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patbond-flutter/lib/features/community/media_uploader.dart
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新增:媒体上传客户端——MediaUploader 编排状态机 + 预签名直传 + 进度组件,修正 media 端点误挂 community 服务(T3-13)
- MediaUploader:选图→压缩(80→60 降质阶梯,10 MiB 超限拒绝)→createUpload
  →预签名 PUT 直传(进度回调)→confirm→ready assetId 交付;并发槽位 2、
  顺序即 position、单图失败不拖垮整批;凭据过期预检与存储侧 403 各自动
  换新凭据一次;失败重试复用压缩产物、从 createUpload 全新开始
- 孤儿防护:未 confirm 的 assetId 只以管线局部变量存在,快照 assetId 与
  ready 态断言绑定,buildAttachRequests 非全员 ready 即抛 StateError
- 线路修正:media 两步上传端点由 user 服务(:8082 MediaController)提供,
  T3-12 误挂 community 客户端(:8084 无 media 路由),补 mediaApi 分端口
  直连,compose 真链路实测证实
- UploadProgressOverlay 四态进度层(05 号规范 §3.3);直传层本地
  HttpServer 三线路测试(200/403/断连);compose 冒烟测试
  (PATBOND_MEDIA_SMOKE=1 启用,默认跳过)
- 新依赖:image_picker、flutter_image_compress(03 号评估选型)
- flutter test 379 全绿(基线 347,+32)、analyze 0、format 无 diff

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
2026-09-09 12:21:20 +08:00

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import 'dart:async';
import 'package:flutter/foundation.dart';
import 'package:patbond_flutter/core/network/api_exception.dart';
import 'package:patbond_flutter/features/community/community_models.dart';
import 'package:patbond_flutter/features/community/community_repository.dart';
import 'package:patbond_flutter/features/community/media_compression.dart';
import 'package:patbond_flutter/features/community/media_direct_upload.dart';
import 'package:patbond_flutter/features/community/media_picking.dart';
/// 单张图的上传阶段(05 号规范 §3.3 四视觉态的底层状态模型)。
///
/// 生命周期:queued → compressing → uploading(progress) → confirming
/// → ready | failed(retryable?)。ready 是唯一可交付态——**assetId 只在
/// ready 态对外可见**(孤儿防护:未 confirm 的 asset 不得被引用)。
enum MediaItemPhase {
queued,
compressing,
uploading,
confirming,
ready,
failed,
}
/// 单张图的不可变状态快照(UI 消费;内部任务状态见 _UploadTask)。
@immutable
class MediaUploadItem {
const MediaUploadItem({
required this.localId,
required this.phase,
required this.previewBytes,
this.progress = 0,
this.assetId,
this.errorMessage,
this.retryable = false,
}) : assert(
(assetId != null) == (phase == MediaItemPhase.ready),
'assetId 与 ready 态严格绑定(孤儿防护)',
);
/// 本地稳定标识(重试/删除寻址用,与服务端无关)。
final int localId;
final MediaItemPhase phase;
/// 缩略预览字节(原图,UI 直接 Image.memory 渲染)。
final Uint8List previewBytes;
/// 直传进度 0..1uploading 有意义;confirming 视作 1.0)。
final double progress;
/// ready 态的可引用 asset 标识;其余态恒为 null(构造期断言兜底)。
final String? assetId;
/// failed 态的用户可读原因。
final String? errorMessage;
/// failed 态是否可重试(false = 终态,如压缩后仍超限)。
final bool retryable;
bool get isReady => phase == MediaItemPhase.ready;
bool get isFailed => phase == MediaItemPhase.failed;
bool get isBusy => !isReady && !isFailed;
}
/// 内部任务:可变状态 + 生命周期旗标(cancelled 后一切在途结果作废)。
class _UploadTask {
_UploadTask({required this.localId, required this.source});
final int localId;
final PickedMediaImage source;
MediaItemPhase phase = MediaItemPhase.queued;
double progress = 0;
String? errorMessage;
bool retryable = false;
bool cancelled = false;
/// 压缩产物缓存(重试跳过重压缩)。
CompressedMediaImage? compressed;
/// confirm 成功前的服务端 assetId 只以管线局部变量存在,**不落任务
/// 状态、不出现在 [MediaUploadItem] 快照**——孤儿防护的结构保证;
/// confirm 通过后才写入 [readyAssetId]。
String? readyAssetId;
MediaUploadItem snapshot() => MediaUploadItem(
localId: localId,
phase: phase,
previewBytes: source.bytes,
progress: progress,
assetId: readyAssetId,
errorMessage: errorMessage,
retryable: retryable,
);
}
/// 媒体上传编排器(T3-13,03 号评估 §4.3 冻结接口的定稿实现)。
///
/// 职责:选图 → 压缩(降质阶梯 80→60,仍超 10 MiB 拒绝为终态失败)→
/// createUpload → 预签名 PUT 直传(进度回调;Content-Type 按
/// requiredHeaders 原样携带)→ confirm → ready assetId 交付。
///
/// 语义要点:
/// - **顺序保持**items 顺序 = 加入顺序 = position 语义;并发上传的
/// 完成先后不影响顺序([buildAttachRequests] 按当前列表序发号)。
/// - **单飞槽位**:至多 [maxConcurrentUploads] 张同时占用网络管线,
/// 单图失败不拖垮整批。
/// - **凭据过期**:PUT 前过期预检、存储侧 403 各触发一次自动
/// re-createUpload(换新 assetId 新凭据);再失败交给手动重试。
/// - **失败重试**retry 复用压缩产物、从 createUpload 全新开始
/// (统一覆盖「对象未上传保持 uploading」与「内容不符置 failed 终态」
/// 两种服务端分支——旧 asset 弃引用,由服务端超时清理兜底)。
/// - **孤儿防护**:未 confirm 的 assetId 只以管线局部变量存在;
/// 对外可见的 [MediaUploadItem.assetId] 与 ready 态严格绑定(断言),
/// [buildAttachRequests] 仅在全员 ready 时可用。
/// - 预签名凭据只存内存、用完即弃,不持久化(既有纪律)。
class MediaUploader extends ChangeNotifier {
MediaUploader({
required this._repository,
MediaImagePicker? picker,
MediaImageCompressor? compressor,
MediaDirectUploadClient? directUpload,
this.maxImages = 9,
this.maxConcurrentUploads = 2,
this.maxByteSize = 10 * 1024 * 1024,
DateTime Function()? now,
}) : _picker = picker ?? SystemMediaImagePicker(),
_compressor = compressor ?? const NativeMediaImageCompressor(),
_directUpload = directUpload ?? DioMediaDirectUploadClient(),
_now = now ?? DateTime.now,
_slots = maxConcurrentUploads;
final CommunityRepository _repository;
final MediaImagePicker _picker;
final MediaImageCompressor _compressor;
final MediaDirectUploadClient _directUpload;
final DateTime Function() _now;
/// 九宫格上限(05 号规范 §3.2)。
final int maxImages;
final int maxConcurrentUploads;
/// 与服务端 byteSize 上限一致(10 MiB13 号报告偏差 #7)。
final int maxByteSize;
/// 凭据过期预检安全边距:距 expiresAt 不足此值即视为过期,直接换新。
static const credentialsSafetyMargin = Duration(seconds: 30);
/// 压缩降质阶梯(80 常规 → 60 兜底;仍超限即终态拒绝)。
static const qualityLadder = [80, 60];
final List<_UploadTask> _tasks = [];
int _nextLocalId = 1;
bool _picking = false;
int _slots;
final List<Completer<void>> _slotWaiters = [];
// ---- 对外状态 ----
/// 选择器是否拉起中(uploader 级 picking 态)。
bool get isPicking => _picking;
List<MediaUploadItem> get items =>
List.unmodifiable(_tasks.map((task) => task.snapshot()));
bool get isEmpty => _tasks.isEmpty;
int get remainingSlots => maxImages - _tasks.length;
int get readyCount =>
_tasks.where((t) => t.phase == MediaItemPhase.ready).length;
bool get allReady => _tasks.isNotEmpty && readyCount == _tasks.length;
bool get hasFailure => _tasks.any((t) => t.phase == MediaItemPhase.failed);
bool get hasBusyItem => _picking || _tasks.any((t) => t.snapshot().isBusy);
/// 页级汇总进度(05 号规范 §3.3 线性进度条):各图等权。
double get overallProgress {
if (_tasks.isEmpty) return 0;
var sum = 0.0;
for (final task in _tasks) {
sum += switch (task.phase) {
MediaItemPhase.ready => 1.0,
MediaItemPhase.uploading => task.progress,
MediaItemPhase.confirming => 1.0,
_ => 0.0,
};
}
return sum / _tasks.length;
}
/// 交付口(T3-17 发布页组 CreatePostRequest.media 用):
/// 仅全员 ready 时可用——**任何非 ready 项在场即抛 [StateError]**
/// 从类型上杜绝未 confirm asset 被引用。position 按当前列表序 0..n-1。
List<PostMediaAttachRequest> buildAttachRequests({int coverIndex = 0}) {
if (!allReady) {
throw StateError('存在未就绪的上传项,不得引用(孤儿防护)');
}
return [
for (final (index, task) in _tasks.indexed)
PostMediaAttachRequest(
assetId: task.readyAssetId!,
position: index,
isCover: index == coverIndex,
),
];
}
// ---- 操作 ----
/// 拉起系统选择器并把所选图片加入上传管线(剩余槽位自动截断)。
Future<void> pickAndAdd() async {
if (_picking || remainingSlots <= 0) return;
_picking = true;
notifyListeners();
try {
final images = await _picker.pickImages(limit: remainingSlots);
_picking = false;
addImages(images);
} catch (_) {
_picking = false;
notifyListeners();
}
}
/// 直接加入图片(选择器旁路,测试与分享外链场景用)。
void addImages(List<PickedMediaImage> images) {
for (final image in images.take(remainingSlots)) {
final task = _UploadTask(localId: _nextLocalId++, source: image);
_tasks.add(task);
unawaited(_run(task));
}
notifyListeners();
}
/// 重试一张可重试失败图:复用压缩产物,从 createUpload 全新开始。
void retry(int localId) {
final task = _taskOrNull(localId);
if (task == null ||
task.phase != MediaItemPhase.failed ||
!task.retryable) {
return;
}
task.errorMessage = null;
task.retryable = false;
task.progress = 0;
task.phase = MediaItemPhase.queued;
notifyListeners();
unawaited(_run(task));
}
/// 移除一张图(任意态可移除);在途请求结果一律作废,未 confirm 的
/// 服务端 asset 弃引用(服务端超时清理兜底)。
void remove(int localId) {
final task = _taskOrNull(localId);
if (task == null) return;
task.cancelled = true;
_tasks.remove(task);
notifyListeners();
}
/// 清空全部(发布成功/离开页面时调用)。
void reset() {
for (final task in _tasks) {
task.cancelled = true;
}
_tasks.clear();
_picking = false;
notifyListeners();
}
_UploadTask? _taskOrNull(int localId) {
for (final task in _tasks) {
if (task.localId == localId) return task;
}
return null;
}
// ---- 管线 ----
Future<void> _run(_UploadTask task) async {
await _acquireSlot();
try {
if (task.cancelled) return;
final compressed = await _compress(task);
if (compressed == null || task.cancelled) return;
await _uploadAndConfirm(task, compressed);
} finally {
_releaseSlot();
}
}
/// 压缩(降质阶梯);超限终态失败返回 null。
Future<CompressedMediaImage?> _compress(_UploadTask task) async {
final cached = task.compressed;
if (cached != null) return cached;
_transition(task, MediaItemPhase.compressing);
try {
for (final quality in qualityLadder) {
final result = await _compressor.compress(
task.source,
quality: quality,
);
if (task.cancelled) return null;
if (result.byteSize <= maxByteSize) {
task.compressed = result;
return result;
}
}
} catch (_) {
_fail(task, message: '图片处理失败', retryable: true);
return null;
}
_fail(task, message: '图片过大,压缩后仍超过 10 MB', retryable: false);
return null;
}
Future<void> _uploadAndConfirm(
_UploadTask task,
CompressedMediaImage compressed,
) async {
// createUpload:登记 mime/byteSize,取预签名 PUT 凭据(内存态,不持久化)。
MediaUploadCredentials credentials;
try {
credentials = await _createUpload(compressed);
} on Exception catch (error) {
if (!task.cancelled) _failFromApi(task, error);
return;
}
if (task.cancelled) return;
// 直传 PUT:过期预检与存储侧 403 各允许一次自动换新凭据。
_transition(task, MediaItemPhase.uploading);
var renewed = false;
while (true) {
if (_credentialsExpired(credentials)) {
if (renewed) {
_fail(task, message: '上传凭据已过期', retryable: true);
return;
}
renewed = true;
try {
credentials = await _createUpload(compressed);
} on Exception catch (error) {
if (!task.cancelled) _failFromApi(task, error);
return;
}
if (task.cancelled) return;
// 回到循环顶复检新凭据(服务端时钟异常仍过期即失败,不无限重取)。
continue;
}
try {
await _directUpload.put(
url: credentials.uploadUrl,
headers: credentials.requiredHeaders,
bytes: compressed.bytes,
onProgress: (sent, total) {
if (task.cancelled || total <= 0) return;
task.progress = sent / total;
notifyListeners();
},
);
break;
} on MediaDirectUploadException catch (error) {
if (task.cancelled) return;
if (error.isCredentialRejected && !renewed) {
renewed = true;
try {
credentials = await _createUpload(compressed);
} on Exception catch (creationError) {
_failFromApi(task, creationError);
return;
}
if (task.cancelled) return;
task.progress = 0;
notifyListeners();
continue;
}
_fail(
task,
message: error.statusCode == null ? '网络中断,上传失败' : '上传被存储服务拒绝',
retryable: true,
);
return;
}
}
if (task.cancelled) return;
// confirm42205 对象未上传保持 uploading / 内容不符置 failed 终态,
// 客户端统一按「可重试 + 重试换新 asset」处理,两分支都正确收敛。
_transition(task, MediaItemPhase.confirming);
final MediaAsset asset;
try {
asset = await _repository.completeMediaUpload(credentials.assetId);
} on Exception catch (error) {
if (!task.cancelled) _failFromApi(task, error);
return;
}
if (task.cancelled) return;
if (asset.status != MediaAssetStatus.ready) {
_fail(task, message: '上传确认未通过', retryable: true);
return;
}
task.readyAssetId = asset.id;
task.progress = 1;
_transition(task, MediaItemPhase.ready);
}
Future<MediaUploadCredentials> _createUpload(
CompressedMediaImage compressed,
) {
return _repository.createMediaUpload(
CreateMediaUploadRequest(
kind: MediaKind.image,
purpose: MediaPurpose.postImage,
mimeType: compressed.mimeType,
byteSize: compressed.byteSize,
),
);
}
bool _credentialsExpired(MediaUploadCredentials credentials) =>
!_now().add(credentialsSafetyMargin).isBefore(credentials.expiresAt);
void _failFromApi(_UploadTask task, Exception error) {
// 参数被服务端拒绝(40000mime/byteSize 白名单外)重试无意义,终态。
final retryable =
error is! ApiBusinessException || error.code != ApiCodes.paramError;
_fail(
task,
message: error is ApiBusinessException ? error.message : '网络异常,请重试',
retryable: retryable,
);
}
void _fail(
_UploadTask task, {
required String message,
required bool retryable,
}) {
if (task.cancelled) return;
task.phase = MediaItemPhase.failed;
task.errorMessage = message;
task.retryable = retryable;
notifyListeners();
}
void _transition(_UploadTask task, MediaItemPhase phase) {
if (task.cancelled) return;
task.phase = phase;
notifyListeners();
}
Future<void> _acquireSlot() {
if (_slots > 0) {
_slots--;
return Future.value();
}
final waiter = Completer<void>();
_slotWaiters.add(waiter);
return waiter.future;
}
void _releaseSlot() {
if (_slotWaiters.isNotEmpty) {
_slotWaiters.removeAt(0).complete();
} else {
_slots++;
}
}
}