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

namespace Млаумчерб.Клиент.сеть.NetworkTaskFactories;

public class LibrariesDownloadTaskFactory : INetworkTaskFactory
{
    private VersionDescriptor _descriptor;
    private Libraries _libraries;
    private SHA1 _hasher;
    private List<Libraries.JarLib> _libsToDownload = new();

    public LibrariesDownloadTaskFactory(VersionDescriptor descriptor, Libraries libraries)
    {
        _descriptor = descriptor;
        _libraries = libraries;
        _hasher = SHA1.Create();
    }
    
    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();
        
        foreach (var l in _libraries.Libs)
        {
            if (!File.Exists(l.jarFilePath))
            {
                _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");
        ParallelOptions opt = new() { MaxDegreeOfParallelism = ParallelDownloadsN, CancellationToken = ct };
        await Parallel.ForEachAsync(_libsToDownload, opt, async (l, _ct) =>
        {
            Приложение.Логгер.LogDebug(nameof(Сеть), 
                $"downloading library '{l.name}' to '{l.jarFilePath}'");
            await DownloadFileHTTP(l.artifact.url, l.jarFilePath, _ct, pr.AddBytesCount);
            //TODO: extract natives from jar
        });
        Приложение.Логгер.LogInfo(nameof(Сеть), "finished downloading libraries");
    }
}