error
	var vc voltha.VolthaServiceClient
	if vc = att.device.VolthaClient(); vc == nil {
		logger.Error(ctx, "Delete flow failed: Voltha Client Unavailable")
		return errors.New("voltha client unavailable")
	}

	if _, err = vc.UpdateLogicalDeviceFlowTable(att.ctx, flowUpdate); err != nil {
		logger.Errorw(ctx, "Flow delete failed", log.Fields{"Reason": err.Error()})
		return err
	}
	return nil
}

// AuditGroups audit the groups which includes fetching the existing groups at the
// voltha and identifying the delta between the ones held here and the
// ones held at VOLTHA. The delta must be cleaned up to keep both the
// components in sync
func (att *AuditTablesTask) AuditGroups() (map[uint32]*ofp.OfpGroupDesc, error) {
	// Build the map for easy and faster processing
	rcvdGroups = make(map[uint32]*ofp.OfpGroupDesc)

	if att.stop {
		return rcvdGroups, tasks.ErrTaskCancelError
	}

	var vc voltha.VolthaServiceClient
	if vc = att.device.VolthaClient(); vc == nil {
		logger.Error(ctx, "Group Audit Failed: Voltha Client Unavailable")
		return rcvdGroups, nil
	}

	// ---------------------------------
	// Perform the audit of groups first
	// Retrieve the groups from the device
	g, err := vc.ListLogicalDeviceFlowGroups(att.ctx, &common.ID{Id: att.device.ID})
	if err != nil {
		logger.Warnw(ctx, "Audit of groups failed", log.Fields{"Reason": err.Error()})
		return rcvdGroups, err
	}

	groupsToAdd = []*of.Group{}
	groupsToMod = []*of.Group{}
	for _, group := range g.Items {
		rcvdGroups[group.Desc.GroupId] = group.Desc
	}
	logger.Debugw(ctx, "Received Groups", log.Fields{"Groups": rcvdGroups})

	// Verify all groups that are in the controller but not in the device
	att.device.groups.Range(att.compareGroupEntries)

	if !att.stop {
		// Add the groups missing at the device
		logger.Debugw(ctx, "Missing Groups", log.Fields{"Groups": groupsToAdd})
		att.AddMissingGroups(groupsToAdd)

		// Update groups with group member mismatch
		logger.Debugw(ctx, "Modify Groups", log.Fields{"Groups": groupsToMod})
		att.UpdateMismatchGroups(groupsToMod)

		// Note: Excess groups will be deleted after ensuring the connected
		// flows are also removed as part fo audit flows
	} else {
		err = tasks.ErrTaskCancelError
	}
	// The groups remaining in the received groups are the excess groups at
	// the device
	return rcvdGroups, err
}

// compareGroupEntries to compare the group entries
func (att *AuditTablesTask) compareGroupEntries(key, value interface{}) bool {
	if att.stop {
		return false
	}

	groupID := key.(uint32)
	dbGroup := value.(*of.Group)
	logger.Debugw(ctx, "Auditing Group", log.Fields{"Groupid": groupID})
	if rcvdGrp, ok := rcvdGroups[groupID]; ok {
		// The group exists in the device too.
		// Compare the group members and add to modify list if required
		compareGroupMembers(dbGroup, rcvdGrp)
		delete(rcvdGroups, groupID)
	} else {
		// The group exists at the controller but not at the device
		// Push the group to the device
		logger.Debugw(ctx, "Adding Group To Missing Groups", log.Fields{"GroupId": groupID})
		groupsToAdd = append(groupsToAdd, value.(*of.Group))
	}
	return true
}

func compareGroupMembers(refGroup *of.Group, rcvdGroup *ofp.OfpGroupDesc) {
	portList := []uint32{}
	refPortList := []uint32{}

	// Collect port list from response Group Mod structure
	// If PON is configured even for one group, then only PON shall be considered for compared for all groups
	for _, bucket := range rcvdGroup.Buckets {
		for _, actionBucket := range bucket.Actions {
			if actionBucket.Type == ofp.OfpActionType_OFPAT_OUTPUT {
				action := actionBucket.GetOutput()
				portList = append(portList, action.Port)
			}
		}
	}

	refPortList = append(refPortList, refGroup.Buckets...)

	// Is port list differs, trigger group update
	if !util.IsSliceSame(refPortList, portList) {
		groupsToMod = append(groupsToMod, refGroup)
	}
}

// AddMissingGroups - addmissing groups to Voltha
func (att *AuditTablesTask) AddMissingGroups(groupList []*of.Group) {
	att.PushGroups(groupList, of.GroupCommandAdd)
}

// UpdateMismatchGroups - updates mismatched groups to Voltha
func (att *AuditTablesTask) UpdateMismatchGroups(groupList []*of.Group) {
	att.PushGroups(groupList, of.GroupCommandMod)
}

// PushGroups - The groups missing/to be updated in the device are reinstalled att the audit
func (att *AuditTablesTask) PushGroups(groupList []*of.Group, grpCommand of.GroupCommand) {
	logger.Debugw(ctx, "Pushing Groups", log.Fields{"Number": len(groupList), "Command": grpCommand})

	var vc voltha.VolthaServiceClient
	if vc = att.device.VolthaClient(); vc == nil {
		logger.Error(ctx, "Update Group Table Failed: Voltha Client Unavailable")
		return
	}
	for _, group := range groupList {
		group.Command = grpCommand
		groupUpdate := of.CreateGroupTableUpdate(group)
		if _, err := vc.UpdateLogicalDeviceFlowGroupTable(att.ctx, groupUpdate); err != nil {
			logger.Errorw(ctx, "Update Group Table Failed", log.Fields{"Reason": err.Error()})
		}
	}
}

// DelExcessGroups - Delete the excess groups held at the VOLTHA
func (att *AuditTablesTask) DelExcessGroups(groups map[uint32]*ofp.OfpGroupDesc) {
	logger.Debugw(ctx, "Deleting Excess Groups", log.Fields{"Number of Groups": len(groups)})

	var vc voltha.VolthaServiceClient
	if vc = att.device.VolthaClient(); vc == nil {
		logger.Error(ctx, "Delete Excess Groups Failed: Voltha Client Unavailable")
		return
	}

	// Let's cycle through the groups to delete the excess groups
	for _, groupDesc := range groups {
		logger.Debugw(ctx, "Deleting Group", log.Fields{"GroupId": groupDesc.GroupId})
		group := &of.Group{}
		group.Device = att.device.ID
		group.GroupID = groupDesc.GroupId

		// Group Members should be deleted before triggered group delete
		group.Command = of.GroupCommandMod
		groupUpdate := of.CreateGroupTableUpdate(group)
		if _, err := vc.UpdateLogicalDeviceFlowGroupTable(att.ctx, groupUpdate); err != nil {
			logger.Errorw(ctx, "Update Group Table Failed", log.Fields{"Reason": err.Error()})
		}

		group.Command = of.GroupCommandDel
		groupUpdate = of.CreateGroupTableUpdate(group)
		if _, err := vc.UpdateLogicalDeviceFlowGroupTable(att.ctx, groupUpdate); err != nil {
			logger.Errorw(ctx, "Update Group Table Failed", log.Fields{"Reason": err.Error()})
		}
	}
}

func (att *AuditTablesTask) AuditPorts() error {
	if att.stop {
		return tasks.ErrTaskCancelError
	}

	var vc voltha.VolthaServiceClient
	if vc = att.device.VolthaClient(); vc == nil {
		logger.Error(ctx, "Flow Audit Failed: Voltha Client Unavailable")
		return nil
	}
	ofpps, err := vc.ListLogicalDevicePorts(att.ctx, &common.ID{Id: att.device.ID})
	if err != nil {
		return err
	}

	// Compute the difference between the ports received and ports at VGC
	// First build a map of all the received ports under missing ports. We
	// will eliminate the ports that are in the device from the missing ports
	// so that the elements remaining are missing ports. The ones that are
	// not in missing ports are added to excess ports which should be deleted
	// from the VGC.
	missingPorts := make(map[uint32]*ofp.OfpPort)
	for _, ofpp := range ofpps.Items {
		missingPorts[ofpp.OfpPort.PortNo] = ofpp.OfpPort
	}

	excessPorts := make(map[uint32]*DevicePort)
	processPortState := func(id uint32, vgcPort *DevicePort) {
		logger.Debugw(ctx, "Process Port State Ind", log.Fields{"Port No": vgcPort.ID, "Port Name": vgcPort.Name})

		if ofpPort, ok := missingPorts[id]; ok {
			if vgcPort.Name != ofpPort.Name {
				logger.Infow(ctx, "Port Name Mismatch", log.Fields{"vgcPort": vgcPort.Name, "ofpPort": ofpPort.Name, "ID": id})
				att.DeleteMismatchPorts(ctx, vgcPort, ofpPort.Name)
				return
			}
			if ((vgcPort.State == PortStateDown) && (ofpPort.State == uint32(ofp.OfpPortState_OFPPS_LIVE))) || ((vgcPort.State == PortStateUp) && (ofpPort.State != uint32(ofp.OfpPortState_OFPPS_LIVE))) {
				// This port exists in the received list and the map at
				// VGC. This is common so delete it
				logger.Infow(ctx, "Port State Mismatch", log.Fields{"Port": vgcPort.ID, "OfpPort": ofpPort.PortNo, "ReceivedState": ofpPort.State, "CurrentState": vgcPort.State})
				att.device.ProcessPortState(ctx, ofpPort.PortNo, ofpPort.State, ofpPort.Name, false)
			}
			delete(missingPorts, id)
		} else {
			// This port is missing from the received list. This is an
			// excess port at VGC. This must be added to excess ports
			excessPorts[id] = vgcPort
		}
		logger.Debugw(ctx, "Processed Port State Ind", log.Fields{"Port No": vgcPort.ID, "Port Name": vgcPort.Name})
	}
	// 1st process the NNI port before all other ports so that the device state can be updated.
	for id, vgcPort := range att.device.PortsByID {
		if util.IsNniPort(id) {
			logger.Debugw(ctx, "Processing NNI port state", log.Fields{"Port ID": vgcPort.ID, "Port Name": vgcPort.Name})
			processPortState(id, vgcPort)
		}
	}

	for id, vgcPort := range att.device.PortsByID {
		if util.IsNniPort(id) {
			// NNI port already processed
			continue
		}
		if att.stop {
			break
		}
		processPortState(id, vgcPort)
	}

	if att.stop {
		logger.Warnw(ctx, "Audit Device Task Canceled", log.Fields{"Context": att.ctx, "Task": att.taskID})
		return tasks.ErrTaskCancelError
	}
	att.AddMissingPorts(ctx, missingPorts)
	att.DelExcessPorts(ctx, excessPorts)
	return nil
}

// AddMissingPorts to add the missing ports
func (att *AuditTablesTask) AddMissingPorts(cntx context.Context, mps map[uint32]*ofp.OfpPort) {
	logger.Debugw(ctx, "Device Audit - Add Missing Ports", log.Fields{"NumPorts": len(mps)})

	addMissingPort := func(mp *ofp.OfpPort) {
		logger.Debugw(ctx, "Process Port Add Ind", log.Fields{"Port No": mp.PortNo, "Port Name": mp.Name})

		if err := att.device.AddPort(cntx, mp); err != nil {
			logger.Warnw(ctx, "AddPort Failed", log.Fields{"No": mp.PortNo, "Name": mp.Name, "Reason": err})
		}
		if mp.State == uint32(ofp.OfpPortState_OFPPS_LIVE) {
			att.device.ProcessPortState(cntx, mp.PortNo, mp.State, mp.Name, false)
		}
		logger.Debugw(ctx, "Processed Port Add Ind", log.Fields{"Port No": mp.PortNo, "Port Name": mp.Name})
	}

	// 1st process the NNI port before all other ports so that the flow provisioning for UNIs can be enabled
	for portNo, mp := range mps {
		if util.IsNniPort(portNo) {
			logger.Debugw(ctx, "Adding Missing NNI port", log.Fields{"PortNo": mp.PortNo, "Port Name": mp.Name, "Port Status": mp.State})
			addMissingPort(mp)
		}
	}

	for portNo, mp := range mps {
		if !util.IsNniPort(portNo) {
			addMissingPort(mp)
		}
	}
}

// DelExcessPorts to delete the excess ports
func (att *AuditTablesTask) DelExcessPorts(cntx context.Context, eps map[uint32]*DevicePort) {
	logger.Debugw(ctx, "Device Audit - Delete Excess Ports", log.Fields{"NumPorts": len(eps)})
	for portNo, ep := range eps {
		// Now delete the port from the device @ VGC
		logger.Debugw(ctx, "Device Audit - Deleting Port", log.Fields{"PortId": portNo})
		if err := att.device.DelPort(cntx, ep.ID, ep.Name); err != nil {
			logger.Warnw(ctx, "DelPort Failed", log.Fields{"PortId": portNo, "Reason": err})
		}
	}
}

func (att *AuditTablesTask) DeleteMismatchPorts(cntx context.Context, vgcPort *DevicePort, ofpPortName string) {
	logger.Infow(ctx, "Deleting port in VGC due to mismatch with voltha", log.Fields{"vgcPortID": vgcPort.ID, "vgcPortName": vgcPort.Name})
	_ = att.device.DelPort(cntx, vgcPort.ID, vgcPort.Name)
	if p := att.device.GetPortByName(ofpPortName); p != nil {
		logger.Infow(ctx, "Delete port by name in VGC due to mismatch with voltha", log.Fields{"portID": p.ID, "portName": p.Name})
		_ = att.device.DelPort(cntx, p.ID, p.Name)
	}
}