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

using System;
using System.Collections.Generic;
using System.Linq;

namespace Decentralized.Domain
{
    /// <summary>二手显卡贩子的类型：老实人按真实价卖；中间商加价；骗子夹带假卡，按标称型号的价卖。</summary>
    public enum DealerKind { Honest, Middleman, Scammer }

    /// <summary>贩子带来的一张卡。老实人不报价（按真实价值卖）；其他贩子 <see cref="Quoted"/> 为真，按 <see cref="CardValue.Quote"/> 报价，
    /// <see cref="MarkupPct"/> 是加价百分比，玩家指出外观问题或假货迹象就按维度扣回去。</summary>
    public sealed class UsedCard
    {
        public string Model;
        public string FakeOf;
        public double Health;
        public int MarkupPct;
        public bool Quoted;
    }

    public static class UsedDealers
    {
        public const double MiddlemanMarkup = 0.08, ScamDiscount = CardValue.ScamDiscount;
        public const double FakeShareMiddleman = 0.10, FakeShareScammer = 0.45;

        /// <summary>今天来的贩子的类型：骗子越往后越多。</summary>
        public static DealerKind Kind(int day, Rng rng)
        {
            double scam = Math.Min(0.30, 0.10 + day * 0.004);
            double r = rng.NextDouble();
            return r < scam ? DealerKind.Scammer : r < scam + 0.30 ? DealerKind.Middleman : DealerKind.Honest;
        }

        /// <summary>能出现在二手市场上的型号：按天数放开，旗舰第 30 天起。</summary>
        public static string[] Pool(int day)
        {
            var list = new List<string>(Dealer.Basic);
            if (day >= Dealer.AdvancedFromDay) list.AddRange(Dealer.Advanced);
            if (day >= Dealer.FlagshipFromDay) list.AddRange(Dealer.Flagship);
            return list.ToArray();
        }

        public static List<UsedCard> Cards(DealerKind kind, int day, Rng rng)
        {
            var pool = Pool(day);
            int count = rng.Range(3, 5);
            var cards = new List<UsedCard>();
            for (int i = 0; i < count; i++)
            {
                double share = kind == DealerKind.Scammer ? FakeShareScammer : kind == DealerKind.Middleman ? FakeShareMiddleman : 0;
                var label = pool[rng.Range(0, pool.Length - 1)];
                var card = new UsedCard { Model = label, Health = 25 + rng.NextDouble() * 60 };
                var cheaper = Hardware.Specs.Values.Where(s => !s.Asic && s.Price * 2 <= Hardware.Specs[label].Price).Select(s => s.Model).ToArray();
                if (cheaper.Length > 0 && rng.Chance(share)) card.FakeOf = cheaper[rng.Range(0, cheaper.Length - 1)];
                card.Quoted = kind != DealerKind.Honest;
                card.MarkupPct = kind == DealerKind.Middleman ? (int)Math.Round(MiddlemanMarkup * 100) : 0;
                cards.Add(card);
            }
            return cards;
        }
    }
}