campus-errand/server/Helpers/BusinessHelpers.cs

using CampusErrand.Data;
using CampusErrand.Models;
using CampusErrand.Models.Dtos;
using Microsoft.EntityFrameworkCore;

namespace CampusErrand.Helpers;

/// <summary>
/// 业务辅助方法集合
/// </summary>
public static class BusinessHelpers
{
    /// <summary>
    /// Banner 请求校验
    /// </summary>
    internal static List<object> ValidateBannerRequest(BannerRequest request)
    {
        var errors = new List<object>();
        if (string.IsNullOrWhiteSpace(request.ImageUrl))
            errors.Add(new { field = "imageUrl", message = "图片地址不能为空" });
        if (string.IsNullOrWhiteSpace(request.LinkUrl))
            errors.Add(new { field = "linkUrl", message = "链接地址不能为空" });
        if (string.IsNullOrWhiteSpace(request.LinkType))
            errors.Add(new { field = "linkType", message = "链接类型不能为空" });
        else if (!Enum.TryParse<LinkType>(request.LinkType, true, out var parsed) || !Enum.IsDefined(parsed))
            errors.Add(new { field = "linkType", message = "链接类型不合法" });
        return errors;
    }

    /// <summary>
    /// 门店请求校验
    /// </summary>
    internal static List<object> ValidateShopRequest(ShopRequest request)
    {
        var errors = new List<object>();
        if (string.IsNullOrWhiteSpace(request.Name))
            errors.Add(new { field = "name", message = "门店名称不能为空" });
        if (string.IsNullOrWhiteSpace(request.Photo))
            errors.Add(new { field = "photo", message = "门店照片不能为空" });
        if (string.IsNullOrWhiteSpace(request.Location))
            errors.Add(new { field = "location", message = "门店位置不能为空" });
        if (string.IsNullOrWhiteSpace(request.PackingFeeType))
            errors.Add(new { field = "packingFeeType", message = "打包费类型不能为空" });
        if (request.PackingFeeAmount < 0)
            errors.Add(new { field = "packingFeeAmount", message = "打包费金额不能为负数" });
        return errors;
    }

    /// <summary>
    /// 菜品请求校验
    /// </summary>
    internal static List<object> ValidateDishRequest(DishRequest request)
    {
        var errors = new List<object>();
        if (string.IsNullOrWhiteSpace(request.Name))
            errors.Add(new { field = "name", message = "菜品名称不能为空" });
        if (string.IsNullOrWhiteSpace(request.Photo))
            errors.Add(new { field = "photo", message = "菜品照片不能为空" });
        if (request.Price < 0)
            errors.Add(new { field = "price", message = "菜品价格不能为负数" });
        return errors;
    }

    /// <summary>
    /// 计算单个门店的打包费
    /// Fixed 模式：固定金额，不论菜品数量
    /// PerItem 模式：菜品总份数 × 单份打包费
    /// </summary>
    internal static decimal CalculatePackingFee(PackingFeeType feeType, decimal feeAmount, int totalQuantity)
    {
        return feeType switch
        {
            PackingFeeType.Fixed => feeAmount,
            PackingFeeType.PerItem => feeAmount * totalQuantity,
            _ => 0m
        };
    }

    /// <summary>
    /// 计算平台佣金分成
    /// 根据佣金区间规则计算：百分比类型按比例，固定类型扣除固定金额
    /// </summary>
    internal static decimal CalculatePlatformFee(decimal commission, List<CommissionRule> rules)
    {
        // 查找匹配的佣金区间
        var matchedRule = rules
            .Where(r => commission >= r.MinAmount && (r.MaxAmount == null || commission <= r.MaxAmount))
            .FirstOrDefault();

        if (matchedRule == null) return 0m;

        return matchedRule.RateType switch
        {
            CommissionRateType.Percentage => Math.Round(commission * matchedRule.Rate / 100m, 2),
            CommissionRateType.Fixed => Math.Min(matchedRule.Rate, commission),
            _ => 0m
        };
    }

    /// <summary>
    /// 获取用户可见的系统消息（按目标类型过滤）
    /// </summary>
    internal static async Task<List<SystemMessage>> GetVisibleSystemMessages(AppDbContext db, int userId, User? user)
    {
        var allMessages = await db.SystemMessages.ToListAsync();
        return allMessages.Where(m =>
        {
            if (m.TargetType == MessageTargetType.All) return true;
            if (m.TargetType == MessageTargetType.OrderUser)
                return user != null && user.Role != UserRole.Runner;
            if (m.TargetType == MessageTargetType.RunnerUser)
                return user != null && (user.Role == UserRole.Runner || user.Role == UserRole.Admin);
            if (m.TargetType == MessageTargetType.Specific && m.TargetUserIds != null)
            {
                try
                {
                    var ids = System.Text.Json.JsonSerializer.Deserialize<List<int>>(m.TargetUserIds);
                    return ids != null && ids.Contains(userId);
                }
                catch { return false; }
            }
            return false;
        }).ToList();
    }

    /// <summary>
    /// 解冻已到期的收益记录：将冻结期满的收益从 Frozen 变为 Available
    /// </summary>
    internal static async Task UnfreezeEarnings(AppDbContext db)
    {
        var now = DateTime.UtcNow;
        var frozenEarnings = await db.Earnings
            .Where(e => e.Status == EarningStatus.Frozen && e.FrozenUntil <= now)
            .ToListAsync();

        foreach (var earning in frozenEarnings)
        {
            earning.Status = EarningStatus.Available;
        }

        if (frozenEarnings.Count > 0)
        {
            await db.SaveChangesAsync();
        }
    }

    /// <summary>
    /// 自动确认超过24小时未处理的待确认订单
    /// </summary>
    internal static async Task AutoConfirmExpiredOrders(AppDbContext db)
    {
        var cutoff = DateTime.UtcNow.AddHours(-24);
        var expiredOrders = await db.Orders
            .Where(o => o.Status == OrderStatus.WaitConfirm && o.CompletedAt != null && o.CompletedAt <= cutoff)
            .ToListAsync();

        foreach (var order in expiredOrders)
        {
            order.Status = OrderStatus.Completed;

            // 计算佣金收益（商品金额平台不抽成，全额给跑腿）
            var rules = await db.CommissionRules.OrderBy(r => r.MinAmount).ToListAsync();
            var platformFee = CalculatePlatformFee(order.Commission, rules);
            var netEarning = order.Commission - platformFee + (order.GoodsAmount ?? 0);

            var freezeDaysConfig = await db.SystemConfigs.FirstOrDefaultAsync(c => c.Key == "freeze_days");
            var freezeDays = 1;
            if (freezeDaysConfig != null && int.TryParse(freezeDaysConfig.Value, out var configDays))
                freezeDays = configDays;

            db.Earnings.Add(new Earning
            {
                UserId = order.RunnerId!.Value,
                OrderId = order.Id,
                GoodsAmount = order.GoodsAmount,
                Commission = order.Commission,
                PlatformFee = platformFee,
                NetEarning = netEarning,
                Status = EarningStatus.Frozen,
                FrozenUntil = DateTime.UtcNow.AddDays(freezeDays),
                CreatedAt = DateTime.UtcNow
            });
        }

        if (expiredOrders.Count > 0)
        {
            await db.SaveChangesAsync();
            Console.WriteLine($"[定时任务] 自动确认了 {expiredOrders.Count} 个超时订单");
        }
    }

    /// <summary>
    /// 生成唯一的随机6位数字UID
    /// </summary>
    internal static async Task<string> GenerateUniqueUid(AppDbContext db)
    {
        for (var i = 0; i < 100; i++)
        {
            var uid = Random.Shared.Next(100000, 999999).ToString();
            var exists = await db.Users.AnyAsync(u => u.Uid == uid);
            if (!exists) return uid;
        }
        // 极端情况：用7位
        return Random.Shared.Next(1000000, 9999999).ToString();
    }
}