using GB5Shared.DTO.Framework.AutoNumber;
using GB5Shared.DTO.Framework.Criteria;
using GB5Shared.DTO.Framework.Login;
using GB5Shared.GenerateAutoNumber;
using GB5Shared.QueryExecutor;
using PayRollBLL.Common;
using PayRollDAL.CustomeCode.ShiftPattern;
using PayRollDAL.DTO.ShiftPattern;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace PayRollBLL.ShiftPattern
{
    public class ShiftPatternBLL : IShiftPatternBLL
    {
        private readonly IShiftPatternDAL _ShiftPatternDAL;
        private readonly AutoNumber _AutoNumber;
        private readonly IQueryExecutor _QueryExecutor;
        private readonly IEntityValidationClient _EntityValidationClient;

        public ShiftPatternBLL(
            IShiftPatternDAL shiftPatternDAL,
            AutoNumber autoNumber,
            IQueryExecutor queryExecutor,
            IEntityValidationClient entityValidationClient)
        {
            _ShiftPatternDAL = shiftPatternDAL;
            _AutoNumber = autoNumber;
            _QueryExecutor = queryExecutor;
            _EntityValidationClient = entityValidationClient;
        }

        // ── Get single record (3-level hierarchy) ────────────────────────

        public async Task<ShiftPatternDTO> GetShiftPattern(int ShiftPatternId, LoginDTO LoginDTO)
        {
            return await _ShiftPatternDAL.GetShiftPattern(ShiftPatternId, LoginDTO).ConfigureAwait(false);
        }

        // ── Save (insert or update) ───────────────────────────────────────

        public async Task<string> SaveShiftPattern(ShiftPatternDTO ShiftPatternDTO, LoginDTO LoginDTO, CancellationToken ct = default)
        {
            if (ShiftPatternDTO == null)
                throw new ArgumentNullException(nameof(ShiftPatternDTO));

            bool isNew = ShiftPatternDTO.ShiftPatternId == 0;

            // 1. Guard: block replacing days/detail rows that are already referenced by an
            //    employee assignment (MEMPLOYEE.SHIFTPATTERNDETAILID). Only applies on update —
            //    a brand-new pattern has nothing existing to be "replaced".
            if (!isNew)
            {
                var employeesInUse = await _ShiftPatternDAL
                    .GetEmployeesUsingShiftPattern(ShiftPatternDTO.ShiftPatternId, LoginDTO)
                    .ConfigureAwait(false);

                if (employeesInUse != null && employeesInUse.Count > 0)
                    throw new InvalidOperationException(
                        "This shift pattern cannot be modified because it is already assigned to one or more employees.");
            }

            // 2. External validation service (GB4 parity: BaseShiftPatternValidationUri).
            var (isValid, errorMessage) = await _EntityValidationClient
                .ValidateAsync("ShiftPatternBaseUri", ShiftPatternDTO, LoginDTO, ct)
                .ConfigureAwait(false);

            if (!isValid)
                throw new InvalidOperationException(errorMessage ?? "Shift pattern validation failed.");

            AutoNumberDTO? autoNumberDTO = null;

            var trans = await _QueryExecutor.BeginTransactionAsync(LoginDTO).ConfigureAwait(false);
            try
            {
                if (isNew)
                {
                    // 3. Count = 1 (header) + Σ over days of (NumberOfDays + 1)
                    //    — one id for the days row itself, plus one id per detail row under it.
                    int count = 1;
                    if (ShiftPatternDTO.ShiftPatternDaysArray != null)
                    {
                        foreach (var day in ShiftPatternDTO.ShiftPatternDaysArray)
                            count += 1 + day.ShiftPatternDaysNumberofDays;
                    }

                    autoNumberDTO = await _AutoNumber.GetNumberAsync(count, "SHIFTPATTERN", LoginDTO)
                        .ConfigureAwait(false);

                    ShiftPatternDTO.ShiftPatternId = autoNumberDTO.StartNumber;
                    ShiftPatternDTO.ShiftPatternCreatedById = LoginDTO.UserId;
                    ShiftPatternDTO.ShiftPatternCreatedOn = DateTime.UtcNow;

                    // 4. Walk the reserved id block sequentially: every days row consumes one id,
                    //    then every one of its detail rows consumes the next id, and so on.
                    if (ShiftPatternDTO.ShiftPatternDaysArray != null)
                    {
                        int tmpCount = 1;
                        foreach (var day in ShiftPatternDTO.ShiftPatternDaysArray)
                        {
                            day.ShiftPatternDaysId = autoNumberDTO.StartNumber + tmpCount;
                            tmpCount++;

                            if (day.ShiftPatternDetailArray != null)
                            {
                                foreach (var detail in day.ShiftPatternDetailArray)
                                {
                                    detail.ShiftPatternDetailId = autoNumberDTO.StartNumber + tmpCount;
                                    tmpCount++;
                                }
                            }
                        }
                    }
                }

                ShiftPatternDTO.ShiftPatternModifiedById = LoginDTO.UserId;
                ShiftPatternDTO.ShiftPatternModifiedOn = DateTime.UtcNow;

                int rows = isNew
                    ? await _ShiftPatternDAL.SaveShiftPattern(ShiftPatternDTO, LoginDTO, trans).ConfigureAwait(false)
                    : await _ShiftPatternDAL.UpdateShiftPattern(ShiftPatternDTO, LoginDTO, trans).ConfigureAwait(false);

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

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

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

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

        public async Task<string> DeleteShiftPattern(int ShiftPatternId, LoginDTO LoginDTO)
        {
            return await _ShiftPatternDAL.DeleteShiftPattern(ShiftPatternId, LoginDTO).ConfigureAwait(false);
        }

        // ── Full-DTO header list ─────────────────────────────────────────

        public async Task<string> GetShiftPatternList(CriteriaDTO CriteriaDTO, LoginDTO LoginDTO)
        {
            return await _ShiftPatternDAL.GetShiftPatternList(CriteriaDTO, LoginDTO).ConfigureAwait(false);
        }

        // ── Sub-endpoint: all detail rows for a pattern ──────────────────

        public async Task<List<ShiftPatternDetailDTO>> LoadShiftPatternDetails(int ShiftPatternId, LoginDTO LoginDTO)
        {
            return await _ShiftPatternDAL.LoadShiftPatternDetails(ShiftPatternId, LoginDTO).ConfigureAwait(false);
        }

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

        public async Task<string> GetSelectListShiftPattern(int FirstNumber, int MaxResult, CriteriaDTO CriteriaDTO, LoginDTO LoginDTO, bool IsCount = false)
        {
            return await _ShiftPatternDAL
                .GetSelectListShiftPattern(FirstNumber, MaxResult, CriteriaDTO, LoginDTO, IsCount)
                .ConfigureAwait(false);
        }
    }
}