fix: simplify artist image provider, remove unnecessary LookupArtist call
The previous implementation called LookupArtist (rate-limited MB API) before fetching url-rels, wasting a rate limiter slot. The fetchURL for rels also bypassed the MB rate limiter, risking 503 rejections. Rewrite: fetch MB url-rels once (direct HTTP, cached 30 days), parse both image and wikidata relations from the same response, resolve Wikimedia thumb URL. No dependency on MusicBrainzClient — just the Cache for storage and a plain http.Client. Also cleared 34 stale cached empty results from previous failed resolution attempts that were blocking image lookup.
This commit is contained in:
+101
-141
@@ -29,14 +29,17 @@ const (
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// artistImageTimeout is the HTTP timeout for image URL lookups.
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artistImageTimeout = 10 * time.Second
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// artistImageCacheTTL is how long resolved image URLs are cached.
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artistImageCacheTTL = 30 * 24 * time.Hour
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)
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// ArtistImageProvider resolves artist MBIDs to image URLs. It
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// checks multiple sources in priority order and caches results in
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// the explore_cache. Designed to be extended with additional
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// sources (fanart.tv, etc.) by adding to the providers slice.
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// fetches the artist's MB url-rels (once, cached 30 days), extracts
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// image sources from them, and returns a Wikimedia Commons thumbnail
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// URL. Designed to be extended with additional sources (fanart.tv,
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// etc.) by adding to the resolve chain.
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type ArtistImageProvider struct {
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mb *MusicBrainzClient
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cache *Cache
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client *http.Client
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logger *slog.Logger
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@@ -45,12 +48,10 @@ type ArtistImageProvider struct {
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// NewArtistImageProvider creates a provider that resolves artist
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// images via MusicBrainz relationships and Wikidata.
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func NewArtistImageProvider(
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mb *MusicBrainzClient,
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cache *Cache,
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logger *slog.Logger,
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) *ArtistImageProvider {
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return &ArtistImageProvider{
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mb: mb,
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cache: cache,
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client: &http.Client{Timeout: artistImageTimeout},
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logger: logger,
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@@ -59,111 +60,114 @@ func NewArtistImageProvider(
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// GetArtistImageURL returns a Wikimedia Commons thumbnail URL for
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// the given artist MBID, or "" if no image is available. Results
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// are cached in explore_cache with a 30-day TTL.
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// are cached for 30 days.
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func (p *ArtistImageProvider) GetArtistImageURL(artistMBID string) string {
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if artistMBID == "" {
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return ""
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}
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// Check resolved URL cache first.
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cacheKey := "artist-image:" + artistMBID
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// Check cache.
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if data, ok := p.cache.Get(cacheKey); ok {
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return string(data)
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}
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// Resolve image URL.
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imageURL := p.resolve(artistMBID)
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// Fetch MB url-rels (cached separately, shared with other uses).
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rels := p.fetchMBRels(artistMBID)
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if rels == nil {
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p.cache.Set(cacheKey, []byte(""), artistImageCacheTTL, artistMBID, "artist")
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// Cache the result (even empty string = no image found).
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cacheTTL := 30 * 24 * time.Hour
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p.cache.Set(cacheKey, []byte(imageURL), cacheTTL, artistMBID, "artist")
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return ""
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}
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// Try each source in priority order.
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imageURL := p.fromDirectImageRel(rels)
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if imageURL == "" {
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imageURL = p.fromWikidataRel(rels)
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}
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// Cache the result (even "" = no image).
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p.cache.Set(cacheKey, []byte(imageURL), artistImageCacheTTL, artistMBID, "artist")
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if imageURL != "" {
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p.logger.Debug("artist image resolved",
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"mbid", artistMBID,
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"url", imageURL,
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)
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}
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return imageURL
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}
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// resolve tries each source in order and returns the first image
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// URL found.
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func (p *ArtistImageProvider) resolve(artistMBID string) string {
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// Source 1: MB direct image relation (Commons wiki page link).
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if url := p.fromMBImageRelation(artistMBID); url != "" {
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return url
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}
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// ---------------------------------------------------------------------------
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// MB url-rels fetching (shared by all sources)
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// ---------------------------------------------------------------------------
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// Source 2: MB wikidata relation → Wikidata P18 → Commons thumb.
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if url := p.fromWikidata(artistMBID); url != "" {
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return url
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}
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// No image found from any source.
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return ""
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type mbRelation struct {
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Type string `json:"type"`
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URL struct {
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Resource string `json:"resource"`
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} `json:"url"`
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}
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// ---------------------------------------------------------------------------
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// Source 1: MB direct image relation
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// ---------------------------------------------------------------------------
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// fromMBImageRelation checks the artist's MB url-rels for a direct
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// "image" type pointing to Wikimedia Commons.
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func (p *ArtistImageProvider) fromMBImageRelation(artistMBID string) string {
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ctx := context.Background()
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artist, err := p.mb.LookupArtist(ctx, artistMBID)
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if err != nil || artist == nil {
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return ""
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}
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// The LookupArtist doesn't include rels in our current wrapper.
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// We need the raw MB data with url-rels. Check if there's a
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// cached response that includes relations.
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func (p *ArtistImageProvider) fetchMBRels(artistMBID string) []mbRelation {
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cacheKey := "mb:artist-rels:" + artistMBID
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if data, ok := p.cache.Get(cacheKey); ok {
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return p.parseImageFromRels(data)
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var envelope struct {
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Relations []mbRelation `json:"relations"`
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}
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if err := json.Unmarshal(data, &envelope); err == nil {
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return envelope.Relations
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}
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}
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// Fetch with url-rels included.
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url := fmt.Sprintf(
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"https://musicbrainz.org/ws/2/artist/%s?fmt=json&inc=url-rels",
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artistMBID,
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)
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body, err := p.fetchURL(ctx, url)
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body, err := p.fetchURL(url)
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if err != nil {
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return ""
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p.logger.Debug("artist image: MB rels fetch failed",
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"mbid", artistMBID,
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"error", err,
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)
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return nil
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}
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// Cache the response.
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cacheTTL := 30 * 24 * time.Hour
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p.cache.Set(cacheKey, body, cacheTTL, artistMBID, "artist")
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p.cache.Set(cacheKey, body, artistImageCacheTTL, artistMBID, "artist")
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return p.parseImageFromRels(body)
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var envelope struct {
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Relations []mbRelation `json:"relations"`
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}
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if err := json.Unmarshal(body, &envelope); err != nil {
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return nil
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}
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return envelope.Relations
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}
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func (p *ArtistImageProvider) parseImageFromRels(data []byte) string {
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var mb struct {
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Relations []struct {
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Type string `json:"type"`
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URL struct {
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Resource string `json:"resource"`
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} `json:"url"`
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} `json:"relations"`
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}
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// ---------------------------------------------------------------------------
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// Source 1: direct image relation (Commons wiki page link)
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// ---------------------------------------------------------------------------
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if err := json.Unmarshal(data, &mb); err != nil {
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return ""
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}
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for _, rel := range mb.Relations {
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func (p *ArtistImageProvider) fromDirectImageRel(rels []mbRelation) string {
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for _, rel := range rels {
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if rel.Type != "image" {
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continue
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}
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resource := rel.URL.Resource
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// Direct Commons file link: "https://commons.wikimedia.org/wiki/File:Name.jpg"
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if strings.Contains(resource, "commons.wikimedia.org/wiki/File:") {
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filename := resource[strings.LastIndex(resource, "File:")+5:]
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// "https://commons.wikimedia.org/wiki/File:Name.jpg"
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if idx := strings.LastIndex(resource, "File:"); idx >= 0 {
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filename := resource[idx+5:]
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return wikimediaThumbURL(filename)
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}
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@@ -173,33 +177,40 @@ func (p *ArtistImageProvider) parseImageFromRels(data []byte) string {
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}
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// ---------------------------------------------------------------------------
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// Source 2: Wikidata P18
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// Source 2: Wikidata P18 property
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// ---------------------------------------------------------------------------
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// fromWikidata looks up the artist's Wikidata Q-ID from MB rels,
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// then fetches the P18 (image) property from Wikidata.
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func (p *ArtistImageProvider) fromWikidata(artistMBID string) string {
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// Get the wikidata Q-ID from cached MB rels.
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qid := p.getWikidataQID(artistMBID)
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func (p *ArtistImageProvider) fromWikidataRel(rels []mbRelation) string {
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// Find the wikidata Q-ID.
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qid := ""
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for _, rel := range rels {
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if rel.Type == "wikidata" {
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parts := strings.Split(rel.URL.Resource, "/")
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qid = parts[len(parts)-1]
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break
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}
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}
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if qid == "" {
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return ""
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}
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// Check cache for Wikidata image.
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cacheKey := "wikidata-image:" + qid
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// Check cache for this Wikidata entity.
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cacheKey := "wikidata-p18:" + qid
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if data, ok := p.cache.Get(cacheKey); ok {
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return string(data)
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}
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// Fetch P18 from Wikidata API.
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ctx := context.Background()
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// Fetch P18 from Wikidata.
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url := fmt.Sprintf(
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"%s?action=wbgetclaims&entity=%s&property=P18&format=json",
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wikidataAPIBase, qid,
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)
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body, err := p.fetchURL(ctx, url)
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body, err := p.fetchURL(url)
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if err != nil {
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return ""
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}
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@@ -216,78 +227,24 @@ func (p *ArtistImageProvider) fromWikidata(artistMBID string) string {
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} `json:"claims"`
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}
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if err := json.Unmarshal(body, &wd); err != nil || len(wd.Claims.P18) == 0 {
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// Cache empty result.
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cacheTTL := 30 * 24 * time.Hour
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p.cache.Set(cacheKey, []byte(""), cacheTTL, "", "")
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thumbURL := ""
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return ""
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if err := json.Unmarshal(body, &wd); err == nil && len(wd.Claims.P18) > 0 {
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filename := strings.ReplaceAll(wd.Claims.P18[0].Mainsnak.Datavalue.Value, " ", "_")
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thumbURL = wikimediaThumbURL(filename)
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}
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filename := strings.ReplaceAll(wd.Claims.P18[0].Mainsnak.Datavalue.Value, " ", "_")
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thumbURL := wikimediaThumbURL(filename)
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cacheTTL := 30 * 24 * time.Hour
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p.cache.Set(cacheKey, []byte(thumbURL), cacheTTL, "", "")
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p.cache.Set(cacheKey, []byte(thumbURL), artistImageCacheTTL, "", "")
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return thumbURL
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}
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func (p *ArtistImageProvider) getWikidataQID(artistMBID string) string {
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cacheKey := "mb:artist-rels:" + artistMBID
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data, ok := p.cache.Get(cacheKey)
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if !ok {
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// Need to fetch rels — fromMBImageRelation should have
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// populated this, but if not, fetch now.
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ctx := context.Background()
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url := fmt.Sprintf(
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"https://musicbrainz.org/ws/2/artist/%s?fmt=json&inc=url-rels",
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artistMBID,
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)
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var err error
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data, err = p.fetchURL(ctx, url)
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if err != nil {
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return ""
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}
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cacheTTL := 30 * 24 * time.Hour
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p.cache.Set(cacheKey, data, cacheTTL, artistMBID, "artist")
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}
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var mb struct {
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Relations []struct {
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Type string `json:"type"`
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URL struct {
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Resource string `json:"resource"`
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} `json:"url"`
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} `json:"relations"`
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}
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if err := json.Unmarshal(data, &mb); err != nil {
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return ""
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}
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for _, rel := range mb.Relations {
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if rel.Type == "wikidata" {
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parts := strings.Split(rel.URL.Resource, "/")
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return parts[len(parts)-1]
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}
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}
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return ""
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}
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// ---------------------------------------------------------------------------
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// Helpers
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// ---------------------------------------------------------------------------
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// wikimediaThumbURL constructs a Wikimedia Commons thumbnail URL
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// from a filename. The URL scheme uses MD5 hashing of the filename
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// for directory bucketing.
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// from a filename using the MD5 directory bucketing scheme.
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func wikimediaThumbURL(filename string) string {
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if filename == "" {
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return ""
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@@ -304,7 +261,10 @@ func wikimediaThumbURL(filename string) string {
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)
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}
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func (p *ArtistImageProvider) fetchURL(ctx context.Context, url string) ([]byte, error) {
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func (p *ArtistImageProvider) fetchURL(url string) ([]byte, error) {
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ctx, cancel := context.WithTimeout(context.Background(), artistImageTimeout)
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defer cancel()
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req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
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if err != nil {
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return nil, err
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@@ -38,7 +38,7 @@ func NewExploreService(logger *slog.Logger, db *database.DB) *Service {
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lb := NewListenBrainzClient(limiter, cache, logger.WithGroup("listenbrainz"))
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index := NewSearchIndex(db, lb, logger.WithGroup("search-index"))
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artProxy := NewCoverArtProxy(db, limiter)
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artistImg := NewArtistImageProvider(mb, cache, logger.WithGroup("artist-image"))
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artistImg := NewArtistImageProvider(cache, logger.WithGroup("artist-image"))
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logger.Info("explore service created")
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Reference in New Issue
Block a user