From 1249238d3abd35c7aef3183b3a59403db1a65fa4 Mon Sep 17 00:00:00 2001
From: Philipp Wolfer <ph.wolfer@gmail.com>
Date: Sun, 26 Nov 2023 12:22:11 +0100
Subject: [PATCH] lastfm: loves export

---
 internal/backends/lastfm/lastfm.go | 80 +++++++++++++++++++++++++++++-
 1 file changed, 79 insertions(+), 1 deletion(-)

diff --git a/internal/backends/lastfm/lastfm.go b/internal/backends/lastfm/lastfm.go
index 0b8c957..f215654 100644
--- a/internal/backends/lastfm/lastfm.go
+++ b/internal/backends/lastfm/lastfm.go
@@ -17,6 +17,9 @@ package lastfm
 
 import (
 	"net/url"
+	"sort"
+	"strconv"
+	"time"
 
 	"github.com/shkh/lastfm-go/lastfm"
 	"github.com/spf13/viper"
@@ -25,8 +28,11 @@ import (
 	"golang.org/x/oauth2"
 )
 
+const MaxItemsPerGet = 50
+
 type LastfmApiBackend struct {
-	client *lastfm.Api
+	client   *lastfm.Api
+	username string
 }
 
 func (b *LastfmApiBackend) Name() string { return "lastfm" }
@@ -35,6 +41,7 @@ func (b *LastfmApiBackend) FromConfig(config *viper.Viper) models.Backend {
 	clientId := config.GetString("client-id")
 	clientSecret := config.GetString("client-secret")
 	b.client = lastfm.New(clientId, clientSecret)
+	b.username = config.GetString("username")
 	return b
 }
 
@@ -52,3 +59,74 @@ func (b *LastfmApiBackend) OAuth2Setup(token oauth2.TokenSource) error {
 	}
 	return b.client.LoginWithToken(t.AccessToken)
 }
+
+func (b *LastfmApiBackend) ExportLoves(oldestTimestamp time.Time, results chan models.LovesResult, progress chan models.Progress) {
+	// Choose a high offset, we attempt to search the loves backwards starting
+	// at the oldest one.
+	page := 1
+	perPage := MaxItemsPerGet
+
+	defer close(results)
+
+	loves := make(models.LovesList, 0, 2*MaxItemsPerGet)
+	p := models.Progress{Total: int64(perPage)}
+	var totalCount int
+
+out:
+	for {
+		result, err := b.client.User.GetLovedTracks(lastfm.P{
+			"user":  b.username,
+			"limit": MaxItemsPerGet,
+			"page":  page,
+		})
+		if err != nil {
+			progress <- p.Complete()
+			results <- models.LovesResult{Error: err}
+			return
+		}
+
+		p.Total = int64(result.Total)
+		count := len(result.Tracks)
+		if count == 0 {
+			break out
+		}
+
+		for _, track := range result.Tracks {
+			timestamp, err := strconv.ParseInt(track.Date.Uts, 10, 64)
+			if err != nil {
+				progress <- p.Complete()
+				results <- models.LovesResult{Error: err}
+				return
+			}
+			if timestamp > oldestTimestamp.Unix() {
+				totalCount += 1
+				love := models.Love{
+					Created:       time.Unix(timestamp, 0),
+					UserName:      result.User,
+					RecordingMbid: models.MBID(track.Mbid),
+					Track: models.Track{
+						TrackName:     track.Name,
+						ArtistNames:   []string{track.Artist.Name},
+						RecordingMbid: models.MBID(track.Mbid),
+						ArtistMbids:   []models.MBID{models.MBID(track.Artist.Mbid)},
+						AdditionalInfo: models.AdditionalInfo{
+							"lastfm_url": track.Url,
+						},
+					},
+				}
+				loves = append(loves, love)
+			} else {
+				break out
+			}
+		}
+
+		p.Elapsed += int64(count)
+		progress <- p
+
+		page += 1
+	}
+
+	sort.Sort(loves)
+	results <- models.LovesResult{Loves: loves, Total: totalCount}
+	progress <- p.Complete()
+}