mirror of
https://github.com/bggRGjQaUbCoE/PiliPlus.git
synced 2026-06-01 08:38:18 +08:00
feat: video download
Signed-off-by: bggRGjQaUbCoE <githubaccount56556@proton.me>
This commit is contained in:
576
lib/services/download/download_service.dart
Normal file
576
lib/services/download/download_service.dart
Normal file
@@ -0,0 +1,576 @@
|
||||
import 'dart:async';
|
||||
import 'dart:convert' show jsonDecode, utf8;
|
||||
import 'dart:io' show Directory, File, FileSystemEntity;
|
||||
|
||||
import 'package:PiliPlus/http/download.dart';
|
||||
import 'package:PiliPlus/http/init.dart';
|
||||
import 'package:PiliPlus/models/common/video/video_quality.dart';
|
||||
import 'package:PiliPlus/models_new/download/bili_download_entry_info.dart';
|
||||
import 'package:PiliPlus/models_new/download/bili_download_media_file_info.dart';
|
||||
import 'package:PiliPlus/models_new/pgc/pgc_info_model/episode.dart' as pgc;
|
||||
import 'package:PiliPlus/models_new/pgc/pgc_info_model/result.dart';
|
||||
import 'package:PiliPlus/models_new/video/video_detail/data.dart';
|
||||
import 'package:PiliPlus/models_new/video/video_detail/episode.dart' as ugc;
|
||||
import 'package:PiliPlus/models_new/video/video_detail/page.dart';
|
||||
import 'package:PiliPlus/services/download/download_manager.dart';
|
||||
import 'package:PiliPlus/utils/extension.dart';
|
||||
import 'package:PiliPlus/utils/id_utils.dart';
|
||||
import 'package:PiliPlus/utils/path_utils.dart';
|
||||
import 'package:PiliPlus/utils/utils.dart';
|
||||
import 'package:archive/archive.dart' show Inflate;
|
||||
import 'package:dio/dio.dart' show Options, ResponseType;
|
||||
import 'package:flutter/foundation.dart';
|
||||
import 'package:flutter_smart_dialog/flutter_smart_dialog.dart';
|
||||
import 'package:get/get.dart';
|
||||
import 'package:path/path.dart' as path;
|
||||
import 'package:synchronized/synchronized.dart';
|
||||
|
||||
// ref https://github.com/10miaomiao/bilimiao2/blob/master/bilimiao-download/src/main/java/cn/a10miaomiao/bilimiao/download/DownloadService.kt
|
||||
|
||||
class DownloadService extends GetxService {
|
||||
static const _entryFile = 'entry.json';
|
||||
static const _indexFile = 'index.json';
|
||||
static const _danmakuFile = 'danmaku.xml';
|
||||
static const _coverFile = 'cover.jpg';
|
||||
|
||||
final _lock = Lock();
|
||||
|
||||
final downloaFlag = RxnInt();
|
||||
final waitDownloadQueue = <BiliDownloadEntryInfo>[];
|
||||
final downloadList = RxList<BiliDownloadEntryInfo>();
|
||||
|
||||
final curDownload = Rxn<BiliDownloadEntryInfo>();
|
||||
void _updateCurStatus(DownloadStatus status) {
|
||||
if (curDownload.value != null) {
|
||||
curDownload
|
||||
..value!.status = status
|
||||
..refresh();
|
||||
}
|
||||
}
|
||||
|
||||
DownloadManager? _downloadManager;
|
||||
DownloadManager? _audioDownloadManager;
|
||||
|
||||
Completer? _completer;
|
||||
Future<void>? get waitForInitialization => _completer?.future;
|
||||
|
||||
@override
|
||||
void onInit() {
|
||||
super.onInit();
|
||||
readDownloadList();
|
||||
}
|
||||
|
||||
Future<void> readDownloadList() async {
|
||||
_completer = Completer();
|
||||
final downloadDir = Directory(await _getDownloadPath());
|
||||
final list = <BiliDownloadEntryInfo>[];
|
||||
for (final dir in downloadDir.listSync()) {
|
||||
if (dir is Directory) {
|
||||
list.addAll(await _readDownloadDirectory(dir));
|
||||
}
|
||||
}
|
||||
downloadList.value = list
|
||||
..sort((a, b) => b.timeUpdateStamp.compareTo(a.timeUpdateStamp));
|
||||
if (!_completer!.isCompleted) {
|
||||
_completer!.complete();
|
||||
}
|
||||
}
|
||||
|
||||
Future<List<BiliDownloadEntryInfo>> _readDownloadDirectory(
|
||||
FileSystemEntity pageDir,
|
||||
) async {
|
||||
final result = <BiliDownloadEntryInfo>[];
|
||||
|
||||
if (!pageDir.existsSync() || pageDir is! Directory) {
|
||||
return result;
|
||||
}
|
||||
|
||||
for (final entryDir in pageDir.listSync()) {
|
||||
if (entryDir is Directory) {
|
||||
final entryFile = File(path.join(entryDir.path, _entryFile));
|
||||
if (entryFile.existsSync()) {
|
||||
try {
|
||||
final entryJson = await entryFile.readAsString();
|
||||
final entry = BiliDownloadEntryInfo.fromJson(jsonDecode(entryJson))
|
||||
..pageDirPath = pageDir.path
|
||||
..entryDirPath = entryDir.path;
|
||||
result.add(entry);
|
||||
if (!entry.isCompleted) {
|
||||
waitDownloadQueue.add(entry);
|
||||
}
|
||||
} catch (_) {
|
||||
if (kDebugMode) rethrow;
|
||||
}
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
return result;
|
||||
}
|
||||
|
||||
void downloadVideo(
|
||||
Part page,
|
||||
VideoDetailData? videoDetail,
|
||||
ugc.EpisodeItem? videoArc,
|
||||
VideoQuality videoQuality,
|
||||
) {
|
||||
final cid = page.cid!;
|
||||
if (downloadList.indexWhere((e) => e.cid == cid) != -1) {
|
||||
return;
|
||||
}
|
||||
final pageData = PageInfo(
|
||||
cid: cid,
|
||||
page: page.page!,
|
||||
from: page.from,
|
||||
part: page.part,
|
||||
vid: page.vid,
|
||||
hasAlias: false,
|
||||
tid: 0,
|
||||
width: 0,
|
||||
height: 0,
|
||||
rotate: 0,
|
||||
downloadTitle: '视频已缓存完成',
|
||||
downloadSubtitle: videoDetail?.title ?? videoArc!.title,
|
||||
);
|
||||
final currentTime = DateTime.now().millisecondsSinceEpoch ~/ 1000;
|
||||
final entry = BiliDownloadEntryInfo(
|
||||
mediaType: 2,
|
||||
hasDashAudio: true,
|
||||
isCompleted: false,
|
||||
totalBytes: 0,
|
||||
downloadedBytes: 0,
|
||||
title: videoDetail?.title ?? videoArc!.title!,
|
||||
typeTag: videoQuality.code.toString(),
|
||||
cover: videoDetail?.pic ?? videoArc!.cover!,
|
||||
preferedVideoQuality: videoQuality.code,
|
||||
qualityPithyDescription: videoQuality.desc,
|
||||
guessedTotalBytes: 0,
|
||||
totalTimeMilli: (page.duration ?? 0) * 1000,
|
||||
danmakuCount:
|
||||
videoDetail?.stat?.danmaku ?? videoArc?.arc?.stat?.danmaku ?? 0,
|
||||
timeUpdateStamp: currentTime,
|
||||
timeCreateStamp: currentTime,
|
||||
canPlayInAdvance: true,
|
||||
interruptTransformTempFile: false,
|
||||
avid: videoDetail?.aid ?? videoArc!.aid!,
|
||||
spid: 0,
|
||||
seasonId: null,
|
||||
ep: null,
|
||||
source: null,
|
||||
bvid: videoDetail?.bvid ?? videoArc!.bvid!,
|
||||
ownerId: videoDetail?.owner?.mid ?? videoArc?.arc?.author?.mid,
|
||||
ownerName: videoDetail?.owner?.name ?? videoArc?.arc?.author?.name,
|
||||
pageData: pageData,
|
||||
);
|
||||
_createDownload(entry);
|
||||
}
|
||||
|
||||
void downloadBangumi(
|
||||
int index,
|
||||
PgcInfoModel pgcItem,
|
||||
pgc.EpisodeItem episode,
|
||||
VideoQuality quality,
|
||||
) {
|
||||
final cid = episode.cid!;
|
||||
if (downloadList.indexWhere((e) => e.cid == cid) != -1) {
|
||||
return;
|
||||
}
|
||||
final currentTime = DateTime.now().millisecondsSinceEpoch ~/ 1000;
|
||||
final source = SourceInfo(
|
||||
avId: episode.aid!,
|
||||
cid: cid,
|
||||
);
|
||||
final ep = EpInfo(
|
||||
avId: source.avId,
|
||||
page: index,
|
||||
danmaku: source.cid,
|
||||
cover: episode.cover!,
|
||||
episodeId: episode.id!,
|
||||
index: episode.title!,
|
||||
indexTitle: episode.longTitle ?? '',
|
||||
showTitle: episode.showTitle,
|
||||
from: episode.from ?? 'bangumi',
|
||||
seasonType: pgcItem.type ?? (episode.from == 'pugv' ? -1 : 0),
|
||||
width: 0,
|
||||
height: 0,
|
||||
rotate: 0,
|
||||
link: episode.link ?? '',
|
||||
bvid: episode.bvid ?? IdUtils.av2bv(source.avId),
|
||||
sortIndex: index,
|
||||
);
|
||||
final entry = BiliDownloadEntryInfo(
|
||||
mediaType: 2,
|
||||
hasDashAudio: true,
|
||||
isCompleted: false,
|
||||
totalBytes: 0,
|
||||
downloadedBytes: 0,
|
||||
title: pgcItem.seasonTitle ?? pgcItem.title ?? '',
|
||||
typeTag: quality.code.toString(),
|
||||
cover: episode.cover!,
|
||||
preferedVideoQuality: quality.code,
|
||||
qualityPithyDescription: quality.desc,
|
||||
guessedTotalBytes: 0,
|
||||
totalTimeMilli:
|
||||
(episode.duration ?? 0) *
|
||||
(episode.from == 'pugv' ? 1000 : 1), // pgc millisec,, pugv sec
|
||||
danmakuCount: pgcItem.stat?.danmaku ?? 0,
|
||||
timeUpdateStamp: currentTime,
|
||||
timeCreateStamp: currentTime,
|
||||
canPlayInAdvance: true,
|
||||
interruptTransformTempFile: false,
|
||||
spid: 0,
|
||||
seasonId: pgcItem.seasonId!.toString(),
|
||||
bvid: episode.bvid ?? IdUtils.av2bv(source.avId),
|
||||
avid: source.avId,
|
||||
ep: ep,
|
||||
source: source,
|
||||
ownerId: pgcItem.upInfo?.mid,
|
||||
ownerName: pgcItem.upInfo?.uname,
|
||||
pageData: null,
|
||||
);
|
||||
_createDownload(entry);
|
||||
}
|
||||
|
||||
Future<void> _createDownload(BiliDownloadEntryInfo entry) async {
|
||||
final entryDir = await _getDownloadEntryDir(entry);
|
||||
final entryJsonFile = File(path.join(entryDir.path, _entryFile));
|
||||
final entryJsonStr = Utils.jsonEncoder.convert(entry.toJson());
|
||||
await entryJsonFile.writeAsBytes(utf8.encode(entryJsonStr));
|
||||
entry
|
||||
..pageDirPath = entryDir.parent.path
|
||||
..entryDirPath = entryDir.path
|
||||
..status = DownloadStatus.wait;
|
||||
downloadList.insert(0, entry);
|
||||
downloaFlag.refresh();
|
||||
final currStatus = curDownload.value?.status?.index;
|
||||
if (currStatus == null || currStatus > 3) {
|
||||
startDownload(entry);
|
||||
} else {
|
||||
waitDownloadQueue.add(entry);
|
||||
}
|
||||
}
|
||||
|
||||
Future<Directory> _getDownloadEntryDir(BiliDownloadEntryInfo entry) async {
|
||||
late final String dirName;
|
||||
late final String pageDirName;
|
||||
if (entry.ep case final ep?) {
|
||||
dirName = 's_${entry.seasonId}';
|
||||
pageDirName = ep.episodeId.toString();
|
||||
} else if (entry.pageData case final page?) {
|
||||
dirName = entry.avid.toString();
|
||||
pageDirName = 'c_${page.cid}';
|
||||
}
|
||||
final pageDir = Directory(
|
||||
path.join(await _getDownloadPath(), dirName, pageDirName),
|
||||
);
|
||||
if (!pageDir.existsSync()) {
|
||||
await pageDir.create(recursive: true);
|
||||
}
|
||||
return pageDir;
|
||||
}
|
||||
|
||||
Future<String> _getDownloadPath() async {
|
||||
final dir = Directory(downloadPath);
|
||||
if (!dir.existsSync()) {
|
||||
await dir.create(recursive: true);
|
||||
}
|
||||
return dir.path;
|
||||
}
|
||||
|
||||
Future<void> startDownload(BiliDownloadEntryInfo entry) {
|
||||
return _lock.synchronized(() async {
|
||||
await _downloadManager?.cancel(isDelete: false);
|
||||
await _audioDownloadManager?.cancel(isDelete: false);
|
||||
_downloadManager = null;
|
||||
_audioDownloadManager = null;
|
||||
final prevStatus = curDownload.value?.status?.index;
|
||||
if (prevStatus != null && prevStatus <= 3) {
|
||||
curDownload.value?.status = DownloadStatus.pause;
|
||||
}
|
||||
|
||||
curDownload.value = entry;
|
||||
await _startDownload(entry);
|
||||
});
|
||||
}
|
||||
|
||||
Future<bool> downloadDanmaku({
|
||||
required BiliDownloadEntryInfo entry,
|
||||
bool isUpdate = false,
|
||||
}) async {
|
||||
final cid = entry.pageData?.cid ?? entry.source?.cid;
|
||||
if (cid == null) {
|
||||
return false;
|
||||
}
|
||||
final danmakuXMLFile = File(path.join(entry.entryDirPath, _danmakuFile));
|
||||
if (isUpdate || !danmakuXMLFile.existsSync()) {
|
||||
try {
|
||||
if (!isUpdate) {
|
||||
_updateCurStatus(DownloadStatus.getDanmaku);
|
||||
}
|
||||
final res = await Request().get(
|
||||
'https://comment.bilibili.com/$cid.xml',
|
||||
options: Options(responseType: ResponseType.bytes),
|
||||
);
|
||||
final xmlBytes = Inflate((res.data as Uint8List)).getBytes();
|
||||
await danmakuXMLFile.writeAsBytes(xmlBytes);
|
||||
return true;
|
||||
} catch (e) {
|
||||
if (!isUpdate) {
|
||||
_updateCurStatus(DownloadStatus.failDanmaku);
|
||||
}
|
||||
if (kDebugMode) {
|
||||
SmartDialog.showToast(e.toString());
|
||||
}
|
||||
return false;
|
||||
}
|
||||
}
|
||||
return true;
|
||||
}
|
||||
|
||||
Future<bool> _downloadCover({
|
||||
required BiliDownloadEntryInfo entry,
|
||||
}) async {
|
||||
try {
|
||||
await Request.dio.download(
|
||||
entry.cover.http2https,
|
||||
path.join(entry.entryDirPath, _coverFile),
|
||||
);
|
||||
return true;
|
||||
} catch (_) {}
|
||||
return false;
|
||||
}
|
||||
|
||||
Future<void> _startDownload(BiliDownloadEntryInfo entry) async {
|
||||
try {
|
||||
_updateCurStatus(DownloadStatus.getPlayUrl);
|
||||
|
||||
final BiliDownloadMediaInfo mediaFileInfo =
|
||||
await DownloadHttp.getVideoUrl(
|
||||
entry: entry,
|
||||
ep: entry.ep,
|
||||
source: entry.source,
|
||||
pageData: entry.pageData,
|
||||
);
|
||||
|
||||
final videoDir = Directory(path.join(entry.entryDirPath, entry.typeTag));
|
||||
if (!videoDir.existsSync()) {
|
||||
await videoDir.create(recursive: true);
|
||||
}
|
||||
|
||||
final res = await Future.wait([
|
||||
downloadDanmaku(entry: entry),
|
||||
_downloadCover(entry: entry),
|
||||
]);
|
||||
|
||||
if (!res.first) {
|
||||
return;
|
||||
}
|
||||
|
||||
final mediaJsonFile = File(path.join(videoDir.path, _indexFile));
|
||||
final mediaJsonStr = Utils.jsonEncoder.convert(mediaFileInfo.toJson());
|
||||
await mediaJsonFile.writeAsString(mediaJsonStr);
|
||||
|
||||
if (curDownload.value?.cid != entry.cid) {
|
||||
return;
|
||||
}
|
||||
|
||||
switch (mediaFileInfo) {
|
||||
case Type1 mediaFileInfo:
|
||||
final first = mediaFileInfo.segmentList.first;
|
||||
_downloadManager = DownloadManager(
|
||||
url: first.url,
|
||||
path: path.join(videoDir.path, PathUtils.videoNameType1),
|
||||
onTaskRunning: _onTaskRunning,
|
||||
onTaskComplete: _onTaskComplete,
|
||||
onTaskError: _onTaskError,
|
||||
)..start();
|
||||
break;
|
||||
case Type2 mediaFileInfo:
|
||||
_downloadManager = DownloadManager(
|
||||
url: mediaFileInfo.video.first.baseUrl,
|
||||
path: path.join(videoDir.path, PathUtils.videoNameType2),
|
||||
onTaskRunning: _onTaskRunning,
|
||||
onTaskComplete: _onTaskComplete,
|
||||
onTaskError: _onTaskError,
|
||||
)..start();
|
||||
final audio = mediaFileInfo.audio;
|
||||
if (audio != null && audio.isNotEmpty) {
|
||||
_audioDownloadManager = DownloadManager(
|
||||
url: audio.first.baseUrl,
|
||||
path: path.join(videoDir.path, PathUtils.audioNameType2),
|
||||
onTaskRunning: _onAudioTaskRunning,
|
||||
onTaskComplete: _onAudioTaskComplete,
|
||||
onTaskError: _onAudioTaskError,
|
||||
)..start();
|
||||
}
|
||||
late final first = mediaFileInfo.video.first;
|
||||
entry.pageData
|
||||
?..width = first.width
|
||||
..height = first.height;
|
||||
entry.ep
|
||||
?..width = first.width
|
||||
..height = first.height;
|
||||
_updateBiliDownloadEntryJson(entry);
|
||||
break;
|
||||
default:
|
||||
break;
|
||||
}
|
||||
} catch (e) {
|
||||
_updateCurStatus(DownloadStatus.failPlayUrl);
|
||||
if (kDebugMode) {
|
||||
debugPrint('get download url error: $e');
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
Future<void> _updateBiliDownloadEntryJson(BiliDownloadEntryInfo entry) async {
|
||||
final entryJsonFile = File(path.join(entry.entryDirPath, _entryFile));
|
||||
final entryJsonStr = Utils.jsonEncoder.convert(entry.toJson());
|
||||
await entryJsonFile.writeAsString(entryJsonStr);
|
||||
}
|
||||
|
||||
void _onTaskRunning({required int progress, required int total}) {
|
||||
if (progress == 0 && total != 0) {
|
||||
if (curDownload.value case final curEntryInfo?) {
|
||||
_updateBiliDownloadEntryJson(curEntryInfo..totalBytes = total);
|
||||
}
|
||||
}
|
||||
if (curDownload.value case final entry?) {
|
||||
entry
|
||||
..downloadedBytes = progress
|
||||
..status = DownloadStatus.downloading;
|
||||
curDownload.refresh();
|
||||
}
|
||||
}
|
||||
|
||||
void _onTaskComplete() {
|
||||
final audioStatus = _audioDownloadManager?.status;
|
||||
final status = switch (audioStatus) {
|
||||
DownloadStatus.downloading => DownloadStatus.audioDownloading,
|
||||
DownloadStatus.failDownload => DownloadStatus.failDownloadAudio,
|
||||
null => DownloadStatus.completed,
|
||||
_ => audioStatus,
|
||||
};
|
||||
_updateCurStatus(status);
|
||||
if (status == DownloadStatus.completed) {
|
||||
_completeDownload();
|
||||
} else {
|
||||
if (curDownload.value case final curEntryInfo?) {
|
||||
_updateBiliDownloadEntryJson(
|
||||
curEntryInfo..downloadedBytes = curEntryInfo.totalBytes,
|
||||
);
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
void _onTaskError({
|
||||
required int progress,
|
||||
required int total,
|
||||
required Object error,
|
||||
}) {
|
||||
_updateCurStatus(DownloadStatus.failDownload);
|
||||
if (curDownload.value case final curEntryInfo?) {
|
||||
curEntryInfo
|
||||
..totalBytes = total
|
||||
..downloadedBytes = progress;
|
||||
_updateBiliDownloadEntryJson(curEntryInfo);
|
||||
}
|
||||
}
|
||||
|
||||
void _onAudioTaskRunning({required int progress, required int total}) {}
|
||||
|
||||
void _onAudioTaskComplete() {
|
||||
if (_downloadManager?.status == DownloadStatus.completed) {
|
||||
_completeDownload();
|
||||
}
|
||||
}
|
||||
|
||||
void _onAudioTaskError({
|
||||
required int progress,
|
||||
required int total,
|
||||
required Object error,
|
||||
}) {
|
||||
if (_downloadManager?.status == DownloadStatus.completed) {
|
||||
_updateCurStatus(DownloadStatus.failDownloadAudio);
|
||||
}
|
||||
}
|
||||
|
||||
Future<void> _completeDownload() async {
|
||||
final entry = curDownload.value;
|
||||
if (entry == null) {
|
||||
return;
|
||||
}
|
||||
entry
|
||||
..downloadedBytes = entry.totalBytes
|
||||
..isCompleted = true;
|
||||
await _updateBiliDownloadEntryJson(entry);
|
||||
downloaFlag.refresh();
|
||||
curDownload.value = null;
|
||||
_downloadManager = null;
|
||||
_audioDownloadManager = null;
|
||||
_nextDownload();
|
||||
}
|
||||
|
||||
void _nextDownload() {
|
||||
if (waitDownloadQueue.isNotEmpty) {
|
||||
final next = waitDownloadQueue.removeAt(0);
|
||||
if (downloadList.contains(next)) {
|
||||
startDownload(next);
|
||||
} else {
|
||||
_nextDownload();
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
Future<void> deleteDownload({
|
||||
required BiliDownloadEntryInfo entry,
|
||||
}) async {
|
||||
if (curDownload.value?.cid == entry.cid) {
|
||||
await cancelDownload(isDelete: true);
|
||||
}
|
||||
final downloadDir = Directory(entry.pageDirPath);
|
||||
if (downloadDir.existsSync()) {
|
||||
if (downloadDir.listSync().length <= 1) {
|
||||
await downloadDir.tryDel(recursive: true);
|
||||
} else {
|
||||
final entryDir = Directory(entry.entryDirPath);
|
||||
if (entryDir.existsSync()) {
|
||||
await entryDir.tryDel(recursive: true);
|
||||
}
|
||||
}
|
||||
}
|
||||
downloadList.remove(entry);
|
||||
waitDownloadQueue.remove(entry);
|
||||
downloaFlag.refresh();
|
||||
}
|
||||
|
||||
Future<void> deletePage({required String pageDirPath}) async {
|
||||
await Directory(pageDirPath).tryDel(recursive: true);
|
||||
downloadList.removeWhere((e) => e.pageDirPath == pageDirPath);
|
||||
downloaFlag.refresh();
|
||||
}
|
||||
|
||||
Future<void> cancelDownload({
|
||||
required bool isDelete,
|
||||
bool downloadNext = true,
|
||||
}) async {
|
||||
await _downloadManager?.cancel(isDelete: isDelete);
|
||||
await _audioDownloadManager?.cancel(isDelete: isDelete);
|
||||
_downloadManager = null;
|
||||
_audioDownloadManager = null;
|
||||
if (!isDelete) {
|
||||
final entry = curDownload.value;
|
||||
if (entry != null) {
|
||||
await _updateBiliDownloadEntryJson(entry);
|
||||
}
|
||||
}
|
||||
if (isDelete) {
|
||||
curDownload.value = null;
|
||||
} else {
|
||||
_updateCurStatus(DownloadStatus.pause);
|
||||
}
|
||||
if (downloadNext) {
|
||||
_nextDownload();
|
||||
}
|
||||
}
|
||||
}
|
||||
Reference in New Issue
Block a user