using System.Threading;
using Thread = System.Threading.Thread;
using WhiteMagic;
using WhiteMagic.Native;
using WhiteMagic.Thread;
using Xunit;

namespace WhiteMagicTest.Thread;

/// <summary>
/// Tests for <see cref="RemoteThread"/> open/suspend/resume and context round-trip.
/// </summary>
public sealed class RemoteThreadTests
{
    [Fact]
    public void Open_by_id_succeeds_for_current_thread()
    {
        using var magic = Magic.OpenInProcess();
        int currentId = (int)NativeMethods.GetCurrentThreadId();

        using var thread = new RemoteThread(magic.Memory, currentId);
        Assert.Equal(currentId, thread.Id);
    }

    [Fact]
    public void Suspend_returns_prior_count_and_stops_worker()
    {
        using var magic = Magic.OpenInProcess();
        using var cts = new CancellationTokenSource();
        var started = new ManualResetEventSlim(false);
        int osThreadId = 0;

        var worker = new System.Threading.Thread(() =>
        {
            osThreadId = (int)NativeMethods.GetCurrentThreadId();
            started.Set();
            while (!cts.IsCancellationRequested)
                System.Threading.Thread.Sleep(10);
        });

        worker.Start();
        started.Wait();

        try
        {
            using var thread = new RemoteThread(magic.Memory, osThreadId);

            uint prior = thread.Suspend();
            Assert.True(prior < 0xFFFFFFFF);

            cts.Cancel();
            // Worker cannot observe cancellation while suspended.
            Assert.False(worker.Join(100));

            thread.Resume();
            Assert.True(worker.Join(1000));
        }
        finally
        {
            if (worker.IsAlive)
            {
                cts.Cancel();
                using var thread = new RemoteThread(magic.Memory, osThreadId);
                thread.Resume();
                worker.Join(1000);
            }
        }
    }

    [Fact]
    public void Resume_restarts_a_suspended_worker()
    {
        using var magic = Magic.OpenInProcess();
        using var cts = new CancellationTokenSource();
        var started = new ManualResetEventSlim(false);
        var resumed = new ManualResetEventSlim(false);
        int osThreadId = 0;

        var worker = new System.Threading.Thread(() =>
        {
            osThreadId = (int)NativeMethods.GetCurrentThreadId();
            started.Set();
            while (!cts.IsCancellationRequested)
            {
                resumed.Set();
                System.Threading.Thread.Sleep(10);
            }
        });

        worker.Start();
        started.Wait();

        try
        {
            using var thread = new RemoteThread(magic.Memory, osThreadId);
            thread.Suspend();
            resumed.Reset();

            uint prior = thread.Resume();
            Assert.True(prior < 0xFFFFFFFF);

            // Worker must reach the resumed flag again.
            Assert.True(resumed.Wait(1000));
            cts.Cancel();
            Assert.True(worker.Join(1000));
        }
        finally
        {
            if (worker.IsAlive)
            {
                cts.Cancel();
                using var thread = new RemoteThread(magic.Memory, osThreadId);
                thread.Resume();
                worker.Join(1000);
            }
        }
    }

    [Fact]
    public void GetTeb_returns_managed_teb_for_thread()
    {
        using var magic = Magic.OpenInProcess();
        int currentId = (int)NativeMethods.GetCurrentThreadId();

        using var thread = new RemoteThread(magic.Memory, currentId);
        using var teb = thread.GetTeb();

        Assert.NotEqual(IntPtr.Zero, teb.ReadTebAddress());
    }
}