package actor

import (
	"context"
	"fmt"
	"log"
	"net"
	"time"

	messages "git.tornberg.me/go-cart-actor/pkg/messages"
	"google.golang.org/grpc"
	"google.golang.org/grpc/reflection"
)

// ControlServer implements the ControlPlane gRPC services.
// It delegates to a grain pool and cluster operations to a synced pool.
type ControlServer[V any] struct {
	messages.UnimplementedControlPlaneServer

	pool GrainPool[V]
}

func (s *ControlServer[V]) AnnounceOwnership(ctx context.Context, req *messages.OwnershipAnnounce) (*messages.OwnerChangeAck, error) {
	err := s.pool.HandleOwnershipChange(req.Host, req.Ids)
	if err != nil {
		return &messages.OwnerChangeAck{
			Accepted: false,
			Message:  "owner change failed",
		}, err
	}

	log.Printf("Ack count: %d", len(req.Ids))
	return &messages.OwnerChangeAck{
		Accepted: true,
		Message:  "ownership announced",
	}, nil
}

func (s *ControlServer[V]) AnnounceExpiry(ctx context.Context, req *messages.ExpiryAnnounce) (*messages.OwnerChangeAck, error) {
	err := s.pool.HandleRemoteExpiry(req.Host, req.Ids)
	return &messages.OwnerChangeAck{
		Accepted: err == nil,
		Message:  "expiry acknowledged",
	}, nil
}

// ControlPlane: Ping
func (s *ControlServer[V]) Ping(ctx context.Context, _ *messages.Empty) (*messages.PingReply, error) {

	return &messages.PingReply{
		Host:     s.pool.Hostname(),
		UnixTime: time.Now().Unix(),
	}, nil
}

// ControlPlane: Negotiate (merge host views)
func (s *ControlServer[V]) Negotiate(ctx context.Context, req *messages.NegotiateRequest) (*messages.NegotiateReply, error) {

	s.pool.Negotiate(req.KnownHosts)
	return &messages.NegotiateReply{Hosts: req.GetKnownHosts()}, nil
}

// ControlPlane: GetCartIds (locally owned carts only)
func (s *ControlServer[V]) GetLocalActorIds(ctx context.Context, _ *messages.Empty) (*messages.ActorIdsReply, error) {
	return &messages.ActorIdsReply{Ids: s.pool.GetLocalIds()}, nil
}

// ControlPlane: Closing (peer shutdown notification)
func (s *ControlServer[V]) Closing(ctx context.Context, req *messages.ClosingNotice) (*messages.OwnerChangeAck, error) {
	if req.GetHost() != "" {
		s.pool.RemoveHost(req.GetHost())
	}
	return &messages.OwnerChangeAck{
		Accepted: true,
		Message:  "removed host",
	}, nil
}

// StartGRPCServer configures and starts the unified gRPC server on the given address.
// It registers both the CartActor and ControlPlane services.
func NewControlServer[V any](addr string, pool GrainPool[V]) (*grpc.Server, error) {
	lis, err := net.Listen("tcp", addr)
	if err != nil {
		return nil, fmt.Errorf("failed to listen: %w", err)
	}

	grpcServer := grpc.NewServer()
	server := &ControlServer[V]{
		pool: pool,
	}

	messages.RegisterControlPlaneServer(grpcServer, server)
	reflection.Register(grpcServer)

	log.Printf("gRPC server listening on %s", addr)
	go func() {
		if err := grpcServer.Serve(lis); err != nil {
			log.Fatalf("failed to serve gRPC: %v", err)
		}
	}()

	return grpcServer, nil
}