// Distributed under the MIT License (MIT) (see accompanying LICENSE file)

#pragma once

#include "ImGuiInputState.h"

#include <Widgets/SLeafWidget.h>


class FImGuiModuleManager;

// Slate widget for rendering ImGui output and storing Slate inputs.
class SImGuiWidget : public SLeafWidget
{
	typedef SLeafWidget Super;

public:

	SLATE_BEGIN_ARGS(SImGuiWidget)
	{}
	SLATE_ARGUMENT(FImGuiModuleManager*, ModuleManager)
	SLATE_ARGUMENT(int32, ContextIndex)
	SLATE_END_ARGS()

	void Construct(const FArguments& InArgs);

	~SImGuiWidget();

	// Get index of the context that this widget is targeting.
	int32 GetContextIndex() const { return ContextIndex; }

	// Get input state associated with this widget.
	const FImGuiInputState& GetInputState() const { return InputState; }

	//----------------------------------------------------------------------------------------------------
	// SWidget overrides
	//----------------------------------------------------------------------------------------------------

	virtual bool SupportsKeyboardFocus() const override { return true; }

	virtual FReply OnKeyChar(const FGeometry& MyGeometry, const FCharacterEvent& CharacterEvent) override;

	virtual FReply OnKeyDown(const FGeometry& MyGeometry, const FKeyEvent& KeyEvent) override;

	virtual FReply OnKeyUp(const FGeometry& MyGeometry, const FKeyEvent& KeyEvent) override;

	virtual FReply OnMouseButtonDown(const FGeometry& MyGeometry, const FPointerEvent& MouseEvent) override;

	virtual FReply OnMouseButtonDoubleClick(const FGeometry& MyGeometry, const FPointerEvent& MouseEvent) override;

	virtual FReply OnMouseButtonUp(const FGeometry& MyGeometry, const FPointerEvent& MouseEvent) override;

	virtual FReply OnMouseWheel(const FGeometry& MyGeometry, const FPointerEvent& MouseEvent) override;

	virtual FReply OnMouseMove(const FGeometry& MyGeometry, const FPointerEvent& MouseEvent) override;

	virtual FReply OnFocusReceived(const FGeometry& MyGeometry, const FFocusEvent& FocusEvent) override;

	virtual void OnFocusLost(const FFocusEvent& FocusEvent) override;

	virtual void OnMouseEnter(const FGeometry& MyGeometry, const FPointerEvent& MouseEvent) override;

	virtual void OnMouseLeave(const FPointerEvent& MouseEvent) override;

private:

	enum class EInputMode
	{
		None,
		MouseOnly,
		MouseAndKeyboard
	};

	FORCEINLINE void CopyModifierKeys(const FInputEvent& InputEvent);
	FORCEINLINE void CopyModifierKeys(const FPointerEvent& MouseEvent);

	// Determine new input mode based on requirement hints.
	void UpdateInputMode(bool bNeedKeyboard, bool bNeedMouse);

	void OnPostImGuiUpdate();

	virtual int32 OnPaint(const FPaintArgs& Args, const FGeometry& AllottedGeometry, const FSlateRect& MyClippingRect, FSlateWindowElementList& OutDrawElements, int32 LayerId, const FWidgetStyle& WidgetStyle, bool bParentEnabled) const override;

	virtual FVector2D ComputeDesiredSize(float) const override;

	FImGuiModuleManager* ModuleManager = nullptr;

	mutable TArray<FSlateVertex> VertexBuffer;
	mutable TArray<SlateIndex> IndexBuffer;

	int32 ContextIndex = 0;

	EInputMode InputMode = EInputMode::None;

	FImGuiInputState InputState;
};