package command

import (
	"context"
	"errors"
	"fmt"
	"github.com/chrislusf/seaweedfs/weed/glog"
	"github.com/chrislusf/seaweedfs/weed/pb"
	"github.com/chrislusf/seaweedfs/weed/pb/filer_pb"
	"github.com/chrislusf/seaweedfs/weed/replication"
	"github.com/chrislusf/seaweedfs/weed/replication/sink"
	"github.com/chrislusf/seaweedfs/weed/replication/sink/filersink"
	"github.com/chrislusf/seaweedfs/weed/replication/source"
	"github.com/chrislusf/seaweedfs/weed/security"
	statsCollect "github.com/chrislusf/seaweedfs/weed/stats"
	"github.com/chrislusf/seaweedfs/weed/util"
	"github.com/chrislusf/seaweedfs/weed/util/grace"
	"google.golang.org/grpc"
	"os"
	"strings"
	"time"
)

type SyncOptions struct {
	isActivePassive *bool
	filerA          *string
	filerB          *string
	aPath           *string
	bPath           *string
	aReplication    *string
	bReplication    *string
	aCollection     *string
	bCollection     *string
	aTtlSec         *int
	bTtlSec         *int
	aDiskType       *string
	bDiskType       *string
	aDebug          *bool
	bDebug          *bool
	aFromTsMs       *int64
	bFromTsMs       *int64
	aProxyByFiler   *bool
	bProxyByFiler   *bool
	metricsHttpPort *int
	clientId        int32
	clientEpoch     int32
}

var (
	syncOptions    SyncOptions
	syncCpuProfile *string
	syncMemProfile *string
)

func init() {
	cmdFilerSynchronize.Run = runFilerSynchronize // break init cycle
	syncOptions.isActivePassive = cmdFilerSynchronize.Flag.Bool("isActivePassive", false, "one directional follow from A to B if true")
	syncOptions.filerA = cmdFilerSynchronize.Flag.String("a", "", "filer A in one SeaweedFS cluster")
	syncOptions.filerB = cmdFilerSynchronize.Flag.String("b", "", "filer B in the other SeaweedFS cluster")
	syncOptions.aPath = cmdFilerSynchronize.Flag.String("a.path", "/", "directory to sync on filer A")
	syncOptions.bPath = cmdFilerSynchronize.Flag.String("b.path", "/", "directory to sync on filer B")
	syncOptions.aReplication = cmdFilerSynchronize.Flag.String("a.replication", "", "replication on filer A")
	syncOptions.bReplication = cmdFilerSynchronize.Flag.String("b.replication", "", "replication on filer B")
	syncOptions.aCollection = cmdFilerSynchronize.Flag.String("a.collection", "", "collection on filer A")
	syncOptions.bCollection = cmdFilerSynchronize.Flag.String("b.collection", "", "collection on filer B")
	syncOptions.aTtlSec = cmdFilerSynchronize.Flag.Int("a.ttlSec", 0, "ttl in seconds on filer A")
	syncOptions.bTtlSec = cmdFilerSynchronize.Flag.Int("b.ttlSec", 0, "ttl in seconds on filer B")
	syncOptions.aDiskType = cmdFilerSynchronize.Flag.String("a.disk", "", "[hdd|ssd|<tag>] hard drive or solid state drive or any tag on filer A")
	syncOptions.bDiskType = cmdFilerSynchronize.Flag.String("b.disk", "", "[hdd|ssd|<tag>] hard drive or solid state drive or any tag on filer B")
	syncOptions.aProxyByFiler = cmdFilerSynchronize.Flag.Bool("a.filerProxy", false, "read and write file chunks by filer A instead of volume servers")
	syncOptions.bProxyByFiler = cmdFilerSynchronize.Flag.Bool("b.filerProxy", false, "read and write file chunks by filer B instead of volume servers")
	syncOptions.aDebug = cmdFilerSynchronize.Flag.Bool("a.debug", false, "debug mode to print out filer A received files")
	syncOptions.bDebug = cmdFilerSynchronize.Flag.Bool("b.debug", false, "debug mode to print out filer B received files")
	syncOptions.aFromTsMs = cmdFilerSynchronize.Flag.Int64("a.fromTsMs", 0, "synchronization from timestamp on filer A. The unit is millisecond")
	syncOptions.bFromTsMs = cmdFilerSynchronize.Flag.Int64("b.fromTsMs", 0, "synchronization from timestamp on filer B. The unit is millisecond")
	syncCpuProfile = cmdFilerSynchronize.Flag.String("cpuprofile", "", "cpu profile output file")
	syncMemProfile = cmdFilerSynchronize.Flag.String("memprofile", "", "memory profile output file")
	syncOptions.metricsHttpPort = cmdFilerSynchronize.Flag.Int("metricsPort", 0, "metrics listen port")
	syncOptions.clientId = util.RandomInt32()
}

var cmdFilerSynchronize = &Command{
	UsageLine: "filer.sync -a=<oneFilerHost>:<oneFilerPort> -b=<otherFilerHost>:<otherFilerPort>",
	Short:     "resumable continuous synchronization between two active-active or active-passive SeaweedFS clusters",
	Long: `resumable continuous synchronization for file changes between two active-active or active-passive filers

	filer.sync listens on filer notifications. If any file is updated, it will fetch the updated content,
	and write to the other destination. Different from filer.replicate:

	* filer.sync only works between two filers.
	* filer.sync does not need any special message queue setup.
	* filer.sync supports both active-active and active-passive modes.
	
	If restarted, the synchronization will resume from the previous checkpoints, persisted every minute.
	A fresh sync will start from the earliest metadata logs.

`,
}

func runFilerSynchronize(cmd *Command, args []string) bool {

	util.LoadConfiguration("security", false)
	grpcDialOption := security.LoadClientTLS(util.GetViper(), "grpc.client")

	grace.SetupProfiling(*syncCpuProfile, *syncMemProfile)

	filerA := pb.ServerAddress(*syncOptions.filerA)
	filerB := pb.ServerAddress(*syncOptions.filerB)

	// start filer.sync metrics server
	go statsCollect.StartMetricsServer(*syncOptions.metricsHttpPort)

	// read a filer signature
	aFilerSignature, aFilerErr := replication.ReadFilerSignature(grpcDialOption, filerA)
	if aFilerErr != nil {
		glog.Errorf("get filer 'a' signature %d error from %s to %s: %v", aFilerSignature, *syncOptions.filerA, *syncOptions.filerB, aFilerErr)
		return true
	}
	// read b filer signature
	bFilerSignature, bFilerErr := replication.ReadFilerSignature(grpcDialOption, filerB)
	if bFilerErr != nil {
		glog.Errorf("get filer 'b' signature %d error from %s to %s: %v", bFilerSignature, *syncOptions.filerA, *syncOptions.filerB, bFilerErr)
		return true
	}

	go func() {
		// a->b
		// set synchronization start timestamp to offset
		initOffsetError := initOffsetFromTsMs(grpcDialOption, filerB, aFilerSignature, *syncOptions.bFromTsMs)
		if initOffsetError != nil {
			glog.Errorf("init offset from timestamp %d error from %s to %s: %v", *syncOptions.bFromTsMs, *syncOptions.filerA, *syncOptions.filerB, initOffsetError)
			os.Exit(2)
		}
		for {
			syncOptions.clientEpoch++
			err := doSubscribeFilerMetaChanges(syncOptions.clientId, syncOptions.clientEpoch, grpcDialOption, filerA, *syncOptions.aPath, *syncOptions.aProxyByFiler, filerB,
				*syncOptions.bPath, *syncOptions.bReplication, *syncOptions.bCollection, *syncOptions.bTtlSec, *syncOptions.bProxyByFiler, *syncOptions.bDiskType,
				*syncOptions.bDebug, aFilerSignature, bFilerSignature)
			if err != nil {
				glog.Errorf("sync from %s to %s: %v", *syncOptions.filerA, *syncOptions.filerB, err)
				time.Sleep(1747 * time.Millisecond)
			}
		}
	}()

	if !*syncOptions.isActivePassive {
		// b->a
		// set synchronization start timestamp to offset
		initOffsetError := initOffsetFromTsMs(grpcDialOption, filerA, bFilerSignature, *syncOptions.aFromTsMs)
		if initOffsetError != nil {
			glog.Errorf("init offset from timestamp %d error from %s to %s: %v", *syncOptions.aFromTsMs, *syncOptions.filerB, *syncOptions.filerA, initOffsetError)
			os.Exit(2)
		}
		go func() {
			for {
				syncOptions.clientEpoch++
				err := doSubscribeFilerMetaChanges(syncOptions.clientId, syncOptions.clientEpoch, grpcDialOption, filerB, *syncOptions.bPath, *syncOptions.bProxyByFiler, filerA,
					*syncOptions.aPath, *syncOptions.aReplication, *syncOptions.aCollection, *syncOptions.aTtlSec, *syncOptions.aProxyByFiler, *syncOptions.aDiskType,
					*syncOptions.aDebug, bFilerSignature, aFilerSignature)
				if err != nil {
					glog.Errorf("sync from %s to %s: %v", *syncOptions.filerB, *syncOptions.filerA, err)
					time.Sleep(2147 * time.Millisecond)
				}
			}
		}()
	}

	select {}

	return true
}

// initOffsetFromTsMs Initialize offset
func initOffsetFromTsMs(grpcDialOption grpc.DialOption, targetFiler pb.ServerAddress, sourceFilerSignature int32, fromTsMs int64) error {
	if fromTsMs <= 0 {
		return nil
	}
	// convert to nanosecond
	fromTsNs := fromTsMs * 1000_000
	// If not successful, exit the program.
	setOffsetErr := setOffset(grpcDialOption, targetFiler, SyncKeyPrefix, sourceFilerSignature, fromTsNs)
	if setOffsetErr != nil {
		return setOffsetErr
	}
	glog.Infof("setOffset from timestamp ms success! start offset: %d from %s to %s", fromTsNs, *syncOptions.filerA, *syncOptions.filerB)
	return nil
}

func doSubscribeFilerMetaChanges(clientId int32, clientEpoch int32, grpcDialOption grpc.DialOption, sourceFiler pb.ServerAddress, sourcePath string, sourceReadChunkFromFiler bool, targetFiler pb.ServerAddress, targetPath string,
	replicationStr, collection string, ttlSec int, sinkWriteChunkByFiler bool, diskType string, debug bool, sourceFilerSignature int32, targetFilerSignature int32) error {

	// if first time, start from now
	// if has previously synced, resume from that point of time
	sourceFilerOffsetTsNs, err := getOffset(grpcDialOption, targetFiler, getSignaturePrefixByPath(sourcePath), sourceFilerSignature)
	if err != nil {
		return err
	}

	glog.V(0).Infof("start sync %s(%d) => %s(%d) from %v(%d)", sourceFiler, sourceFilerSignature, targetFiler, targetFilerSignature, time.Unix(0, sourceFilerOffsetTsNs), sourceFilerOffsetTsNs)

	// create filer sink
	filerSource := &source.FilerSource{}
	filerSource.DoInitialize(sourceFiler.ToHttpAddress(), sourceFiler.ToGrpcAddress(), sourcePath, sourceReadChunkFromFiler)
	filerSink := &filersink.FilerSink{}
	filerSink.DoInitialize(targetFiler.ToHttpAddress(), targetFiler.ToGrpcAddress(), targetPath, replicationStr, collection, ttlSec, diskType, grpcDialOption, sinkWriteChunkByFiler)
	filerSink.SetSourceFiler(filerSource)

	persistEventFn := genProcessFunction(sourcePath, targetPath, filerSink, debug)

	processEventFn := func(resp *filer_pb.SubscribeMetadataResponse) error {
		message := resp.EventNotification
		for _, sig := range message.Signatures {
			if sig == targetFilerSignature && targetFilerSignature != 0 {
				fmt.Printf("%s skipping %s change to %v\n", targetFiler, sourceFiler, message)
				return nil
			}
		}
		return persistEventFn(resp)
	}

	var lastLogTsNs = time.Now().UnixNano()
	var clientName = fmt.Sprintf("syncFrom_%s_To_%s", string(sourceFiler), string(targetFiler))
	processEventFnWithOffset := pb.AddOffsetFunc(processEventFn, 3*time.Second, func(counter int64, lastTsNs int64) error {
		now := time.Now().UnixNano()
		glog.V(0).Infof("sync %s to %s progressed to %v %0.2f/sec", sourceFiler, targetFiler, time.Unix(0, lastTsNs), float64(counter)/(float64(now-lastLogTsNs)/1e9))
		lastLogTsNs = now
		// collect synchronous offset
		statsCollect.FilerSyncOffsetGauge.WithLabelValues(sourceFiler.String(), targetFiler.String(), clientName, sourcePath).Set(float64(lastTsNs))
		return setOffset(grpcDialOption, targetFiler, getSignaturePrefixByPath(sourcePath), sourceFilerSignature, lastTsNs)
	})

	return pb.FollowMetadata(sourceFiler, grpcDialOption, clientName, clientId, clientEpoch,
		sourcePath, nil, sourceFilerOffsetTsNs, 0, targetFilerSignature, processEventFnWithOffset, pb.RetryForeverOnError)

}

const (
	SyncKeyPrefix = "sync."
)

// When each business is distinguished according to path, and offsets need to be maintained separately.
func getSignaturePrefixByPath(path string) string {
	// compatible historical version
	if path == "/" {
		return SyncKeyPrefix
	} else {
		return SyncKeyPrefix + path
	}
}

func getOffset(grpcDialOption grpc.DialOption, filer pb.ServerAddress, signaturePrefix string, signature int32) (lastOffsetTsNs int64, readErr error) {

	readErr = pb.WithFilerClient(false, filer, grpcDialOption, func(client filer_pb.SeaweedFilerClient) error {
		syncKey := []byte(signaturePrefix + "____")
		util.Uint32toBytes(syncKey[len(signaturePrefix):len(signaturePrefix)+4], uint32(signature))

		resp, err := client.KvGet(context.Background(), &filer_pb.KvGetRequest{Key: syncKey})
		if err != nil {
			return err
		}

		if len(resp.Error) != 0 {
			return errors.New(resp.Error)
		}
		if len(resp.Value) < 8 {
			return nil
		}

		lastOffsetTsNs = int64(util.BytesToUint64(resp.Value))

		return nil
	})

	return

}

func setOffset(grpcDialOption grpc.DialOption, filer pb.ServerAddress, signaturePrefix string, signature int32, offsetTsNs int64) error {
	return pb.WithFilerClient(false, filer, grpcDialOption, func(client filer_pb.SeaweedFilerClient) error {

		syncKey := []byte(signaturePrefix + "____")
		util.Uint32toBytes(syncKey[len(signaturePrefix):len(signaturePrefix)+4], uint32(signature))

		valueBuf := make([]byte, 8)
		util.Uint64toBytes(valueBuf, uint64(offsetTsNs))

		resp, err := client.KvPut(context.Background(), &filer_pb.KvPutRequest{
			Key:   syncKey,
			Value: valueBuf,
		})
		if err != nil {
			return err
		}

		if len(resp.Error) != 0 {
			return errors.New(resp.Error)
		}

		return nil

	})

}

func genProcessFunction(sourcePath string, targetPath string, dataSink sink.ReplicationSink, debug bool) func(resp *filer_pb.SubscribeMetadataResponse) error {
	// process function
	processEventFn := func(resp *filer_pb.SubscribeMetadataResponse) error {
		message := resp.EventNotification

		var sourceOldKey, sourceNewKey util.FullPath
		if message.OldEntry != nil {
			sourceOldKey = util.FullPath(resp.Directory).Child(message.OldEntry.Name)
		}
		if message.NewEntry != nil {
			sourceNewKey = util.FullPath(message.NewParentPath).Child(message.NewEntry.Name)
		}

		if debug {
			glog.V(0).Infof("received %v", resp)
		}

		if !strings.HasPrefix(resp.Directory, sourcePath) {
			return nil
		}

		// handle deletions
		if filer_pb.IsDelete(resp) {
			if !strings.HasPrefix(string(sourceOldKey), sourcePath) {
				return nil
			}
			key := buildKey(dataSink, message, targetPath, sourceOldKey, sourcePath)
			if !dataSink.IsIncremental() {
				return dataSink.DeleteEntry(key, message.OldEntry.IsDirectory, message.DeleteChunks, message.Signatures)
			}
			return nil
		}

		// handle new entries
		if filer_pb.IsCreate(resp) {
			if !strings.HasPrefix(string(sourceNewKey), sourcePath) {
				return nil
			}
			key := buildKey(dataSink, message, targetPath, sourceNewKey, sourcePath)
			return dataSink.CreateEntry(key, message.NewEntry, message.Signatures)
		}

		// this is something special?
		if filer_pb.IsEmpty(resp) {
			return nil
		}

		// handle updates
		if strings.HasPrefix(string(sourceOldKey), sourcePath) {
			// old key is in the watched directory
			if strings.HasPrefix(string(sourceNewKey), sourcePath) {
				// new key is also in the watched directory
				if !dataSink.IsIncremental() {
					oldKey := util.Join(targetPath, string(sourceOldKey)[len(sourcePath):])
					message.NewParentPath = util.Join(targetPath, message.NewParentPath[len(sourcePath):])
					foundExisting, err := dataSink.UpdateEntry(string(oldKey), message.OldEntry, message.NewParentPath, message.NewEntry, message.DeleteChunks, message.Signatures)
					if foundExisting {
						return err
					}

					// not able to find old entry
					if err = dataSink.DeleteEntry(string(oldKey), message.OldEntry.IsDirectory, false, message.Signatures); err != nil {
						return fmt.Errorf("delete old entry %v: %v", oldKey, err)
					}
				}
				// create the new entry
				newKey := buildKey(dataSink, message, targetPath, sourceNewKey, sourcePath)
				return dataSink.CreateEntry(newKey, message.NewEntry, message.Signatures)

			} else {
				// new key is outside of the watched directory
				if !dataSink.IsIncremental() {
					key := buildKey(dataSink, message, targetPath, sourceOldKey, sourcePath)
					return dataSink.DeleteEntry(key, message.OldEntry.IsDirectory, message.DeleteChunks, message.Signatures)
				}
			}
		} else {
			// old key is outside of the watched directory
			if strings.HasPrefix(string(sourceNewKey), sourcePath) {
				// new key is in the watched directory
				key := buildKey(dataSink, message, targetPath, sourceNewKey, sourcePath)
				return dataSink.CreateEntry(key, message.NewEntry, message.Signatures)
			} else {
				// new key is also outside of the watched directory
				// skip
			}
		}

		return nil
	}
	return processEventFn
}

func buildKey(dataSink sink.ReplicationSink, message *filer_pb.EventNotification, targetPath string, sourceKey util.FullPath, sourcePath string) (key string) {
	if !dataSink.IsIncremental() {
		key = util.Join(targetPath, string(sourceKey)[len(sourcePath):])
	} else {
		var mTime int64
		if message.NewEntry != nil {
			mTime = message.NewEntry.Attributes.Mtime
		} else if message.OldEntry != nil {
			mTime = message.OldEntry.Attributes.Mtime
		}
		dateKey := time.Unix(mTime, 0).Format("2006-01-02")
		key = util.Join(targetPath, dateKey, string(sourceKey)[len(sourcePath):])
	}

	return escapeKey(key)
}