feat: Load media downloaded as file for offline use

app/src/main/java/com/cappielloantonio/tempo/util/ExternalAudioReader.java

@@ -0,0 +1,102 @@
+package com.cappielloantonio.tempo.util;
+
+import android.net.Uri;
+
+import androidx.documentfile.provider.DocumentFile;
+
+import com.cappielloantonio.tempo.App;
+import com.cappielloantonio.tempo.subsonic.models.Child;
+import com.cappielloantonio.tempo.subsonic.models.PodcastEpisode;
+
+import java.text.Normalizer;
+import java.util.HashMap;
+import java.util.Locale;
+import java.util.Map;
+
+public class ExternalAudioReader {
+
+    private static final Map<String, DocumentFile> cache = new HashMap<>();
+    private static String cachedDirUri;
+
+    private static String sanitizeFileName(String name) {
+        String sanitized = name.replaceAll("[\\/:*?\\\"<>|]", "_");
+        sanitized = sanitized.replaceAll("\\s+", " ").trim();
+        return sanitized;
+    }
+
+    private static String normalizeForComparison(String name) {
+        String s = sanitizeFileName(name);
+        s = Normalizer.normalize(s, Normalizer.Form.NFKD);
+        s = s.replaceAll("\\p{InCombiningDiacriticalMarks}+", "");
+        return s.toLowerCase(Locale.ROOT);
+    }
+
+    private static synchronized void ensureCache() {
+        String uriString = Preferences.getDownloadDirectoryUri();
+        if (uriString == null) {
+            cache.clear();
+            cachedDirUri = null;
+            return;
+        }
+
+        if (uriString.equals(cachedDirUri)) return;
+
+        cache.clear();
+        DocumentFile directory = DocumentFile.fromTreeUri(App.getContext(), Uri.parse(uriString));
+        if (directory != null && directory.canRead()) {
+            for (DocumentFile file : directory.listFiles()) {
+                String existing = file.getName();
+                if (existing != null) {
+                    String base = existing.replaceFirst("\\.[^\\.]+$", "");
+                    cache.put(normalizeForComparison(base), file);
+                }
+            }
+        }
+
+        cachedDirUri = uriString;
+    }
+
+    /** Rebuilds the cache on next access. */
+    public static synchronized void refreshCache() {
+        cachedDirUri = null;
+        cache.clear();
+    }
+
+    private static String buildKey(String artist, String title, String album) {
+        String name = artist != null && !artist.isEmpty() ? artist + " - " + title : title;
+        if (album != null && !album.isEmpty()) name += " (" + album + ")";
+        return normalizeForComparison(name);
+    }
+
+    private static Uri findUri(String artist, String title, String album) {
+        ensureCache();
+        if (cachedDirUri == null) return null;
+
+        DocumentFile file = cache.get(buildKey(artist, title, album));
+        return file != null && file.exists() ? file.getUri() : null;
+    }
+
+    public static Uri getUri(Child media) {
+        return findUri(media.getArtist(), media.getTitle(), media.getAlbum());
+    }
+
+    public static Uri getUri(PodcastEpisode episode) {
+        return findUri(episode.getArtist(), episode.getTitle(), episode.getAlbum());
+    }
+
+    public static boolean delete(Child media) {
+        ensureCache();
+        if (cachedDirUri == null) return false;
+
+        String key = buildKey(media.getArtist(), media.getTitle(), media.getAlbum());
+        DocumentFile file = cache.get(key);
+        boolean deleted = false;
+        if (file != null && file.exists()) {
+            deleted = file.delete();
+        }
+        if (deleted) {
+            cache.remove(key);
+        }
+        return deleted;
+    }
+}