using System;
using System.Collections.Generic;
using System.Linq;
using EventCubeMelt;
using UnityEngine;
using Random = UnityEngine.Random;

namespace EventCubeMelt.Utils
{
    public static class SlotsGenerator
    {
        // 已废弃
        public static List<int> GenerateSlots(int num,List<float> rates, List<int> data,List<int> rand)
        {
            var r = Random.value; // [0,1)
            // // 随机一次或者两层
            int count;
            //
            if (rates.Count < 2)
            {
                rates.Add(0.4f);
            }
            var r1 = rates[0];
            var r2 = rates[1];
            
            if (r < r1 )      count = 1;   // 5%
            else if (r < r2)  count = 2;   // 10%
            else              count = 0;   // 85%
            
            var list =  PickPositions(count,data,rand );
            ELog($"GenerateSlots -> {r} ,r1 = {r1} ,r2 = {r2}  count = {count} {string.Join(",",rand)} =>  {string.Join(",",list)}");
            return list;
        }
        public static List<int> GenerateSlots2(int num, List<float> rates, List<int> data, List<int> rand,List<int> collectIds)
        {
            
            if (collectIds is not { Count: > 0 } )
                return data;
            if (rand is not { Count: > 0 })
                return data;
            
            var ls = new List<int>();
            for (var i = 0; i < num; i++)
            {
                var index  = RandomSel(rates);
                if (index < 0 || index >= collectIds.Count)
                    continue;
                
                var value = collectIds[index];

                // var has = rand.Any(item => item.id == value) ;
                // ls.Add(has ? value : RandomRand(rand));
                
                var randIndex = Random.Range(0,rand.Count);
                ls.Add(rand.Contains(value) ? value : rand[randIndex]);
            }
            var list =  PickPositionVer2(data,ls );
            // ELog($"GenerateSlots2 -> {r} ,r1 = {r1} ,r2 = {r2}  count = {count} {string.Join(",",rand)} =>  {string.Join(",",list)}");
            return list;
        }

        // private static int RandomRand(List<(int id,int weight)> rand)
        // {
        //     // 计算总权重
        //     // 计算总权重
        //     int totalWeight = 0;
        //     foreach (var item in rand)
        //     {
        //         if (item.weight < 0)
        //             continue;
        //         totalWeight += item.weight;
        //     }
        //
        //     if (totalWeight == 0)
        //         return 101;
        //
        //     // 在 Unity 环境中生成随机数
        //     int r = Random.Range(0, totalWeight);
        //     // 遍历查找
        //     int cumWeight = 0;
        //     foreach (var item in rand)
        //     {
        //         cumWeight += item.weight;
        //         if (r < cumWeight)
        //         {
        //             return item.id;
        //         }
        //     }
        //
        //     return 101;
        //
        // }
        private static int RandomSel(List<float> probabilities)
        {
            var randomValue = Random.value;
            var cumulative = 0f;
            for (int i = 0; i < probabilities.Count; i++)
            {
                cumulative += probabilities[i];
                if (randomValue < cumulative)
                {
                    return i;
                }
            }
            return -1;
        }
        private static List<int> PickPositionVer2(List<int> data, List<int> rand)
        {
            var result = new List<int>(data);
            // 如果没有随机数，直接返回
            if (rand == null || rand.Count == 0) 
            {
                return result;
            }
            var count = rand.Count;
            
            // 收集非零位置
            var nonZeroPositions = new List<int>();
            for (var i = 0; i < data.Count; i++)
            {
                if (data[i] != 0)
                {
                    nonZeroPositions.Add(i);
                }
            }
            
            var actualCount = Math.Min(count, nonZeroPositions.Count);
            
            // 随机选择位置
            // Random random = new Random();
            var selectedPositions = new List<int>();

            // 部分洗牌：只洗需要选择的部分
            for (var i = 0; i < actualCount; i++)
            {
                var randomIndex = Random.Range(i, nonZeroPositions.Count);
                // 交换位置
                (nonZeroPositions[i], nonZeroPositions[randomIndex]) = (nonZeroPositions[randomIndex], nonZeroPositions[i]);
                selectedPositions.Add(nonZeroPositions[i]);
            }
            
            // 随机也洗牌
            rand.ShuffleInPlace();
            // 使用rand中的值替换
            for (var i = 0; i < selectedPositions.Count; i++)
            {
                var position = selectedPositions[i];
                var randIndex = i % rand.Count;  // 循环使用rand中的值
                result[position] = rand[randIndex];
            }

            return result;
        }
        private static List<int> PickPositions(int count ,List<int> data,List<int> rand)
        {
            
            // 如果没有随机数，直接返回
            if (rand == null || rand.Count == 0 || count == 0) 
            {
                // return result;
                return data;
            }
            var result = new List<int>(data);
            
            // 收集非零位置
            var nonZeroPositions = new List<int>();
            for (var i = 0; i < data.Count; i++)
            {
                if (data[i] != 0)
                {
                    nonZeroPositions.Add(i);
                }
            }
            
            var actualCount = Math.Min(count, nonZeroPositions.Count);
            
            // 随机选择位置
            // Random random = new Random();
            var selectedPositions = new List<int>();

            // 部分洗牌：只洗需要选择的部分
            for (var i = 0; i < actualCount; i++)
            {
                var randomIndex = Random.Range(i, nonZeroPositions.Count);
                // 交换位置
                (nonZeroPositions[i], nonZeroPositions[randomIndex]) = (nonZeroPositions[randomIndex], nonZeroPositions[i]);
                selectedPositions.Add(nonZeroPositions[i]);
            }
            
            // 随机也洗牌
            rand.ShuffleInPlace();
            // 使用rand中的值替换
            for (var i = 0; i < selectedPositions.Count; i++)
            {
                var position = selectedPositions[i];
                var randIndex = i % rand.Count;  // 循环使用rand中的值
                result[position] = rand[randIndex];
            }

            return result;
        }
        
        // 就地洗牌；O(n)，无偏。默认用 Random.Shared（.NET 6+）
        public static void ShuffleInPlace<T>(this IList<T> list)
        {
            if (list == null) 
                throw new ArgumentNullException(nameof(list));
            var n = list.Count;
            for (int i = n - 1; i > 0; i--)
            {
                int j = Random.Range(0, i + 1);
                if (j != i) 
                    (list[i], list[j]) = (list[j], list[i]); // 交换
            }
        }

        // 返回打乱后的副本（不修改原集合）
        public static List<T> Shuffled<T>(this IEnumerable<T> source)
        {
            if (source == null) 
                throw new ArgumentNullException(nameof(source));
            var list = new List<T>(source);
            list.ShuffleInPlace();
            return list;
        }
        
        #region LOG
        private static void ELog(string message)
        {
#if UNITY_EDITOR
            if (!EventCubeMeltLogPolicy.EnableELog) return;
            Debug.Log($"<color=orange> SlotsGenerator => {message} </color>");
#endif
        }
        #endregion
    }
}