// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System.Drawing;
 
namespace System.Windows.Forms;
 
public partial class ToolStripDropDownButton
{
    private protected class ToolStripDropDownButtonInternalLayout : ToolStripItemInternalLayout
    {
        private readonly ToolStripDropDownButton _ownerItem;
        private static readonly Size s_logicalDropDownArrowSize = new(5, 3);
        private static Size s_dropDownArrowSize = s_logicalDropDownArrowSize;
        private Padding _dropDownArrowPadding;
        private Rectangle _dropDownArrowRect = Rectangle.Empty;
 
        public ToolStripDropDownButtonInternalLayout(ToolStripDropDownButton ownerItem)
            : base(ownerItem)
        {
            const int LogicalDropDownArrowPadding = 2;
            int dpi = ownerItem.DeviceDpi;
 
            // These 2 values are used to calculate size of the clickable drop down button on the right of the image/text.
            s_dropDownArrowSize = ScaleHelper.ScaleToDpi(s_logicalDropDownArrowSize, dpi);
            _dropDownArrowPadding = new(ScaleHelper.ScaleToDpi(LogicalDropDownArrowPadding, dpi));
 
            _ownerItem = ownerItem;
        }
 
        public override Size GetPreferredSize(Size constrainingSize)
        {
            Size preferredSize = base.GetPreferredSize(constrainingSize);
            if (_ownerItem.ShowDropDownArrow)
            {
                if (_ownerItem.TextDirection == ToolStripTextDirection.Horizontal)
                {
                    preferredSize.Width += DropDownArrowRect.Width + _dropDownArrowPadding.Horizontal;
                }
                else
                {
                    preferredSize.Height += DropDownArrowRect.Height + _dropDownArrowPadding.Vertical;
                }
            }
 
            return preferredSize;
        }
 
        protected override ToolStripItemLayoutOptions CommonLayoutOptions()
        {
            ToolStripItemLayoutOptions options = base.CommonLayoutOptions();
 
            if (_ownerItem.ShowDropDownArrow)
            {
                if (_ownerItem.TextDirection == ToolStripTextDirection.Horizontal)
                {
                    // We're rendering horizontal.... make sure to take care of RTL issues.
 
                    int widthOfDropDown = s_dropDownArrowSize.Width + _dropDownArrowPadding.Horizontal;
                    options.Client.Width -= widthOfDropDown;
 
                    if (_ownerItem.RightToLeft == RightToLeft.Yes)
                    {
                        // if RightToLeft.Yes: [ v | rest of drop down button ]
                        options.Client.Offset(widthOfDropDown, 0);
                        _dropDownArrowRect = new Rectangle(_dropDownArrowPadding.Left, 0, s_dropDownArrowSize.Width, _ownerItem.Bounds.Height);
                    }
                    else
                    {
                        // if RightToLeft.No [ rest of drop down button | v ]
                        _dropDownArrowRect = new Rectangle(options.Client.Right, 0, s_dropDownArrowSize.Width, _ownerItem.Bounds.Height);
                    }
                }
                else
                {
                    // else we're rendering vertically.
                    int heightOfDropDown = s_dropDownArrowSize.Height + _dropDownArrowPadding.Vertical;
 
                    options.Client.Height -= heightOfDropDown;
 
                    // [ rest of button / v]
                    _dropDownArrowRect = new Rectangle(0, options.Client.Bottom + _dropDownArrowPadding.Top, _ownerItem.Bounds.Width - 1, s_dropDownArrowSize.Height);
                }
            }
 
            return options;
        }
 
        public Rectangle DropDownArrowRect
        {
            get
            {
                return _dropDownArrowRect;
            }
        }
    }
}