using Indotalent.ConfigBackEnd.Exceptions;
using Indotalent.ConfigBackEnd.Extensions;
using Indotalent.Infrastructure.Database;
using MediatR;
using Microsoft.EntityFrameworkCore;

namespace Indotalent.Features.Payroll.Payrolls.Cqrs;

public class CreatePayrollProcessRequest
{
    public string? PeriodName { get; set; }
    public DateTime? FromDate { get; set; }
    public DateTime? ToDate { get; set; }
    public string? Description { get; set; }
}

public class CreatePayrollProcessResponse
{
    public string? Id { get; set; }
    public string? AutoNumber { get; set; }
}

public record CreatePayrollProcessCommand(CreatePayrollProcessRequest Data) : IRequest<CreatePayrollProcessResponse>;

public class CreatePayrollProcessHandler : IRequestHandler<CreatePayrollProcessCommand, CreatePayrollProcessResponse>
{
    private readonly AppDbContext _context;

    public CreatePayrollProcessHandler(AppDbContext context) => _context = context;

    public async Task<CreatePayrollProcessResponse> Handle(CreatePayrollProcessCommand request, CancellationToken cancellationToken)
    {
        var isExists = await _context.PayrollProcess
            .AnyAsync(x => x.PeriodName == request.Data.PeriodName, cancellationToken);

        if (isExists)
        {
            throw new AlreadyExistsException("Payroll Period", request.Data.PeriodName ?? string.Empty);
        }

        var entityName = nameof(Data.Entities.PayrollProcess);

        var autoNo = await _context.GenerateAutoNumberAsync(
            entityName: entityName,
            prefixTemplate: $"PAY/{request.Data.FromDate?.ToString("yyyyMM") ?? DateTime.Now.ToString("yyyyMM")}/",
            ct: cancellationToken
        );

        var payrollProcess = new Data.Entities.PayrollProcess
        {
            AutoNumber = autoNo,
            PeriodName = request.Data.PeriodName,
            FromDate = request.Data.FromDate ?? DateTime.Now,
            ToDate = request.Data.ToDate ?? DateTime.Now,
            Description = request.Data.Description,
            Status = "Draft",
            ProcessedBy = "System Admin",
            ProcessedAt = DateTime.Now
        };

        var employees = await _context.Employee
            .Include(x => x.EmployeeIncome)
            .Include(x => x.EmployeeDeduction)
            .Where(x => x.EmployeeStatus == "Active")
            .ToListAsync(cancellationToken);

        decimal grandBasicSalary = 0;
        decimal grandTotalIncome = 0;
        decimal grandTotalDeduction = 0;

        foreach (var emp in employees)
        {
            var totalIncome = emp.EmployeeIncome?.Sum(x => x.Amount) ?? 0m;
            var totalDeduction = emp.EmployeeDeduction?.Sum(x => x.Amount) ?? 0m;
            var takeHomePay = emp.BasicSalary + totalIncome - totalDeduction;

            var detail = new Data.Entities.PayrollDetail
            {
                PayrollProcess = payrollProcess,
                EmployeeId = emp.Id,
                EmployeeCode = emp.Code,
                EmployeeName = $"{emp.FirstName} {emp.LastName}",
                BasicSalary = emp.BasicSalary,
                TotalIncome = totalIncome,
                TotalDeduction = totalDeduction,
                TakeHomePay = takeHomePay
            };

            if (emp.EmployeeIncome != null)
            {
                foreach (var inc in emp.EmployeeIncome)
                {
                    detail.Components.Add(new Data.Entities.PayrollComponent
                    {
                        PayrollDetail = detail,
                        ComponentName = "Income Component",
                        ComponentType = "Income",
                        Amount = inc.Amount,
                        Description = inc.Description
                    });
                }
            }

            if (emp.EmployeeDeduction != null)
            {
                foreach (var ded in emp.EmployeeDeduction)
                {
                    detail.Components.Add(new Data.Entities.PayrollComponent
                    {
                        PayrollDetail = detail,
                        ComponentName = "Deduction Component",
                        ComponentType = "Deduction",
                        Amount = ded.Amount,
                        Description = ded.Description
                    });
                }
            }

            grandBasicSalary += detail.BasicSalary;
            grandTotalIncome += totalIncome;
            grandTotalDeduction += totalDeduction;

            _context.PayrollDetail.Add(detail);
        }

        payrollProcess.TotalEmployees = employees.Count;
        payrollProcess.TotalBasicSalary = grandBasicSalary;
        payrollProcess.TotalIncome = grandTotalIncome;
        payrollProcess.TotalDeduction = grandTotalDeduction;
        payrollProcess.TotalGross = grandBasicSalary + grandTotalIncome;
        payrollProcess.TotalTakeHomePay = payrollProcess.TotalGross - grandTotalDeduction;

        _context.PayrollProcess.Add(payrollProcess);
        await _context.SaveChangesAsync(cancellationToken);

        return new CreatePayrollProcessResponse
        {
            Id = payrollProcess.Id,
            AutoNumber = payrollProcess.AutoNumber
        };
    }
}