probably-decentralized/src/Decentralized.Domain/Stablecoins.cs

using System;
using System.Collections.Generic;

namespace Decentralized.Domain
{
    /// <summary>
    /// 三种稳定币的价格与状态：CRC（上层，托管银行出事时脱锚、可能减记），CRT（黑市，镇压或火并时脱锚，
    /// 镇压期间按黑市声望出卖客户），CRA（革命军，质押付息，补贴池告急或外生触发时进入三天死亡螺旋）。
    /// </summary>
    public sealed class Stablecoins
    {
        public double Crc = 1, Crt = 1, Cra = 1;
        public int CrcDepegEnd = -1, CrtDepegEnd = -1;
        public bool CrcHaircutPending;
        public double CraSubsidy = Tuning.CraSubsidy0;
        public int CraWarnDay = -1, CraSpiralDay = -1;
        public double RevPower = 50;
        public List<double> RevHistory = new List<double>();

        public double Price(string asset)
        {
            switch (asset)
            {
                case Assets.CRC: return Crc;
                case Assets.CRT: return Crt;
                case Assets.CRA: return Cra;
                default: return 1;
            }
        }

        /// <summary>减记发生时返回 CRC 持有量要乘的系数（其余情况为 1）。</summary>
        public double OnEventStart(MarketEvent ev, int day, Rng rng)
        {
            if (ev == MarketEvent.RevRaidUpper && CrcDepegEnd < 0 && rng.Chance(Tuning.CrcDepegChance))
            {
                Crc = rng.Range(Tuning.CrcDepegMin, Tuning.CrcDepegMax);
                CrcDepegEnd = day + rng.Range(Tuning.CrcDepegDaysMin, Tuning.CrcDepegDaysMax);
                CrcHaircutPending = rng.Chance(Tuning.CrcHaircutChance);
            }
            if ((ev == MarketEvent.GangWar || ev == MarketEvent.Crackdown) && CrtDepegEnd < 0 && rng.Chance(Tuning.CrtDepegChance))
            {
                Crt = rng.Range(Tuning.CrtDepegMin, Tuning.CrtDepegMax);
                CrtDepegEnd = day + rng.Range(Tuning.CrtDepegDaysMin, Tuning.CrtDepegDaysMax);
            }
            return 1;
        }

        /// <summary>镇压开始时，玩家持有的 CRT 被冻结一半的概率：黑市声望 0 时 40%，50 以上为 0。</summary>
        public static double CrtFreezeChance(double blackMarketRep) =>
            Math.Max(0, Tuning.CrtFreezeBase - blackMarketRep * Tuning.CrtFreezePerRep);

        public bool CraSubsidyLow => CraSubsidy <= Tuning.CraSubsidy0 * Tuning.CraSubsidyWarn;

        /// <summary>CRA 的预兆：外生螺旋的新闻已出，或补贴池告急（利率下调）。螺旋开始后不再算预兆。</summary>
        public bool CraWarning(int day) => (CraWarnDay >= 0 && CraWarnDay <= day || CraSubsidyLow) && Cra >= 0.97;

        public double CraRate => CraSubsidyLow ? Tuning.CraRateLow : Tuning.CraRate;

        /// <summary>
        /// 夜间结算。返回 CRC 持有量要乘的系数（减记兑现时为 0.95，否则为 1）。
        /// playerStaked：玩家的 CRA 质押额，用来算补贴支出（玩家的利息由调用方按 <see cref="CraRate"/> 发放）。
        /// </summary>
        public double Night(int day, Rng rng, double playerStaked)
        {
            double crcFactor = 1;
            if (CrcDepegEnd == day)
            {
                Crc = 1;
                if (CrcHaircutPending) crcFactor = Tuning.CrcHaircut;
                CrcDepegEnd = -1;
                CrcHaircutPending = false;
            }
            if (CrtDepegEnd == day)
            {
                Crt = 1;
                CrtDepegEnd = -1;
            }
            RevHistory.Add(RevPower);
            if (RevHistory.Count > 7) RevHistory.RemoveAt(0);
            RevPower = Math.Max(0, Math.Min(100, RevPower + rng.Gauss() * 3));

            if (CraSpiralDay < 0)
            {
                CraSubsidy -= (Tuning.CraNpcStake + playerStaked) * CraRate;
                bool revFalling = RevHistory.Count == 7 && RevPower < RevHistory[0] - 5;
                double weekly = Tuning.CraSpiralWeekly * (revFalling ? 3 : 1);
                double daily = 1 - Math.Pow(1 - weekly, 1.0 / 7);
                if (CraWarnDay < 0 && (rng.Chance(daily) || CraSubsidy <= 0))
                {
                    CraWarnDay = day;
                    CraSpiralDay = day + rng.Range(Tuning.CraWarnLeadMin, Tuning.CraWarnLeadMax);
                }
            }
            if (CraSpiralDay > 0 && day >= CraSpiralDay)
                Cra = Tuning.CraSpiralPath[Math.Min(day - CraSpiralDay, Tuning.CraSpiralPath.Length - 1)];
            return crcFactor;
        }
    }
}