using Masuit.Tools.RandomSelector;
using System;
using System.Collections.Generic;
using System.Linq;

namespace Masuit.Tools
{
    public static partial class Extensions
    {
        public static int TotalWeight<T>(this WeightedSelector<T> selector)
        {
            return selector.Items.Count == 0 ? 0 : selector.Items.Sum(t => t.Weight);
        }

        public static List<WeightedItem<T>> OrderByWeightDescending<T>(this WeightedSelector<T> selector)
        {
            return selector.Items.OrderByDescending(item => item.Weight).ToList();
        }

        public static List<WeightedItem<T>> OrderByWeightAscending<T>(this WeightedSelector<T> selector)
        {
            return selector.Items.OrderBy(item => item.Weight).ToList();
        }

        public static T WeightedItem<T>(this IEnumerable<WeightedItem<T>> list)
        {
            return new WeightedSelector<T>(list).Select();
        }

        public static IEnumerable<T> WeightedItems<T>(this IEnumerable<WeightedItem<T>> list, int count)
        {
            return new WeightedSelector<T>(list).SelectMultiple(count);
        }

        /// <summary>
        /// 执行权重筛选，取多个元素
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="source">原始数据</param>
        /// <param name="count">目标个数</param>
        /// <param name="keySelector">按哪个属性进行权重筛选</param>
        /// <param name="option">抽取选项</param>
        /// <returns></returns>
        public static IEnumerable<T> WeightedItems<T>(this IEnumerable<T> source, int count, Func<T, int> keySelector, SelectorOption option = null)
        {
            var items = source as IList<T> ?? source.ToList();
            if (!items.Any())
            {
                return items;
            }

            var selector = new WeightedSelector<T>(items.Select(t => new WeightedItem<T>(t, keySelector(t))), option);
            return selector.SelectMultiple(count);
        }

        /// <summary>
        /// 执行权重筛选，取1个元素
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="source">原始数据</param>
        /// <param name="keySelector">按哪个属性进行权重筛选</param>
        /// <param name="option">抽取选项</param>
        /// <returns></returns>
        public static T WeightedBy<T>(this IEnumerable<T> source, Func<T, int> keySelector, SelectorOption option = null)
        {
            var selector = new WeightedSelector<T>(source.Select(t => new WeightedItem<T>(t, keySelector(t))), option);
            return selector.Select();
        }
    }
}