EnvelopeGenerator/EnvelopeGenerator.Application/Receivers/Queries/ReadReceiverQuery.cs

using AutoMapper;
using DigitalData.Core.Abstraction.Application.Repository;
using EnvelopeGenerator.Application.Common.Dto.Receiver;
using EnvelopeGenerator.Application.Common.Query;
using MediatR;
using EnvelopeGenerator.Domain.Entities;
using Microsoft.EntityFrameworkCore;
using System.ComponentModel.DataAnnotations.Schema;

namespace EnvelopeGenerator.Application.Receivers.Queries;

/// <summary>
/// Stellt eine Abfrage dar, um die Details eines Empfängers zu lesen.
/// um spezifische Informationen über einen Empfänger abzurufen.
/// </summary>
public record ReadReceiverQuery : ReceiverQueryBase, IRequest<IEnumerable<ReceiverDto>>
{
    /// <summary>
    /// Suchbegriff für eine teilweise Übereinstimmung in der E-Mail Adresse des Empfängers
    /// </summary>
    public virtual string? EmailAddressSearch { get; set; }

    /// <summary>
    /// Checks whether any of the specified query criteria have a value.
    /// </summary>
    /// <remarks>
    /// This property returns <c>true</c> if at least one of the fields 
    /// <see cref="ReceiverQueryBase.Id"/>, <see cref="ReceiverQueryBase.EmailAddress"/>, <see cref="EmailAddressSearch"/>, or <see cref="ReceiverQueryBase.Signature"/> is not null.
    /// <para>Usage example: The query can be executed only if at least one criterion is specified.</para>
    /// </remarks>
    [NotMapped]
    public override bool HasAnyCriteria => EmailAddressSearch is not null || base.HasAnyCriteria;
}

/// <summary>
/// 
/// </summary>
public class ReadReceiverQueryHandler : IRequestHandler<ReadReceiverQuery, IEnumerable<ReceiverDto>>
{
    private readonly IRepository<Receiver> _repository;
    private readonly IMapper _mapper;

    /// <summary>
    /// 
    /// </summary>
    /// <param name="repository"></param>
    /// <param name="mapper"></param>
    public ReadReceiverQueryHandler(IRepository<Receiver> repository, IMapper mapper)
    {
        _repository = repository;
        _mapper = mapper;
    }

    /// <summary>
    /// 
    /// </summary>
    /// <param name="request"></param>
    /// <param name="cancellationToken"></param>
    /// <returns></returns>
    public async Task<IEnumerable<ReceiverDto>> Handle(ReadReceiverQuery request, CancellationToken cancellationToken)
    {
        var query = _repository.Query;

        if (request.Id is int id)
        {
            query = query.Where(r => r.Id == id);
        }

        if (request.EmailAddress is string email)
        {
            query = query.Where(r => r.EmailAddress == email);
        }

        if (!string.IsNullOrWhiteSpace(request.EmailAddressSearch))
        {
            query = query.Where(r => EF.Functions.Like(r.EmailAddress, $"%{request.EmailAddressSearch}%"));
        }

        if (request.Signature is string signature)
        {
            query = query.Where(r => r.Signature == signature);
        }

        var receiver = await query.ToListAsync(cancellationToken);
        return _mapper.Map<IEnumerable<ReceiverDto>>(receiver);
    }
}