namespace NoChillquarium;

/// <summary>
/// UI panel that paints a sprite via <see cref="PanelStyle.BackgroundImage"/> (Texture).
/// Mirror via CSS class <c>mirror-x</c> (Style.Transform is not a string in S&amp;box).
/// </summary>
[Library( "spritebox" )]
public class SpriteBox : Panel
{
	string _spriteId;
	Texture _applied;
	bool _mirror;
	bool _filled;

	public string Sprite
	{
		get => _spriteId;
		set
		{
			if ( string.Equals( _spriteId, value, StringComparison.OrdinalIgnoreCase ) )
				return;
			_spriteId = value;
			ApplyTexture();
		}
	}

	public string SpriteId
	{
		get => Sprite;
		set => Sprite = value;
	}

	/// <summary>When true, adds CSS class mirror-x (scaleX -1).</summary>
	public bool Mirror
	{
		get => _mirror;
		set
		{
			if ( _mirror == value )
				return;
			_mirror = value;
			SetClass( "mirror-x", _mirror );
		}
	}

	public SpriteBox()
	{
		AddClass( "spritebox" );
		EnsureFill();
	}

	public override void Tick()
	{
		base.Tick();
		// Only recover if texture never bound (panel recreated mid-frame).
		if ( _applied is null && !string.IsNullOrEmpty( _spriteId ) )
			ApplyTexture();
	}

	void EnsureFill()
	{
		if ( _filled )
			return;
		Style.Width = Length.Fraction( 1f );
		Style.Height = Length.Fraction( 1f );
		try
		{
			Style.BackgroundSizeX = Length.Percent( 100f );
			Style.BackgroundSizeY = Length.Percent( 100f );
		}
		catch
		{
			// optional style props
		}
		_filled = true;
	}

	void ApplyTexture()
	{
		EnsureFill();
		SetClass( "mirror-x", _mirror );

		if ( string.IsNullOrWhiteSpace( _spriteId ) )
		{
			Style.BackgroundImage = null;
			_applied = null;
			return;
		}

		var tex = SpriteCatalog.GetTexture( _spriteId );
		if ( tex is null )
		{
			Style.BackgroundImage = null;
			_applied = null;
			return;
		}

		if ( !ReferenceEquals( _applied, tex ) )
			Style.BackgroundImage = tex;

		_applied = tex;
	}
}