ListenBrainz: Skip importing existing loves

backends/listenbrainz/listenbrainz.go

@@ -116,6 +116,17 @@ func (b ListenBrainzApiBackend) ImportLoves(loves []models.Love, oldestTimestamp
 		LastTimestamp: oldestTimestamp,
 		ImportErrors:  make([]string, 0),
 	}
+
+	existingLoves, err := b.ExportLoves(time.Unix(0, 0))
+	if err != nil {
+		return result, err
+	}
+
+	existingMbids := make(map[string]bool, len(existingLoves))
+	for _, love := range existingLoves {
+		existingMbids[string(love.RecordingMbid)] = true
+	}
+
 	for _, love := range loves {
 		if love.Created.Unix() <= oldestTimestamp.Unix() {
 			continue
@@ -123,19 +134,29 @@ func (b ListenBrainzApiBackend) ImportLoves(loves []models.Love, oldestTimestamp
 
 		// TODO: Support love import without recording MBID
 		if love.RecordingMbid != "" {
-			resp, err := b.client.SendFeedback(Feedback{
+			ok := false
-				RecordingMbid: string(love.RecordingMbid),
+			errMsg := ""
-				Score:         1,
+			if existingMbids[string(love.RecordingMbid)] {
-			})
+				ok = true
+			} else {
+				resp, err := b.client.SendFeedback(Feedback{
+					RecordingMbid: string(love.RecordingMbid),
+					Score:         1,
+				})
+				ok = err == nil && resp.Status == "ok"
+				if err != nil {
+					errMsg = err.Error()
+				}
+			}
 
-			if err == nil && resp.Status == "ok" {
+			if ok {
 				result.ImportCount += 1
 				if love.Created.Unix() > result.LastTimestamp.Unix() {
 					result.LastTimestamp = love.Created
 				}
 			} else {
 				msg := fmt.Sprintf("Failed import of \"%s\" by %s: %v",
-					love.TrackName, love.ArtistName(), err.Error())
+					love.TrackName, love.ArtistName(), errMsg)
 				result.ImportErrors = append(result.ImportErrors, msg)
 			}
 		}