EnvelopeGenerator/EnvelopeGenerator.Application/Configuration/Queries/ReadDefaultConfigQuery.cs

using AutoMapper;
using DigitalData.Core.Abstraction.Application.Repository;
using DigitalData.Core.Exceptions;
using EnvelopeGenerator.Application.Common.Dto;
using EnvelopeGenerator.Domain.Entities;
using MediatR;
using Microsoft.EntityFrameworkCore;

namespace EnvelopeGenerator.Application.Configuration.Queries;

/// <summary>
/// 
/// </summary>
public record ReadDefaultConfigQuery : IRequest<ConfigDto>
{
    /// <summary>
    /// 
    /// </summary>
    public bool EnforceSingleResult { get; init; }
}

/// <summary>
/// 
/// </summary>
public class ReadDefaultConfigQueryHandler : IRequestHandler<ReadDefaultConfigQuery, ConfigDto>
{
    private readonly IRepository<Config> _repo;

    private readonly IMapper _mapper;

    /// <summary>
    /// 
    /// </summary>
    /// <param name="repo"></param>
    /// <param name="mapper"></param>
    public ReadDefaultConfigQueryHandler(IRepository<Config> repo, IMapper mapper)
    {
        _repo = repo;
        _mapper = mapper;
    }

    /// <summary>
    /// 
    /// </summary>
    /// <param name="request"></param>
    /// <param name="cancel"></param>
    /// <returns></returns>
    /// <exception cref="InvalidOperationException"></exception>
    public async Task<ConfigDto> Handle(ReadDefaultConfigQuery request, CancellationToken cancel)
    {
        var config = request.EnforceSingleResult
            ? await _repo.Query.SingleOrDefaultAsync(cancel)
            : await _repo.Query.FirstOrDefaultAsync(cancel)
            ?? throw new NotFoundException("Default configuration could not be found. Ensure at least one configuration record exists in the database.");
        return _mapper.Map<ConfigDto>(config);
    }
}