lastfm: listens export

README.md

@@ -11,6 +11,7 @@ Scotty transfers your listens/scrobbles and favorite tracks between various musi
 - Transfer loved tracks from Funkwhale to ListenBrainz
 - Submit listens stored in a Rockbox `.scrobbler.log` file to ListenBrainz, Last.fm or Maloja
 - Store your favorite tracks from Deezer as a JSPF playlist
+- Backup your listening history from ListenBrainz or Last.fm
 
 
 ## Installation
@@ -44,7 +45,7 @@ deezer         | ✓              | ⨯              | ✓            | -
 dump           | ⨯              | ✓              | ⨯            | ✓
 funkwhale      | ✓              | ⨯              | ✓            | -
 jspf           | -              | ✓              | -            | ✓
-lastfm         | -              | -              | ✓            | ✓
+lastfm         | ✓              | ✓              | ✓            | ✓
 listenbrainz   | ✓              | ✓              | ✓            | ✓
 maloja         | ✓              | ✓              | ⨯            | ⨯
 scrobbler-log  | ✓              | ✓              | ⨯            | ⨯

internal/backends/lastfm/lastfm.go

@@ -31,8 +31,10 @@ import (
 )
 
 const (
-	MaxItemsPerGet       = 1000
-	MaxListensPerRequest = 50
+	MaxItemsPerGet          = 1000
+	MaxListensPerGet        = 200
+	MaxListensPerSubmission = 50
+	MaxPage                 = 1000000
 )
 
 type LastfmApiBackend struct {
@@ -69,10 +71,98 @@ func (b *LastfmApiBackend) OAuth2Setup(token oauth2.TokenSource) error {
 	return nil
 }
 
+func (b *LastfmApiBackend) ExportListens(oldestTimestamp time.Time, results chan models.ListensResult, progress chan models.Progress) {
+	page := MaxPage
+	minTime := oldestTimestamp
+	perPage := MaxItemsPerGet
+
+	defer close(results)
+
+	// We need to gather the full list of listens in order to sort them
+	p := models.Progress{Total: int64(page)}
+
+out:
+	for page > 0 {
+		args := lastfm.P{
+			"user":  b.username,
+			"limit": MaxListensPerGet,
+			// last.fm includes the listen with the exact timestamp in the result
+			"from": oldestTimestamp.Add(time.Second).Unix(),
+			"page": page,
+		}
+		result, err := b.client.User.GetRecentTracks(args)
+		if err != nil {
+			results <- models.ListensResult{Error: err}
+			progress <- p.Complete()
+			return
+		}
+
+		count := len(result.Tracks)
+		if count == 0 {
+			// The page was outside of the result range, adjust and request again
+			if page > result.TotalPages {
+				page = result.TotalPages
+				continue
+			}
+			break
+		}
+
+		listens := make(models.ListensList, 0, 2*perPage)
+		for _, scrobble := range result.Tracks {
+			timestamp, err := strconv.ParseInt(scrobble.Date.Uts, 10, 64)
+			if err != nil {
+				results <- models.ListensResult{Error: err}
+				progress <- p.Complete()
+				break out
+			}
+			if timestamp > oldestTimestamp.Unix() {
+				p.Elapsed += 1
+				listen := models.Listen{
+					ListenedAt: time.Unix(timestamp, 0),
+					UserName:   b.username,
+					Track: models.Track{
+						TrackName:     scrobble.Name,
+						ArtistNames:   []string{},
+						ReleaseName:   scrobble.Album.Name,
+						RecordingMbid: models.MBID(scrobble.Mbid),
+						ArtistMbids:   []models.MBID{},
+						ReleaseMbid:   models.MBID(scrobble.Album.Mbid),
+					},
+				}
+				if scrobble.Artist.Name != "" {
+					listen.Track.ArtistNames = []string{scrobble.Artist.Name}
+				}
+				if scrobble.Artist.Mbid != "" {
+					listen.Track.ArtistMbids = []models.MBID{models.MBID(scrobble.Artist.Mbid)}
+				}
+				listens = append(listens, listen)
+			} else {
+				break out
+			}
+		}
+
+		sort.Sort(listens)
+		minTime = listens[len(listens)-1].ListenedAt
+		page -= 1
+
+		results <- models.ListensResult{
+			Listens:         listens,
+			Total:           result.Total,
+			OldestTimestamp: minTime,
+		}
+		p.Total = int64(result.TotalPages)
+		p.Elapsed = int64(result.TotalPages - page)
+		progress <- p
+	}
+
+	results <- models.ListensResult{OldestTimestamp: minTime}
+	progress <- p.Complete()
+}
+
 func (b *LastfmApiBackend) ImportListens(export models.ListensResult, importResult models.ImportResult, progress chan models.Progress) (models.ImportResult, error) {
 	total := len(export.Listens)
-	for i := 0; i < total; i += MaxListensPerRequest {
-		listens := export.Listens[i:min(i+MaxListensPerRequest, total)]
+	for i := 0; i < total; i += MaxListensPerSubmission {
+		listens := export.Listens[i:min(i+MaxListensPerSubmission, total)]
 		count := len(listens)
 		if count == 0 {
 			break