refactor: modularize downloader architecture

util.go

@@ -0,0 +1,37 @@
+package main
+
+import (
+	"errors"
+	"os"
+	"regexp"
+	"strings"
+
+	"path/filepath"
+)
+
+func (a *App) fail(t *Task, err error) {
+	if t.LocalPath != "" {
+		_ = os.Remove(t.LocalPath + ".part")
+	}
+	if err == nil {
+		err = errors.New("unknown download error")
+	}
+	t.Status, t.Error = "error", err.Error()
+	a.db.Save(t)
+}
+
+var bad = regexp.MustCompile(`[/\\:*?"<>|]+`)
+
+func safe(s string) string {
+	s = strings.TrimSpace(s)
+	s = bad.ReplaceAllString(s, "_")
+	s = strings.Trim(s, ". ")
+	if s == "" {
+		return "Unknown"
+	}
+	return s
+}
+
+func audioPath(dir, artist, title, format string) string {
+	return filepath.Join(dir, safe(artist)+" - "+safe(title)+"."+normalizedFormat(format))
+}