// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
namespace Microsoft.AspNetCore.Razor.TagHelpers;
 
/// <summary>
/// Restricts children of the <see cref="ITagHelper"/>'s element.
/// </summary>
/// <remarks>Combining this attribute with a <see cref="HtmlTargetElementAttribute"/> that specifies its
/// <see cref="HtmlTargetElementAttribute.TagStructure"/> as <see cref="TagStructure.WithoutEndTag"/> will result
/// in this attribute being ignored.</remarks>
[AttributeUsage(AttributeTargets.Class, Inherited = false, AllowMultiple = false)]
public sealed class RestrictChildrenAttribute : Attribute
{
    /// <summary>
    /// Instantiates a new instance of the <see cref="RestrictChildrenAttribute"/> class.
    /// </summary>
    /// <param name="childTag">
    /// The tag name of an element allowed as a child.
    /// </param>
    /// <param name="childTags">
    /// Additional names of elements allowed as children.
    /// </param>
    public RestrictChildrenAttribute(string childTag, params string[] childTags)
    {
        var concatenatedNames = new string[1 + childTags.Length];
        concatenatedNames[0] = childTag;
 
        childTags.CopyTo(concatenatedNames, 1);
 
        ChildTags = concatenatedNames;
    }
 
    /// <summary>
    /// Get the names of elements allowed as children.
    /// </summary>
    public IEnumerable<string> ChildTags { get; }
}