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

namespace BlueWest.Collections
{
    public static class IEnumerableExtensions
    {

        public static TSource? FirstOrNull<TSource>(this TSource[] source, Func<TSource, bool> predicate) where TSource : struct =>
            source.TryGetFirst(predicate);
        
        private static TSource? TryGetFirst<TSource>(this TSource[] source, Func<TSource, bool> predicate) where TSource : struct
        {
            for (var i = 0; i < source.Length; i++)
            {
                if (predicate(source[i]))
                {
                    return source[i];
                }
            }

            return null;
        }

        public static TSource FirstOrNullRef<TSource>(this IEnumerable<TSource> source, Func<TSource, bool> predicate) where TSource : class =>
            source.TryGetFirstClass(predicate);
        
        public static TSource? FirstOrNullStruct<TSource>(this IEnumerable<TSource> source, Func<TSource, bool> predicate) where TSource : struct =>
            source.TryGetFirstStruct(predicate);
        
        private static TSource? TryGetFirstStruct<TSource>(this IEnumerable<TSource> source, Func<TSource, bool> predicate) where TSource : struct
        {
            foreach (TSource obj in source)
            {
                if (predicate(obj))
                {
                    return obj;
                }
            }
            return null;
        }
        private static TSource TryGetFirstClass<TSource>(this IEnumerable<TSource> source, Func<TSource, bool> predicate) where TSource : class
        {
            foreach (TSource obj in source)
            {
                if (predicate(obj))
                {
                    return obj;
                }
            }
            return null;
        }
        
    }
    
}