using ValidationException = Hutopy.Application.Common.Exceptions.ValidationException;

namespace Hutopy.Application.Common.Behaviours;

public class ValidationBehaviour<TRequest, TResponse>(IEnumerable<IValidator<TRequest>> validators)
    : IPipelineBehavior<TRequest, TResponse>
    where TRequest : notnull
{
    public async Task<TResponse> Handle(TRequest request, RequestHandlerDelegate<TResponse> next, CancellationToken cancellationToken)
    {
        if (!validators.Any()) return await next();

        var context = new ValidationContext<TRequest>(request);

        var validationResults = await Task.WhenAll(
            validators.Select(v =>
                v.ValidateAsync(context, cancellationToken)));

        var failures = validationResults
            .Where(r => r.Errors.Any())
            .SelectMany(r => r.Errors)
            .ToList();

        if (failures.Count != 0) throw new ValidationException(failures);
        
        return await next();
    }
}