using AgriculturalPlatform.Api.Data;
using Microsoft.EntityFrameworkCore;

namespace AgriculturalPlatform.Api.Services;

/// <summary>业务单号生成：前缀 + 日期 + 当日序号（如 CG20260812-0001）</summary>
public class NumberGenerator(AppDbContext db)
{
    public async Task<string> NextAsync(string prefix, DateOnly? date = null)
    {
        var day = date ?? DateOnly.FromDateTime(DateTime.Now);
        var seq = 1;
        try
        {
            // 从各单据表按当日已存在数量生成序号
            var todayStart = day.ToDateTime(TimeOnly.MinValue);
            var todayEnd = todayStart.AddDays(1);
            var count = prefix switch
            {
                "CG" => await db.PurchaseOrders.CountAsync(x => x.CreatedAt >= todayStart && x.CreatedAt < todayEnd),
                "ZF" => await db.PaymentRecords.CountAsync(x => x.CreatedAt >= todayStart && x.CreatedAt < todayEnd),
                "FP" => await db.Invoices.CountAsync(x => x.CreatedAt >= todayStart && x.CreatedAt < todayEnd),
                "PK" => await db.Invoices
                    .Where(x => x.CreatedAt >= todayStart && x.CreatedAt < todayEnd && x.BatchNo != "")
                    .Select(x => x.BatchNo).Distinct().CountAsync(),
                _ => 0
            };
            seq = count + 1;
        }
        catch
        {
            // 数据库不可用时使用随机序号
        }

        return $"{prefix}{day:yyyyMMdd}-{seq:D4}";
    }
}