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

namespace Млаумчерб.Клиент.сеть.NetworkTaskFactories;

public class VersionFileDownloadTaskFactory : INetworkTaskFactory
{
    private VersionDescriptor _descriptor;
    private IOPath _filePath;
    private SHA1 _hasher;
    
    public VersionFileDownloadTaskFactory(VersionDescriptor descriptor)
    {
        _descriptor = descriptor;
        _filePath = Пути.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 Task Download(NetworkProgressReporter pr, CancellationToken ct)
    {
        return DownloadFileHTTP(_descriptor.downloads.client.url, _filePath, ct, pr.AddBytesCount);
    }
}