Refactor handler to use generic IRepository for templates

Replaces IEmailTemplateRepository with IRepository<EmailTemplate> in ReadEmailTemplateQueryHandler. Updates method logic to use LINQ queries and FirstOrDefaultAsync. Cleans up obsolete attributes, comments, and using directives. Renames cancellation token parameter for consistency.

EnvelopeGenerator.Application/EmailTemplates/Queries/Read/ReadEmailTemplateQuery.cs

@@ -1,8 +1,9 @@
 using AutoMapper;
 using MediatR;
-using EnvelopeGenerator.Application.Common.Interfaces.Repositories;
-using EnvelopeGenerator.Domain.Constants;
 using EnvelopeGenerator.Application.Common.Dto;
+using DigitalData.Core.Abstraction.Application.Repository;
+using EnvelopeGenerator.Domain.Entities;
+using Microsoft.EntityFrameworkCore;
 
 namespace EnvelopeGenerator.Application.EmailTemplates.Queries.Read;
 
@@ -21,39 +22,35 @@ public class ReadEmailTemplateQueryHandler : IRequestHandler<ReadEmailTemplateQu
 {
     private readonly IMapper _mapper;
 
-    [Obsolete("Use Read-method returning IReadQuery<TEntity> instead.")]
-    private readonly IEmailTemplateRepository _repository;
+    private readonly IRepository<EmailTemplate> _repo;
 
     /// <summary>
     /// Initialisiert eine neue Instanz der <see cref="EmailTemplateController"/>-Klasse.
     /// </summary>
     /// <param name="mapper">
-    /// <param name="repository">
+    /// <param name="repo">
     /// Die AutoMapper-Instanz, die zum Zuordnen von Objekten verwendet wird.
     /// </param>
-    [Obsolete("Use Read-method returning IReadQuery<TEntity> instead.")]
-    public ReadEmailTemplateQueryHandler(IMapper mapper, IEmailTemplateRepository repository)
+    public ReadEmailTemplateQueryHandler(IMapper mapper, IRepository<EmailTemplate> repo)
     {
         _mapper = mapper;
-        _repository = repository;
+        _repo = repo;
     }
 
     /// <summary>
     /// 
     /// </summary>
     /// <param name="request"></param>
-    /// <param name="cancellationToken"></param>
+    /// <param name="cancel"></param>
     /// <returns></returns>
     /// <exception cref="InvalidOperationException"></exception>
     [Obsolete("Use IRepository")]
-    public async Task<EmailTemplateDto?> Handle(ReadEmailTemplateQuery request, CancellationToken cancellationToken)
+    public async Task<EmailTemplateDto?> Handle(ReadEmailTemplateQuery request, CancellationToken cancel)
     {
-        var temp = request.Id is int id
-            ? await _repository.ReadByIdAsync(id)
-            : request.Type is EmailTemplateType type
-                ? await _repository.ReadByNameAsync(type)
-                : throw new InvalidOperationException("Either a valid integer ID or a valid EmailTemplateType must be provided in the request.");
+        var query = request.Id is int id
+            ? _repo.Query.Where(temp => temp.Id == id)
+            : _repo.Query.Where(temp => temp.Name == request.Type!.ToString());
 
-        return _mapper.Map<EmailTemplateDto>(temp);
+        return _mapper.Map<EmailTemplateDto>(await query.FirstOrDefaultAsync(cancel));
     }
 }