feat: add system service (#2083)

* feat: add system service

* chore: update

api/v2/system_service.go

@@ -0,0 +1,55 @@
+package v2
+
+import (
+	"context"
+	"os"
+
+	apiv2pb "github.com/usememos/memos/proto/gen/api/v2"
+	"github.com/usememos/memos/server/profile"
+	"github.com/usememos/memos/store"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+)
+
+type SystemService struct {
+	apiv2pb.UnimplementedSystemServiceServer
+
+	Profile *profile.Profile
+	Store   *store.Store
+}
+
+// NewSystemService creates a new SystemService.
+func NewSystemService(profile *profile.Profile, store *store.Store) *SystemService {
+	return &SystemService{
+		Profile: profile,
+		Store:   store,
+	}
+}
+
+func (s *SystemService) GetSystemInfo(ctx context.Context, _ *apiv2pb.GetSystemInfoRequest) (*apiv2pb.GetSystemInfoResponse, error) {
+	defaultSystemInfo := &apiv2pb.SystemInfo{}
+
+	// Get the database size if the user is a host.
+	userIDPtr := ctx.Value(UserIDContextKey)
+	if userIDPtr != nil {
+		userID := userIDPtr.(int32)
+		user, err := s.Store.GetUser(ctx, &store.FindUser{
+			ID: &userID,
+		})
+		if err != nil {
+			return nil, status.Errorf(codes.Internal, "failed to get user: %v", err)
+		}
+		if user != nil && user.Role == store.RoleHost {
+			fi, err := os.Stat(s.Profile.DSN)
+			if err != nil {
+				return nil, status.Errorf(codes.Internal, "failed to get file info: %v", err)
+			}
+			defaultSystemInfo.DbSize = fi.Size()
+		}
+	}
+
+	response := &apiv2pb.GetSystemInfoResponse{
+		SystemInfo: defaultSystemInfo,
+	}
+	return response, nil
+}