namespace Admin.NET.Plugin.AiDOP.Supply;

/// <summary>
/// 采购申请合并服务。P3 阶段仅合并本次生成且尚未入库的 PR 候选，不改动历史 PR。
/// </summary>
public class PurchaseRequestMergeService : ITransient
{
    public PurchaseRequestMergeResult MergeGeneratedRequests(List<PurchaseRequestMain> requests)
    {
        if (requests.Count <= 1)
        {
            return new PurchaseRequestMergeResult
            {
                Requests = requests,
                OriginalCount = requests.Count,
                MergedCount = requests.Count
            };
        }

        var merged = requests
            .GroupBy(x => new
            {
                x.TenantId,
                x.CompanyId,
                x.FactoryId,
                x.IcitemId,
                x.PrPurchaseId,
                x.IsRequireGoods,
                SupplierType = x.SupplierType ?? string.Empty,
                WeekStart = GetWeekStart(x.PrSsendDate)
            })
            .Select(group =>
            {
                var rows = group.OrderBy(x => x.PrSsendDate).ThenBy(x => x.PrSarriveDate).ThenBy(x => x.Id).ToList();
                var first = rows.First();
                first.PrRqty = rows.Sum(x => x.PrRqty ?? 0);
                first.PrAqty = rows.Sum(x => x.PrAqty ?? 0);
                first.PrSqty = rows.Sum(x => x.PrSqty ?? 0);
                first.PrSsendDate = rows.Min(x => x.PrSsendDate);
                first.PrSarriveDate = rows.Min(x => x.PrSarriveDate);
                first.CreateTime = rows.Min(x => x.CreateTime);
                first.UpdateTime = DateTime.Now;
                return first;
            })
            .ToList();

        return new PurchaseRequestMergeResult
        {
            Requests = merged,
            OriginalCount = requests.Count,
            MergedCount = merged.Count
        };
    }

    private static DateTime? GetWeekStart(DateTime? value)
    {
        if (!value.HasValue) return null;
        var date = value.Value.Date;
        var diff = ((int)date.DayOfWeek + 6) % 7;
        return date.AddDays(-diff);
    }
}

public sealed class PurchaseRequestMergeResult
{
    public List<PurchaseRequestMain> Requests { get; set; } = new();
    public int OriginalCount { get; set; }
    public int MergedCount { get; set; }
    public int ReducedCount => Math.Max(OriginalCount - MergedCount, 0);
}