package grpcserver

import (
	"context"
	"log/slog"
	"net"
	"time"

	commonpb "gitea.haiyihy.com/hy/chatappcommon/proto"
	"google.golang.org/grpc"
)

// RegisterService 定义用户注册能力。
type RegisterService interface {
	Register(ctx context.Context, request *commonpb.RegisterRequest) (*commonpb.RegisterResponse, error)
}

// Server 包装用户服务 gRPC 服务端。
type Server struct {
	addr            string
	shutdownTimeout time.Duration
	logger          *slog.Logger
	grpcServer      *grpc.Server
}

type handler struct {
	commonpb.UnimplementedChatAppUserServiceServer
	service RegisterService
}

func (h handler) Register(ctx context.Context, request *commonpb.RegisterRequest) (*commonpb.RegisterResponse, error) {
	return h.service.Register(ctx, request)
}

// New 创建 gRPC 服务。
func New(addr string, shutdownTimeout time.Duration, logger *slog.Logger, service RegisterService) *Server {
	grpcServer := grpc.NewServer()
	commonpb.RegisterChatAppUserServiceServer(grpcServer, handler{service: service})
	return &Server{
		addr:            addr,
		shutdownTimeout: shutdownTimeout,
		logger:          logger,
		grpcServer:      grpcServer,
	}
}

// Run 启动 gRPC 服务并在退出时优雅停机。
func (s *Server) Run(ctx context.Context) error {
	listener, err := net.Listen("tcp", s.addr)
	if err != nil {
		return err
	}

	go func() {
		<-ctx.Done()
		done := make(chan struct{})
		go func() {
			s.grpcServer.GracefulStop()
			close(done)
		}()

		select {
		case <-done:
		case <-time.After(s.shutdownTimeout):
			s.grpcServer.Stop()
		}
	}()

	s.logger.Info("user grpc server started", "addr", s.addr)
	if err := s.grpcServer.Serve(listener); err != nil {
		return err
	}
	return nil
}