feat: implemented link previews (server files) (#3073)

* feat: implmented link previews (server files)

* chore: updated variable name

* chore: renamed service file from `metadata_service.go` to `link_service.go`

* fix: passing errors

* fix: fixed linter warnong about `ctx`

server/route/api/v2/link_service.go

+package v2
+
+import (
+	"context"
+
+	getter "github.com/usememos/memos/plugin/http-getter"
+	apiv2pb "github.com/usememos/memos/proto/gen/api/v2"
+)
+
+func (*APIV2Service) GetMetadata(_ context.Context, request *apiv2pb.GetLinkMetadataRequest) (*apiv2pb.GetLinkMetadataResponse, error) {
+	urlStr := request.Url
+
+	htmlMeta, err := getter.GetHTMLMeta(urlStr)
+	if err != nil {
+		return nil, err
+	}
+
+	return &apiv2pb.GetLinkMetadataResponse{
+		Metadata: &apiv2pb.Metadata{
+			Title:       htmlMeta.Title,
+			Description: htmlMeta.Description,
+			Image:       htmlMeta.Image,
+		},
+	}, nil
+}

server/route/api/v2/v2.go

@@ -30,6 +30,7 @@ type APIV2Service struct {
 	apiv2pb.UnimplementedInboxServiceServer
 	apiv2pb.UnimplementedActivityServiceServer
 	apiv2pb.UnimplementedWebhookServiceServer
+	apiv2pb.UnimplementedLinkServiceServer
 
 	Secret  string
 	Profile *profile.Profile
@@ -66,6 +67,7 @@ func NewAPIV2Service(secret string, profile *profile.Profile, store *store.Store
 	apiv2pb.RegisterInboxServiceServer(grpcServer, apiv2Service)
 	apiv2pb.RegisterActivityServiceServer(grpcServer, apiv2Service)
 	apiv2pb.RegisterWebhookServiceServer(grpcServer, apiv2Service)
+	apiv2pb.RegisterLinkServiceServer(grpcServer, apiv2Service)
 	reflection.Register(grpcServer)
 
 	return apiv2Service
@@ -119,6 +121,9 @@ func (s *APIV2Service) RegisterGateway(ctx context.Context, e *echo.Echo) error
 	if err := apiv2pb.RegisterWebhookServiceHandler(context.Background(), gwMux, conn); err != nil {
 		return err
 	}
+	if err := apiv2pb.RegisterLinkServiceHandler(context.Background(), gwMux, conn); err != nil {
+		return err
+	}
 	e.Any("/api/v2/*", echo.WrapHandler(gwMux))
 
 	// GRPC web proxy.