using DigitalData.Core.Abstraction.Application.Repository;
using MediatR;
using System.Linq.Expressions;

namespace EnvelopeGenerator.Application.Common.Commands;

/// <summary>
/// 
/// </summary>
/// <typeparam name="TUpdateDto"></typeparam>
/// <typeparam name="TEntity"></typeparam>
public abstract record UpdateCommand<TUpdateDto, TEntity> : IRequest where TUpdateDto : class where TEntity : class
{
    /// <summary>
    /// 
    /// </summary>
    public TUpdateDto Update { get; init; } = null!;

    /// <summary>
    /// 
    /// </summary>
    /// <returns></returns>
    public abstract Expression<Func<TEntity, bool>> BuildQueryExpression();
}

/// <summary>
/// 
/// </summary>
/// <typeparam name="TCommand"></typeparam>
/// <typeparam name="TUpdateDto"></typeparam>
/// <typeparam name="TEntity"></typeparam>
public class UpdateCommandHandler<TCommand, TUpdateDto, TEntity> : IRequestHandler<TCommand>
    where TUpdateDto : class
    where TEntity : class
    where TCommand : UpdateCommand<TUpdateDto, TEntity>
{
    /// <summary>
    /// 
    /// </summary>
    protected readonly IRepository<TEntity> Repository;

    /// <summary>
    /// 
    /// </summary>
    /// <param name="repository"></param>
    public UpdateCommandHandler(IRepository<TEntity> repository)
    {
        Repository = repository;
    }

    /// <summary>
    /// 
    /// </summary>
    /// <param name="request"></param>
    /// <param name="cancel"></param>
    /// <returns></returns>
    public Task Handle(TCommand request, CancellationToken cancel)
        => Repository.UpdateAsync(request.Update, request.BuildQueryExpression(), cancel);
}