// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using System;
using System.IO;
using System.Text;
using Microsoft.Build.Framework;
using Microsoft.Build.Utilities;

namespace Microsoft.DotNet.Build.Tasks.Installers;

/// <summary>
/// Create a .deb package from a control file and a data file.
/// </summary>
/// <remarks>
/// Implements the format specified in https://manpages.debian.org/bookworm/dpkg-dev/deb.5.en.html
/// </remarks>
[MSBuildMultiThreadableTask]
public sealed class CreateDebPackage : Task, IMultiThreadableTask
{
    private static readonly DateTime UnixEpoch = new(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);
    private static readonly uint Permissions = Convert.ToUInt32("100644", 8);

    /// <summary>Injected by MSBuild so paths resolve against the project directory in multithreaded builds.</summary>
    public TaskEnvironment TaskEnvironment { get; set; } = TaskEnvironment.Fallback;

    [Required]
    public string OutputDebPackagePath { get; set; }

    [Required]
    public ITaskItem ControlFile { get; set; }

    [Required]
    public ITaskItem DataFile { get; set; }

    public override bool Execute()
    {
        ulong timestamp = (ulong)(DateTime.UtcNow - UnixEpoch).TotalSeconds;
        using ArWriter arWriter = new(File.Open(TaskEnvironment.GetAbsolutePath(OutputDebPackagePath), FileMode.Create), false);
        arWriter.AddEntry(new ArEntry("debian-binary", timestamp, 0, 0, Permissions, new MemoryStream(Encoding.ASCII.GetBytes("2.0\n"))));
        using Stream controlFile = File.OpenRead(TaskEnvironment.GetAbsolutePath(ControlFile.ItemSpec));
        arWriter.AddEntry(new ArEntry("control.tar.gz", timestamp, 0, 0, Permissions, controlFile));
        using Stream dataFile = File.OpenRead(TaskEnvironment.GetAbsolutePath(DataFile.ItemSpec));
        arWriter.AddEntry(new ArEntry("data.tar.gz", timestamp, 0, 0, Permissions, dataFile));
        return true;
    }
}