feat(tags): fetch genre and add it to file tags with --genre

internal/provider/genre.go

@@ -0,0 +1,86 @@
+package provider
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+	"strings"
+
+	"github.com/PuerkitoBio/goquery"
+)
+
+type GenreProvider struct{}
+
+func (p GenreProvider) Fetch(ctx context.Context, httpClient *http.Client, artist, title string) (string, error) {
+	reqUrl := fmt.Sprintf("https://www.last.fm/music/%s/%s/+tags", artist, title)
+	doc, err := p.fetchPage(ctx, httpClient, reqUrl)
+	if err != nil {
+		return "", err
+	}
+
+	tags := p.parse(doc)
+	if len(tags) == 0 {
+		return "", fmt.Errorf("no data found")
+	}
+
+	if len(tags) > 1 {
+		tags = tags[:2]
+	}
+	genre := p.formatTags(tags)
+
+	return genre, nil
+}
+
+func (p GenreProvider) fetchPage(ctx context.Context, httpClient *http.Client, reqUrl string) (*goquery.Document, error) {
+	req, err := http.NewRequestWithContext(ctx, "GET", reqUrl, nil)
+	if err != nil {
+		return nil, err
+	}
+
+	resp, err := httpClient.Do(req)
+	if err != nil {
+		return nil, err
+	}
+	defer resp.Body.Close()
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("unexpected status code: %d", resp.StatusCode)
+	}
+
+	doc, err := goquery.NewDocumentFromReader(resp.Body)
+	if err != nil {
+		return nil, err
+	}
+
+	return doc, nil
+}
+
+func (p GenreProvider) parse(doc *goquery.Document) []string {
+	var tags []string
+	doc.Find("ol.big-tags .big-tags-item-name a").Each(func(_ int, s *goquery.Selection) {
+		tag := strings.TrimSpace(s.Text())
+		if tag != "" {
+			tags = append(tags, tag)
+		}
+	})
+
+	return tags
+}
+
+func (p GenreProvider) formatTags(tags []string) string {
+	var formatted []string
+	for _, tag := range tags {
+		tag = strings.TrimSpace(tag)
+		if tag == "" {
+			continue
+		}
+
+		words := strings.Fields(tag)
+		for i, w := range words {
+			words[i] = strings.Title(w)
+		}
+		formatted = append(formatted, strings.Join(words, " "))
+	}
+
+	return strings.Join(formatted, "/")
+}