now it works

2024-11-06 00:04:12 +05:00
parent 612976dfe6
commit 1f663902e2
54 changed files with 763 additions and 586 deletions
--- a/Mlaumcherb.Client.Avalonia/сеть/DataSize.cs
+++ b/Mlaumcherb.Client.Avalonia/сеть/DataSize.cs
@@ -0,0 +1,23 @@
+namespace Mlaumcherb.Client.Avalonia.сеть;
+
+public record struct DataSize(long Bytes)
+{
+    static string BytesToHumanReadable(long bytes)
+    {
+        long K = bytes / 1024;
+        if (K == 0)
+            return $"{bytes}b";
+        float M = K / 1024f;
+        if (M < 1)
+            return $"{K:N1}Kb";
+        float G = M / 1024f;
+        if (G < 1)
+            return $"{M:N1}Mb";
+        return $"{G:N1}Gb";
+    }
+
+    public override string ToString() => BytesToHumanReadable(Bytes);
+    
+    public static implicit operator DataSize(long bytes) => new DataSize(bytes);
+}
+
--- a/Mlaumcherb.Client.Avalonia/сеть/NetworkProgressReporter.cs
+++ b/Mlaumcherb.Client.Avalonia/сеть/NetworkProgressReporter.cs
@@ -0,0 +1,61 @@
+using Mlaumcherb.Client.Avalonia.зримое;
+using Timer = DTLib.Timer;
+
+namespace Mlaumcherb.Client.Avalonia.сеть;
+
+public record struct DownloadProgress(DataSize Downloaded, DataSize Total, DataSize PerSecond)
+{
+    public override string ToString()
+    {
+        return $"{Downloaded}/{Total} ({PerSecond}/s)";
+    }
+}
+
+public class NetworkProgressReporter : IDisposable
+{
+    private readonly Action<DownloadProgress> _reportProgressDelegate;
+    private long _totalSize;
+    private long _curSize;
+    private long _prevSize;
+    private int _timerDelay = 1000;
+    private Timer _timer;
+    
+    public NetworkProgressReporter(long totalSize, Action<DownloadProgress> reportProgressDelegate)
+    {
+        _totalSize = totalSize;
+        _reportProgressDelegate = reportProgressDelegate;
+        _timer = new Timer(true, _timerDelay, ReportProgress);
+    }
+
+    // atomic add
+    public void AddBytesCount(byte[] buffer, int offset, int count)
+    {
+        Interlocked.Add(ref _curSize, count);
+    }
+    
+    public void Start()
+    {
+        _timer.Start();
+    }
+
+    public void Stop()
+    {
+        _timer.Stop();
+        _timer.InvokeAction();
+    }
+
+    public void Dispose()
+    {
+        Stop();
+    }
+
+    void ReportProgress()
+    {
+        long bytesPerSec = (_curSize - _prevSize) / (_timerDelay / 1000);
+        _prevSize = _curSize;
+        var p = new DownloadProgress(_curSize, _totalSize, bytesPerSec);
+        LauncherApp.Logger.LogDebug(nameof(ReportProgress),
+            $"download progress {p}");
+        _reportProgressDelegate(p);
+    }
+}
--- a/Mlaumcherb.Client.Avalonia/сеть/NetworkTask.cs
+++ b/Mlaumcherb.Client.Avalonia/сеть/NetworkTask.cs
@@ -0,0 +1,77 @@
+namespace Mlaumcherb.Client.Avalonia.сеть;
+
+public class NetworkTask : IDisposable
+{
+    public readonly string Name;
+
+    public enum Status
+    {
+        Initialized,
+        Started,
+        Completed,
+        Cancelled,
+        Failed
+    };
+
+    public Status DownloadStatus { get; private set; } = Status.Initialized;
+
+    public event Action? OnStart; 
+    public event Action<DownloadProgress>? OnProgress;
+    public event Action<Status>? OnStop; 
+
+    public delegate Task DownloadAction(NetworkProgressReporter progressReporter, CancellationToken ct);
+
+    private readonly DownloadAction _downloadAction;
+    private CancellationTokenSource _cts = new();
+    private NetworkProgressReporter _progressReporter;
+
+    public NetworkTask(string name, long dataSize, DownloadAction downloadAction)
+    {
+        Name = name;
+        _downloadAction = downloadAction;
+        _progressReporter = new NetworkProgressReporter(dataSize, ReportProgress);
+    }
+    
+    private void ReportProgress(DownloadProgress p) => OnProgress?.Invoke(p);
+
+    public async Task StartAsync()
+    {
+        if(DownloadStatus == Status.Started || DownloadStatus == Status.Completed)
+            return;
+        DownloadStatus = Status.Started;
+        try
+        {
+            _progressReporter.Start();
+            OnStart?.Invoke();
+            await _downloadAction(_progressReporter, _cts.Token);
+            DownloadStatus = Status.Completed;
+        }
+        catch (OperationCanceledException)
+        {
+            DownloadStatus = Status.Cancelled;
+        }
+        catch
+        {
+            DownloadStatus = Status.Failed;
+            throw;
+        }
+        finally
+        {
+            _progressReporter.Stop();
+            OnStop?.Invoke(DownloadStatus);
+        }
+    } 
+
+    public void Cancel()
+    {
+        DownloadStatus = Status.Cancelled;
+        _cts.Cancel();
+        _cts = new CancellationTokenSource();
+    }
+
+    public void Dispose()
+    {
+        _cts.Dispose();
+        _progressReporter.Dispose();
+    }
+}
--- a/Mlaumcherb.Client.Avalonia/сеть/TaskFactories/AssetsDownloadTaskFactory.cs
+++ b/Mlaumcherb.Client.Avalonia/сеть/TaskFactories/AssetsDownloadTaskFactory.cs
@@ -0,0 +1,137 @@
+using System.Net;
+using System.Net.Http;
+using System.Security.Cryptography;
+using DTLib.Extensions;
+using Mlaumcherb.Client.Avalonia.зримое;
+using Mlaumcherb.Client.Avalonia.классы;
+using Mlaumcherb.Client.Avalonia.холопы;
+using static Mlaumcherb.Client.Avalonia.сеть.Сеть;
+
+namespace Mlaumcherb.Client.Avalonia.сеть.TaskFactories;
+
+public class AssetsDownloadTaskFactory : INetworkTaskFactory
+{
+    private const string ASSET_SERVER_URL = "https://resources.download.minecraft.net/";
+    private GameVersionDescriptor _descriptor;
+    private SHA1 _hasher;
+    private IOPath _indexFilePath;
+    List<AssetDownloadProperties> _assetsToDownload = new();
+
+    public AssetsDownloadTaskFactory(GameVersionDescriptor descriptor)
+    {
+        _descriptor = descriptor;
+        _hasher = SHA1.Create();
+        _indexFilePath = PathHelper.GetAssetIndexFilePath(_descriptor.assetIndex.id);
+    }
+    
+    public async Task<NetworkTask?> CreateAsync(bool checkHashes)
+    {
+        if (!await CheckFilesAsync(checkHashes))
+            return new NetworkTask(
+                $"assets '{_descriptor.assetIndex.id}'",
+                GetTotalSize(),
+                Download
+            );
+        
+        return null;
+    }
+    private async Task<bool> CheckFilesAsync(bool checkHashes)
+    {
+        if(!File.Exists(_indexFilePath))
+        {
+            LauncherApp.Logger.LogInfo(nameof(Сеть), $"started downloading asset index to '{_indexFilePath}'");
+            await DownloadFile(_descriptor.assetIndex.url, _indexFilePath);
+            LauncherApp.Logger.LogInfo(nameof(Сеть), "finished downloading asset index");
+        }
+
+        string indexFileText = File.ReadAllText(_indexFilePath);
+        var assetIndex = JsonConvert.DeserializeObject<AssetIndex>(indexFileText) 
+                     ?? throw new Exception($"can't deserialize asset index file '{_indexFilePath}'");
+        
+        _assetsToDownload.Clear();
+        // removing duplicates for Dictionary (idk how can it be possible, but Newtonsoft.Json creates them)
+        HashSet<string> assetHashes = new HashSet<string>();
+        foreach (var pair in assetIndex.objects)
+        {
+            if (assetHashes.Add(pair.Value.hash))
+            {
+                var a = new AssetDownloadProperties(pair.Key, pair.Value);
+                if (!File.Exists(a.filePath))
+                {
+                    _assetsToDownload.Add(a);
+                }
+                else if(checkHashes)
+                {
+                    await using var fs = File.OpenRead(a.filePath);
+                    string hash = _hasher.ComputeHash(fs).HashToString();
+                    if (hash != a.hash)
+                        _assetsToDownload.Add(a);
+                }
+            }
+        }
+        
+        return _assetsToDownload.Count == 0;
+    }
+
+    private long GetTotalSize()
+    {
+        long totalSize = 0;
+        foreach (var a in _assetsToDownload) 
+            totalSize += a.size;
+        return totalSize;
+    }
+
+    private class AssetDownloadProperties
+    {
+        public string name;
+        public string hash;
+        public long size;
+        public string url;
+        public IOPath filePath;
+
+        public AssetDownloadProperties(string key, AssetProperties p)
+        {
+            name = key;
+            hash = p.hash;
+            size = p.size;
+            string hashStart = hash.Substring(0, 2);
+            url = $"{ASSET_SERVER_URL}/{hashStart}/{hash}";
+            filePath = Path.Concat(IOPath.ArrayCast(["assets", "objects", hashStart, hash], true));
+        }
+    }
+    
+    private async Task Download(NetworkProgressReporter pr, CancellationToken ct)
+    {
+        LauncherApp.Logger.LogInfo(nameof(Сеть), $"started downloading assets '{_descriptor.assetIndex.id}'");
+        ParallelOptions opt = new()
+        {
+            MaxDegreeOfParallelism = LauncherApp.Config.max_parallel_downloads,
+            CancellationToken = ct
+        };
+        await Parallel.ForEachAsync(_assetsToDownload, opt, 
+        async (a, _ct) =>
+        {
+            bool completed = false;
+            while(!completed)
+            {
+                LauncherApp.Logger.LogDebug(nameof(Сеть), $"downloading asset '{a.name}' {a.hash}");
+                try
+                {
+                    await DownloadFile(a.url, a.filePath, _ct, pr.AddBytesCount);
+                    completed = true;
+                }
+                catch (HttpRequestException httpException)
+                {
+                    // wait on rate limit
+                    if(httpException.StatusCode == HttpStatusCode.TooManyRequests)
+                    {
+                        LauncherApp.Logger.LogDebug(nameof(Сеть), "rate limit hit");
+                        await Task.Delay(1000, _ct);
+                    }
+                    else throw;
+                }
+            }
+        });
+        LauncherApp.Logger.LogInfo(nameof(Сеть), $"finished downloading assets '{_descriptor.assetIndex.id}'");
+    }
+}
--- a/Mlaumcherb.Client.Avalonia/сеть/TaskFactories/INetworkTaskFactory.cs
+++ b/Mlaumcherb.Client.Avalonia/сеть/TaskFactories/INetworkTaskFactory.cs
@@ -0,0 +1,7 @@
+namespace Mlaumcherb.Client.Avalonia.сеть.TaskFactories;
+
+public interface INetworkTaskFactory
+{
+    /// <returns>unstarted network task or null if there is nothing to download</returns>
+    Task<NetworkTask?> CreateAsync(bool checkHashes);
+}
--- a/Mlaumcherb.Client.Avalonia/сеть/TaskFactories/JavaDownloadTaskFactory.cs
+++ b/Mlaumcherb.Client.Avalonia/сеть/TaskFactories/JavaDownloadTaskFactory.cs
@@ -0,0 +1,123 @@
+using System.Security.Cryptography;
+using DTLib.Extensions;
+using Mlaumcherb.Client.Avalonia.зримое;
+using Mlaumcherb.Client.Avalonia.классы;
+using Mlaumcherb.Client.Avalonia.холопы;
+using static Mlaumcherb.Client.Avalonia.сеть.Сеть;
+
+namespace Mlaumcherb.Client.Avalonia.сеть.TaskFactories;
+
+public class JavaDownloadTaskFactory : INetworkTaskFactory
+{
+    private const string CATALOG_URL =
+        "https://launchermeta.mojang.com/v1/products/java-runtime/2ec0cc96c44e5a76b9c8b7c39df7210883d12871/all.json";
+    private GameVersionDescriptor _descriptor;
+    private IOPath _javaVersionDir;
+    private SHA1 _hasher;
+    private JavaDistributiveManifest? _distributiveManifest;
+    private List<(IOPath path, JavaDistributiveElementProps props)> _filesToDownload = new();
+    
+    public JavaDownloadTaskFactory(GameVersionDescriptor descriptor)
+    {
+        _descriptor = descriptor;
+        _javaVersionDir = PathHelper.GetJavaRuntimeDir(_descriptor.javaVersion.component);
+        _hasher = SHA1.Create();
+    }
+
+    public async Task<NetworkTask?> CreateAsync(bool checkHashes)
+    {
+        var catalog = await DownloadStringAndDeserialize<JavaVersionCatalog>(CATALOG_URL);
+        var versionProps = catalog.GetVersionProps(_descriptor.javaVersion);
+        _distributiveManifest = await DownloadStringAndDeserialize<JavaDistributiveManifest>(versionProps.manifest.url);
+        
+        NetworkTask? networkTask = null;
+        if (!CheckFiles(checkHashes))
+            networkTask = new(
+                    $"java runtime '{_descriptor.javaVersion.component}'",
+                    GetTotalSize(),
+                    Download
+                );
+        return networkTask;
+    }
+
+    private bool CheckFiles(bool checkHashes)
+    {
+        _filesToDownload.Clear();
+        foreach (var pair in _distributiveManifest!.files)
+        {
+            if (pair.Value.type != "file")
+                continue;
+
+            if (pair.Value.downloads != null)
+            {
+                var artifact = pair.Value.downloads;
+                IOPath file_path = Path.Concat(_javaVersionDir, pair.Key);
+                if (!File.Exists(file_path))
+                {
+                    _filesToDownload.Add((file_path, pair.Value));
+                }
+                else if(checkHashes)
+                {
+                    using var fs = File.OpenRead(file_path);
+                    if (_hasher.ComputeHash(fs).HashToString() != artifact.raw.sha1)
+                    {
+                        _filesToDownload.Add((file_path, pair.Value));
+                    }
+                }
+            }
+        }
+
+        return _filesToDownload.Count == 0;
+    }
+    
+    private long GetTotalSize()
+    {
+        long totalSize = 0;
+        foreach (var file in _filesToDownload)
+        {
+            if(file.props.downloads == null)
+                continue;
+            totalSize += file.props.downloads.lzma?.size ?? file.props.downloads.raw.size;
+        }
+        return totalSize;
+    }
+
+    private async Task Download(NetworkProgressReporter pr, CancellationToken ct)
+    {
+        LauncherApp.Logger.LogInfo(nameof(Сеть), "started downloading java runtime " +
+                    $"{_descriptor.javaVersion.majorVersion} '{_descriptor.javaVersion.component}'");
+        
+        ParallelOptions opt = new()
+        {
+            MaxDegreeOfParallelism = LauncherApp.Config.max_parallel_downloads,
+            CancellationToken = ct
+        };
+        await Parallel.ForEachAsync(_filesToDownload, opt, async (f, _ct) =>
+        {
+            if (f.props.downloads!.lzma != null)
+            {
+                LauncherApp.Logger.LogDebug(nameof(Сеть), $"downloading lzma-compressed file '{f.path}'");
+                await using var pipe = new TransformStream(await GetStream(f.props.downloads.lzma.url, _ct));
+                pipe.AddTransform(pr.AddBytesCount);
+                await using var fs = File.OpenWrite(f.path);
+                LZMAHelper.Decompress(pipe, fs);
+            }
+            else
+            {
+                LauncherApp.Logger.LogDebug(nameof(Сеть), $"downloading raw file '{f.path}'");
+                await DownloadFile(f.props.downloads.raw.url, f.path, _ct, pr.AddBytesCount);
+            }
+            
+            if(!OperatingSystem.IsWindows() && f.props.executable is true)
+            {
+                LauncherApp.Logger.LogDebug(nameof(Сеть), $"adding execute rights to file '{f.path}'");
+                System.IO.File.SetUnixFileMode(f.path.ToString(), UnixFileMode.UserExecute);
+            }
+        });
+        
+        LauncherApp.Logger.LogInfo(nameof(Сеть), "finished downloading java runtime " + 
+                    $"{_descriptor.javaVersion.majorVersion} '{_descriptor.javaVersion.component}'");
+    }
+    
+    
+}
--- a/Mlaumcherb.Client.Avalonia/сеть/TaskFactories/LibrariesDownloadTaskFactory.cs
+++ b/Mlaumcherb.Client.Avalonia/сеть/TaskFactories/LibrariesDownloadTaskFactory.cs
@@ -0,0 +1,107 @@
+using System.IO.Compression;
+using System.Security.Cryptography;
+using DTLib.Extensions;
+using Mlaumcherb.Client.Avalonia.зримое;
+using Mlaumcherb.Client.Avalonia.классы;
+using Mlaumcherb.Client.Avalonia.холопы;
+using static Mlaumcherb.Client.Avalonia.сеть.Сеть;
+
+namespace Mlaumcherb.Client.Avalonia.сеть.TaskFactories;
+
+public class LibrariesDownloadTaskFactory : INetworkTaskFactory
+{
+    private GameVersionDescriptor _descriptor;
+    private Libraries _libraries;
+    private SHA1 _hasher;
+    private List<Libraries.JarLib> _libsToDownload = new();
+    private IOPath _nativesDir;
+
+    public LibrariesDownloadTaskFactory(GameVersionDescriptor descriptor, Libraries libraries)
+    {
+        _descriptor = descriptor;
+        _libraries = libraries;
+        _hasher = SHA1.Create();
+        _nativesDir = PathHelper.GetNativeLibrariesDir(descriptor.id);
+    }
+    
+    public Task<NetworkTask?> CreateAsync(bool checkHashes)
+    {
+        NetworkTask? networkTask = null;
+        if (!CheckFiles(checkHashes))
+            networkTask = new NetworkTask(
+                $"libraries '{_descriptor.id}'",
+                GetTotalSize(),
+                Download
+            );
+        return Task.FromResult(networkTask);
+    }
+    
+    private bool CheckFiles(bool checkHashes)
+    {
+        _libsToDownload.Clear();
+        bool nativeDirExists = Directory.Exists(_nativesDir);
+        
+        foreach (var l in _libraries.Libs)
+        {
+            if (!File.Exists(l.jarFilePath))
+            {
+                _libsToDownload.Add(l);
+            }
+            else if (!nativeDirExists && l is Libraries.NativeLib)
+            {
+                _libsToDownload.Add(l);
+            }
+            else if (checkHashes)
+            {
+                using var fs = File.OpenRead(l.jarFilePath);
+                string hash = _hasher.ComputeHash(fs).HashToString();
+                if(hash != l.artifact.sha1)
+                    _libsToDownload.Add(l);
+            }
+        }
+
+        return _libsToDownload.Count == 0;
+    }
+    
+    private long GetTotalSize()
+    {
+        long total = 0;
+        foreach (var l in _libsToDownload)
+            total += l.artifact.size;
+        return total;
+    }
+
+    private async Task Download(NetworkProgressReporter pr, CancellationToken ct)
+    {
+        LauncherApp.Logger.LogInfo(nameof(Сеть), $"started downloading libraries '{_descriptor.id}'");
+        
+        ParallelOptions opt = new()
+        {
+            MaxDegreeOfParallelism = LauncherApp.Config.max_parallel_downloads,
+            CancellationToken = ct
+        };
+        await Parallel.ForEachAsync(_libsToDownload, opt, async (l, _ct) =>
+        {
+            LauncherApp.Logger.LogDebug(nameof(Сеть), $"downloading library '{l.name}' to '{l.jarFilePath}'");
+            await DownloadFile(l.artifact.url, l.jarFilePath, _ct, pr.AddBytesCount);
+            if (l is Libraries.NativeLib n)
+            {
+                var zipf = File.OpenRead(n.jarFilePath);
+                ZipFile.ExtractToDirectory(zipf, _nativesDir.ToString(), true);
+                if (n.extractionOptions?.exclude != null)
+                {
+                    foreach (var excluded in n.extractionOptions.exclude)
+                    {
+                        IOPath path = Path.Concat(_nativesDir, excluded);
+                        if(Directory.Exists(path))
+                            Directory.Delete(path);
+                        if(File.Exists(path))
+                            File.Delete(path);
+                    }
+                }
+            }
+        });
+        
+        LauncherApp.Logger.LogInfo(nameof(Сеть), $"finished downloading libraries '{_descriptor.id}'");
+    }
+}
--- a/Mlaumcherb.Client.Avalonia/сеть/TaskFactories/VersionFileDownloadTaskFactory.cs
+++ b/Mlaumcherb.Client.Avalonia/сеть/TaskFactories/VersionFileDownloadTaskFactory.cs
@@ -0,0 +1,57 @@
+using System.Security.Cryptography;
+using DTLib.Extensions;
+using Mlaumcherb.Client.Avalonia.зримое;
+using Mlaumcherb.Client.Avalonia.классы;
+using Mlaumcherb.Client.Avalonia.холопы;
+using static Mlaumcherb.Client.Avalonia.сеть.Сеть;
+
+namespace Mlaumcherb.Client.Avalonia.сеть.TaskFactories;
+
+public class VersionFileDownloadTaskFactory : INetworkTaskFactory
+{
+    private GameVersionDescriptor _descriptor;
+    private IOPath _filePath;
+    private SHA1 _hasher;
+    
+    public VersionFileDownloadTaskFactory(GameVersionDescriptor descriptor)
+    {
+        _descriptor = descriptor;
+        _filePath = PathHelper.GetVersionJarFilePath(_descriptor.id);
+        _hasher = SHA1.Create();
+    }
+
+    public Task<NetworkTask?> CreateAsync(bool checkHashes)
+    {
+        NetworkTask? networkTask = null;
+        if (!CheckFiles(checkHashes))
+            networkTask = new NetworkTask(
+                    $"version file '{_descriptor.id}'",
+                    GetTotalSize(),
+                    Download
+                );
+        return Task.FromResult(networkTask);
+    }
+
+    private bool CheckFiles(bool checkHashes)
+    {
+        if (!File.Exists(_filePath))
+            return false;
+        if (!checkHashes)
+            return true;
+        using var fs = File.OpenRead(_filePath);
+        string hash = _hasher.ComputeHash(fs).HashToString();
+        return hash == _descriptor.downloads.client.sha1;
+    }
+
+    private long GetTotalSize()
+    {
+        return _descriptor.downloads.client.size;
+    }
+    
+    private async Task Download(NetworkProgressReporter pr, CancellationToken ct)
+    {
+        LauncherApp.Logger.LogInfo(nameof(Сеть), $"started downloading version file '{_descriptor.id}'");
+        await DownloadFile(_descriptor.downloads.client.url, _filePath, ct, pr.AddBytesCount);
+        LauncherApp.Logger.LogInfo(nameof(Сеть), $"finished downloading version file '{_descriptor.id}'");
+    }
+}
--- a/Mlaumcherb.Client.Avalonia/сеть/Сеть.cs
+++ b/Mlaumcherb.Client.Avalonia/сеть/Сеть.cs
@@ -0,0 +1,87 @@
+using System.Net.Http;
+using Mlaumcherb.Client.Avalonia.зримое;
+using Mlaumcherb.Client.Avalonia.классы;
+
+namespace Mlaumcherb.Client.Avalonia.сеть;
+
+public static class Сеть
+{
+    private static HttpClient _http = new();
+
+    static Сеть()
+    {
+        // thanks for Sashok :3
+        // https://github.com/new-sashok724/Launcher/blob/23485c3f7de6620d2c6b7b2dd9339c3beb6a0366/Launcher/source/helper/IOHelper.java#L259
+        _http.DefaultRequestHeaders.Add("User-Agent", "Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.0)");
+    }
+
+    public static Task<string> GetString(string url, CancellationToken ct = default) => _http.GetStringAsync(url, ct);
+    public static Task<Stream> GetStream(string url, CancellationToken ct = default) => _http.GetStreamAsync(url, ct);
+    
+    public static async Task DownloadFile(string url, Stream outStream, CancellationToken ct = default, 
+        params TransformStream.TransformFuncDelegate[] transforms)
+    {
+        await using var pipe = new TransformStream(await GetStream(url, ct));
+        if (transforms.Length > 0) 
+            pipe.AddTransforms(transforms);
+        await pipe.CopyToAsync(outStream, ct);
+    }
+    
+    public static async Task DownloadFile(string url, IOPath outPath, CancellationToken ct = default, 
+        params TransformStream.TransformFuncDelegate[] transforms)
+    {
+        await using var file = File.OpenWrite(outPath);
+        await DownloadFile(url, file, ct, transforms);
+    }
+    
+    public static async Task<T> DownloadStringAndDeserialize<T>(string url)
+    {
+        var text = await _http.GetStringAsync(url);
+        var result = JsonConvert.DeserializeObject<T>(text)
+            ?? throw new Exception($"can't deserialize {typeof(T).Name}");
+        return result;
+    }
+    
+    private static readonly string[] VERSION_MANIFEST_URLS =
+    {
+        "https://piston-meta.mojang.com/mc/game/version_manifest_v2.json"
+    };
+
+    private static async Task<List<RemoteVersionDescriptorProps>> GetRemoteVersionDescriptorsAsync()
+    {
+        List<RemoteVersionDescriptorProps> descriptors = new();
+        foreach (var url in VERSION_MANIFEST_URLS)
+        {
+            try
+            {
+                var catalog = await DownloadStringAndDeserialize<GameVersionCatalog>(url);
+                descriptors.AddRange(catalog.versions);
+            }
+            catch (Exception ex)
+            {
+                LauncherApp.Logger.LogWarn(nameof(Сеть), ex);
+            }
+        }
+
+        return descriptors;
+    }
+
+    private static List<GameVersionProps>? _versionPropsList;
+
+    /// <returns>empty list if couldn't find any remote versions</returns>
+    public static async Task<IReadOnlyList<GameVersionProps>> GetDownloadableVersions()
+    {
+        if (_versionPropsList == null)
+        {
+            _versionPropsList = new();
+            var rvdlist = await GetRemoteVersionDescriptorsAsync();
+            foreach (var r in rvdlist)
+            {
+                if (r.type == "release")
+                    _versionPropsList.Add(new GameVersionProps(r.id, r.url));
+            }
+        }
+
+        return _versionPropsList;
+    }
+}