using GB5Shared.DTO.Framework.AutoNumber;
using GB5Shared.DTO.Framework.Criteria;
using GB5Shared.DTO.Framework.Login;
using GB5Shared.GenerateAutoNumber;
using GB5Shared.QueryExecutor;
using PayRollDAL.CustomeCode.Relieving;
using PayRollDAL.DTO.Relieving;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace PayRollBLL.Relieving
{
    public class RelievingBLL : IRelievingBLL
    {
        private readonly IRelievingDAL _RelievingDAL;
        private readonly AutoNumber _AutoNumber;
        private readonly VoucherNumberService _VoucherNumberService;
        private readonly IQueryExecutor _QueryExecutor;

        public RelievingBLL(
            IRelievingDAL relievingDAL,
            AutoNumber autoNumber,
            VoucherNumberService voucherNumberService,
            IQueryExecutor queryExecutor)
        {
            _RelievingDAL = relievingDAL;
            _AutoNumber = autoNumber;
            _VoucherNumberService = voucherNumberService;
            _QueryExecutor = queryExecutor;
        }

        // ── Get single record ─────────────────────────────────────────────

        public async Task<RelievingDTO> GetRelieving(int RelievingId, LoginDTO LoginDTO)
        {
            return await _RelievingDAL.GetRelieving(RelievingId, LoginDTO).ConfigureAwait(false);
        }

        // ── Save (insert or update) ───────────────────────────────────────
        // GB4 parity: RelievingBLL.SaveRelieving — autonumber block sized for
        // header + all detail rows (GenericDal.GetNumber(Count,"RELIEVING",...)),
        // VNO generated only on insert (VnoGenerationDLL.GetNextVno when
        // BIZTransactionType.NOGenerationType==0 — VoucherNumberService returns
        // null for manual mode, so the number is left as supplied by the caller).
        // Transaction shared across autonumber-consuming inserts so a rollback
        // reverts both the counter and the entity rows, matching GB4 semantics.

        public async Task<string> SaveRelieving(RelievingDTO RelievingDTO, LoginDTO LoginDTO)
        {
            if (RelievingDTO == null)
                throw new ArgumentNullException(nameof(RelievingDTO));

            bool isNew = RelievingDTO.RelievingId == 0;
            AutoNumberDTO? autoNumberDTO = null;

            // An omitted/unparseable reference date (e.g. "0") deserializes to
            // default(DateTime) = 0001-01-01, which is below SQL Server's DATETIME
            // floor (1/1/1753) and throws SqlDateTime overflow on save.
            if (RelievingDTO.RelievingReferenceDate == default)
                RelievingDTO.RelievingReferenceDate = RelievingDTO.RelievingRelievingDate;

            var trans = await _QueryExecutor.BeginTransactionAsync(LoginDTO).ConfigureAwait(false);
            try
            {
                if (isNew)
                {
                    int count = 1 + (RelievingDTO.RelievingDetailArray?.Count ?? 0);
                    autoNumberDTO = await _AutoNumber.GetNumberAsync(count, "RELIEVING", LoginDTO)
                        .ConfigureAwait(false);

                    RelievingDTO.RelievingId = autoNumberDTO.StartNumber;
                    RelievingDTO.RelievingCreatedById = LoginDTO.UserId;
                    RelievingDTO.RelievingCreatedOn = DateTime.UtcNow;

                    if (RelievingDTO.RelievingDetailArray != null)
                    {
                        int tmpCount = 1;
                        foreach (var detail in RelievingDTO.RelievingDetailArray)
                        {
                            detail.RelievingDetailId = autoNumberDTO.StartNumber + tmpCount;
                            tmpCount++;
                        }
                    }

                    string? generatedNumber = await _VoucherNumberService
                        .GetNextVoucherNumberAsync(
                            RelievingDTO.BIZTransactionTypeId,
                            RelievingDTO.RelievingRelievingDate,
                            LoginDTO,
                            transaction: trans)
                        .ConfigureAwait(false);

                    if (generatedNumber != null)
                        RelievingDTO.RelievingRelievingNumber = generatedNumber;
                }

                RelievingDTO.RelievingModifiedById = LoginDTO.UserId;
                RelievingDTO.RelievingModifiedOn = DateTime.UtcNow;

                int rows = isNew
                    ? await _RelievingDAL.SaveRelieving(RelievingDTO, LoginDTO, trans).ConfigureAwait(false)
                    : await _RelievingDAL.UpdateRelieving(RelievingDTO, LoginDTO, trans).ConfigureAwait(false);

                await _QueryExecutor.CommitAsync(trans).ConfigureAwait(false);

                if (rows <= 0)
                    return isNew ? "Failed to save separation." : "Failed to update separation.";

                return isNew
                    ? "Details Saved Successfully"
                    : "Details Updated Successfully";
            }
            catch (Exception)
            {
                await _QueryExecutor.RollbackAsync(trans).ConfigureAwait(false);
                if (autoNumberDTO != null)
                    await _AutoNumber.RollbackAutoNumber("RELIEVING", autoNumberDTO.StartNumber, LoginDTO)
                        .ConfigureAwait(false);
                throw;
            }
        }

        // ── Delete ────────────────────────────────────────────────────────

        public async Task<string> DeleteRelieving(int RelievingId, LoginDTO LoginDTO)
        {
            return await _RelievingDAL.DeleteRelieving(RelievingId, LoginDTO).ConfigureAwait(false);
        }

        // ── Picklist ──────────────────────────────────────────────────────

        public async Task<string> GetSelectListRelieving(int FirstNumber, int MaxResult, CriteriaDTO CriteriaDTO, LoginDTO LoginDTO)
        {
            return await _RelievingDAL
                .GetSelectListRelieving(FirstNumber, MaxResult, CriteriaDTO, LoginDTO)
                .ConfigureAwait(false);
        }

        // ── Save Relieving Settlement (separate settlement grid) ────────────
        // GB4 parity: RelievingBLL.SaveRelievingSettlement.
        //   1. Sums Add (OperationType==0) / Sub (OperationType==1) amounts across the
        //      whole incoming list, and pushes SETTLEMENTAMOUNT = Add - Sub onto the
        //      parent Relieving header (GB4's "Update Releiving Table" block).
        //   2. New rows (Id==0) get autonumbers and are inserted.
        //   3. Existing rows (Id!=0) are update-path: GB4 deleted ALL settlement rows
        //      for the row's RelievingId and re-inserted, ONCE PER DTO IN THE LOOP — so
        //      N update-rows sharing a RelievingId caused N delete+reinsert cycles.
        //      Fixed here: group update-rows by RelievingId and delete-once per distinct
        //      RelievingId, then write all of that group's rows — same end result, no
        //      redundant churn. GB4's raw string-concatenated delete
        //      ("...WHERE RELIEVINGID =" + id) is also replaced with the parameterized
        //      DELETE_RELIEVINGSETTLEMENT_BY_RELIEVINGID query.
        // Whole batch (new-row inserts, update-row delete+reinsert, header amount update)
        // is wrapped in one transaction; autonumber allocation happens before the
        // transaction per the established SaveFoo/SaveTLeave pattern.
        public async Task<string> SaveRelievingSettlement(List<RelievingSettlementDTO> RelievingSettlementDTOs, LoginDTO LoginDTO)
        {
            if (RelievingSettlementDTOs == null || RelievingSettlementDTOs.Count == 0)
                return "No settlement rows supplied.";

            double add = 0;
            double sub = 0;
            foreach (var dto in RelievingSettlementDTOs)
            {
                if (dto.RelievingSettlementOperationType == 0) // Add
                    add += dto.RelievingSettlementAmount;
                else if (dto.RelievingSettlementOperationType == 1) // Sub
                    sub += dto.RelievingSettlementAmount;
            }

            var newRows = RelievingSettlementDTOs.Where(d => d.RelievingSettlementId == 0).ToList();
            var updateRows = RelievingSettlementDTOs.Where(d => d.RelievingSettlementId != 0).ToList();

            AutoNumberDTO? autoNumberDTO = null;
            if (newRows.Count > 0)
                autoNumberDTO = await _AutoNumber.GetNumberAsync(newRows.Count, "RELIEVINGSETTLEMENT", LoginDTO)
                    .ConfigureAwait(false);

            var trans = await _QueryExecutor.BeginTransactionAsync(LoginDTO).ConfigureAwait(false);
            try
            {
                int t = 0;
                foreach (var dto in newRows)
                {
                    dto.RelievingSettlementId = autoNumberDTO!.StartNumber + t;
                    t++;
                    await _RelievingDAL.SaveRelievingSettlementDetail(dto, LoginDTO, trans).ConfigureAwait(false);
                }

                // Group update-path rows by RelievingId so each distinct header's existing
                // settlement rows are deleted exactly once, not once per DTO (see note above).
                foreach (var group in updateRows.GroupBy(d => d.RelievingId))
                {
                    await _RelievingDAL.DeleteRelievingSettlementsByRelievingId(group.Key, LoginDTO, trans)
                        .ConfigureAwait(false);

                    foreach (var dto in group)
                        await _RelievingDAL.SaveRelievingSettlementDetail(dto, LoginDTO, trans).ConfigureAwait(false);
                }

                decimal settlementAmount = (decimal)(add - sub);
                int headerRelievingId = RelievingSettlementDTOs[0].RelievingId;
                await _RelievingDAL.UpdateRelievingSettlementAmount(headerRelievingId, settlementAmount, LoginDTO, trans)
                    .ConfigureAwait(false);

                await _QueryExecutor.CommitAsync(trans).ConfigureAwait(false);

                return "Details Saved Successfully";
            }
            catch (Exception)
            {
                await _QueryExecutor.RollbackAsync(trans).ConfigureAwait(false);
                if (autoNumberDTO != null)
                    await _AutoNumber.RollbackAutoNumber("RELIEVINGSETTLEMENT", autoNumberDTO.StartNumber, LoginDTO)
                        .ConfigureAwait(false);
                throw;
            }
        }
    }
}