using System.IO.Compression;
using System.Security.Cryptography;
using DTLib.Extensions;
using Млаумчерб.Клиент.зримое;
using Млаумчерб.Клиент.классы;
using static Млаумчерб.Клиент.сеть.Сеть;

namespace Млаумчерб.Клиент.сеть.NetworkTaskFactories;

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 = Пути.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)
    {
        Приложение.Логгер.LogInfo(nameof(Сеть), $"started downloading libraries '{_descriptor.id}'");
        
        ParallelOptions opt = new()
        {
            MaxDegreeOfParallelism = Приложение.Настройки.максимум_параллельных_загрузок,
            CancellationToken = ct
        };
        await Parallel.ForEachAsync(_libsToDownload, opt, async (l, _ct) =>
        {
            Приложение.Логгер.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);
                    }
                }
            }
        });
        
        Приложение.Логгер.LogInfo(nameof(Сеть), $"finished downloading libraries '{_descriptor.id}'");
    }
}