namespace InnovEnergy.Lib.SysTools.Utils;

internal static class EnumerableUtils
{

    public static IEnumerable<T> Pad<T>(this IEnumerable<T> src, Int32 length, T padding)
    {
        using var enumerator = src.GetEnumerator();
        while (enumerator.MoveNext() && length-- > 0)
            yield return enumerator.Current;

        while (length-- > 0)
            yield return padding;
    }

    public static Dictionary<T, IReadOnlyList<T>> IndexColumn<T>(this IEnumerable<IEnumerable<T>> src, UInt16 index)
    {
        var d = new Dictionary<T, IReadOnlyList<T>>();

        foreach (var outer in src)
        {
            var inner = outer.ToList();
            var key = inner[index];
            d.Add(key, inner);
        }

        return d;
    }


    public static IEnumerable<(TLeft left, TRight right)> Zip<TLeft, TRight>(IEnumerable<TLeft> left,
        IEnumerable<TRight> right)
    {
        using var l = left.GetEnumerator();
        using var r = right.GetEnumerator();
        while (l.MoveNext() && r.MoveNext())
            yield return (l.Current, r.Current);
    }

    public static IEnumerator<T> Enumerator<T>(this T t)
    {
        yield return t;
    }

    public static IEnumerable<T> Enumerable<T>(this T t)
    {
        yield return t;
    }

    public static IEnumerable<T> Flatten<T>(this IEnumerable<IEnumerable<T>> src) => src.SelectMany(s => s);

    public static void ForEach<T>(this IEnumerable<T> enumerable, Action<T> action)
    {
        foreach (var e in enumerable)
            action(e);
    }



    public static IEnumerable<T> WhereNot<T>(this IEnumerable<T> enumerable, Func<T,Boolean> predicate)
    {
        return enumerable.Where(e => !predicate(e));
    }


    public static IEnumerable<T> EmptyIfNull<T>(this IEnumerable<T> enumerable)
    {
        return enumerable ?? new T[0];
    }

    // // https://stackoverflow.com/a/34006336/141397
    // public static Int32 CombineHashes(this ITuple tupled, Int32 seed = 1009, Int32 factor = 9176)
    // {
    //     var hash = seed;
    //
    //     for (var i = 0; i < tupled.Length; i++)
    //     {
    //         unchecked
    //         {
    //             hash = hash * factor + tupled[i].GetHashCode();
    //         }
    //     }
    //
    //     return hash;
    // }

}