feat: improve cover selection algorithm

scanner/coverresolve/cover.go

@@ -0,0 +1,83 @@
+package coverresolve
+
+import (
+	"regexp"
+	"sort"
+	"strconv"
+	"strings"
+)
+
+var DefaultKeywords = []string{
+	"cover",
+	"folder",
+	"front",
+	"albumart",
+	"album",
+	"artist",
+	"scan",
+}
+
+// Helper function to extract the number from the filename
+func extractNumber(filename string) int {
+	re := regexp.MustCompile(`\d+`)
+	matches := re.FindAllString(filename, -1)
+	if len(matches) == 0 {
+		return 0
+	}
+	num, _ := strconv.Atoi(matches[0])
+	return num
+}
+
+type CoverAlternative struct {
+	Name  string
+	Score int
+}
+
+func SelectCover(covers []string) string {
+	if len(covers) == 0 {
+		return ""
+	}
+
+	coverAlternatives := make([]CoverAlternative, 0)
+
+	for _, keyword := range DefaultKeywords {
+		if len(coverAlternatives) > 0 {
+			break
+		}
+
+		for _, cover := range covers {
+			if strings.Contains(strings.ToLower(cover), keyword) {
+				coverAlternatives = append(coverAlternatives, CoverAlternative{
+					Name:  cover,
+					Score: 0,
+				})
+			}
+		}
+	}
+
+	// parse the integer from the filename
+	// eg. cover(1).jpg will have higher score than cover(114514).jpg
+	for i := range coverAlternatives {
+		coverAlternatives[i].Score -= extractNumber(coverAlternatives[i].Name)
+	}
+
+	// sort by score
+	sort.Slice(coverAlternatives, func(i, j int) bool {
+		return coverAlternatives[i].Score > coverAlternatives[j].Score
+	})
+
+	if len(coverAlternatives) == 0 {
+		return covers[0]
+	}
+
+	return coverAlternatives[0].Name
+}
+
+func IsCover(name string) bool {
+	for _, ext := range []string{"jpg", "jpeg", "png", "bmp", "gif"} {
+		if strings.HasSuffix(strings.ToLower(name), "."+ext) {
+			return true
+		}
+	}
+	return false
+}