// Copyright (C) 2014 Nippon Telegraph and Telephone Corporation.
//
// 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 table

import (
	"bytes"
	log "github.com/Sirupsen/logrus"
	"github.com/osrg/gobgp/packet"
	"net"
	"reflect"
	"time"
)

func nlri2Path(m *bgp.BGPMessage, p *PeerInfo, now time.Time) []*Path {
	updateMsg := m.Body.(*bgp.BGPUpdate)
	pathAttributes := updateMsg.PathAttributes
	pathList := make([]*Path, 0)
	for _, nlri_info := range updateMsg.NLRI {
		// define local variable to pass nlri's address to CreatePath
		var nlri bgp.NLRInfo = nlri_info
		// create Path object
		path := NewPath(p, &nlri, false, pathAttributes, false, now, false)
		pathList = append(pathList, path)
	}
	return pathList
}

func withdraw2Path(m *bgp.BGPMessage, p *PeerInfo, now time.Time) []*Path {
	updateMsg := m.Body.(*bgp.BGPUpdate)
	pathAttributes := updateMsg.PathAttributes
	pathList := make([]*Path, 0)
	for _, nlriWithdraw := range updateMsg.WithdrawnRoutes {
		// define local variable to pass nlri's address to CreatePath
		var w bgp.WithdrawnRoute = nlriWithdraw
		// create withdrawn Path object
		path := NewPath(p, &w, true, pathAttributes, false, now, false)
		pathList = append(pathList, path)
	}
	return pathList
}

func mpreachNlri2Path(m *bgp.BGPMessage, p *PeerInfo, now time.Time) []*Path {
	updateMsg := m.Body.(*bgp.BGPUpdate)
	pathAttributes := updateMsg.PathAttributes
	attrList := []*bgp.PathAttributeMpReachNLRI{}

	for _, attr := range pathAttributes {
		a, ok := attr.(*bgp.PathAttributeMpReachNLRI)
		if ok {
			attrList = append(attrList, a)
			break
		}
	}
	pathList := make([]*Path, 0)

	for _, mp := range attrList {
		nlri_info := mp.Value
		for _, nlri := range nlri_info {
			path := NewPath(p, nlri, false, pathAttributes, false, now, false)
			pathList = append(pathList, path)
		}
	}
	return pathList
}

func mpunreachNlri2Path(m *bgp.BGPMessage, p *PeerInfo, now time.Time) []*Path {
	updateMsg := m.Body.(*bgp.BGPUpdate)
	pathAttributes := updateMsg.PathAttributes
	attrList := []*bgp.PathAttributeMpUnreachNLRI{}

	for _, attr := range pathAttributes {
		a, ok := attr.(*bgp.PathAttributeMpUnreachNLRI)
		if ok {
			attrList = append(attrList, a)
			break
		}
	}
	pathList := make([]*Path, 0)

	for _, mp := range attrList {
		nlri_info := mp.Value

		for _, nlri := range nlri_info {
			path := NewPath(p, nlri, true, pathAttributes, false, now, false)
			pathList = append(pathList, path)
		}
	}
	return pathList
}

func ProcessMessage(m *bgp.BGPMessage, peerInfo *PeerInfo) []*Path {
	pathList := make([]*Path, 0)
	now := time.Now()
	pathList = append(pathList, nlri2Path(m, peerInfo, now)...)
	pathList = append(pathList, withdraw2Path(m, peerInfo, now)...)
	pathList = append(pathList, mpreachNlri2Path(m, peerInfo, now)...)
	pathList = append(pathList, mpunreachNlri2Path(m, peerInfo, now)...)
	return pathList
}

type TableManager struct {
	Tables   map[bgp.RouteFamily]*Table
	Vrfs     map[string]*Vrf
	localAsn uint32
	owner    string
}

func NewTableManager(owner string, rfList []bgp.RouteFamily) *TableManager {
	t := &TableManager{
		Tables: make(map[bgp.RouteFamily]*Table),
		Vrfs:   make(map[string]*Vrf),
		owner:  owner,
	}
	for _, rf := range rfList {
		t.Tables[rf] = NewTable(rf)
	}
	return t
}

func (manager *TableManager) OwnerName() string {
	return manager.owner
}

func (manager *TableManager) calculate(destinationList []*Destination) ([]*Path, error) {
	newPaths := make([]*Path, 0)

	for _, destination := range destinationList {
		// compute best path

		log.WithFields(log.Fields{
			"Topic": "table",
			"Owner": manager.owner,
			"Key":   destination.GetNlri().String(),
		}).Debug("Processing destination")

		newBestPath, reason, err := destination.Calculate(manager.localAsn)

		if err != nil {
			log.Error(err)
			continue
		}

		destination.setBestPathReason(reason)
		currentBestPath := destination.GetBestPath()

		if newBestPath != nil && newBestPath.Equal(currentBestPath) {
			// best path is not changed
			log.WithFields(log.Fields{
				"Topic":    "table",
				"Owner":    manager.owner,
				"Key":      destination.GetNlri().String(),
				"peer":     newBestPath.GetSource().Address,
				"next_hop": newBestPath.GetNexthop().String(),
				"reason":   reason,
			}).Debug("best path is not changed")
			continue
		}

		if newBestPath == nil {
			log.WithFields(log.Fields{
				"Topic": "table",
				"Owner": manager.owner,
				"Key":   destination.GetNlri().String(),
			}).Debug("best path is nil")

			if len(destination.GetKnownPathList()) == 0 {
				// create withdraw path
				if currentBestPath != nil {
					log.WithFields(log.Fields{
						"Topic":    "table",
						"Owner":    manager.owner,
						"Key":      destination.GetNlri().String(),
						"peer":     currentBestPath.GetSource().Address,
						"next_hop": currentBestPath.GetNexthop().String(),
					}).Debug("best path is lost")

					p := destination.GetBestPath()
					newPaths = append(newPaths, p.Clone(true))
				}
				destination.setBestPath(nil)
			} else {
				log.WithFields(log.Fields{
					"Topic": "table",
					"Owner": manager.owner,
					"Key":   destination.GetNlri().String(),
				}).Error("known path list is not empty")
			}
		} else {
			log.WithFields(log.Fields{
				"Topic":    "table",
				"Owner":    manager.owner,
				"Key":      newBestPath.GetNlri().String(),
				"peer":     newBestPath.GetSource().Address,
				"next_hop": newBestPath.GetNexthop(),
				"reason":   reason,
			}).Debug("new best path")

			newPaths = append(newPaths, newBestPath)
			destination.setBestPath(newBestPath)
		}

		if len(destination.GetKnownPathList()) == 0 && destination.GetBestPath() == nil {
			rf := destination.getRouteFamily()
			t := manager.Tables[rf]
			t.deleteDest(destination)
			log.WithFields(log.Fields{
				"Topic":        "table",
				"Owner":        manager.owner,
				"Key":          destination.GetNlri().String(),
				"route_family": rf,
			}).Debug("destination removed")
		}
	}
	return newPaths, nil
}

func (manager *TableManager) DeletePathsforPeer(peerInfo *PeerInfo, rf bgp.RouteFamily) ([]*Path, error) {
	if t, ok := manager.Tables[rf]; ok {
		destinationList := t.DeleteDestByPeer(peerInfo)
		return manager.calculate(destinationList)
	}
	return []*Path{}, nil
}

func (manager *TableManager) ProcessPaths(pathList []*Path) ([]*Path, error) {
	destinationList := make([]*Destination, 0, len(pathList))
	for _, path := range pathList {
		rf := path.GetRouteFamily()
		if t, ok := manager.Tables[rf]; ok {
			destinationList = append(destinationList, t.insert(path))
			if rf == bgp.RF_EVPN {
				dsts := manager.handleMacMobility(path)
				if len(dsts) > 0 {
					destinationList = append(destinationList, dsts...)
				}
			}
		}
	}
	return manager.calculate(destinationList)
}

// EVPN MAC MOBILITY HANDLING
//
// RFC7432 15. MAC Mobility
//
// A PE receiving a MAC/IP Advertisement route for a MAC address with a
// different Ethernet segment identifier and a higher sequence number
// than that which it had previously advertised withdraws its MAC/IP
// Advertisement route.
func (manager *TableManager) handleMacMobility(path *Path) []*Destination {
	dsts := make([]*Destination, 0)
	nlri := path.GetNlri().(*bgp.EVPNNLRI)
	if path.IsWithdraw || path.IsLocal() || nlri.RouteType != bgp.EVPN_ROUTE_TYPE_MAC_IP_ADVERTISEMENT {
		return nil
	}
	for _, path2 := range manager.GetPathList(bgp.RF_EVPN) {
		if !path2.IsLocal() || path2.GetNlri().(*bgp.EVPNNLRI).RouteType != bgp.EVPN_ROUTE_TYPE_MAC_IP_ADVERTISEMENT {
			continue
		}
		f := func(p *Path) (uint32, net.HardwareAddr, int) {
			nlri := p.GetNlri().(*bgp.EVPNNLRI)
			d := nlri.RouteTypeData.(*bgp.EVPNMacIPAdvertisementRoute)
			ecs := p.GetExtCommunities()
			seq := -1
			for _, ec := range ecs {
				if t, st := ec.GetTypes(); t == bgp.EC_TYPE_EVPN && st == bgp.EC_SUBTYPE_MAC_MOBILITY {
					seq = int(ec.(*bgp.MacMobilityExtended).Sequence)
					break
				}
			}
			return d.ETag, d.MacAddress, seq
		}
		e1, m1, s1 := f(path)
		e2, m2, s2 := f(path2)
		if e1 == e2 && bytes.Equal(m1, m2) && s1 > s2 {
			path2.IsWithdraw = true
			dsts = append(dsts, manager.Tables[bgp.RF_EVPN].insert(path2))
		}
	}
	return dsts
}

func (manager *TableManager) GetPathList(rf bgp.RouteFamily) []*Path {
	if _, ok := manager.Tables[rf]; !ok {
		return []*Path{}
	}
	destinations := manager.Tables[rf].GetDestinations()
	paths := make([]*Path, 0, len(destinations))
	for _, dest := range destinations {
		paths = append(paths, dest.knownPathList...)
	}
	return paths
}

func (manager *TableManager) GetBestPathList(rf bgp.RouteFamily) []*Path {
	if _, ok := manager.Tables[rf]; !ok {
		return []*Path{}
	}
	destinations := manager.Tables[rf].GetDestinations()
	paths := make([]*Path, 0, len(destinations))
	for _, dest := range destinations {
		paths = append(paths, dest.GetBestPath())
	}
	return paths
}

// process BGPUpdate message
// this function processes only BGPUpdate
func (manager *TableManager) ProcessUpdate(fromPeer *PeerInfo, message *bgp.BGPMessage) ([]*Path, error) {
	// check msg's type if it's BGPUpdate
	if message.Header.Type != bgp.BGP_MSG_UPDATE {
		log.WithFields(log.Fields{
			"Topic": "table",
			"Owner": manager.owner,
			"key":   fromPeer.Address.String(),
			"Type":  message.Header.Type,
		}).Warn("message is not BGPUpdate")
		return []*Path{}, nil
	}

	return manager.ProcessPaths(ProcessMessage(message, fromPeer))
}

type AdjRib struct {
	adjRibIn  map[bgp.RouteFamily]map[string]*ReceivedRoute
	adjRibOut map[bgp.RouteFamily]map[string]*ReceivedRoute
}

func NewAdjRib(rfList []bgp.RouteFamily) *AdjRib {
	r := &AdjRib{
		adjRibIn:  make(map[bgp.RouteFamily]map[string]*ReceivedRoute),
		adjRibOut: make(map[bgp.RouteFamily]map[string]*ReceivedRoute),
	}
	for _, rf := range rfList {
		r.adjRibIn[rf] = make(map[string]*ReceivedRoute)
		r.adjRibOut[rf] = make(map[string]*ReceivedRoute)
	}
	return r
}

func (adj *AdjRib) update(rib map[bgp.RouteFamily]map[string]*ReceivedRoute, pathList []*Path) {
	for _, path := range pathList {
		rf := path.GetRouteFamily()
		key := path.getPrefix()
		old, found := rib[rf][key]
		if path.IsWithdraw {
			if found {
				delete(rib[rf], key)
			}
		} else {
			if found && reflect.DeepEqual(old.path.GetPathAttrs(), path.GetPathAttrs()) {
				path.setTimestamp(old.path.GetTimestamp())
			}
			rib[rf][key] = NewReceivedRoute(path, false)
		}
	}
}

func (adj *AdjRib) UpdateIn(pathList []*Path) {
	adj.update(adj.adjRibIn, pathList)
}

func (adj *AdjRib) UpdateOut(pathList []*Path) {
	adj.update(adj.adjRibOut, pathList)
}

func (adj *AdjRib) getPathList(rib map[string]*ReceivedRoute) []*Path {
	pathList := make([]*Path, 0, len(rib))
	for _, rr := range rib {
		pathList = append(pathList, rr.path)
	}
	return pathList
}

func (adj *AdjRib) GetInPathList(rf bgp.RouteFamily) []*Path {
	if _, ok := adj.adjRibIn[rf]; !ok {
		return []*Path{}
	}
	return adj.getPathList(adj.adjRibIn[rf])
}

func (adj *AdjRib) GetOutPathList(rf bgp.RouteFamily) []*Path {
	if _, ok := adj.adjRibOut[rf]; !ok {
		return []*Path{}
	}
	return adj.getPathList(adj.adjRibOut[rf])
}

func (adj *AdjRib) GetInCount(rf bgp.RouteFamily) int {
	if _, ok := adj.adjRibIn[rf]; !ok {
		return 0
	}
	return len(adj.adjRibIn[rf])
}

func (adj *AdjRib) GetOutCount(rf bgp.RouteFamily) int {
	if _, ok := adj.adjRibOut[rf]; !ok {
		return 0
	}
	return len(adj.adjRibOut[rf])
}

func (adj *AdjRib) DropAll(rf bgp.RouteFamily) {
	if _, ok := adj.adjRibIn[rf]; ok {
		// replace old one
		adj.adjRibIn[rf] = make(map[string]*ReceivedRoute)
		adj.adjRibOut[rf] = make(map[string]*ReceivedRoute)
	}
}

type ReceivedRoute struct {
	path     *Path
	filtered bool
}

func (rr *ReceivedRoute) String() string {
	return rr.path.getPrefix()
}

func NewReceivedRoute(path *Path, filtered bool) *ReceivedRoute {

	rroute := &ReceivedRoute{
		path:     path,
		filtered: filtered,
	}
	return rroute
}