137 lines
3.8 KiB
Dart
137 lines
3.8 KiB
Dart
import 'api_service.dart';
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import '../core/utils/app_logger.dart';
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import '../core/utils/file_utils.dart';
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import '../core/utils/time_flow_decoder.dart';
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/// 缩略图缓存条目
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class _ThumbCacheEntry {
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final String imageUrl;
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final DateTime expiresAt;
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_ThumbCacheEntry({required this.imageUrl, required this.expiresAt});
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bool get isExpired => DateTime.now().isAfter(expiresAt);
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}
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/// 缩略图服务 — 获取、解码、缓存缩略图 URL
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class ThumbnailService {
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static ThumbnailService? _instance;
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static ThumbnailService get instance {
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_instance ??= ThumbnailService._();
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return _instance!;
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}
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ThumbnailService._();
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// 内存缓存: fileUri -> cache entry
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final Map<String, _ThumbCacheEntry> _urlCache = {};
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// 请求去重: fileUri -> in-flight Future
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final Map<String, Future<String?>> _inFlightRequests = {};
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/// 获取缩略图图片 URL
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/// [fileUri] 文件的 relativePath（如 /path/to/file.jpg）
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/// [contextHint] 可选，加速服务端 DB 查询
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Future<String?> getThumbnailUrl({
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required String fileUri,
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String? contextHint,
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}) async {
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final cacheKey = fileUri;
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// 1. 检查内存缓存
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final cached = _urlCache[cacheKey];
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if (cached != null && !cached.isExpired) {
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return cached.imageUrl;
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}
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if (cached != null) {
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_urlCache.remove(cacheKey);
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}
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// 2. 检查请求去重
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final inFlight = _inFlightRequests[cacheKey];
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if (inFlight != null) {
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return inFlight;
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}
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// 3. 发起请求
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final future = _fetchThumbnailUrl(fileUri, contextHint);
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_inFlightRequests[cacheKey] = future;
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try {
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return await future;
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} finally {
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_inFlightRequests.remove(cacheKey);
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}
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}
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Future<String?> _fetchThumbnailUrl(String fileUri, String? contextHint) async {
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try {
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final uri = FileUtils.toCloudreveUri(fileUri);
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final headers = contextHint != null
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? <String, dynamic>{'X-Cr-Context-Hint': contextHint}
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: null;
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// _parseResponse 已提取 ApiResponse.data，response 即 {url, obfuscated, expires}
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final response = await ApiService.instance.get<Map<String, dynamic>>(
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'/file/thumb',
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queryParameters: {'uri': uri},
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headers: headers,
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);
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AppLogger.d('ThumbnailService: response for $fileUri = $response');
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var url = response['url'] as String? ?? '';
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final obfuscated = response['obfuscated'] as bool? ?? false;
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final expiresStr = response['expires'] as String?;
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// 解码混淆 URL
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if (obfuscated && url.isNotEmpty) {
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final decoded = TimeFlowDecoder.decodeTimeFlowString(url);
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if (decoded == null) {
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AppLogger.w('Failed to decode obfuscated thumbnail URL for $fileUri');
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return null;
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}
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url = decoded;
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}
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if (url.isEmpty) return null;
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AppLogger.d('ThumbnailService: resolved URL for $fileUri = $url');
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// 解析过期时间，缓存提前 30 秒过期
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DateTime expiresAt;
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if (expiresStr != null) {
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try {
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expiresAt = DateTime.parse(expiresStr).subtract(const Duration(seconds: 30));
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} catch (_) {
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expiresAt = DateTime.now().add(const Duration(minutes: 5));
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}
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} else {
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expiresAt = DateTime.now().add(const Duration(minutes: 5));
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}
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// 存入内存缓存
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_urlCache[fileUri] = _ThumbCacheEntry(
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imageUrl: url,
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expiresAt: expiresAt,
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);
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return url;
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} catch (e) {
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AppLogger.d('ThumbnailService: failed to get thumbnail URL for $fileUri: $e');
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return null;
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}
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}
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/// 移除指定文件的缓存 URL
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void evictUrl(String fileUri) {
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_urlCache.remove(fileUri);
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}
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/// 清空所有缓存（目录切换时调用）
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void clearAll() {
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_urlCache.clear();
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_inFlightRequests.clear();
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}
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}
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