// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
#nullable enable
 
using System.ComponentModel;
using System.Drawing.Design;
 
namespace System.Windows.Forms.Design;
 
internal class DataMemberFieldEditor : UITypeEditor
{
    private DesignBindingPicker? _designBindingPicker;
 
    public override bool IsDropDownResizable => true;
 
    public override object? EditValue(ITypeDescriptorContext? context, IServiceProvider provider, object? value)
    {
        if (provider is null || context is null || context?.Instance is not { } instance)
        {
            return value;
        }
 
        if (TypeDescriptor.GetProperties(instance)[nameof(ComboBox.DataSource)] is not PropertyDescriptor property)
        {
            return value;
        }
 
        object? dataSource = property.GetValue(instance);
 
        if (dataSource is null )
        {
            return value;
        }
 
        _designBindingPicker ??= new();
 
        DesignBinding oldSelection = new DesignBinding(dataSource, (string?)value);
        DesignBinding? newSelection = _designBindingPicker.Pick(
            context,
            provider,
            showDataSources: false,
            showDataMembers: true,
            selectListMembers: false,
            rootDataSource: dataSource,
            rootDataMember: string.Empty,
            initialSelectedItem: oldSelection
        );
 
        if (newSelection is null)
        {
            return value;
        }
 
        return newSelection.DataMember;
    }
 
    public override UITypeEditorEditStyle GetEditStyle(ITypeDescriptorContext? context) => UITypeEditorEditStyle.DropDown;
}