using PayRollDAL.DTO.SAP;
using System.Collections.Generic;
using System.Linq;
using System.Text.Json;

namespace PayRollBLL.SAP.Builders
{
    /// <summary>
    /// SAP Infotype 585 — Deductions (80D, 80E, 80G, etc.).
    /// Service: ZPY_ITDEC_DEDUCT_SRV / DeductionHeaderSet
    /// Source: TDECLARATIONDETAIL rows where DeclarationDetailType == 5 (Expenses).
    /// One SAP item per unique employee + section + particulars combination.
    /// </summary>
    public class SAP585Builder : ISapInfotypeBuilder
    {
        private const byte ExpenseType = 5;

        public int    Infotype       => 585;
        public string DisplayName    => "Deductions (80D, 80G, etc.)";
        public string EndpointPath   => "/sap/opu/odata/sap/ZPY_ITDEC_DEDUCT_SRV/DeductionHeaderSet";
        public string MsgNavProperty => "NAV2DEDUCTIONMSG";

        public string Build(IEnumerable<ITDeclarationSapDTO> rows, string date, string remarks)
        {
            var items = rows
                .Where(r => r.DeclarationDetailId.HasValue && r.DeclarationDetailType == ExpenseType)
                .GroupBy(r => new { r.EmployeeCode, r.FiscalYear, r.SectionDetail, r.Particulars })
                .Select(g => new Sap585Item
                {
                    EmployeeID     = g.Key.EmployeeCode,
                    FiscalYear     = g.Key.FiscalYear,
                    // ConsiderActual: SAP flag — empty = use declared/approved amounts as-is
                    ConsiderActual = string.Empty,
                    Section        = g.Key.SectionDetail,
                    Particulars    = g.Key.Particulars,
                    Declared       = SapFmt.Amount(g.Sum(r => r.DeclaredAmount)),
                    Approved       = SapFmt.Amount(g.Sum(r => r.ApprovedAmount)),
                    Remarks        = g.First().DetailRemarks,
                })
                .ToList();

            if (items.Count == 0) return string.Empty;

            var payload = new Sap585Payload
            {
                Date              = date,
                Remarks           = remarks,
                NAV2DEDUCTIONITEM = items,
            };

            return JsonSerializer.Serialize(payload, SapJsonOptions.Plain);
        }
    }
}