refactor: split modules and harden scraping workflows

internal/service/download_live_snapshot.go

@@ -0,0 +1,44 @@
+package service
+
+import "time"
+
+func (d *DownloadService) currentTime() time.Time {
+	if d != nil && d.now != nil {
+		return d.now()
+	}
+	return time.Now()
+}
+
+func (d *DownloadService) recordLiveTorrentSnapshot(live []QBitTorrent) {
+	if d == nil {
+		return
+	}
+	snapshot := cloneQBitTorrentSlice(live)
+	d.mu.Lock()
+	d.liveTorrents = snapshot
+	d.liveTorrentsAt = d.currentTime()
+	d.mu.Unlock()
+}
+
+func (d *DownloadService) LiveTorrentSnapshot(maxAge time.Duration) []QBitTorrent {
+	if d == nil {
+		return nil
+	}
+	now := d.currentTime()
+	d.mu.Lock()
+	defer d.mu.Unlock()
+	if d.liveTorrentsAt.IsZero() {
+		return nil
+	}
+	if maxAge > 0 && now.Sub(d.liveTorrentsAt) > maxAge {
+		return nil
+	}
+	return cloneQBitTorrentSlice(d.liveTorrents)
+}
+
+func cloneQBitTorrentSlice(in []QBitTorrent) []QBitTorrent {
+	if len(in) == 0 {
+		return nil
+	}
+	return append([]QBitTorrent(nil), in...)
+}