govno

internal/app/controller.go

@@ -14,8 +14,8 @@ func NewController() *Controller {
 	}
 }
 
-func (c *Controller) StartTorrent(path string) error {
-	return c.engine.LoadTorrent(path)
+func (c *Controller) StartTorrent(path, outputRoot string) error {
+	return c.engine.LoadTorrent(path, outputRoot)
 }
 
 func (c *Controller) StopTorrent() {

internal/torrent/debug.go

@@ -0,0 +1,17 @@
+package torrent
+
+import "log"
+
+// debug enables verbose protocol and scheduler logs.
+var debug = true
+
+func debugf(format string, args ...any) {
+	if !debug {
+		return
+	}
+	log.Printf(format, args...)
+}
+
+func SetDebug(enabled bool) {
+	debug = enabled
+}

internal/torrent/engine.go

@@ -8,6 +8,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"log"
 	"net"
 	"os"
 	"path/filepath"
@@ -39,6 +40,10 @@ type Engine struct {
 	completedPieces int
 	totalPieces     int
 	outputPath      string
+	outputRoot      string
+	downloadSpeed   float64
+	speedAt         time.Time
+	speedBytes      int64
 }
 
 type Status struct {
@@ -50,6 +55,7 @@ type Status struct {
 
 	CompletedPieces int
 	DownloadedBytes int64
+	DownloadSpeed   float64
 	TotalBytes      int64
 	OutputPath      string
 
@@ -98,13 +104,17 @@ func NewEngine() *Engine {
 	}
 }
 
-func (e *Engine) LoadTorrent(path string) error {
+func (e *Engine) LoadTorrent(path, outputRoot string) error {
 	e.Stop()
 	e.resetStateForNewLoad()
 	e.setPhase("loading_metadata")
+	outputRoot = normalizeOutputRoot(outputRoot)
+	log.Printf("loading torrent metadata from %s", path)
+	debugf("download root selected: %s", outputRoot)
 
 	tf, err := torrentfile.Open(path)
 	if err != nil {
+		log.Printf("failed to parse torrent %s: %v", path, err)
 		e.setError(err)
 		e.setPhase("failed")
 		return err
@@ -131,7 +141,11 @@ func (e *Engine) LoadTorrent(path string) error {
 	e.totalPieces = len(tf.PieceHashes)
 	e.downloadedBytes = 0
 	e.completedPieces = 0
-	e.outputPath = buildOutputPath(tf, "downloads")
+	e.outputRoot = outputRoot
+	e.outputPath = buildOutputPath(tf, outputRoot)
+	e.downloadSpeed = 0
+	e.speedAt = time.Now()
+	e.speedBytes = 0
 	if len(peers) == 0 {
 		warnErr := fmt.Errorf("no peers yet via %d trackers", len(trackerStatuses))
 		if trErr := firstTrackerError(trackerStatuses); trErr != nil {
@@ -143,6 +157,7 @@ func (e *Engine) LoadTorrent(path string) error {
 	}
 	e.phase = "ready"
 	e.mu.Unlock()
+	log.Printf("torrent loaded: name=%s size=%d peers=%d output=%s", tf.Name, tf.Length, len(peers), e.outputPath)
 
 	go e.runDownload(downloadCtx, tf)
 	return nil
@@ -182,6 +197,7 @@ func (e *Engine) Status() Status {
 		Phase:           e.phase,
 		CompletedPieces: e.completedPieces,
 		DownloadedBytes: e.downloadedBytes,
+		DownloadSpeed:   e.downloadSpeed,
 		OutputPath:      e.outputPath,
 	}
 
@@ -207,6 +223,7 @@ func (e *Engine) queryTrackers(ctx context.Context, tf *torrentfile.TorrentFile,
 	statuses := make([]TrackerStatus, 0, len(trackersToTry))
 
 	for _, announce := range trackersToTry {
+		log.Printf("tracker announce: %s", announce)
 		perTrackerCtx, cancel := context.WithTimeout(ctx, opts.Timeout)
 		peers, err := tracker.GetPeersFromURL(perTrackerCtx, announce, tf, opts)
 		cancel()
@@ -215,6 +232,7 @@ func (e *Engine) queryTrackers(ctx context.Context, tf *torrentfile.TorrentFile,
 		if err != nil {
 			st.State = "error"
 			st.Error = err.Error()
+			log.Printf("tracker announce failed %s: %v", announce, err)
 			statuses = append(statuses, st)
 			continue
 		}
@@ -226,6 +244,7 @@ func (e *Engine) queryTrackers(ctx context.Context, tf *torrentfile.TorrentFile,
 			st.PeerCount = len(peers)
 		}
 		statuses = append(statuses, st)
+		log.Printf("tracker announce result %s: peers=%d state=%s", announce, st.PeerCount, st.State)
 
 		for _, peer := range peers {
 			addPeer(peerMap, peer, announce)
@@ -250,9 +269,11 @@ func (e *Engine) runDownload(ctx context.Context, tf *torrentfile.TorrentFile) {
 	defer e.clearCancel()
 
 	e.setPhase("preparing_download")
+	log.Printf("preparing download to %s", e.outputRoot)
 
-	partPath, partFile, err := createPartFile(tf)
+	partPath, partFile, err := createPartFile(tf, e.outputRoot)
 	if err != nil {
+		log.Printf("failed to create part file: %v", err)
 		e.setTerminalError("failed", fmt.Errorf("create temp file: %w", err))
 		return
 	}
@@ -294,6 +315,7 @@ func (e *Engine) runDownload(ctx context.Context, tf *torrentfile.TorrentFile) {
 	defer cleanupWorkers()
 
 	e.setPhase("downloading")
+	log.Printf("download started: pieces=%d peers=%d", len(tf.PieceHashes), len(e.snapshotPeers()))
 	lastProgressAt := time.Now()
 	lastReannounceAt := time.Now()
 	startWorkers(e.snapshotPeers())
@@ -313,22 +335,27 @@ func (e *Engine) runDownload(ctx context.Context, tf *torrentfile.TorrentFile) {
 				continue
 			}
 			lastProgressAt = time.Now()
+			debugf("piece completed: %d/%d", e.currentCompletedPieces(), len(tf.PieceHashes))
 		case <-scheduler.Done():
 			downloadCompleted = true
 		case workerKey := <-workerDoneCh:
 			delete(startedWorkers, workerKey)
+			debugf("worker finished for peer %s", workerKey)
 		case <-heartbeatTicker.C:
+			e.updateSpeed(time.Now())
 			if time.Since(lastReannounceAt) >= reannounceInterval {
 				e.setPhase("querying_trackers")
 				refreshCtx, cancel := context.WithTimeout(ctx, 20*time.Second)
-				_ = e.refreshPeersFromTrackers(refreshCtx, tf)
+				added := e.refreshPeersFromTrackers(refreshCtx, tf)
 				cancel()
 				lastReannounceAt = time.Now()
 				e.setPhase("downloading")
+				debugf("reannounce complete, added peers=%d total=%d", added, len(e.snapshotPeers()))
 			}
 			startWorkers(e.snapshotPeers())
 
 			if time.Since(lastProgressAt) >= downloadStallTimeout {
+				log.Printf("download stalled: no progress for %s", downloadStallTimeout.Round(time.Second))
 				e.setTerminalError("stalled", fmt.Errorf("download stalled: no piece progress for %s", downloadStallTimeout.Round(time.Second)))
 				return
 			}
@@ -338,19 +365,24 @@ func (e *Engine) runDownload(ctx context.Context, tf *torrentfile.TorrentFile) {
 	cleanupWorkers()
 
 	e.setPhase("writing_files")
-	if err := materializeDownloadedFiles(tf, partPath, "downloads"); err != nil {
+	if err := materializeDownloadedFiles(tf, partPath, e.outputRoot); err != nil {
+		log.Printf("failed to materialize files: %v", err)
 		e.setTerminalError("failed", fmt.Errorf("write output files: %w", err))
 		return
 	}
 
-	_ = os.Remove(partPath)
+	if err := os.Remove(partPath); err != nil && !errors.Is(err, os.ErrNotExist) {
+		log.Printf("failed to remove part file %s: %v", partPath, err)
+	}
 
 	e.mu.Lock()
 	e.downloadedBytes = int64(tf.Length)
 	e.completedPieces = len(tf.PieceHashes)
 	e.phase = "completed"
 	e.lastErr = nil
+	e.downloadSpeed = 0
 	e.mu.Unlock()
+	log.Printf("download completed: %s", e.outputPath)
 }
 
 func (e *Engine) runPeerWorker(
@@ -363,11 +395,13 @@ func (e *Engine) runPeerWorker(
 	e.setPeerState(peer.Address, peer.Port, "connecting", "")
 
 	peerAddr := net.JoinHostPort(peer.Address, strconv.Itoa(int(peer.Port)))
+	debugf("starting peer worker for %s", peerAddr)
 	client, err := newPeerClient(ctx, peerAddr, tf.InfoHash, e.peerID, len(tf.PieceHashes))
 	if err != nil {
 		if ctx.Err() != nil {
 			e.setPeerState(peer.Address, peer.Port, "stopped", "")
 		} else {
+			log.Printf("peer %s connection failed: %v", peerAddr, err)
 			e.setPeerState(peer.Address, peer.Port, "error", err.Error())
 		}
 		return
@@ -389,6 +423,7 @@ func (e *Engine) runPeerWorker(
 			if ctx.Err() != nil {
 				e.setPeerState(peer.Address, peer.Port, "stopped", "")
 			} else {
+				log.Printf("peer %s scheduler acquire failed: %v", peerAddr, err)
 				e.setPeerState(peer.Address, peer.Port, "error", err.Error())
 			}
 			return
@@ -411,13 +446,16 @@ func (e *Engine) runPeerWorker(
 		pieceSize := pieceSizeForIndex(tf, task.Index)
 		pieceData, err := client.DownloadPiece(ctx, task.Index, pieceSize)
 		if err != nil {
-			_, _ = scheduler.Report(ctx, task.Index, false)
+			if _, reportErr := scheduler.Report(ctx, task.Index, false); reportErr != nil && ctx.Err() == nil {
+				log.Printf("scheduler report failure for piece %d after peer error: %v", task.Index, reportErr)
+			}
 			if ctx.Err() != nil {
 				e.setPeerState(peer.Address, peer.Port, "stopped", "")
 				return
 			}
 
 			consecutiveFailures++
+			log.Printf("peer %s disconnected: %v", peerAddr, err)
 			e.setPeerState(peer.Address, peer.Port, "error", err.Error())
 			if shouldDropPeer(err) || consecutiveFailures >= 3 {
 				return
@@ -427,8 +465,11 @@ func (e *Engine) runPeerWorker(
 
 		hash := sha1.Sum(pieceData)
 		if hash != tf.PieceHashes[task.Index] {
-			_, _ = scheduler.Report(ctx, task.Index, false)
+			if _, reportErr := scheduler.Report(ctx, task.Index, false); reportErr != nil && ctx.Err() == nil {
+				log.Printf("scheduler report hash mismatch for piece %d failed: %v", task.Index, reportErr)
+			}
 			consecutiveFailures++
+			log.Printf("peer %s piece %d hash mismatch", peerAddr, task.Index)
 			e.setPeerState(peer.Address, peer.Port, "error", fmt.Sprintf("piece %d hash mismatch", task.Index))
 			if consecutiveFailures >= 3 {
 				return
@@ -438,7 +479,10 @@ func (e *Engine) runPeerWorker(
 
 		offset := int64(task.Index * tf.PieceLength)
 		if _, err := partFile.WriteAt(pieceData, offset); err != nil {
-			_, _ = scheduler.Report(ctx, task.Index, false)
+			if _, reportErr := scheduler.Report(ctx, task.Index, false); reportErr != nil && ctx.Err() == nil {
+				log.Printf("scheduler report write failure for piece %d failed: %v", task.Index, reportErr)
+			}
+			log.Printf("io error writing piece %d from peer %s: %v", task.Index, peerAddr, err)
 			e.setPeerState(peer.Address, peer.Port, "error", fmt.Sprintf("write piece %d: %v", task.Index, err))
 			return
 		}
@@ -454,6 +498,9 @@ func (e *Engine) runPeerWorker(
 		}
 		if accepted {
 			e.recordPieceComplete(peer.Address, peer.Port, len(pieceData))
+			debugf("peer %s committed piece %d", peerAddr, task.Index)
+		} else {
+			debugf("scheduler rejected piece %d report from %s", task.Index, peerAddr)
 		}
 
 		consecutiveFailures = 0
@@ -512,6 +559,7 @@ func (e *Engine) refreshPeersFromTrackers(ctx context.Context, tf *torrentfile.T
 			waitErr = fmt.Errorf("waiting for peers: %w", trErr)
 		}
 		e.lastErr = waitErr
+		debugf("reannounce returned no peers")
 		return 0
 	}
 	e.lastErr = nil
@@ -540,6 +588,9 @@ func (e *Engine) refreshPeersFromTrackers(ctx context.Context, tf *torrentfile.T
 			return e.peers[i].Address < e.peers[j].Address
 		})
 	}
+	if added > 0 {
+		log.Printf("discovered %d new peers (total=%d)", added, len(e.peers))
+	}
 
 	return added
 }
@@ -550,11 +601,18 @@ func (e *Engine) currentDownloadedBytes() int64 {
 	return e.downloadedBytes
 }
 
+func (e *Engine) currentCompletedPieces() int {
+	e.mu.RLock()
+	defer e.mu.RUnlock()
+	return e.completedPieces
+}
+
 func (e *Engine) recordPieceComplete(address string, port uint16, pieceSize int) {
 	e.mu.Lock()
 	defer e.mu.Unlock()
 	e.downloadedBytes += int64(pieceSize)
 	e.completedPieces++
+	e.updateSpeedLocked(time.Now())
 	for i := range e.peers {
 		if e.peers[i].Address == address && e.peers[i].Port == port {
 			e.peers[i].DownloadedPieces++
@@ -580,6 +638,7 @@ func (e *Engine) setTerminalError(phase string, err error) {
 	defer e.mu.Unlock()
 	e.phase = phase
 	e.lastErr = err
+	e.downloadSpeed = 0
 }
 
 func (e *Engine) progressUnsafe() float64 {
@@ -628,6 +687,36 @@ func (e *Engine) resetStateForNewLoad() {
 	e.completedPieces = 0
 	e.totalPieces = 0
 	e.outputPath = ""
+	e.outputRoot = ""
+	e.downloadSpeed = 0
+	e.speedAt = time.Time{}
+	e.speedBytes = 0
+}
+
+func (e *Engine) updateSpeed(now time.Time) {
+	e.mu.Lock()
+	defer e.mu.Unlock()
+	e.updateSpeedLocked(now)
+}
+
+func (e *Engine) updateSpeedLocked(now time.Time) {
+	if e.speedAt.IsZero() {
+		e.speedAt = now
+		e.speedBytes = e.downloadedBytes
+		e.downloadSpeed = 0
+		return
+	}
+	elapsed := now.Sub(e.speedAt).Seconds()
+	if elapsed < 0.8 {
+		return
+	}
+	delta := e.downloadedBytes - e.speedBytes
+	if delta < 0 {
+		delta = 0
+	}
+	e.downloadSpeed = float64(delta) / elapsed
+	e.speedAt = now
+	e.speedBytes = e.downloadedBytes
 }
 
 func (e *Engine) setError(err error) {
@@ -755,8 +844,8 @@ func firstTrackerError(statuses []TrackerStatus) error {
 	return nil
 }
 
-func createPartFile(tf *torrentfile.TorrentFile) (string, *os.File, error) {
-	partsDir := filepath.Join("downloads", ".parts")
+func createPartFile(tf *torrentfile.TorrentFile, outputRoot string) (string, *os.File, error) {
+	partsDir := filepath.Join(outputRoot, ".ztorrent-parts")
 	if err := os.MkdirAll(partsDir, 0o755); err != nil {
 		return "", nil, err
 	}
@@ -834,12 +923,7 @@ func safeOutputPath(root, rel string) (string, error) {
 }
 
 func buildOutputPath(tf *torrentfile.TorrentFile, outputRoot string) string {
-	if len(tf.Files) == 1 {
-		if path, err := safeOutputPath(outputRoot, tf.Files[0].Path); err == nil {
-			return path
-		}
-	}
-	return filepath.Join(outputRoot, sanitizePathPart(tf.Name))
+	return filepath.Join(outputRoot, tf.Name)
 }
 
 func sanitizePathPart(s string) string {
@@ -864,3 +948,16 @@ func sanitizePathPart(s string) string {
 	}
 	return out
 }
+
+func normalizeOutputRoot(root string) string {
+	root = strings.TrimSpace(root)
+	if root == "" {
+		cwd, err := os.Getwd()
+		if err == nil && cwd != "" {
+			return cwd
+		}
+		return "."
+	}
+	clean := filepath.Clean(root)
+	return clean
+}

internal/torrent/peerwire.go

@@ -7,6 +7,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"log"
 	"net"
 	"time"
 
@@ -50,8 +51,10 @@ func newPeerClient(ctx context.Context, addr string, infoHash [20]byte, peerID [
 	dialer := net.Dialer{Timeout: peerConnectTimeout}
 	conn, err := dialer.DialContext(ctx, "tcp", addr)
 	if err != nil {
+		log.Printf("peer dial failed %s: %v", addr, err)
 		return nil, err
 	}
+	log.Printf("connected to peer %s", addr)
 
 	pc := &peerClient{
 		conn:         conn,
@@ -72,8 +75,10 @@ func newPeerClient(ctx context.Context, addr string, infoHash [20]byte, peerID [
 		conn.Close()
 		return nil, err
 	}
+	debugf("sent interested to %s", addr)
 
 	if err := pc.readInitialMessages(ctx); err != nil {
+		log.Printf("peer %s initial message read failed: %v", addr, err)
 		conn.Close()
 		return nil, err
 	}
@@ -132,6 +137,7 @@ func (pc *peerClient) readInitialMessages(ctx context.Context) error {
 		msg, err := readWireMessage(pc.conn)
 		if err != nil {
 			if isTimeout(err) {
+				debugf("peer initial message window finished")
 				return nil
 			}
 			return err
@@ -166,12 +172,14 @@ func (pc *peerClient) waitForUnchoke(ctx context.Context) error {
 		}
 		pc.consumeMessage(msg)
 		if msg.ID == msgUnchoke {
+			debugf("peer unchoked")
 			return nil
 		}
 	}
 }
 
 func (pc *peerClient) sendRequest(ctx context.Context, pieceIndex, begin, length int) error {
+	debugf("request piece %d offset %d length %d", pieceIndex, begin, length)
 	payload := make([]byte, 12)
 	binary.BigEndian.PutUint32(payload[0:4], uint32(pieceIndex))
 	binary.BigEndian.PutUint32(payload[4:8], uint32(begin))
@@ -214,6 +222,7 @@ func (pc *peerClient) readPieceBlock(ctx context.Context, pieceIndex, begin, exp
 			if len(block) > expectedLen {
 				block = block[:expectedLen]
 			}
+			debugf("received piece %d offset %d block=%d", pieceIndex, begin, len(block))
 			return block, nil
 		case msgChoke:
 			pc.consumeMessage(msg)
@@ -228,8 +237,10 @@ func (pc *peerClient) consumeMessage(msg wireMessage) {
 	switch msg.ID {
 	case msgChoke:
 		pc.peerIsChoked = true
+		debugf("peer sent choke")
 	case msgUnchoke:
 		pc.peerIsChoked = false
+		debugf("peer sent unchoke")
 	case msgHave:
 		if len(msg.Payload) < 4 {
 			return
@@ -238,9 +249,11 @@ func (pc *peerClient) consumeMessage(msg wireMessage) {
 		if idx >= 0 && idx < len(pc.have) {
 			pc.have[idx] = true
 			pc.hasPieceInfo = true
+			debugf("received have piece %d", idx)
 		}
 	case msgBitfield:
 		pc.hasPieceInfo = true
+		debugf("received bitfield (%d bytes)", len(msg.Payload))
 		for i := range pc.have {
 			pc.have[i] = bitfieldHasPiece(msg.Payload, i)
 		}
@@ -248,6 +261,7 @@ func (pc *peerClient) consumeMessage(msg wireMessage) {
 }
 
 func (pc *peerClient) sendHandshake(ctx context.Context, infoHash [20]byte, peerID [20]byte) error {
+	debugf("sending handshake")
 	payload := make([]byte, 49+len(wireProtocolString))
 	payload[0] = byte(len(wireProtocolString))
 	copy(payload[1:1+len(wireProtocolString)], wireProtocolString)
@@ -288,6 +302,7 @@ func (pc *peerClient) readHandshake(ctx context.Context, expectedInfoHash [20]by
 	if !bytes.Equal(rest[infoHashOffset:infoHashOffset+20], expectedInfoHash[:]) {
 		return errors.New("peer info_hash mismatch")
 	}
+	debugf("handshake complete")
 
 	return nil
 }

internal/torrent/piecescheduler.go

@@ -149,6 +149,7 @@ func (ps *pieceScheduler) run(pieceCount int) {
 			pieceIndex := selectPendingPiece(states, req.have, req.hasInfo)
 			if pieceIndex >= 0 {
 				states[pieceIndex] = pieceInProgress
+				debugf("scheduler assigned piece %d", pieceIndex)
 				req.responseCh <- assignPieceResponse{
 					task: pieceTask{Index: pieceIndex},
 					ok:   true,
@@ -164,11 +165,13 @@ func (ps *pieceScheduler) run(pieceCount int) {
 
 			if req.success {
 				if states[req.pieceIndex] == pieceDone {
+					debugf("scheduler report piece %d ignored (already done)", req.pieceIndex)
 					req.responseCh <- false
 					continue
 				}
 				states[req.pieceIndex] = pieceDone
 				completed++
+				debugf("scheduler report piece %d success (%d/%d)", req.pieceIndex, completed, pieceCount)
 				select {
 				case ps.progressCh <- req.pieceIndex:
 				default:
@@ -179,6 +182,7 @@ func (ps *pieceScheduler) run(pieceCount int) {
 
 			if states[req.pieceIndex] == pieceInProgress {
 				states[req.pieceIndex] = piecePending
+				debugf("scheduler report piece %d failed, re-queued", req.pieceIndex)
 			}
 			req.responseCh <- false
 		}

ui/window.go

@@ -27,6 +27,7 @@ type desktopUI struct {
 	window     fyne.Window
 
 	pathEntry        *widget.Entry
+	downloadDirEntry *widget.Entry
 	progress         *widget.ProgressBar
 	phaseLabel       *widget.Label
 	phaseMetricLabel *widget.Label
@@ -38,6 +39,7 @@ type desktopUI struct {
 	pieceCountLabel  *widget.Label
 	downloadedLabel  *widget.Label
 	outputLabel      *widget.Label
+	speedLabel       *widget.Label
 	peerCountLabel   *widget.Label
 
 	mu       sync.RWMutex
@@ -68,6 +70,7 @@ func newDesktopUI(controller *appcore.Controller) *desktopUI {
 		window:           w,
 		stopRefresh:      make(chan struct{}),
 		pathEntry:        widget.NewEntry(),
+		downloadDirEntry: widget.NewEntry(),
 		progress:         widget.NewProgressBar(),
 		phaseLabel:       widget.NewLabel("Phase: idle"),
 		phaseMetricLabel: widget.NewLabel("idle"),
@@ -79,14 +82,22 @@ func newDesktopUI(controller *appcore.Controller) *desktopUI {
 		pieceCountLabel:  widget.NewLabel("-"),
 		downloadedLabel:  widget.NewLabel("0 / 0"),
 		outputLabel:      widget.NewLabel("-"),
+		speedLabel:       widget.NewLabel("0 B/s"),
 		peerCountLabel:   widget.NewLabel("0"),
 	}
 
 	ui.pathEntry.SetPlaceHolder("/path/to/file.torrent")
+	ui.downloadDirEntry.SetPlaceHolder("/path/to/download/folder")
+	if home, err := os.UserHomeDir(); err == nil {
+		ui.downloadDirEntry.SetText(home)
+	}
 
-	browseButton := widget.NewButton("Browse", ui.onBrowse)
+	browseButton := widget.NewButton("Browse Torrent", ui.onBrowse)
+	browseOutputButton := widget.NewButton("Browse Folder", ui.onBrowseOutputFolder)
 	loadButton := widget.NewButton("Load Torrent", ui.onLoad)
-	topRow := container.NewBorder(nil, nil, nil, container.NewHBox(browseButton, loadButton), ui.pathEntry)
+	torrentRow := container.NewBorder(nil, nil, nil, browseButton, ui.pathEntry)
+	outputRow := container.NewBorder(nil, nil, nil, container.NewHBox(browseOutputButton, loadButton), ui.downloadDirEntry)
+	topRows := container.NewVBox(torrentRow, outputRow)
 
 	metaGrid := container.NewGridWithColumns(4,
 		wrapMetric("Name", ui.nameLabel),
@@ -94,6 +105,7 @@ func newDesktopUI(controller *appcore.Controller) *desktopUI {
 		wrapMetric("Piece length", ui.pieceLabel),
 		wrapMetric("Completed pieces", ui.pieceCountLabel),
 		wrapMetric("Downloaded", ui.downloadedLabel),
+		wrapMetric("Speed", ui.speedLabel),
 		wrapMetric("Output", ui.outputLabel),
 		wrapMetric("Discovered peers", ui.peerCountLabel),
 		wrapMetric("Phase", ui.phaseMetricLabel),
@@ -117,7 +129,7 @@ func newDesktopUI(controller *appcore.Controller) *desktopUI {
 	)
 
 	content := container.NewBorder(
-		container.NewVBox(topRow),
+		topRows,
 		nil,
 		nil,
 		nil,
@@ -172,12 +184,26 @@ func (ui *desktopUI) onLoad() {
 		ui.setError("select a .torrent file first")
 		return
 	}
+	downloadRoot := strings.TrimSpace(ui.downloadDirEntry.Text)
+	if downloadRoot == "" {
+		ui.setError("select a download folder first")
+		return
+	}
+	info, err := os.Stat(downloadRoot)
+	if err != nil {
+		ui.setError("download folder is not accessible: " + err.Error())
+		return
+	}
+	if !info.IsDir() {
+		ui.setError("download path must be a folder")
+		return
+	}
 
 	ui.setMessage("Loading torrent...")
 	ui.setError("")
 
 	go func() {
-		err := ui.controller.StartTorrent(path)
+		err := ui.controller.StartTorrent(path, downloadRoot)
 		status := ui.controller.Status()
 		ui.updateFromStatus(status)
 		if err != nil {
@@ -188,6 +214,20 @@ func (ui *desktopUI) onLoad() {
 	}()
 }
 
+func (ui *desktopUI) onBrowseOutputFolder() {
+	fd := dialog.NewFolderOpen(func(uri fyne.ListableURI, err error) {
+		if err != nil {
+			ui.setError(err.Error())
+			return
+		}
+		if uri == nil {
+			return
+		}
+		ui.downloadDirEntry.SetText(uri.Path())
+	}, ui.window)
+	fd.Show()
+}
+
 func (ui *desktopUI) refreshLoop() {
 	ticker := time.NewTicker(1200 * time.Millisecond)
 	defer ticker.Stop()
@@ -216,6 +256,7 @@ func (ui *desktopUI) updateFromStatus(status torrent.Status) {
 			ui.pieceCountLabel.SetText("-")
 		}
 		ui.downloadedLabel.SetText(fmt.Sprintf("%d / %d", status.DownloadedBytes, status.TotalBytes))
+		ui.speedLabel.SetText(formatBytesRate(status.DownloadSpeed))
 		ui.outputLabel.SetText(status.OutputPath)
 		ui.peerCountLabel.SetText(strconv.Itoa(status.PeerCount))
 
@@ -237,6 +278,23 @@ func (ui *desktopUI) updateFromStatus(status torrent.Status) {
 	})
 }
 
+func formatBytesRate(bytesPerSec float64) string {
+	if bytesPerSec < 0 {
+		bytesPerSec = 0
+	}
+	units := []string{"B/s", "KB/s", "MB/s", "GB/s", "TB/s"}
+	value := bytesPerSec
+	unit := 0
+	for value >= 1024 && unit < len(units)-1 {
+		value /= 1024
+		unit++
+	}
+	if unit == 0 {
+		return fmt.Sprintf("%.0f %s", value, units[unit])
+	}
+	return fmt.Sprintf("%.2f %s", value, units[unit])
+}
+
 func (ui *desktopUI) setMessage(msg string) {
 	fyne.Do(func() {
 		ui.messageLabel.SetText(msg)