/*
 *                     GNU AFFERO GENERAL PUBLIC LICENSE
 *                       Version 3, 19 November 2007
 *  Copyright (C) 2007 Free Software Foundation, Inc. <https://fsf.org/>
 *  Everyone is permitted to copy and distribute verbatim copies
 *  of this license document, but changing it is not allowed.
 */
using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace UVtools.Core.Extensions;

public static class ParallelExtensions
{
    //public static readonly ParallelOptions ParallelSingleThread = new() { MaxDegreeOfParallelism = 1 };
    public static void ForAllInApproximateOrder<TSource>(this ParallelQuery<TSource> source, Action<TSource> action)
    {
        Partitioner.Create(source)
            .AsParallel()
            .AsOrdered()
            .ForAll(action);
    }

    public static void ForEachInApproximateOrder<TSource>(this ParallelQuery<TSource> source, Action<TSource> action)
    {

        source = Partitioner.Create(source)
            .AsParallel()
            .AsOrdered();

        Parallel.ForEach(source, action);

    }

    public static IEnumerable<T1> OrderedParallel<T, T1>(this IEnumerable<T> list, Func<T, T1> action)
    {
        var unorderedResult = new ConcurrentBag<(long, T1)>();
        Parallel.ForEach(list, (o, state, i) =>
        {
            unorderedResult.Add((i, action.Invoke(o)));
        });
        var ordered = unorderedResult.OrderBy(o => o.Item1);
        return ordered.Select(o => o.Item2);
    }
}