package wdclient

import (
	"context"
	"fmt"
	"math/rand"
	"time"

	"github.com/chrislusf/seaweedfs/weed/glog"
	"github.com/chrislusf/seaweedfs/weed/pb/master_pb"
	"github.com/chrislusf/seaweedfs/weed/util"
	"google.golang.org/grpc"
)

type MasterClient struct {
	ctx            context.Context
	name           string
	currentMaster  string
	masters        []string
	grpcDialOption grpc.DialOption

	vidMap
}

func NewMasterClient(ctx context.Context, grpcDialOption grpc.DialOption, clientName string, masters []string) *MasterClient {
	return &MasterClient{
		ctx:            ctx,
		name:           clientName,
		masters:        masters,
		grpcDialOption: grpcDialOption,
		vidMap:         newVidMap(),
	}
}

func (mc *MasterClient) GetMaster() string {
	return mc.currentMaster
}

func (mc *MasterClient) WaitUntilConnected() {
	for mc.currentMaster == "" {
		time.Sleep(time.Duration(rand.Int31n(200)) * time.Millisecond)
	}
}

func (mc *MasterClient) KeepConnectedToMaster() {
	glog.V(1).Infof("%s bootstraps with masters %v", mc.name, mc.masters)
	for {
		mc.tryAllMasters()
		time.Sleep(time.Second)
	}
}

func (mc *MasterClient) tryAllMasters() {
	nextHintedLeader := ""
	for _, master := range mc.masters {

		nextHintedLeader = mc.tryConnectToMaster(master)
		for nextHintedLeader != "" {
			nextHintedLeader = mc.tryConnectToMaster(nextHintedLeader)
		}

		mc.currentMaster = ""
		mc.vidMap = newVidMap()
	}
}

func (mc *MasterClient) tryConnectToMaster(master string) (nextHintedLeader string) {
	glog.V(1).Infof("%s Connecting to master %v", mc.name, master)
	gprcErr := withMasterClient(context.Background(), master, mc.grpcDialOption, func(ctx context.Context, client master_pb.SeaweedClient) error {

		stream, err := client.KeepConnected(ctx)
		if err != nil {
			glog.V(0).Infof("%s failed to keep connected to %s: %v", mc.name, master, err)
			return err
		}

		if err = stream.Send(&master_pb.KeepConnectedRequest{Name: mc.name}); err != nil {
			glog.V(0).Infof("%s failed to send to %s: %v", mc.name, master, err)
			return err
		}

		if mc.currentMaster == "" {
			glog.V(1).Infof("%s Connected to %v", mc.name, master)
			mc.currentMaster = master
		}

		for {
			volumeLocation, err := stream.Recv()
			if err != nil {
				glog.V(0).Infof("%s failed to receive from %s: %v", mc.name, master, err)
				return err
			}

			// maybe the leader is changed
			if volumeLocation.Leader != "" {
				glog.V(1).Infof("redirected to leader %v", volumeLocation.Leader)
				nextHintedLeader = volumeLocation.Leader
				return nil
			}

			// process new volume location
			loc := Location{
				Url:       volumeLocation.Url,
				PublicUrl: volumeLocation.PublicUrl,
			}
			for _, newVid := range volumeLocation.NewVids {
				glog.V(1).Infof("%s: %s adds volume %d", mc.name, loc.Url, newVid)
				mc.addLocation(newVid, loc)
			}
			for _, deletedVid := range volumeLocation.DeletedVids {
				glog.V(1).Infof("%s: %s removes volume %d", mc.name, loc.Url, deletedVid)
				mc.deleteLocation(deletedVid, loc)
			}
		}

	})
	if gprcErr != nil {
		glog.V(0).Infof("%s failed to connect with master %v: %v", mc.name, master, gprcErr)
	}
	return
}

func withMasterClient(ctx context.Context, master string, grpcDialOption grpc.DialOption, fn func(ctx context.Context, client master_pb.SeaweedClient) error) error {

	masterGrpcAddress, parseErr := util.ParseServerToGrpcAddress(master)
	if parseErr != nil {
		return fmt.Errorf("failed to parse master grpc %v: %v", master, parseErr)
	}

	return util.WithCachedGrpcClient(ctx, func(grpcConnection *grpc.ClientConn) error {
		client := master_pb.NewSeaweedClient(grpcConnection)
		return fn(ctx, client)
	}, masterGrpcAddress, grpcDialOption)

}

func (mc *MasterClient) WithClient(ctx context.Context, fn func(client master_pb.SeaweedClient) error) error {
	return withMasterClient(ctx, mc.currentMaster, mc.grpcDialOption, func(ctx context.Context, client master_pb.SeaweedClient) error {
		return fn(client)
	})
}