// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
namespace System.Windows.Forms;
 
/// <summary>
///  This is a ControlCollection which can be made readonly. In readonly mode, this
///  ControlCollection throws NotSupportedExceptions for any operation that attempts
///  to modify the collection.
/// </summary>
internal class ReadOnlyControlCollection : Control.ControlCollection
{
    private readonly bool _isReadOnly;
 
    public ReadOnlyControlCollection(Control owner, bool isReadOnly)
        : base(owner)
    {
        _isReadOnly = isReadOnly;
    }
 
    public override void Add(Control? value)
    {
        if (value is null)
        {
            return;
        }
 
        if (IsReadOnly)
        {
            throw new NotSupportedException(SR.ReadonlyControlsCollection);
        }
 
        AddInternal(value);
    }
 
    internal virtual void AddInternal(Control? value) => base.Add(value);
 
    public override void Clear()
    {
        if (IsReadOnly)
        {
            throw new NotSupportedException(SR.ReadonlyControlsCollection);
        }
 
        base.Clear();
    }
 
    internal virtual void RemoveInternal(Control value) => base.Remove(value);
 
    public override void RemoveByKey(string? key)
    {
        if (IsReadOnly)
        {
            throw new NotSupportedException(SR.ReadonlyControlsCollection);
        }
 
        base.RemoveByKey(key);
    }
 
    public override bool IsReadOnly => _isReadOnly;
}