#nullable enable
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;

namespace Masuit.Tools
{
    public static partial class IEnumerableExtensions
    {
        #region SyncForEach

        /// <summary>
        /// 遍历IEnumerable
        /// </summary>
        /// <param name="objs"></param>
        /// <param name="action">回调方法</param>
        /// <typeparam name="T"></typeparam>
        public static void ForEach<T>(this IEnumerable<T> objs, Action<T> action)
        {
            foreach (var o in objs)
            {
                action(o);
            }
        }

        #endregion SyncForEach

        #region AsyncForEach

        public static async Task ForeachAsync<T>(this IEnumerable<T> source, int maxParallelCount, Func<T, Task> action)
        {
            using SemaphoreSlim completeSemphoreSlim = new(1);
            using SemaphoreSlim taskCountLimitsemaphoreSlim = new(maxParallelCount);
            await completeSemphoreSlim.WaitAsync();
            int runningtaskCount = source.Count();

            foreach (var item in source)
            {
                await taskCountLimitsemaphoreSlim.WaitAsync();
                Task.Run(async () =>
                {
                    try
                    {
                        await action(item).ContinueWith(task =>
                        {
                            Interlocked.Decrement(ref runningtaskCount);
                            if (runningtaskCount == 0)
                            {
                                completeSemphoreSlim.Release();
                            }
                        });
                    }
                    finally
                    {
                        taskCountLimitsemaphoreSlim.Release();
                    }
                });
            }

            await completeSemphoreSlim.WaitAsync();
        }
        public static async Task ForeachAsync<T>(this IEnumerable<T> source, Func<T, Task> action)
        {
            await ForeachAsync(source, source.Count(), action);
        }
        #endregion AsyncForEach

        /// <summary>
        /// 按字段去重
        /// </summary>
        /// <typeparam name="TSource"></typeparam>
        /// <typeparam name="TKey"></typeparam>
        /// <param name="source"></param>
        /// <param name="keySelector"></param>
        /// <returns></returns>
        public static IEnumerable<TSource> DistinctBy<TSource, TKey>(this IEnumerable<TSource> source, Func<TSource, TKey> keySelector)
        {
            var hash = new HashSet<TKey>();
            return source.Where(p => hash.Add(keySelector(p)));
        }

        /// <summary>
        /// 添加多个元素
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="this"></param>
        /// <param name="values"></param>
        public static void AddRange<T>(this ICollection<T> @this, params T[] values)
        {
            foreach (var obj in values)
            {
                @this.Add(obj);
            }
        }

        /// <summary>
        /// 添加符合条件的多个元素
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="this"></param>
        /// <param name="predicate"></param>
        /// <param name="values"></param>
        public static void AddRangeIf<T>(this ICollection<T> @this, Func<T, bool> predicate, params T[] values)
        {
            foreach (var obj in values)
            {
                if (predicate(obj))
                {
                    @this.Add(obj);
                }
            }
        }

        /// <summary>
        /// 添加不重复的元素
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="this"></param>
        /// <param name="values"></param>
        public static void AddRangeIfNotContains<T>(this ICollection<T> @this, params T[] values)
        {
            foreach (T obj in values)
            {
                if (!@this.Contains(obj))
                {
                    @this.Add(obj);
                }
            }
        }

        /// <summary>
        /// 移除符合条件的元素
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="this"></param>
        /// <param name="where"></param>
        public static void RemoveWhere<T>(this ICollection<T> @this, Func<T, bool> @where)
        {
            foreach (var obj in @this.Where(where).ToList())
            {
                @this.Remove(obj);
            }
        }

        /// <summary>
        /// 在元素之后添加元素
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="list"></param>
        /// <param name="condition">条件</param>
        /// <param name="value">值</param>
        public static void InsertAfter<T>(this IList<T> list, Func<T, bool> condition, T value)
        {
            foreach (var item in list.Select((item, index) => new { item, index }).Where(p => condition(p.item)).OrderByDescending(p => p.index))
            {
                if (item.index + 1 == list.Count)
                {
                    list.Add(value);
                }
                else
                {
                    list.Insert(item.index + 1, value);
                }
            }
        }

        /// <summary>
        /// 在元素之后添加元素
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="list"></param>
        /// <param name="index">索引位置</param>
        /// <param name="value">值</param>
        public static void InsertAfter<T>(this IList<T> list, int index, T value)
        {
            foreach (var item in list.Select((v, i) => new { Value = v, Index = i }).Where(p => p.Index == index).OrderByDescending(p => p.Index))
            {
                if (item.Index + 1 == list.Count)
                {
                    list.Add(value);
                }
                else
                {
                    list.Insert(item.Index + 1, value);
                }
            }
        }

        /// <summary>
        /// 转HashSet
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <typeparam name="TResult"></typeparam>
        /// <param name="source"></param>
        /// <param name="selector"></param>
        /// <returns></returns>
        public static HashSet<TResult> ToHashSet<T, TResult>(this IEnumerable<T> source, Func<T, TResult> selector)
        {
            var set = new HashSet<TResult>();
            set.UnionWith(source.Select(selector));
            return set;
        }

        /// <summary>
        /// 异步Select
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <typeparam name="TResult"></typeparam>
        /// <param name="source"></param>
        /// <param name="selector"></param>
        /// <returns></returns>
        public static async Task<IEnumerable<TResult>> SelectAsync<T, TResult>(this IEnumerable<T> source, Func<T, Task<TResult>> selector)
        {
            return await Task.WhenAll(source.Select(selector));
        }
    }
}