using System;
using System.ComponentModel.DataAnnotations;

namespace LinkDotNet.Blog.Web.Features.Admin.BlogPostEditor.Components;

[AttributeUsage(AttributeTargets.Property)]
public sealed class FallbackUrlValidationAttribute : ValidationAttribute
{
    protected override ValidationResult? IsValid(object? value, ValidationContext validationContext)
    {
        ArgumentNullException.ThrowIfNull(validationContext);

        var model = (CreateNewModel)validationContext.ObjectInstance;

        return model.PreviewImageUrl == model.PreviewImageUrlFallback
            ? new ValidationResult("Preview image url and the fallback preview image url should not be the same.")
            : ValidationResult.Success;
    }
}