//********************************** Banshee Engine (www.banshee3d.com) **************************************************//
//**************** Copyright (c) 2016 Marko Pintera (marko.pintera@gmail.com). All rights reserved. **********************//
#pragma once

#include "BsEditorPrerequisites.h"
#include "EditorWindow/BsEditorWidgetManager.h"
#include "Utility/BsEvent.h"
#include "Math/BsRect2I.h"

namespace bs
{
	/** @addtogroup Implementation
	 *  @{
	 */

	/**
	 * Editor widget represents a single "window" in the editor. It may be dragged,	docked and can share space with multiple
	 * other widgets by using tabs.
	 *
	 * Each widget has its own position, size, GUI and update method. Widget is always docked inside an 
	 * EditorWidgetContainer unless it's being dragged and is not visible.
	 */
	class BS_ED_EXPORT EditorWidgetBase
	{
	public:
		/** Gets a unique name for this widget. This name will be used for referencing the widget by other systems. */
		const String& getName() const { return mName; }

		/** Gets the display name for the widget. This is what editor users will see in the widget title bar. */
		const HString& getDisplayName() const { return mDisplayName; }

		/**	Returns the X position of the widget inside of its container. */
		INT32 getX() const { return mX; }

		/**	Returns the Y position of the widget inside of its container. */
		INT32 getY() const { return mY; }

		/**	Returns the width of the widget in pixels. */
		UINT32 getWidth() const { return mWidth; }

		/**	Returns the height of the widget in pixels. */
		UINT32 getHeight() const { return mHeight; }

		/**	Returns the width of the widget when initially created, in pixels. */
		UINT32 getDefaultWidth() const { return mDefaultWidth; }

		/**	Returns the height of the widget when initially created, in pixels. */
		UINT32 getDefaultHeight() const { return mDefaultHeight; }

		/**	Returns the bounds of the widget in pixels, relative to its parent container. */
		Rect2I getBounds() const { return Rect2I(mX, mY, mWidth, mHeight); }

		/** Makes the widget in or out focus. Widget can only be made in focus if it is active. */
		void setHasFocus(bool focus);

		/**	Checks if the widget has focus (usually means user clicked on it last). */
		bool hasFocus() const { return mHasFocus; }

		/** Makes the widget active in its container. This means the widgets tab is active and the widget is visible. */
		void setActive();

		/** 
		 * Checks is the widget the currently active widget in its container. This means the widget's tab is active or
		 * the widget is the only one in its container. 
		 */
		bool isActive() const { return mIsActive; }

		/**
		 * Gets the parent editor window this widget is docked in. Can be null (for example when widget is in the process of
		 * dragging and not visible).
		 */
		EditorWindowBase* getParentWindow() const;

		/**
		 * Returns the parent widget container. Can be null (for example when widget is in the process of dragging and not 
		 * visible). 
		 */
		EditorWidgetContainer* _getParent() const { return mParent; }

		/**	Converts screen coordinates to coordinates relative to the widget. */
		Vector2I screenToWidgetPos(const Vector2I& screenPos) const;

		/**	Converts widget relative coordinates to screen coordiantes. */
		Vector2I widgetToScreenPos(const Vector2I& widgetPos) const;

		/**	Closes the widget, undocking it from its container and freeing any resources related to it. */
		void close();

		/** Internal method. Called once per frame.	*/
		virtual void update() { }

		Event<void(UINT32, UINT32)> onResized; /**< Triggered whenever widget size changes. */
		Event<void(INT32, INT32)> onMoved; /**< Triggered whenever widget position changes. */
		Event<void(EditorWidgetContainer*)> onParentChanged; /**< Triggered whenever widget parent container changes. */
		Event<void(bool)> onFocusChanged; /**< Triggered whenever widget receives or loses focus. */

		/** @name Internal
		 *  @{
		 */

		/**	Changes the size of the widget (and its internal GUI panel). */
		void _setSize(UINT32 width, UINT32 height);

		/**	Changes the position of the widget (and its internal GUI panel), relative to its parent container. */
		void _setPosition(INT32 x, INT32 y);

		/**
		 * Changes the parent container of the widget (for example when re-docking or moving a widget to another window). 
		 * Parent can be null (for example when widget is in the process of dragging and not visible).
		 */
		void _changeParent(EditorWidgetContainer* parent, UINT32 indx);

		/**	Sets or removes focus for this widget. */
		void _setHasFocus(bool focus);

		/** Disables the widget making its GUI contents not visible. The widget	remains docked in its container. */
		void _disable();

		/**	Enables the widget making its previously hidden GUI contents visible. */
		void _enable();

		/** @} */
	protected:
		friend class EditorWidgetManager;

		EditorWidgetBase(const HString& displayName, const String& name, UINT32 defaultWidth,
			UINT32 defaultHeight, EditorWidgetContainer& parentContainer);
		virtual ~EditorWidgetBase();

		/**	Triggered whenever widget position changes. */
		virtual void doOnMoved(INT32 x, INT32 y);

		/**	Triggered whenever widget size changes. */
		virtual void doOnResized(UINT32 width, UINT32 height);

		/**	Triggered whenever widget parent container changes. */
		virtual void doOnParentChanged();

		/**
		 * Returns the parent GUI widget. Before calling this you must ensure the widget has a container parent otherwise
		 * this method will fail.
		 */
		GUIWidget& getParentWidget() const;

		/**	Frees widget resources and deletes the instance. */
		static void destroy(EditorWidgetBase* widget);

		String mName;
		HString mDisplayName;
		EditorWidgetContainer* mParent = nullptr;
		INT32 mX = 0, mY = 0;
		UINT32 mWidth = 0, mHeight = 0;
		UINT32 mDefaultWidth, mDefaultHeight;
		UINT32 mIndex = 0;
		GUIPanel* mContent = nullptr;
		bool mHasFocus = false;
		bool mIsActive = true;
	};

	/** @} */

	/** @addtogroup EditorWindow-Internal
	 *  @{
	 */

	template <class Type> class EditorWidget;

	/**
	 * Helper class that registers a widget creation callback with the widget manager. The creation callback allows the
	 * runtime to open widgets just by their name without knowing the actual type.
	 */
	template<typename Type>
	struct RegisterWidgetOnStart
	{
	public:
		RegisterWidgetOnStart()
		{
			EditorWidgetManager::preRegisterWidget(Type::getTypeName(), &create);
		}

		/**	Creates a new widget of a specific type and adds it to the provided container. */
		static EditorWidgetBase* create(EditorWidgetContainer& parentContainer)
		{
			return bs_new<Type>(EditorWidget<Type>::ConstructPrivately(), parentContainer);
		}
	};

	/**
	 * Editor widget template class that widgets can inherit from. Ensures that	all widget implementations are automatically
	 * registered with the widget manager.
	 *
	 * @see		EditorWidgetBase
	 */
	template <class Type>
	class EditorWidget : public EditorWidgetBase
	{
		static volatile RegisterWidgetOnStart<Type> RegisterOnStart;

	protected:
		friend struct RegisterWidgetOnStart<Type>;

		struct ConstructPrivately {};

		EditorWidget(const HString& displayName, UINT32 defaultWidth, UINT32 defaultHeight, 
			EditorWidgetContainer& parentContainer)
			:EditorWidgetBase(displayName, Type::getTypeName(), defaultWidth, defaultHeight, parentContainer)
		{ }

	public:

		virtual ~EditorWidget() { }
	};

	template <typename Type>
	volatile RegisterWidgetOnStart<Type> EditorWidget<Type>::RegisterOnStart;

	/** @} */
}