using System;
using System.Collections.Generic;
using System.Threading;

namespace MayShows.Helpers;

public static class ThreadSafeRandom
{
    [ThreadStatic] private static Random? Local;

    public static Random ThisThreadsRandom
    {
        get { return Local ?? (Local = new Random(unchecked(Environment.TickCount * 31 + Thread.CurrentThread.ManagedThreadId))); }
    }
}

// https://stackoverflow.com/a/1262619/3938401
static class ListExtensions
{
    public static void Shuffle<T>(this IList<T> list)
    {
        int n = list.Count;
        while (n > 1)
        {
            n--;
            int k = ThreadSafeRandom.ThisThreadsRandom.Next(n + 1);
            T value = list[k];
            list[k] = list[n];
            list[n] = value;
        }
    }
}