feat(forward): support dry run

app/forward/forward.go

@@ -33,6 +33,7 @@ type Options struct {
 	To     string
 	Mode   forwarder.Mode
 	Silent bool
+	DryRun bool
 }
 
 func Run(ctx context.Context, opts Options) error {
@@ -78,6 +79,7 @@ func Run(ctx context.Context, opts Options) error {
 			Pool:     pool,
 			Iter:     newIter(manager, pool, to, dialogs),
 			Silent:   opts.Silent,
+			DryRun:   opts.DryRun,
 			Mode:     opts.Mode,
 			Progress: newProgress(fwProgress),
 		})

cmd/forward.go

@@ -26,6 +26,7 @@ func NewForward() *cobra.Command {
 	cmd.Flags().StringVar(&opts.To, "to", "", "destination peer, can be a CHAT or router based on expression engine")
 	cmd.Flags().Var(&opts.Mode, "mode", fmt.Sprintf("forward mode: [%s]", strings.Join(forwarder.ModeNames(), ", ")))
 	cmd.Flags().BoolVar(&opts.Silent, "silent", false, "send messages silently")
+	cmd.Flags().BoolVar(&opts.DryRun, "dry-run", false, "do not actually send messages, just show how they would be sent")
 
 	return cmd
 }

pkg/forwarder/clone.go

@@ -11,18 +11,29 @@ import (
 	"go.uber.org/multierr"
 	"golang.org/x/sync/errgroup"
 
-	"github.com/iyear/tdl/pkg/dcpool"
 	"github.com/iyear/tdl/pkg/tmedia"
 )
 
 type CloneOptions struct {
-	Pool     dcpool.Pool
 	Media    *tmedia.Media
 	PartSize int
 	Progress uploader.Progress
 }
 
-func CloneMedia(ctx context.Context, opts CloneOptions) (tg.InputFileClass, error) {
+func (f *Forwarder) CloneMedia(ctx context.Context, opts CloneOptions) (tg.InputFileClass, error) {
+	// if dry run, just return empty input file
+	if f.opts.DryRun {
+		// directly call progress callback
+		if err := opts.Progress.Chunk(ctx, uploader.ProgressState{
+			Uploaded: opts.Media.Size,
+			Total:    opts.Media.Size,
+		}); err != nil {
+			return nil, errors.Wrap(err, "dry run chunk")
+		}
+
+		return &tg.InputFile{}, nil
+	}
+
 	r, w := io.Pipe()
 
 	wg, errctx := errgroup.WithContext(ctx)
@@ -32,7 +43,7 @@ func CloneMedia(ctx context.Context, opts CloneOptions) (tg.InputFileClass, erro
 
 		_, err := downloader.NewDownloader().
 			WithPartSize(opts.PartSize).
-			Download(opts.Pool.Client(ctx, opts.Media.DC), opts.Media.InputFileLoc).
+			Download(f.opts.Pool.Client(ctx, opts.Media.DC), opts.Media.InputFileLoc).
 			Stream(errctx, w)
 		if err != nil {
 			return errors.Wrap(err, "download")
@@ -46,7 +57,7 @@ func CloneMedia(ctx context.Context, opts CloneOptions) (tg.InputFileClass, erro
 
 		var err error
 		upload := uploader.NewUpload(opts.Media.Name, r, opts.Media.Size)
-		file, err = uploader.NewUploader(opts.Pool.Default(ctx)).
+		file, err = uploader.NewUploader(f.opts.Pool.Default(ctx)).
 			WithPartSize(opts.PartSize).
 			WithProgress(opts.Progress).
 			Upload(errctx, upload)

pkg/forwarder/forwarder.go

@@ -7,6 +7,7 @@ import (
 	"time"
 
 	"github.com/go-faster/errors"
+	"github.com/gotd/td/bin"
 	"github.com/gotd/td/telegram/message"
 	"github.com/gotd/td/telegram/peers"
 	"github.com/gotd/td/tg"
@@ -42,6 +43,7 @@ type Options struct {
 	Pool     dcpool.Pool
 	Iter     Iter
 	Silent   bool
+	DryRun   bool
 	Mode     Mode
 	Progress Progress
 }
@@ -134,7 +136,7 @@ func (f *Forwarder) forwardMessage(ctx context.Context, from, to peers.Peer, msg
 		}
 		req.SetFlags()
 
-		if _, err := f.opts.Pool.Default(ctx).MessagesSendMessage(ctx, req); err != nil {
+		if _, err := f.forwardClient(ctx).MessagesSendMessage(ctx, req); err != nil {
 			return errors.Wrap(err, "send message")
 		}
 		return nil
@@ -170,8 +172,7 @@ func (f *Forwarder) forwardMessage(ctx context.Context, from, to peers.Peer, msg
 			return nil, errors.Errorf("unsupported media %T", msg.Media)
 		}
 
-		mediaFile, err := CloneMedia(ctx, CloneOptions{
-			Pool:     f.opts.Pool,
+		mediaFile, err := f.CloneMedia(ctx, CloneOptions{
 			Media:    media,
 			PartSize: viper.GetInt(consts.FlagPartSize),
 			Progress: uploadProgress{
@@ -204,8 +205,7 @@ func (f *Forwarder) forwardMessage(ctx context.Context, from, to peers.Peer, msg
 				return nil, errors.Errorf("empty document thumb %d", msg.ID)
 			}
 
-			thumbFile, err := CloneMedia(ctx, CloneOptions{
-				Pool:     f.opts.Pool,
+			thumbFile, err := f.CloneMedia(ctx, CloneOptions{
 				Media:    thumb,
 				PartSize: viper.GetInt(consts.FlagPartSize),
 				Progress: nopProgress{},
@@ -237,7 +237,7 @@ func (f *Forwarder) forwardMessage(ctx context.Context, from, to peers.Peer, msg
 	case ModeDirect:
 		// it can be forwarded via API
 		if !protectedDialog(from) && !protectedMessage(msg) {
-			builder := message.NewSender(f.opts.Pool.Default(ctx)).
+			builder := message.NewSender(f.forwardClient(ctx)).
 				To(to.InputPeer()).CloneBuilder()
 			if f.opts.Silent {
 				builder = builder.Silent()
@@ -297,7 +297,7 @@ func (f *Forwarder) forwardMessage(ctx context.Context, from, to peers.Peer, msg
 					SendAs:                 nil,
 				}
 				req.SetFlags()
-				if _, err := f.opts.Pool.Default(ctx).MessagesSendMultiMedia(ctx, req); err != nil {
+				if _, err := f.forwardClient(ctx).MessagesSendMultiMedia(ctx, req); err != nil {
 					return errors.Wrap(err, "send multi media")
 				}
 				return nil
@@ -330,7 +330,7 @@ func (f *Forwarder) forwardMessage(ctx context.Context, from, to peers.Peer, msg
 		}
 		req.SetFlags()
 
-		if _, err := f.opts.Pool.Default(ctx).MessagesSendMedia(ctx, req); err != nil {
+		if _, err := f.forwardClient(ctx).MessagesSendMedia(ctx, req); err != nil {
 			return errors.Wrap(err, "send single media")
 		}
 		return nil
@@ -343,6 +343,20 @@ func (f *Forwarder) sentTuple(peer peers.Peer, msg *tg.Message) [2]int64 {
 	return [2]int64{peer.ID(), int64(msg.ID)}
 }
 
+type nopInvoker struct{}
+
+func (n nopInvoker) Invoke(_ context.Context, _ bin.Encoder, _ bin.Decoder) error {
+	return nil
+}
+
+func (f *Forwarder) forwardClient(ctx context.Context) *tg.Client {
+	if f.opts.DryRun {
+		return tg.NewClient(nopInvoker{})
+	}
+
+	return f.opts.Pool.Default(ctx)
+}
+
 func protectedDialog(peer peers.Peer) bool {
 	switch p := peer.(type) {
 	case peers.Chat: