// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
 
using System.Collections.Specialized;
using System.ComponentModel;
using System.Drawing;
using System.Windows.Forms.Layout;
 
namespace System.Windows.Forms;
 
internal abstract class ArrangedElement : Component, IArrangedElement
{
    private Rectangle _bounds = Rectangle.Empty;
    private IArrangedElement? _parent;
    private BitVector32 _state;
    private readonly PropertyStore _propertyStore = new();  // Contains all properties that are not always set.
 
    private static readonly int s_stateVisible = BitVector32.CreateMask();
 
    internal ArrangedElement()
    {
        Padding = DefaultPadding;
        Margin = DefaultMargin;
        _state[s_stateVisible] = true;
    }
 
    public Rectangle Bounds
    {
        get
        {
            return _bounds;
        }
    }
 
    ArrangedElementCollection IArrangedElement.Children
    {
        get { return GetChildren(); }
    }
 
    IArrangedElement? IArrangedElement.Container
    {
        get { return GetContainer(); }
    }
 
    protected virtual Padding DefaultMargin
    {
        get { return Padding.Empty; }
    }
 
    protected virtual Padding DefaultPadding
    {
        get { return Padding.Empty; }
    }
 
    public virtual Rectangle DisplayRectangle
    {
        get
        {
            Rectangle displayRectangle = Bounds;
            return displayRectangle;
        }
    }
 
    public abstract LayoutEngine LayoutEngine
    {
        get;
    }
 
    public Padding Margin
    {
        get { return CommonProperties.GetMargin(this); }
        set
        {
            Debug.Assert((value.Right >= 0 && value.Left >= 0 && value.Top >= 0 && value.Bottom >= 0), "who's setting margin negative?");
            value = LayoutUtils.ClampNegativePaddingToZero(value);
            if (Margin != value)
            { CommonProperties.SetMargin(this, value); }
        }
    }
 
    public virtual Padding Padding
    {
        get { return CommonProperties.GetPadding(this, DefaultPadding); }
        set
        {
            Debug.Assert((value.Right >= 0 && value.Left >= 0 && value.Top >= 0 && value.Bottom >= 0), "who's setting padding negative?");
            value = LayoutUtils.ClampNegativePaddingToZero(value);
            if (Padding != value)
            { CommonProperties.SetPadding(this, value); }
        }
    }
 
    public virtual IArrangedElement? Parent
    {
        get
        {
            return _parent;
        }
        set
        {
            _parent = value;
        }
    }
 
    public virtual bool ParticipatesInLayout
    {
        get
        {
            return Visible;
        }
    }
 
    PropertyStore IArrangedElement.Properties
    {
        get
        {
            return Properties;
        }
    }
 
    private PropertyStore Properties
    {
        get
        {
            return _propertyStore;
        }
    }
 
    public virtual bool Visible
    {
        get
        {
            return _state[s_stateVisible];
        }
        set
        {
            if (_state[s_stateVisible] != value)
            {
                _state[s_stateVisible] = value;
                if (Parent is not null)
                {
                    LayoutTransaction.DoLayout(Parent, this, PropertyNames.Visible);
                }
            }
        }
    }
 
    protected abstract IArrangedElement? GetContainer();
 
    protected abstract ArrangedElementCollection GetChildren();
 
    public virtual Size GetPreferredSize(Size constrainingSize)
    {
        Size preferredSize = LayoutEngine.GetPreferredSize(this, constrainingSize - Padding.Size) + Padding.Size;
 
        return preferredSize;
    }
 
    public virtual void PerformLayout(IArrangedElement container, string? propertyName)
    {
        OnLayout(new LayoutEventArgs(container, propertyName));
    }
 
    protected virtual void OnLayout(LayoutEventArgs e) => LayoutEngine.Layout(this, e);
 
    protected virtual void OnBoundsChanged(Rectangle oldBounds, Rectangle newBounds)
    {
        ((IArrangedElement)this).PerformLayout(this, PropertyNames.Size);
    }
 
    public void SetBounds(Rectangle bounds, BoundsSpecified specified)
    {
        // in this case the parent is telling us to refresh our bounds - don't
        // call PerformLayout
        SetBoundsCore(bounds, specified);
    }
 
    protected virtual void SetBoundsCore(Rectangle bounds, BoundsSpecified specified)
    {
        if (bounds != _bounds)
        {
            Rectangle oldBounds = _bounds;
 
            _bounds = bounds;
            OnBoundsChanged(oldBounds, bounds);
        }
    }
}