using AutobusApi.Application.Common.Exceptions;
using AutobusApi.Application.Common.Interfaces;
using AutobusApi.Domain.Entities;
using AutobusApi.Domain.Enums;
using MediatR;
using Microsoft.EntityFrameworkCore;

namespace AutobusApi.Application.TicketGroups.Commands.UpdateTicketGroup;

public class UpdateTicketGroupCommandHandler : IRequestHandler<UpdateTicketGroupCommand>
{
    private readonly IApplicationDbContext _dbContext;

    public UpdateTicketGroupCommandHandler(IApplicationDbContext dbContext)
    {
        _dbContext = dbContext;
    }

    public async Task Handle(
        UpdateTicketGroupCommand request,
        CancellationToken cancellationToken)
    {
        var ticketGroup = await _dbContext.TicketGroups
            .Include(tg => tg.Tickets)
            .SingleAsync(tg => tg.Id == request.Id, cancellationToken);

        if (ticketGroup == null)
        {
            throw new NotFoundException();
        }

        ticketGroup.BuyerFirstName = request.BuyerFirstName;
        ticketGroup.BuyerLastName = request.BuyerLastName;
        ticketGroup.BuyerPhoneNumber = request.BuyerPhoneNumber;
        ticketGroup.BuyerEmailAddress = request.BuyerEmail;

        ticketGroup.PassengerFirstName = request.PassengerFirstName;
        ticketGroup.PassengerLastName = request.PassengerLastName;
        ticketGroup.PassengerPatronymic = request.PassengerPatronymic;
        ticketGroup.PassengerSex = Enum.Parse<Sex>(request.PassengerSex);
        ticketGroup.PassengerBirthDate = request.PassengerBirthDate;

        ticketGroup.TicketDocument.Type = Enum.Parse<TicketDocumentType>(request.DocumentType);
        ticketGroup.TicketDocument.Information = request.DocumentInformation;

        var compaper = new TicketEqualityComparer();

        var ticketsToBeRemoved = ticketGroup.Tickets
            .ExceptBy(request.Tickets.Select(
                t => new Ticket
                {
                    Id = t.Id ?? 0,
                    DepartureAddressId = t.DepartureAddressId,
                    ArrivalAddressId = t.ArrivalAddressId,
                    VehicleEnrollmentId = t.VehicleEnrollmentId
                }), 
                t => new Ticket 
                {
                    Id = t.Id,
                    DepartureAddressId = t.DepartureAddressId,
                    ArrivalAddressId = t.ArrivalAddressId,
                    VehicleEnrollmentId = t.VehicleEnrollmentId
                }, 
                compaper
            ).ToList();

        var remainingTickets = ticketGroup.Tickets
            .ExceptBy(ticketsToBeRemoved.Select(
                ttbr => new Ticket
                {
                    Id = ttbr.Id,
                    DepartureAddressId = ttbr.DepartureAddressId,
                    ArrivalAddressId = ttbr.ArrivalAddressId,
                    VehicleEnrollmentId = ttbr.VehicleEnrollmentId
                }), 
                t => new Ticket 
                {
                    Id = t.Id,
                    DepartureAddressId = t.DepartureAddressId,
                    ArrivalAddressId = t.ArrivalAddressId,
                    VehicleEnrollmentId = t.VehicleEnrollmentId
                },
                compaper
            ).ToList();

        var newTickets = remainingTickets
            .UnionBy(request.Tickets.Select(
                t => new Ticket 
                {
                    Id = t.Id ?? 0,
                    DepartureAddressId = t.DepartureAddressId,
                    ArrivalAddressId = t.ArrivalAddressId,
                    VehicleEnrollmentId = t.VehicleEnrollmentId
                }),
                rt => new Ticket 
                {
                    Id = rt.Id,
                    DepartureAddressId = rt.DepartureAddressId,
                    ArrivalAddressId = rt.ArrivalAddressId,
                    VehicleEnrollmentId = rt.VehicleEnrollmentId
                },
                compaper
            ).ToList();

        ticketGroup.Tickets = newTickets.ToList();

        await _dbContext.SaveChangesAsync(cancellationToken);
    }

    private class TicketEqualityComparer : IEqualityComparer<Ticket>
    {
        public bool Equals(Ticket? x, Ticket? y)
        {
            return 
                x?.Id == y?.Id &&
                x?.DepartureAddressId == y?.DepartureAddressId &&
                x?.ArrivalAddressId == y?.ArrivalAddressId &&
                x?.VehicleEnrollmentId == y?.VehicleEnrollmentId;
        }

        public int GetHashCode(Ticket obj)
        {
            return 
                obj.ArrivalAddressId.GetHashCode() +
                obj.DepartureAddressId.GetHashCode() +
                obj.VehicleEnrollmentId.GetHashCode();
        }
    }
}