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

namespace Ips.Library.Basic
{
    public static class CollectionExtensions
    {
        public static void AddIf<T>(this ICollection<T> source, bool predicate, T item)
        {
            if (predicate) source.Add(item);
        }

        public static bool AddIfNotContains<T>(this ICollection<T> source, T item)
        {
            if (source.Contains(item))
            {
                return false;
            }

            source.Add(item);
            return true;
        }

        public static IEnumerable<T> AddIfNotContains<T>(this ICollection<T> source, IEnumerable<T> items)
        {
            var addedItems = new List<T>();

            foreach (var item in items)
            {
                if (source.Contains(item))
                {
                    continue;
                }

                source.Add(item);
                addedItems.Add(item);
            }

            return addedItems;
        }

        public static bool AddIfNotContains<T>(this ICollection<T> source, Func<T, bool> predicate, Func<T> itemFactory)
        {
            if (source.Any(predicate))
            {
                return false;
            }

            source.Add(itemFactory());
            return true;
        }

        public static IList<T> RemoveAll<T>(this ICollection<T> source, Func<T, bool> predicate)
        {
            var items = source.Where(predicate).ToList();

            foreach (var item in items)
            {
                source.Remove(item);
            }

            return items;
        }

        public static void RemoveAll<T>(this ICollection<T> source, IEnumerable<T> items)
        {
            foreach (var item in items)
            {
                source.Remove(item);
            }
        }
    }
}