ListenBrainz: Love export and basic import

Love import currently works only for tracks with existing recording MBID

backends/listenbrainz/listenbrainz.go

@@ -44,7 +44,7 @@ func (b ListenBrainzApiBackend) FromConfig(config *viper.Viper) models.Backend {
 func (b ListenBrainzApiBackend) ExportListens(oldestTimestamp time.Time) ([]models.Listen, error) {
 	maxTime := time.Now()
 	minTime := time.Unix(0, 0)
-	listens := make([]models.Listen, 0)
+	listens := make([]models.Listen, 0, 2*MaxItemsPerGet)
 
 out:
 	for {
@@ -76,6 +76,69 @@ out:
 	return listens, nil
 }
 
+func (b ListenBrainzApiBackend) ExportLoves(oldestTimestamp time.Time) ([]models.Love, error) {
+	offset := 0
+	// perPage := MaxItemsPerGet
+
+	loves := make([]models.Love, 0, 2*MaxItemsPerGet)
+
+out:
+	for {
+		result, err := b.client.GetFeedback(b.username, 1, offset)
+		if err != nil {
+			return nil, err
+		}
+
+		count := len(result.Feedback)
+		if count == 0 {
+			break out
+		}
+
+		for _, feedback := range result.Feedback {
+			love := feedback.ToLove()
+			if love.Created.Unix() > oldestTimestamp.Unix() {
+				loves = append(loves, love)
+			} else {
+				break out
+			}
+		}
+
+		offset += 1
+	}
+
+	slices.Reverse(loves)
+	return loves, nil
+}
+
+func (b ListenBrainzApiBackend) ImportLoves(loves []models.Love, oldestTimestamp time.Time) (models.ImportResult, error) {
+	result := models.ImportResult{
+		TotalCount:    len(loves),
+		ImportCount:   0,
+		LastTimestamp: oldestTimestamp,
+	}
+	for _, love := range loves {
+		if love.Created.Unix() <= oldestTimestamp.Unix() {
+			continue
+		}
+
+		// TODO: Support love import without recording MBID
+		if love.RecordingMbid != "" {
+			_, err := b.client.SendFeedback(Feedback{
+				RecordingMbid: string(love.RecordingMbid),
+				Score:         1,
+			})
+
+			if err != nil {
+				result.ImportCount += 1
+				if love.Created.Unix() > result.LastTimestamp.Unix() {
+					result.LastTimestamp = love.Created
+				}
+			}
+		}
+	}
+	return result, nil
+}
+
 func (lbListen Listen) ToListen() models.Listen {
 	track := lbListen.TrackMetadata
 	listen := models.Listen{
@@ -96,3 +159,27 @@ func (lbListen Listen) ToListen() models.Listen {
 	}
 	return listen
 }
+
+func (f Feedback) ToLove() models.Love {
+	track := f.TrackMetadata
+	recordingMbid := models.MBID(f.RecordingMbid)
+	love := models.Love{
+		UserName:      f.UserName,
+		RecordingMbid: recordingMbid,
+		Created:       time.Unix(f.Created, 0),
+		Track: models.Track{
+			TrackName:     track.TrackName,
+			ReleaseName:   track.ReleaseName,
+			ArtistNames:   []string{track.ArtistName},
+			RecordingMbid: recordingMbid,
+			ReleaseMbid:   models.MBID(track.MbidMapping.ReleaseMbid),
+			ArtistMbids:   make([]models.MBID, 0, len(track.MbidMapping.ArtistMbids)),
+		},
+	}
+
+	for _, artistMbid := range track.MbidMapping.ArtistMbids {
+		love.Track.ArtistMbids = append(love.Track.ArtistMbids, models.MBID(artistMbid))
+	}
+
+	return love
+}