using System.Numerics;
using Voile.Input;
using Voile.Rendering;

namespace Voile.UI;

public interface IElement
{
    /// <summary>
    /// This element's position in pixels relative to the viewport top-left edge.
    /// </summary>
    public Vector2 GlobalPosition { get; }
    /// <summary>
    /// The size of this element.
    /// </summary>
    public Rect Size { get; set; }
}

public interface IParentableElement
{
    /// <summary>
    /// This parentable element's children.
    /// </summary>
    public IReadOnlyList<UIElement> Children { get; }
    /// <summary>
    /// Add a child element to this element.
    /// </summary>
    /// <param name="child">Child <see cref="UIElement"/>.</param>
    public void AddChild(UIElement child);
    /// <summary>
    /// Remove a child element from this element.
    /// </summary>
    /// <param name="child">Child <see cref="UIElement"/> to remove.</param>
    public void RemoveChild(UIElement child);
}

public interface IResizeableElement
{
    /// <summary>
    /// Get a minimum rectangle size for this element.
    /// </summary>
    public abstract Rect MinimumSize { get; }
}

public interface IUpdatableElement
{
    /// <summary>
    /// Specifies if this element's properties have changed, making it necessary to update it.
    /// </summary>
    public bool Dirty { get; }
    /// <summary>
    /// Update this element.
    /// </summary>
    void Update();
    /// <summary>
    /// Marks this element as changed, requiring an update.
    /// </summary>
    void MarkDirty();
}

public interface IRenderableElement
{
    /// <summary>
    /// Specifies if this element should be drawn.
    /// </summary>
    public bool Visible { get; set; }
    /// <summary>
    /// Render this element.
    /// </summary>
    /// <param name="renderer">Renderer to call draw operations on.</param>
    /// <param name="style">A style to use to draw this element.</param>
    public void Render(RenderSystem renderer, Style style);
    /// <summary>
    /// Draws this element's size bounds.
    /// </summary>
    /// <param name="renderer">Renderer to use.</param>
    public void DrawSize(RenderSystem renderer);
}

public interface IInputElement
{
    /// <summary>
    /// Specifies if this element should ignore inputs.
    /// </summary>
    public bool IgnoreInput { get; set; }
    /// <summary>
    /// Send an input action to this element.
    /// </summary>
    /// <param name="action">Input action to send.</param>
    void Input(UIInputContext action);
}

public interface IAnchorableElement
{
    public Anchor Anchor { get; set; }
    public Vector2 AnchorOffset { get; set; }
    public void ApplyAnchor(Vector2 parentPosition, Rect parentRect);
}