using Sandbox.UI;

namespace Duccsoft.ImGui;

internal partial class ImGuiSystem
{
	[ConVar( "imgui_mouse_capture" )]
	public static bool EnableMouseCapture { get; set; } = true;

	/// <summary>
	/// Filters in the current mouse state in to the "highest priority" button clicked,
	/// returning null if no button is clicked.
	/// </summary>
	public ImGuiMouseButton? MouseButton
	{
		get
		{
			if ( MouseState.MiddleClickDown )
				return ImGuiMouseButton.Middle;
			else if ( MouseState.RightClickDown )
				return ImGuiMouseButton.Right;
			else if ( MouseState.LeftClickDown )
				return ImGuiMouseButton.Left;

			return null;
		}
	}

	private PassthroughPanel _inputPanel;

	private void InitInput()
	{
		InputState = new ImGuiIO();
		if ( EnableMouseCapture )
		{
			_inputPanel = CreatePassthrough();
		}
	}

	private PassthroughPanel CreatePassthrough()
	{
		var inputPanel = new PassthroughPanel()
		{
			Scene = Scene
		};
		inputPanel.Style.PointerEvents = PointerEvents.All;
		inputPanel.LeftClick += p =>
		{
			if ( p )
			{
				MouseState.LeftClickPosition = Mouse.Position;
			}
			MouseState.LeftClickPressed = p;
			MouseState.LeftClickDown = p;
			MouseState.LeftClickReleased = !p;
		};
		inputPanel.RightClick += p =>
		{
			if ( p )
			{
				MouseState.RightClickPosition = Mouse.Position;
			}
			MouseState.RightClickPressed = p;
			MouseState.RightClickDown = p;
			MouseState.RightClickReleased = !p;
		};
		inputPanel.MiddleClick += p =>
		{
			if ( p )
			{
				MouseState.MiddleClickPosition = Mouse.Position;
			}
			MouseState.MiddleClickPressed = p;
			MouseState.MiddleClickDown = p;
			MouseState.MiddleClickReleased = !p;
		};
		return inputPanel;
	}

	public ImGuiIO InputState { get; private set; }

	private void InitializeInput()
	{
		if ( EnableMouseCapture )
		{
			_inputPanel ??= CreatePassthrough();
		}
		else
		{
			_inputPanel?.Delete();
			_inputPanel = null;
		}
		UpdateMouseState();
	}

	private void ClearInput()
	{
		ClearMouseState();
	}

	private void UpdateMouseState()
	{
		if ( !EnableMouseCapture )
			return;

		InputState.WantCaptureMouse = PreviousHoveredWindowId is not null;
		_inputPanel.Style.PointerEvents = InputState.WantCaptureMouse
			? PointerEvents.All
			: PointerEvents.None;

		MouseState.Position = Mouse.Position;
		switch ( MouseButton )
		{
			case ImGuiMouseButton.Right:
				MouseState.RightClickDragFrameDelta = Mouse.Delta;
				break;
			case ImGuiMouseButton.Middle:
				MouseState.MiddleClickDragFrameDelta = Mouse.Delta;
				break;
			default:
				MouseState.LeftClickDragFrameDelta = Mouse.Delta;
				break;
		}
	}

	private void ClearMouseState()
	{
		if ( !MouseState.LeftClickDown )
		{
			ClickedElementId = null;
		}
		MouseState.LeftClickPressed = false;
		MouseState.LeftClickReleased = false;
		MouseState.LeftClickDragFrameDelta = 0f;
		MouseState.RightClickPressed = false;
		MouseState.RightClickReleased = false;
		MouseState.RightClickDragFrameDelta = 0f;
		MouseState.MiddleClickPressed = false;
		MouseState.MiddleClickReleased = false;
		MouseState.MiddleClickDragFrameDelta = 0f;
	}
}