/*
 * Copyright 2020-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 route

import (
	"context"
	"errors"
	"fmt"
	"sync"

	"github.com/opencord/voltha-lib-go/v4/pkg/log"
	"github.com/opencord/voltha-protos/v4/go/voltha"
	"google.golang.org/grpc/codes"
	"google.golang.org/grpc/status"
)

var ErrNoRoute = errors.New("no route")

// Hop represent a route hop
type Hop struct {
	DeviceID string
	Ingress  uint32
	Egress   uint32
}

// PathID is the identification of a route between two logical ports
type PathID struct {
	Ingress uint32
	Egress  uint32
}

type OFPortLink struct {
	Ingress uint32
	Egress  uint32
}

// listDevicePortsFunc returns device ports
type listDevicePortsFunc func(ctx context.Context, id string) (map[uint32]*voltha.Port, error)

// DeviceRoutes represent the set of routes between logical ports of a logical device
type DeviceRoutes struct {
	logicalDeviceID     string
	rootDeviceID        string
	listDevicePorts     listDevicePortsFunc
	logicalPorts        map[uint32]*voltha.LogicalPort
	RootPorts           map[uint32]uint32
	rootPortsLock       sync.RWMutex
	Routes              map[PathID][]Hop
	routeBuildLock      sync.RWMutex
	devicesPonPorts     map[string][]*voltha.Port
	childConnectionPort map[string]uint32
}

// NewDeviceRoutes creates device graph instance
func NewDeviceRoutes(logicalDeviceID, rootDeviceID string, deviceMgr listDevicePortsFunc) *DeviceRoutes {
	return &DeviceRoutes{
		logicalDeviceID:     logicalDeviceID,
		rootDeviceID:        rootDeviceID,
		listDevicePorts:     deviceMgr,
		RootPorts:           make(map[uint32]uint32),
		Routes:              make(map[PathID][]Hop),
		devicesPonPorts:     make(map[string][]*voltha.Port),
		childConnectionPort: make(map[string]uint32),
		logicalPorts:        make(map[uint32]*voltha.LogicalPort),
	}
}

//IsRootPort returns true if the port is a root port on a logical device
func (dr *DeviceRoutes) IsRootPort(port uint32) bool {
	dr.rootPortsLock.RLock()
	defer dr.rootPortsLock.RUnlock()
	_, exist := dr.RootPorts[port]
	return exist
}

func (dr *DeviceRoutes) GetRoute(ctx context.Context, ingress, egress uint32) ([]Hop, error) {
	dr.routeBuildLock.Lock()
	defer dr.routeBuildLock.Unlock()

	if route, exist := dr.Routes[PathID{Ingress: ingress, Egress: egress}]; exist {
		return route, nil
	}

	uniPort, nniPort, err := dr.getLogicalPorts(ingress, egress)
	if err != nil {
		return nil, fmt.Errorf("no route from:%d to:%d %w", ingress, egress, err)
	}

	childPonPort, err := dr.getChildPonPort(ctx, uniPort.DeviceId)
	if err != nil {
		return nil, err
	}
	rootDevicePonPort, err := dr.getParentPonPort(ctx, uniPort.DeviceId)
	if err != nil {
		return nil, err
	}

	dr.Routes[PathID{Ingress: nniPort.OfpPort.PortNo, Egress: uniPort.DevicePortNo}] = []Hop{
		{DeviceID: nniPort.DeviceId, Ingress: nniPort.DevicePortNo, Egress: rootDevicePonPort},
		{DeviceID: uniPort.DeviceId, Ingress: childPonPort, Egress: uniPort.DevicePortNo},
	}
	dr.Routes[PathID{Ingress: uniPort.DevicePortNo, Egress: nniPort.OfpPort.PortNo}] = getReverseRoute(
		dr.Routes[PathID{Ingress: nniPort.OfpPort.PortNo, Egress: uniPort.DevicePortNo}])

	return dr.Routes[PathID{Ingress: ingress, Egress: egress}], nil

}

//ComputeRoutes calculates all the routes between the logical ports.  This will clear up any existing route
func (dr *DeviceRoutes) ComputeRoutes(ctx context.Context, lps map[uint32]*voltha.LogicalPort) error {
	dr.routeBuildLock.Lock()
	defer dr.routeBuildLock.Unlock()

	logger.Debugw(ctx, "computing-all-routes", log.Fields{"len-logical-ports": len(lps)})
	var err error
	defer func() {
		// On error, clear the routes - any flow request or a port add/delete will trigger the rebuild
		if err != nil {
			dr.reset()
		}
	}()

	if len(lps) < 2 {
		return fmt.Errorf("not enough logical port :%w", ErrNoRoute)
	}

	dr.reset()

	// Setup the physical ports to logical ports map, the nni ports as well as the root ports map
	physPortToLogicalPortMap := make(map[string]uint32)
	nniPorts := make([]*voltha.LogicalPort, 0)
	for _, lp := range lps {
		physPortToLogicalPortMap[concatDeviceIDPortID(lp.DeviceId, lp.DevicePortNo)] = lp.OfpPort.PortNo
		if lp.RootPort {
			nniPorts = append(nniPorts, lp)
			dr.RootPorts[lp.OfpPort.PortNo] = lp.OfpPort.PortNo
		}
		dr.logicalPorts[lp.OfpPort.PortNo] = lp
	}

	if len(nniPorts) == 0 {
		return fmt.Errorf("no nni port :%w", ErrNoRoute)
	}
	var copyFromNNIPort *voltha.LogicalPort
	for idx, nniPort := range nniPorts {
		if idx == 0 {
			copyFromNNIPort = nniPort
		} else if len(dr.Routes) > 0 {
			dr.copyFromExistingNNIRoutes(nniPort, copyFromNNIPort)
			return nil
		}
		// Get root device
		rootDeviceID := nniPort.DeviceId
		rootDevicePorts, err := dr.getDeviceWithCacheUpdate(ctx, nniPort.DeviceId)
		if err != nil {
			return err
		}
		if len(rootDevicePorts) == 0 {
			err = status.Errorf(codes.FailedPrecondition, "no-port-%s", rootDeviceID)
			return err
		}
		for _, rootDevicePort := range rootDevicePorts {
			if rootDevicePort.Type == voltha.Port_PON_OLT {
				logger.Debugw(ctx, "peers", log.Fields{"root-device-id": rootDeviceID, "port-no": rootDevicePort.PortNo, "len-peers": len(rootDevicePort.Peers)})
				for _, rootDevicePeer := range rootDevicePort.Peers {
					childDeviceID := rootDevicePeer.DeviceId
					childDevicePorts, err := dr.getDeviceWithCacheUpdate(ctx, rootDevicePeer.DeviceId)
					if err != nil {
						return err
					}
					childPonPort, err := dr.getChildPonPort(ctx, childDeviceID)
					if err != nil {
						return err
					}
					for _, childDevicePort := range childDevicePorts {
						if childDevicePort.Type == voltha.Port_ETHERNET_UNI {
							childLogicalPort, exist := physPortToLogicalPortMap[concatDeviceIDPortID(childDeviceID, childDevicePort.PortNo)]
							if !exist {
								// This can happen if this logical port has not been created yet for that device
								continue
							}
							dr.Routes[PathID{Ingress: nniPort.OfpPort.PortNo, Egress: childLogicalPort}] = []Hop{
								{DeviceID: rootDeviceID, Ingress: nniPort.DevicePortNo, Egress: rootDevicePort.PortNo},
								{DeviceID: childDeviceID, Ingress: childPonPort, Egress: childDevicePort.PortNo},
							}
							dr.Routes[PathID{Ingress: childLogicalPort, Egress: nniPort.OfpPort.PortNo}] = getReverseRoute(
								dr.Routes[PathID{Ingress: nniPort.OfpPort.PortNo, Egress: childLogicalPort}])
						}
					}
				}
			}
		}
	}
	return nil
}

// AddPort augments the current set of routes with new routes corresponding to the logical port "lp".  If the routes have
// not been built yet then use logical port "lps" to compute all current routes (lps includes lp)
func (dr *DeviceRoutes) AddPort(ctx context.Context, lp *voltha.LogicalPort, deviceID string, devicePorts map[uint32]*voltha.Port, lps map[uint32]*voltha.LogicalPort) error {
	logger.Debugw(ctx, "add-port-to-routes", log.Fields{"port": lp, "count-logical-ports": len(lps)})

	// Adding NNI port
	if lp.RootPort {
		return dr.AddNNIPort(ctx, lp, deviceID, devicePorts, lps)
	}

	// Adding UNI port
	return dr.AddUNIPort(ctx, lp, deviceID, devicePorts, lps)
}

// AddUNIPort setup routes between the logical UNI port lp and all registered NNI ports
func (dr *DeviceRoutes) AddUNIPort(ctx context.Context, lp *voltha.LogicalPort, deviceID string, devicePorts map[uint32]*voltha.Port, lps map[uint32]*voltha.LogicalPort) error {
	logger.Debugw(ctx, "add-uni-port-to-routes", log.Fields{"port": lp, "count-logical-ports": len(lps)})

	dr.routeBuildLock.Lock()
	defer dr.routeBuildLock.Unlock()

	// Add port to logical ports
	dr.logicalPorts[lp.OfpPort.PortNo] = lp

	// Update internal structures with device data
	dr.updateCache(deviceID, devicePorts)

	// Adding a UNI port
	childPonPort, err := dr.getChildPonPort(ctx, lp.DeviceId)
	if err != nil {
		return err
	}
	rootDevicePonPort, err := dr.getParentPonPort(ctx, deviceID)
	if err != nil {
		return err
	}

	// Adding a UNI port
	for _, lPort := range lps {
		if lPort.RootPort {
			dr.Routes[PathID{Ingress: lPort.OfpPort.PortNo, Egress: lp.OfpPort.PortNo}] = []Hop{
				{DeviceID: lPort.DeviceId, Ingress: lPort.DevicePortNo, Egress: rootDevicePonPort},
				{DeviceID: lp.DeviceId, Ingress: childPonPort, Egress: lp.DevicePortNo},
			}
			dr.Routes[PathID{Ingress: lp.OfpPort.PortNo, Egress: lPort.OfpPort.PortNo}] = getReverseRoute(
				dr.Routes[PathID{Ingress: lPort.OfpPort.PortNo, Egress: lp.OfpPort.PortNo}])
		}
	}
	return nil
}

// AddNNIPort setup routes between the logical NNI port lp and all registered UNI ports
func (dr *DeviceRoutes) AddNNIPort(ctx context.Context, lp *voltha.LogicalPort, deviceID string, devicePorts map[uint32]*voltha.Port, lps map[uint32]*voltha.LogicalPort) error {
	logger.Debugw(ctx, "add-port-to-routes", log.Fields{"port": lp, "logical-ports-count": len(lps), "device-id": deviceID})

	dr.routeBuildLock.Lock()
	defer dr.routeBuildLock.Unlock()

	// Update internal structures with device data
	dr.updateCache(deviceID, devicePorts)

	// Setup the physical ports to logical ports map, the nni ports as well as the root ports map
	physPortToLogicalPortMap := make(map[string]uint32)
	for _, lp := range lps {
		physPortToLogicalPortMap[concatDeviceIDPortID(lp.DeviceId, lp.DevicePortNo)] = lp.OfpPort.PortNo
		if lp.RootPort {
			dr.rootPortsLock.Lock()
			dr.RootPorts[lp.OfpPort.PortNo] = lp.OfpPort.PortNo
			dr.rootPortsLock.Unlock()
		}
		dr.logicalPorts[lp.OfpPort.PortNo] = lp
	}

	for _, rootDevicePort := range devicePorts {
		if rootDevicePort.Type == voltha.Port_PON_OLT {
			logger.Debugw(ctx, "peers", log.Fields{"root-device-id": deviceID, "port-no": rootDevicePort.PortNo, "len-peers": len(rootDevicePort.Peers)})
			for _, rootDevicePeer := range rootDevicePort.Peers {
				childDeviceID := rootDevicePeer.DeviceId
				childDevicePorts, err := dr.getDeviceWithCacheUpdate(ctx, rootDevicePeer.DeviceId)
				if err != nil {
					continue
				}

				childPonPort, err := dr.getChildPonPort(ctx, childDeviceID)
				if err != nil {
					continue
				}

				for _, childDevicePort := range childDevicePorts {
					childLogicalPort, exist := physPortToLogicalPortMap[concatDeviceIDPortID(childDeviceID, childDevicePort.PortNo)]
					if !exist {
						// This can happen if this logical port has not been created yet for that device
						continue
					}

					if childDevicePort.Type == voltha.Port_ETHERNET_UNI {
						dr.Routes[PathID{Ingress: lp.OfpPort.PortNo, Egress: childLogicalPort}] = []Hop{
							{DeviceID: deviceID, Ingress: lp.DevicePortNo, Egress: rootDevicePort.PortNo},
							{DeviceID: childDeviceID, Ingress: childPonPort, Egress: childDevicePort.PortNo},
						}
						dr.Routes[PathID{Ingress: childLogicalPort, Egress: lp.OfpPort.PortNo}] = getReverseRoute(
							dr.Routes[PathID{Ingress: lp.OfpPort.PortNo, Egress: childLogicalPort}])
					}
				}
			}
		}
	}
	return nil
}

// AddAllPorts setups up new routes using all ports on the device. lps includes the device's logical port
func (dr *DeviceRoutes) AddAllPorts(ctx context.Context, deviceID string, devicePorts map[uint32]*voltha.Port, lps map[uint32]*voltha.LogicalPort) error {
	logger.Debugw(ctx, "add-all-port-to-routes", log.Fields{"logical-ports-count": len(lps), "device-id": deviceID})
	for _, lp := range lps {
		if lp.DeviceId == deviceID {
			if err := dr.AddPort(ctx, lp, deviceID, devicePorts, lps); err != nil {
				return err
			}
		}
	}
	return nil
}

// Print prints routes
func (dr *DeviceRoutes) Print(ctx context.Context) error {
	dr.routeBuildLock.RLock()
	defer dr.routeBuildLock.RUnlock()
	logger.Debugw(ctx, "Print", log.Fields{"logical-device-id": dr.logicalDeviceID, "logical-ports": dr.logicalPorts})
	if logger.V(log.DebugLevel) {
		output := ""
		routeNumber := 1
		for k, v := range dr.Routes {
			key := fmt.Sprintf("LP:%d->LP:%d", k.Ingress, k.Egress)
			val := ""
			for _, i := range v {
				val += fmt.Sprintf("{%d->%s->%d},", i.Ingress, i.DeviceID, i.Egress)
			}
			val = val[:len(val)-1]
			output += fmt.Sprintf("%d:{%s=>%s}   ", routeNumber, key, fmt.Sprintf("[%s]", val))
			routeNumber++
		}
		if len(dr.Routes) == 0 {
			logger.Debugw(ctx, "no-routes-found", log.Fields{"logical-device-id": dr.logicalDeviceID})
		} else {
			logger.Debugw(ctx, "graph_routes", log.Fields{"logical-device-id": dr.logicalDeviceID, "Routes": output})
		}
	}
	return nil
}

// isUpToDate returns true if device is up to date
func (dr *DeviceRoutes) isUpToDate(ldPorts map[uint32]*voltha.LogicalPort) bool {
	dr.routeBuildLock.Lock()
	defer dr.routeBuildLock.Unlock()
	numNNI, numUNI := 0, 0
	if ldPorts != nil {
		if len(dr.logicalPorts) != len(ldPorts) {
			return false
		}
		numNNI = len(dr.RootPorts)
		numUNI = len(ldPorts) - numNNI
	}
	return len(dr.Routes) == numNNI*numUNI*2
}

// IsRoutesEmpty returns true if there are no routes
func (dr *DeviceRoutes) IsRoutesEmpty() bool {
	dr.routeBuildLock.RLock()
	defer dr.routeBuildLock.RUnlock()
	return len(dr.Routes) == 0
}

// GetHalfRoute returns a half route that has only the egress hop set or the ingress hop set
func (dr *DeviceRoutes) GetHalfRoute(nniAsEgress bool, ingress, egress uint32) ([]Hop, error) {
	dr.routeBuildLock.RLock()
	defer dr.routeBuildLock.RUnlock()
	routes := make([]Hop, 0)
	for routeLink, path := range dr.Routes {
		// If nniAsEgress is set then the half route will only have the egress hop set where the egress port needs to be
		// an NNI port
		if nniAsEgress {
			// Prioritize a specific egress NNI port if set
			if egress != 0 && dr.IsRootPort(egress) && routeLink.Egress == egress {
				routes = append(routes, Hop{})
				routes = append(routes, path[1])
				return routes, nil
			}
			if egress == 0 && dr.IsRootPort(routeLink.Egress) {
				routes = append(routes, Hop{})
				routes = append(routes, path[1])
				return routes, nil
			}
		} else {
			// Here we use the first route whose ingress port matches the ingress input parameter
			if ingress != 0 && routeLink.Ingress == ingress {
				routes = append(routes, path[0])
				routes = append(routes, Hop{})
				return routes, nil
			}
		}
	}
	return routes, fmt.Errorf("no half route found for ingress port %d, egress port %d and nni as egress %t", ingress, egress, nniAsEgress)
}

//getDeviceWithCacheUpdate returns the from the model and updates the PON ports map of that device.
func (dr *DeviceRoutes) getDeviceWithCacheUpdate(ctx context.Context, deviceID string) (map[uint32]*voltha.Port, error) {
	devicePorts, err := dr.listDevicePorts(ctx, deviceID)
	if err != nil {
		logger.Errorw(ctx, "device-not-found", log.Fields{"device-id": deviceID, "error": err})
		return nil, err
	}
	dr.updateCache(deviceID, devicePorts)
	return devicePorts, nil
}

//copyFromExistingNNIRoutes copies routes from an existing set of NNI routes
func (dr *DeviceRoutes) copyFromExistingNNIRoutes(newNNIPort *voltha.LogicalPort, copyFromNNIPort *voltha.LogicalPort) {
	updatedRoutes := make(map[PathID][]Hop)
	for key, val := range dr.Routes {
		if key.Ingress == copyFromNNIPort.OfpPort.PortNo {
			updatedRoutes[PathID{Ingress: newNNIPort.OfpPort.PortNo, Egress: key.Egress}] = []Hop{
				{DeviceID: newNNIPort.DeviceId, Ingress: newNNIPort.DevicePortNo, Egress: val[0].Egress},
				val[1],
			}
		}
		if key.Egress == copyFromNNIPort.OfpPort.PortNo {
			updatedRoutes[PathID{Ingress: key.Ingress, Egress: newNNIPort.OfpPort.PortNo}] = []Hop{
				val[0],
				{DeviceID: newNNIPort.DeviceId, Ingress: val[1].Ingress, Egress: newNNIPort.DevicePortNo},
			}
		}
		updatedRoutes[key] = val
	}
	dr.Routes = updatedRoutes
}

// reset cleans up the device graph
func (dr *DeviceRoutes) reset() {
	dr.rootPortsLock.Lock()
	dr.RootPorts = make(map[uint32]uint32)
	dr.rootPortsLock.Unlock()
	dr.Routes = make(map[PathID][]Hop)
	dr.logicalPorts = make(map[uint32]*voltha.LogicalPort)
	dr.devicesPonPorts = make(map[string][]*voltha.Port)
	dr.childConnectionPort = make(map[string]uint32)
}

//concatDeviceIdPortId formats a portid using the device id and the port number
func concatDeviceIDPortID(deviceID string, portNo uint32) string {
	return fmt.Sprintf("%s:%d", deviceID, portNo)
}

//getReverseRoute returns the reverse of the route
func getReverseRoute(route []Hop) []Hop {
	reverse := make([]Hop, len(route))
	for i, j := 0, len(route)-1; j >= 0; i, j = i+1, j-1 {
		reverse[i].DeviceID, reverse[i].Ingress, reverse[i].Egress = route[j].DeviceID, route[j].Egress, route[j].Ingress
	}
	return reverse
}

// getChildPonPort returns the child PON port number either from cache or from the model. If it is from the model then
// it updates the PON ports map of that device.
func (dr *DeviceRoutes) getChildPonPort(ctx context.Context, deviceID string) (uint32, error) {
	if port, exist := dr.devicesPonPorts[deviceID]; exist {
		// Return only the first PON port of that child device
		return port[0].PortNo, nil
	}

	// Get child device from model
	if _, err := dr.getDeviceWithCacheUpdate(ctx, deviceID); err != nil {
		logger.Errorw(ctx, "device-not-found", log.Fields{"device-id": deviceID, "error": err})
		return 0, err
	}

	// Try again
	if port, exist := dr.devicesPonPorts[deviceID]; exist {
		// Return only the first PON port of that child device
		return port[0].PortNo, nil
	}

	return 0, fmt.Errorf("pon port not found %s", deviceID)
}

// getParentPonPort returns the parent PON port of the child device
func (dr *DeviceRoutes) getParentPonPort(ctx context.Context, childDeviceID string) (uint32, error) {
	if pNo, exist := dr.childConnectionPort[childDeviceID]; exist {
		return pNo, nil
	}

	// Get parent device from the model
	if _, err := dr.getDeviceWithCacheUpdate(ctx, dr.rootDeviceID); err != nil {
		logger.Errorw(ctx, "device-not-found", log.Fields{"device-id": dr.rootDeviceID, "error": err})
		return 0, err
	}
	// Try again
	if pNo, exist := dr.childConnectionPort[childDeviceID]; exist {
		return pNo, nil
	}
	return 0, fmt.Errorf("pon port associated with child device %s not found", childDeviceID)
}

func (dr *DeviceRoutes) updateCache(deviceID string, devicePorts map[uint32]*voltha.Port) {
	for _, port := range devicePorts {
		if port.Type == voltha.Port_PON_ONU || port.Type == voltha.Port_PON_OLT {
			dr.devicesPonPorts[deviceID] = append(dr.devicesPonPorts[deviceID], port)
			for _, peer := range port.Peers {
				if port.Type == voltha.Port_PON_ONU {
					dr.childConnectionPort[port.DeviceId] = peer.PortNo
				} else {
					dr.childConnectionPort[peer.DeviceId] = port.PortNo
				}
			}
		}
	}
}

func (dr *DeviceRoutes) getLogicalPorts(ingress, egress uint32) (uniPort, nniPort *voltha.LogicalPort, err error) {
	inPort, exist := dr.logicalPorts[ingress]
	if !exist {
		err = fmt.Errorf("ingress port %d not found", ingress)
		return
	}
	outPort, exist := dr.logicalPorts[egress]
	if !exist {
		err = fmt.Errorf("egress port %d not found", egress)
		return
	}

	if inPort.RootPort {
		nniPort = inPort
		uniPort = outPort
	} else {
		nniPort = outPort
		uniPort = inPort
	}

	return
}