using System;
using System.Collections.Generic;

[Serializable]
/// <summary>
/// 纯整数红包记录
/// 金额单位：分 (int)
/// </summary>
public class RedPacketRecord
{
    public int Phase { get; set; }          // 阶段：1 或 2
    public int Index { get; set; }          // 第几个包
    public long Amount { get; set; }         // 金额（单位：分，纯整数）

    // 方便调试看日志的格式化方法
    public string GetMoneyString()
    {
        return (Amount / 100) + "." + (Amount % 100).ToString("D2");
    }
}

/// <summary>
/// 纯整数版级联红包算法（支持动态裂变个数）
/// </summary>
public class CascadeRedPacketInt
{
    private Random _random;
    private const int MIN_AMOUNT = 1; // 最小 1 分钱

    // --- 第一阶段配置 ---
    private int _phase1TotalAmount; // 总金额（分）
    private int _phase1Count;       // 第一阶段总人数
    private int _phase1Grabbed = 0; // 已抢人数

    public CascadeRedPacketInt(int totalMoneyCents, int phase1Count, int? seed = null)
    {
        _random = seed.HasValue ? new Random(seed.Value) : new Random();
        _phase1TotalAmount = totalMoneyCents;
        _phase1Count = phase1Count;
    }

    /// <summary>
    /// 核心方法：执行一次完整的“抢大包 -> 拆小包”
    /// </summary>
    /// <param name="subCount">【动态参数】第二轮要裂变出的红包个数</param>
    /// <returns>该用户最终获得的一堆小红包列表</returns>
    public List<RedPacketRecord> GrabFullCycle(int subCount)
    {
        // 1. 第一阶段：从大奖池抢一个金额
        int phase1Amount = GrabPhase1();

        if (phase1Amount <= 0) return null;

        // 2. 第二阶段：把这个金额拆分成 subCount 个小包
        return SplitPhase2(phase1Amount, subCount);
    }

    /// <summary>
    /// 第一阶段逻辑（不变）
    /// </summary>
    private int GrabPhase1()
    {
        if (_phase1Grabbed >= _phase1Count) return -1;

        int amount;
        int remainingCount = _phase1Count - _phase1Grabbed;

        if (_phase1Grabbed == _phase1Count - 1)
        {
            amount = _phase1TotalAmount;
        }
        else
        {
            int avg = _phase1TotalAmount / remainingCount;
            int max = avg * 2;
            int safeMax = _phase1TotalAmount - (remainingCount * MIN_AMOUNT);

            if (max > safeMax) max = safeMax;
            if (max < MIN_AMOUNT) max = MIN_AMOUNT;

            amount = _random.Next(MIN_AMOUNT, max + 1);
        }

        _phase1TotalAmount -= amount;
        _phase1Grabbed++;
        return amount;
    }

    /// <summary>
    /// 第二阶段逻辑（修改点：接收动态个数）
    /// </summary>
    /// <param name="seedAmount">种子金额（第一阶段抢到的钱）</param>
    /// <param name="subCount">要拆分的个数</param>
    private List<RedPacketRecord> SplitPhase2(int seedAmount, int subCount)
    {
        List<RedPacketRecord> subPackets = new List<RedPacketRecord>();
        int remainingAmount = seedAmount;

        // 如果要求的个数小于等于0，直接把钱全给用户（或者你可以选择报错）
        if (subCount <= 0)
        {
            subPackets.Add(new RedPacketRecord { Phase = 2, Index = 1, Amount = seedAmount });
            return subPackets;
        }

        for (int i = 1; i <= subCount; i++)
        {
            int amount;
            int remainingCount = subCount - i;

            if (remainingCount == 0)
            {
                // 最后一个包，兜底拿走所有剩余
                amount = remainingAmount;
            }
            else
            {
                // 二倍均值法
                int avg = remainingAmount / remainingCount;
                int max = avg * 2;

                // 边界保护
                int safeMax = remainingAmount - (remainingCount * MIN_AMOUNT);
                if (max > safeMax) max = safeMax;
                if (max < MIN_AMOUNT) max = MIN_AMOUNT;

                amount = _random.Next(MIN_AMOUNT, max + 1);
            }

            remainingAmount -= amount;
            subPackets.Add(new RedPacketRecord { Phase = 2, Index = i, Amount = amount });
        }

        return subPackets;
    }

    public bool HasNext()
    {
        return _phase1Grabbed < _phase1Count;
    }
}