WebAPISignalRChat/Backend/Diligent.WebAPI.Host/Mediator/Messages/Handlers/AddMessageHandler.cs

using Diligent.WebAPI.Business.Interfaces;
using Diligent.WebAPI.Business.Services;
using Diligent.WebAPI.Data.Entities;
using Diligent.WebAPI.Host.Exceptions;
using Diligent.WebAPI.Host.Mediator.Messages.Commands;
using MediatR;

namespace Diligent.WebAPI.Host.Mediator.Messages.Handlers
{
    public class AddMessageHandler : IRequestHandler<AddMessageCommand, Unit>
    {
        private readonly IRoomRepository _roomRepository;

        public AddMessageHandler(IRoomRepository roomRepository)
        {
            _roomRepository = roomRepository;
        }
        public async Task<Unit> Handle(AddMessageCommand request, CancellationToken cancellationToken)
        {
            var room = await _roomRepository.GetByIdAsync(request.roomId);

            if(room == null)
            {
                throw new NotFoundException("Room is not found");
            }

            await _roomRepository.AddMessage(room, request.message);

            return new Unit();
        }
    }
}