package deliver

import (
	"context"
	"google.golang.org/grpc"
	"google.golang.org/protobuf/proto"
	"sonet/api/gen/postal"
	"sonet/pkg/grpc/discovery"
	"sonet/pkg/utils/logger"
	"sync"
)

type GroupLoader interface {
	Load(uid string) (groupIds []string)
}

type Postal struct {
	conn   *grpc.ClientConn
	Client postal.PostalClient
}

type GroupDeliver struct {
	svcName           string
	groupLoader       GroupLoader
	resolver          discovery.Resolver
	postalDialOptions []grpc.DialOption
	postals           map[string]*Postal
	lock              *sync.RWMutex
}

func NewGroupDeliver(
	msgInServiceName string,
	groupLoader GroupLoader,
	resolver discovery.Resolver,
	postalDialOptions []grpc.DialOption,
) *GroupDeliver {
	return &GroupDeliver{
		svcName:           msgInServiceName,
		groupLoader:       groupLoader,
		resolver:          resolver,
		postalDialOptions: postalDialOptions,
	}
}

func (d *GroupDeliver) Init(ctx context.Context) (err error) {
	// initial all postal clients
	servers, err := d.resolver.ResolveAll(ctx, postal.Postal_ServiceDesc.ServiceName)
	if err != nil {
		return
	}
	d.buildPostals(servers)

	// watch postal server instance
	err = d.watchPostal(ctx)
	if err != nil {
		return
	}
	return
}

// watchPostal watch postal service list
func (d *GroupDeliver) watchPostal(ctx context.Context) (err error) {
	ch, err := d.resolver.Watch(ctx, postal.Postal_ServiceDesc.ServiceName)
	if err != nil {
		return
	}
	go func() {
		for {
			select {
			case <-ctx.Done():
				return
			case servers := <-ch:
				d.buildPostals(servers)
			}
		}
	}()
	return
}

func (d *GroupDeliver) buildPostals(servers []discovery.Server) {
	postals := make(map[string]*Postal)
	for _, server := range servers {
		if p, ok := d.postals[server.Addr]; ok {
			postals[server.Addr] = p
			continue
		}
		// new connection
		conn, err := grpc.DialContext(context.Background(), server.Addr, d.postalDialOptions...)
		if err != nil {
			logger.Errorf("dial postal server %+v error: %v", server.Addr, err)
			continue
		}
		postals[server.Addr] = &Postal{
			conn:   conn,
			Client: postal.NewPostalClient(conn),
		}
	}

	// close old connection
	oldPostals := d.postals
	d.postals = postals
	for addr, p := range oldPostals {
		if _, ok := d.postals[addr]; !ok {
			if err := p.conn.Close(); err != nil {
				logger.Errorf("close old postal conn %s error: %v", addr, err)
			}
		}
	}
}

func (d *GroupDeliver) DeliverGroup(ctx context.Context, gid string, msg proto.Message, options ...Option) (err error) {
	// deliver to all postal
	message, err := protoMessage2Deliver(d.svcName, msg)
	if err != nil {
		return
	}
	req := &postal.ReqDeliverGroup{
		Gid: gid,
		Msg: message,
	}
	for _, p := range d.postals {
		res, err := p.Client.DeliverGroup(ctx, req)
		if err != nil || !res.Ok {
			logger.Errorf("deliver to postal failed: %+v, %v", res, err)
		}
	}
	return
}

func (d *GroupDeliver) GroupJoin(ctx context.Context, uid string, gid []string) (err error) {

	return
}