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

namespace AspClassic.Scripting.Utils;

internal static class CollectionExtensions
{
	internal static ReadOnlyCollection<T> ToReadOnly<T>(this IEnumerable<T> enumerable)
	{
		if (enumerable == null)
		{
			return EmptyReadOnlyCollection<T>.Instance;
		}
		if (enumerable is ReadOnlyCollection<T> result)
		{
			return result;
		}
		if (enumerable is ICollection<T> collection)
		{
			int count = collection.Count;
			if (count == 0)
			{
				return EmptyReadOnlyCollection<T>.Instance;
			}
			T[] array = new T[count];
			collection.CopyTo(array, 0);
			return new ReadOnlyCollection<T>(array);
		}
		return new ReadOnlyCollection<T>(new List<T>(enumerable).ToArray());
	}

	internal static T[] ToArray<T>(this IEnumerable<T> enumerable)
	{
		if (enumerable is ICollection<T> collection)
		{
			T[] array = new T[collection.Count];
			collection.CopyTo(array, 0);
			return array;
		}
		return new List<T>(enumerable).ToArray();
	}

	internal static bool Any<T>(this IEnumerable<T> source, Func<T, bool> predicate)
	{
		foreach (T item in source)
		{
			if (predicate(item))
			{
				return true;
			}
		}
		return false;
	}

	internal static TSource Aggregate<TSource>(this IEnumerable<TSource> source, Func<TSource, TSource, TSource> func)
	{
		using IEnumerator<TSource> enumerator = source.GetEnumerator();
		if (!enumerator.MoveNext())
		{
			throw new ArgumentException("Collection is empty", "source");
		}
		TSource val = enumerator.Current;
		while (enumerator.MoveNext())
		{
			val = func(val, enumerator.Current);
		}
		return val;
	}

	internal static T[] AddFirst<T>(this IList<T> list, T item)
	{
		T[] array = new T[list.Count + 1];
		array[0] = item;
		list.CopyTo(array, 1);
		return array;
	}

	internal static bool TrueForAll<T>(this IEnumerable<T> collection, Predicate<T> predicate)
	{
		ContractUtils.RequiresNotNull(collection, "collection");
		ContractUtils.RequiresNotNull(predicate, "predicate");
		foreach (T item in collection)
		{
			if (!predicate(item))
			{
				return false;
			}
		}
		return true;
	}
}