1+ using System ;
2+ using System . IO ;
3+ using System . Net . Http ;
4+ using System . Threading ;
5+ using System . Threading . Tasks ;
6+
7+ namespace GDPIControl . Extensions
8+ {
9+ internal static class IOExtensions
10+ {
11+ public static Task CopyToAsync ( this Stream source , Stream destination , int bufferSize ) => CopyToAsync ( source , destination , bufferSize , default , default ) ;
12+
13+ public static Task CopyToAsync ( this Stream source , Stream destination , int bufferSize , IProgress < long > progress ) => CopyToAsync ( source , destination , bufferSize , progress , default ) ;
14+
15+ /// <summary>
16+ /// https://stackoverflow.com/a/46497896
17+ /// </summary>
18+ public static async Task CopyToAsync ( this Stream source , Stream destination , int bufferSize , IProgress < long > progress , CancellationToken cancellationToken )
19+ {
20+ if ( source is null ) { throw new ArgumentNullException ( nameof ( source ) ) ; }
21+ if ( ! source . CanRead ) { throw new ArgumentException ( "Has to be readable" , nameof ( source ) ) ; }
22+ if ( destination is null ) { throw new ArgumentNullException ( nameof ( destination ) ) ; }
23+ if ( ! destination . CanWrite ) { throw new ArgumentException ( "Has to be writable" , nameof ( destination ) ) ; }
24+ if ( bufferSize < 0 ) { throw new ArgumentOutOfRangeException ( nameof ( bufferSize ) ) ; }
25+
26+ var buffer = new byte [ bufferSize ] ;
27+ long totalBytesRead = 0 ;
28+ int bytesRead ;
29+ while ( ( bytesRead = await source . ReadAsync ( buffer , 0 , buffer . Length , cancellationToken ) . ConfigureAwait ( false ) ) != 0 )
30+ {
31+ await destination . WriteAsync ( buffer , 0 , bytesRead , cancellationToken ) . ConfigureAwait ( false ) ;
32+ totalBytesRead += bytesRead ;
33+ progress ? . Report ( totalBytesRead ) ;
34+ }
35+ }
36+
37+ /// <summary>
38+ /// Асинхронно скачать файл
39+ /// </summary>
40+ public static Task DownloadAsync ( this HttpClient client , string requestUri , Stream destination ) => DownloadAsync ( client , requestUri , destination , default ( CancellationToken ) ) ;
41+
42+ /// <summary>
43+ /// Асинхронно скачать файл
44+ /// </summary>
45+ public static async Task DownloadAsync ( this HttpClient client , string requestUri , Stream destination , CancellationToken cancellationToken )
46+ {
47+ // Считать только заголовок
48+ using var response = await client . GetAsync ( requestUri , HttpCompletionOption . ResponseHeadersRead , cancellationToken ) ;
49+ response . EnsureSuccessStatusCode ( ) ;
50+ // А содержимое записать прямо в файл
51+ using var download = await response . Content . ReadAsStreamAsync ( ) ;
52+ await download . CopyToAsync ( destination ) ;
53+ }
54+
55+ /// <summary>
56+ /// Асинхронно скачать файл с отчётом о прогрессе
57+ /// </summary>
58+ public static Task DownloadAsync ( this HttpClient client , string requestUri , Stream destination , IProgress < float > progress ) => DownloadAsync ( client , requestUri , destination , progress , default ) ;
59+
60+ /// <summary>
61+ /// Асинхронно скачать файл с отчётом о прогрессе
62+ /// </summary>
63+ public static async Task DownloadAsync ( this HttpClient client , string requestUri , Stream destination , IProgress < float > progress , CancellationToken cancellationToken )
64+ {
65+ // Get the http headers first to examine the content length
66+ using var response = await client . GetAsync ( requestUri , HttpCompletionOption . ResponseHeadersRead , cancellationToken ) ;
67+ response . EnsureSuccessStatusCode ( ) ;
68+ var contentLength = response . Content . Headers . ContentLength ;
69+ using var download = await response . Content . ReadAsStreamAsync ( ) ;
70+ // Ignore progress reporting when no progress reporter was
71+ // passed or when the content length is unknown
72+ if ( ! contentLength . HasValue )
73+ {
74+ await download . CopyToAsync ( destination ) ;
75+ progress . Report ( 1 ) ;
76+ return ;
77+ }
78+
79+ // Convert absolute progress (bytes downloaded) into relative progress (0% - 100%)
80+ var relativeProgress = new Progress < long > ( totalBytes => progress . Report ( ( float ) totalBytes / contentLength . Value ) ) ;
81+ // Use extension method to report progress while downloading
82+ await download . CopyToAsync ( destination , 81920 , relativeProgress , cancellationToken ) ;
83+ progress . Report ( 1 ) ;
84+ }
85+ }
86+ }
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