feat(app): 完善播放协议搜索与空状态

lib/pages/player/player_logic.dart

@@ -3,6 +3,7 @@
 import 'dart:async';
 
 import 'package:flutter/material.dart';
+import 'package:video_player/video_player.dart';
 import 'package:flutter/scheduler.dart';
 import 'package:provider/provider.dart';
 
@@ -88,6 +89,9 @@ class PlayerLogic extends ChangeNotifier {
   String? blockedEpisodeId;
   List<Episode> sessionEpisodes = const [];
   List<String> qualities = const [];
+  List<PlayQualityTrack> qualityTracks = const [];
+  String selectedQuality = 'AUTO';
+  Duration? _qualitySeek;
   int pageRequest = 0;
   bool muted = false;
   double playbackSpeed = 1.0;
@@ -426,6 +430,7 @@ class PlayerLogic extends ChangeNotifier {
         blockedTicket = null;
         blockedEpisodeId = null;
         qualities = const [];
+        qualityTracks = const [];
         sessionEpisodes[index] = episode.withVideoUrl(_fileUrl(localPath));
         return true;
       }
@@ -437,10 +442,18 @@ class PlayerLogic extends ChangeNotifier {
       blockedTicket = null;
       blockedEpisodeId = null;
       qualities = ticket.qualities;
-      if (ticket.accessible && ticket.playUrl.isNotEmpty) {
+      qualityTracks = ticket.tracks;
+      final preferred = qualityPlayUrl(
+        quality: selectedQuality,
+        tracks: qualityTracks,
+        currentUrl: ticket.playUrl,
+      );
+      final playUrl = preferred ?? ticket.playUrl;
+      if (preferred == null) selectedQuality = 'AUTO';
+      if (ticket.accessible && playUrl.isNotEmpty) {
         // 签名地址原样写回，不做任何拼接/改写（AppConfig.mediaUrl 只补 host）
         sessionEpisodes[index] = episode.withVideoUrl(
-          ticket.playUrl,
+          playUrl,
           likeCount: ticket.likeCount,
           commentCount: ticket.commentCount,
           thumbnailsUrl: ticket.thumbnailsUrl,
@@ -470,6 +483,64 @@ class PlayerLogic extends ChangeNotifier {
   String _fileUrl(String path) =>
       path.startsWith('file:') ? path : Uri.file(path).toString();
 
+  /// 切到指定清晰度。新片源出画后再替换，失败则继续播原来的。
+  Future<bool> selectQuality(String quality) async {
+    final index = session.currentIndex;
+    if (index < 0 || index >= sessionEpisodes.length) return false;
+    final current = sessionEpisodes[index];
+    final url = qualityPlayUrl(
+      quality: quality,
+      tracks: qualityTracks,
+      currentUrl: current.videoUrl,
+    );
+    if (url == null || url.isEmpty) return false;
+    if (selectedQuality.toUpperCase() == quality.toUpperCase() &&
+        current.videoUrl == url) {
+      return true;
+    }
+    final previousQuality = selectedQuality;
+    final active = session.active;
+    if (active is VideoPlayerPort && active.controller.value.isInitialized) {
+      _qualitySeek = active.controller.value.position;
+    }
+    selectedQuality = quality.toUpperCase();
+    sessionEpisodes[index] = current.withVideoUrl(url);
+    final switched = await session.replaceCurrent();
+    if (switched) {
+      if (isMounted()) notify();
+      return true;
+    }
+    _qualitySeek = null;
+    selectedQuality = previousQuality;
+    if (index < sessionEpisodes.length) {
+      sessionEpisodes[index] = current;
+    }
+    if (isMounted()) notify();
+    return false;
+  }
+
+  Future<void> _waitUntilFrameReady(VideoPlayerController controller) async {
+    if (controller.value.hasError) {
+      throw StateError('quality source failed');
+    }
+    if (!controller.value.isBuffering) return;
+    final done = Completer<void>();
+    void onChange() {
+      final value = controller.value;
+      if (done.isCompleted) return;
+      if (value.hasError || !value.isBuffering) done.complete();
+    }
+    controller.addListener(onChange);
+    try {
+      await done.future.timeout(const Duration(seconds: 4));
+    } finally {
+      controller.removeListener(onChange);
+    }
+    if (controller.value.hasError) {
+      throw StateError('quality source failed');
+    }
+  }
+
   /// 重试当前集的票据（失败态的"重试"按钮）。
   Future<void> retryTicket() async {
     ticketError = null;
@@ -667,6 +738,15 @@ class PlayerLogic extends ChangeNotifier {
     if (player is! VideoPlayerPort) return;
     try {
       await player.controller.setPlaybackSpeed(playbackSpeed);
+      final override = _qualitySeek;
+      _qualitySeek = null;
+      if (override != null && override > Duration.zero) {
+        await player.seekTo(
+          clampResumePosition(override, player.controller.value.duration),
+        );
+        await _waitUntilFrameReady(player.controller);
+        return;
+      }
       await pendingWrite;
       // 服务端每剧只记一条：只有"记录里的那一集"才定位，其它集从头播
       if (resumePoint == null) await loadResumePoint();
@@ -689,7 +769,7 @@ class PlayerLogic extends ChangeNotifier {
         );
       }
     } catch (_) {
-      // 续看位置取不到不影响播放：从头播。
+      // 续看或清晰度定位失败时仍用已初始化的播放器，不把切换判失败。
     }
   }