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@ -1,7 +1,6 @@
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using System;
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using System.Collections.Generic;
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using System.IO;
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using System.Net;
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using System.Net.Http;
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using System.Security.Cryptography;
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using System.Text;
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@ -9,87 +8,79 @@ using System.Text.RegularExpressions;
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using System.Threading.Tasks;
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using DiscordChatExporter.Domain.Internal;
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using DiscordChatExporter.Domain.Internal.Extensions;
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using Polly;
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using Polly.Retry;
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namespace DiscordChatExporter.Domain.Exporting
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{
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internal partial class MediaDownloader
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{
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private readonly HttpClient _httpClient = Singleton.HttpClient;
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private readonly HttpClient _httpClient;
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private readonly string _workingDirPath;
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private readonly bool _reuseMedia;
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private readonly AsyncRetryPolicy _httpRequestPolicy;
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private readonly Dictionary<string, string> _pathMap = new Dictionary<string, string>();
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// URL -> Local file path
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private readonly Dictionary<string, string> _pathCache =
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new Dictionary<string, string>(StringComparer.Ordinal);
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public MediaDownloader(string workingDirPath, bool reuseMedia)
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public MediaDownloader(HttpClient httpClient, string workingDirPath, bool reuseMedia)
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{
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_httpClient = httpClient;
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_workingDirPath = workingDirPath;
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_reuseMedia = reuseMedia;
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_httpRequestPolicy = Policy
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.Handle<IOException>()
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.WaitAndRetryAsync(8, i => TimeSpan.FromSeconds(0.5 * i));
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}
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public MediaDownloader(string workingDirPath, bool reuseMedia)
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: this(Http.Client, workingDirPath, reuseMedia) {}
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public async ValueTask<string> DownloadAsync(string url)
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{
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return await _httpRequestPolicy.ExecuteAsync(async () =>
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{
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if (_pathMap.TryGetValue(url, out var cachedFilePath))
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return cachedFilePath;
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var fileName = GetFileNameFromUrl(url);
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var filePath = Path.Combine(_workingDirPath, fileName);
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if (_pathCache.TryGetValue(url, out var cachedFilePath))
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return cachedFilePath;
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if (!_reuseMedia)
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{
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filePath = PathEx.MakeUniqueFilePath(filePath);
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}
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var fileName = GetFileNameFromUrl(url);
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var filePath = Path.Combine(_workingDirPath, fileName);
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if (!_reuseMedia || !File.Exists(filePath))
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{
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Directory.CreateDirectory(_workingDirPath);
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await _httpClient.DownloadAsync(url, filePath);
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}
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// Reuse existing files if we're allowed to
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if (_reuseMedia && File.Exists(filePath))
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return _pathCache[url] = filePath;
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return _pathMap[url] = filePath;
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// Download it
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Directory.CreateDirectory(_workingDirPath);
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await Http.ExceptionPolicy.ExecuteAsync(async () =>
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{
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// This catches IOExceptions which is dangerous as we're working also with files
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await _httpClient.DownloadAsync(url, filePath);
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});
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return _pathCache[url] = filePath;
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}
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}
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internal partial class MediaDownloader
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{
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private static int URL_HASH_LENGTH = 5;
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private static string HashUrl(string url)
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private static string GetUrlHash(string url)
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{
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using (var md5 = MD5.Create())
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{
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var inputBytes = Encoding.UTF8.GetBytes(url);
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var hashBytes = md5.ComputeHash(inputBytes);
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var hashBuilder = new StringBuilder();
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for (int i = 0; i < hashBytes.Length; i++)
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{
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hashBuilder.Append(hashBytes[i].ToString("X2"));
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}
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return hashBuilder.ToString().Truncate(URL_HASH_LENGTH);
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}
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}
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using var hash = SHA256.Create();
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private static string GetRandomFileName() => Guid.NewGuid().ToString().Replace("-", "").Substring(0, 16);
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var data = hash.ComputeHash(Encoding.UTF8.GetBytes(url));
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return data.ToHex().Truncate(5); // 5 chars ought to be enough for anybody
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}
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private static string GetFileNameFromUrl(string url)
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{
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var originalFileName = Regex.Match(url, @".+/([^?]*)").Groups[1].Value;
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var urlHash = GetUrlHash(url);
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// Try to extract file name from URL
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var fileName = Regex.Match(url, @".+/([^?]*)").Groups[1].Value;
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// If it's not there, just use the URL hash as the file name
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if (string.IsNullOrWhiteSpace(fileName))
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return urlHash;
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var fileName = !string.IsNullOrWhiteSpace(originalFileName)
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? $"{Path.GetFileNameWithoutExtension(originalFileName).Truncate(42)}-({HashUrl(url)}){Path.GetExtension(originalFileName)}"
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: GetRandomFileName();
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// Otherwise, use the original file name but inject the hash in the middle
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var fileNameWithoutExtension = Path.GetFileNameWithoutExtension(fileName);
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var fileExtension = Path.GetExtension(fileName);
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return PathEx.EscapePath(fileName);
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return PathEx.EscapePath(fileNameWithoutExtension.Truncate(42) + '-' + urlHash + fileExtension);
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}
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}
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}
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Tyrrrz
4 years ago