价格机制

public float CalculateRealMarketPrice(int itemId, int quality)
{
    // 1. 获取基础数据
    ItemBaseData item = GetItemData(itemId);
    
    // 2. 获取各系数
    float Q = GetQualityCoefficient(quality);           // 品质系数
    float S = GetSupplyDemandIndex(itemId);             // 供需指数
    float T = GetTimeCoefficient(item.time_phase);      // 时段系数
    float E = GetEventCoefficient(itemId);              // 事件系数
    float xi = Random.Range(0.95f, 1.05f);             // 随机波动
    
    // 3. 计算真实市场价格
    float realPrice = item.base_value * Q * S * T * E * xi;
    
    return realPrice;
}

public float CalculateSupplyDemandIndex(int itemId)
{
    ItemBaseData item = GetItemData(itemId);
    MarketData market = GetMarketData(itemId);
    
    // 获取当前供需数据
    int demand = market.current_demand;
    int supply = market.current_supply;
    int baseVolume = item.base_trade_volume;
    float k = item.price_sensitivity;
    
    // 计算供需差值比例
    float diffRatio = (float)(demand - supply) / baseVolume * k;
    
    // 使用双曲正切函数限制范围
    float tanhValue = (float)Math.Tanh(diffRatio);
    
    // 计算最终供需指数
    float S = 1.0f + tanhValue;
    
    // 限制范围 [0.5, 2.0]
    return Mathf.Clamp(S, 0.5f, 2.0f);
}

public float CalculateBuyProbability(int itemId, float playerPrice, 
    int stallId, int npcId)
{
    ItemBaseData item = GetItemData(itemId);
    StallData stall = GetStallData(stallId);
    NPCData npc = GetNPCData(npcId);
    
    // 1. 计算真实市场价格
    float marketPrice = CalculateRealMarketPrice(itemId, item.quality_tier);
    
    // 2. 计算价格偏离度
    float deviation = (playerPrice - marketPrice) / marketPrice;
    
    // 3. 计算基础成交概率（使用Sigmoid函数）
    float lambda = 2.0f;  // 价格敏感度参数
    float sigmoid = 1.0f / (1.0f + Mathf.Exp(-(-deviation * lambda)));
    
    // 4. 应用摊位系数
    float L = GetPositionCoefficient(stall.position_level);      // 位置系数
    float D = CalculateDecorationBonus(stall.decoration_list, stall.title_id);  // 装饰总加成
    float T_slot = GetTimeSlotMatch(itemId);                      // 时段匹配
    float R = Random.Range(0.9f, 1.1f);                          // 随机因子
    
    // 5. 计算最终成交概率
    float maxProb = item.max_buy_probability;
    float probability = maxProb * sigmoid * L * D * T_slot * R;
    
    // 6. 限制范围 [0, 1]
    return Mathf.Clamp(probability, 0.0f, 1.0f);
}

public float CalculateDecorationBonus(int[] decorationList, int titleId)
{
    float totalBonus = 1.0f;
    
    // 1. 计算所有已购买装饰的加成
    foreach (int decoId in decorationList)
    {
        DecorationData deco = GetDecorationData(decoId);
        totalBonus += deco.trade_rate_bonus;  // 累加成交率加成
    }
    
    // 2. 加上当前称号的加成
    TitleData title = GetTitleData(titleId);
    totalBonus += title.trade_rate_bonus;
    
    // 3. 限制最大加成（防止过度膨胀）
    return Mathf.Min(totalBonus, 2.0f);  // 最高2倍加成
}

// 装饰数据结构
public class DecorationData
{
    public int id;
    public string name;
    public float trade_rate_bonus;      // 成交率加成（如0.01表示+1%）
    public float offline_income_bonus;  // 离线收益加成
    public float tax_reduction;         // 税费减免
    public int unlock_title_id;         // 解锁所需称号ID
    public int price;                   // 价格
}

public BargainOffer GenerateBargainOffer(int npcId, int saleItemId, float playerPrice)
{
    SaleItemData saleItem = GetSaleItemData(saleItemId);
    NPCData npc = GetNPCData(npcId);
    
    // 1. 计算真实市场价格
    float marketPrice = CalculateRealMarketPrice(
        saleItem.item_id, 
        saleItem.quality
    );
    
    // 2. 检查是否触发议价条件
    float deviation = (playerPrice - marketPrice) / marketPrice;
    if (deviation <= 0.15f)  // 偏离度小于15%不触发
        return null;
    
    // 3. 根据NPC性格计算议价价格
    float personalityFactor = GetNPCPersonalityFactor(npc.personality_type);
    float bargainPrice = marketPrice * personalityFactor;
    
    // 4. 生成议价信息
    BargainOffer offer = new BargainOffer
    {
        npc_id = npcId,
        npc_name = npc.name,
        sale_item_id = saleItemId,
        offer_price = (int)bargainPrice,
        message = GenerateBargainMessage(npc, saleItem, bargainPrice),
        expire_time = DateTime.Now.AddMinutes(30),
        status = OfferStatus.Pending
    };
    
    return offer;
}