// Copyright (C) 2002-2012 Nikolaus Gebhardt
// This file is part of the "Irrlicht Engine".
// For conditions of distribution and use, see copyright notice in irrlicht.h

#pragma once

#include "IReferenceCounted.h"
#include "IGUISkin.h"
#include "rect.h"
#include "EFocusFlags.h" // IWYU pragma: export
#include "IEventReceiver.h"
#include "path.h"

class IOSOperator;
class IEventReceiver;

namespace io
{
class IReadFile;
class IWriteFile;
class IFileSystem;
} // end namespace io
namespace video
{
class IVideoDriver;
class ITexture;
} // end namespace video

namespace gui
{

class IGUIElement;
class IGUIFont;
class IGUISpriteBank;
class IGUIScrollBar;
class IGUIImage;
class IGUICheckBox;
class IGUIListBox;
class IGUIImageList;
class IGUIFileOpenDialog;
class IGUIStaticText;
class IGUIEditBox;
class IGUITabControl;
class IGUITab;
class IGUIComboBox;
class IGUIButton;
class IGUIWindow;

//! GUI Environment. Used as factory and manager of all other GUI elements.
/** \par This element can create the following events of type EGUI_EVENT_TYPE (which are passed on to focused sub-elements):
\li EGET_ELEMENT_FOCUS_LOST
\li EGET_ELEMENT_FOCUSED
\li EGET_ELEMENT_LEFT
\li EGET_ELEMENT_HOVERED
*/
class IGUIEnvironment : public virtual IReferenceCounted
{
public:
	//! Draws all gui elements by traversing the GUI environment starting at the root node.
	/** \param  When true ensure the GuiEnvironment (aka the RootGUIElement) has the same size as the current driver screensize.
				Can be set to false to control that size yourself, p.E when not the full size should be used for UI. */
	virtual void drawAll(bool useScreenSize = true) = 0;

	//! Sets the focus to an element.
	/** Causes a EGET_ELEMENT_FOCUS_LOST event followed by a
	EGET_ELEMENT_FOCUSED event. If someone absorbed either of the events,
	then the focus will not be changed.
	\param element Pointer to the element which shall get the focus.
	\return True on success, false on failure */
	virtual bool setFocus(IGUIElement *element) = 0;

	//! Returns the element which holds the focus.
	/** \return Pointer to the element with focus. */
	virtual IGUIElement *getFocus() const = 0;

	//! Returns the element which was last under the mouse cursor
	/** NOTE: This information is updated _after_ the user-eventreceiver
	received it's mouse-events. To find the hovered element while catching
	mouse events you have to use instead:
	IGUIEnvironment::getRootGUIElement()->getElementFromPoint(mousePos);
	\return Pointer to the element under the mouse. */
	virtual IGUIElement *getHovered() const = 0;

	//! Removes the focus from an element.
	/** Causes a EGET_ELEMENT_FOCUS_LOST event. If the event is absorbed
	then the focus will not be changed.
	\param element Pointer to the element which shall lose the focus.
	\return True on success, false on failure */
	virtual bool removeFocus(IGUIElement *element) = 0;

	//! Returns whether the element has focus
	/** \param element Pointer to the element which is tested.
	\param checkSubElements When true and focus is on a sub-element of element then it will still count as focused and return true
	\return True if the element has focus, else false. */
	virtual bool hasFocus(const IGUIElement *element, bool checkSubElements = false) const = 0;

	//! Returns the current video driver.
	/** \return Pointer to the video driver. */
	virtual video::IVideoDriver *getVideoDriver() const = 0;

	//! Returns the file system.
	/** \return Pointer to the file system. */
	virtual io::IFileSystem *getFileSystem() const = 0;

	//! returns a pointer to the OS operator
	/** \return Pointer to the OS operator. */
	virtual IOSOperator *getOSOperator() const = 0;

	//! Removes all elements from the environment.
	virtual void clear() = 0;

	//! Posts an input event to the environment.
	/** Usually you do not have to
	use this method, it is used by the engine internally.
	\param event The event to post.
	\return True if succeeded, else false. */
	virtual bool postEventFromUser(const SEvent &event) = 0;

	//! This sets a new event receiver for gui events.
	/** Usually you do not have to
	use this method, it is used by the engine internally.
	\param evr Pointer to the new receiver. */
	virtual void setUserEventReceiver(IEventReceiver *evr) = 0;

	//! Returns pointer to the current gui skin.
	/** \return Pointer to the GUI skin. */
	virtual IGUISkin *getSkin() const = 0;

	//! Sets a new GUI Skin
	/** You can use this to change the appearance of the whole GUI
	Environment.
	\param skin New skin to use.
	*/
	virtual void setSkin(IGUISkin *skin) = 0;

	//! Creates a new GUI Skin.
	/** Use setSkin() to set the created skin.
	\param type The type of the new skin.
	\return Pointer to the created skin.
	If you no longer need it, you should call IGUISkin::drop().
	See IReferenceCounted::drop() for more information. */
	virtual IGUISkin *createSkin() = 0;

	//! Creates the image list from the given texture.
	/** \param texture Texture to split into images
	\param imageSize Dimension of each image
	\param useAlphaChannel Flag whether alpha channel of the texture should be honored.
	\return Pointer to the font. Returns 0 if the font could not be loaded.
	This pointer should not be dropped. See IReferenceCounted::drop() for
	more information. */
	virtual IGUIImageList *createImageList(video::ITexture *texture,
			core::dimension2d<s32> imageSize,
			bool useAlphaChannel) = 0;

	//! Returns pointer to the font with the specified filename.
	/** Loads the font if it was not loaded before.
	\param filename Filename of the Font.
	\return Pointer to the font. Returns 0 if the font could not be loaded.
	This pointer should not be dropped. See IReferenceCounted::drop() for
	more information. */
	virtual IGUIFont *getFont(const io::path &filename) = 0;

	//! Adds an externally loaded font to the font list.
	/** This method allows to attach an already loaded font to the list of
	existing fonts. The font is grabbed if non-null and adding was successful.
	\param name Name the font should be stored as.
	\param font Pointer to font to add.
	\return Pointer to the font stored. This can differ from given parameter if the name previously existed. */
	virtual IGUIFont *addFont(const io::path &name, IGUIFont *font) = 0;

	//! remove loaded font
	virtual void removeFont(IGUIFont *font) = 0;

	//! Returns the default built-in font.
	/** \return Pointer to the default built-in font.
	This pointer should not be dropped. See IReferenceCounted::drop() for
	more information. */
	virtual IGUIFont *getBuiltInFont() const = 0;

	//! Returns pointer to the sprite bank which was added with addEmptySpriteBank
	/** TODO: This should load files in the future, but not implemented so far.
	\param filename Name of a spritebank added with addEmptySpriteBank
	\return Pointer to the sprite bank. Returns 0 if it could not be loaded.
	This pointer should not be dropped. See IReferenceCounted::drop() for more information. */
	virtual IGUISpriteBank *getSpriteBank(const io::path &filename) = 0;

	//! Adds an empty sprite bank to the manager
	/** \param name Name of the new sprite bank.
	\return Pointer to the sprite bank.
	This pointer should not be dropped. See IReferenceCounted::drop() for more information. */
	virtual IGUISpriteBank *addEmptySpriteBank(const io::path &name) = 0;

	//! Returns the root gui element.
	/** This is the first gui element, the (direct or indirect) parent of all
	other gui elements. It is a valid IGUIElement, with dimensions the same
	size as the screen.
	\return Pointer to the root element of the GUI. The returned pointer
	should not be dropped. See IReferenceCounted::drop() for more
	information. */
	virtual IGUIElement *getRootGUIElement() = 0;

	//! Adds a button element.
	/** \param rectangle Rectangle specifying the borders of the button.
	\param parent Parent gui element of the button.
	\param id Id with which the gui element can be identified.
	\param text Text displayed on the button.
	\param tooltiptext Text displayed in the tooltip.
	\return Pointer to the created button. Returns 0 if an error occurred.
	This pointer should not be dropped. See IReferenceCounted::drop() for
	more information. */
	virtual IGUIButton *addButton(const core::rect<s32> &rectangle,
			IGUIElement *parent = 0, s32 id = -1, const wchar_t *text = 0, const wchar_t *tooltiptext = 0) = 0;

	//! Adds a scrollbar.
	/** \param horizontal Specifies if the scroll bar is drawn horizontal
	or vertical.
	\param rectangle Rectangle specifying the borders of the scrollbar.
	\param parent Parent gui element of the scroll bar.
	\param id Id to identify the gui element.
	\return Pointer to the created scrollbar. Returns 0 if an error
	occurred. This pointer should not be dropped. See
	IReferenceCounted::drop() for more information. */
	virtual IGUIScrollBar *addScrollBar(bool horizontal, const core::rect<s32> &rectangle,
			IGUIElement *parent = 0, s32 id = -1) = 0;

	//! Adds an image element.
	/** \param image Image to be displayed.
	\param pos Position of the image. The width and height of the image is
	taken from the image.
	\param useAlphaChannel Sets if the image should use the alpha channel
	of the texture to draw itself.
	\param parent Parent gui element of the image.
	\param id Id to identify the gui element.
	\param text Title text of the image (not displayed).
	\return Pointer to the created image element. Returns 0 if an error
	occurred. This pointer should not be dropped. See
	IReferenceCounted::drop() for more information. */
	virtual IGUIImage *addImage(video::ITexture *image, core::position2d<s32> pos,
			bool useAlphaChannel = true, IGUIElement *parent = 0, s32 id = -1, const wchar_t *text = 0) = 0;

	//! Adds an image element.
	/** Use IGUIImage::setImage later to set the image to be displayed.
	\param rectangle Rectangle specifying the borders of the image.
	\param parent Parent gui element of the image.
	\param id Id to identify the gui element.
	\param text Title text of the image (not displayed).
	\param useAlphaChannel Sets if the image should use the alpha channel
	of the texture to draw itself.
	\return Pointer to the created image element. Returns 0 if an error
	occurred. This pointer should not be dropped. See
	IReferenceCounted::drop() for more information. */
	virtual IGUIImage *addImage(const core::rect<s32> &rectangle,
			IGUIElement *parent = 0, s32 id = -1, const wchar_t *text = 0, bool useAlphaChannel = true) = 0;

	//! Adds a checkbox element.
	/** \param checked Define the initial state of the check box.
	\param rectangle Rectangle specifying the borders of the check box.
	\param parent Parent gui element of the check box.
	\param id Id to identify the gui element.
	\param text Title text of the check box.
	\return Pointer to the created check box. Returns 0 if an error
	occurred. This pointer should not be dropped. See
	IReferenceCounted::drop() for more information. */
	virtual IGUICheckBox *addCheckBox(bool checked, const core::rect<s32> &rectangle,
			IGUIElement *parent = 0, s32 id = -1, const wchar_t *text = 0) = 0;

	//! Adds a list box element.
	/** \param rectangle Rectangle specifying the borders of the list box.
	\param parent Parent gui element of the list box.
	\param id Id to identify the gui element.
	\param drawBackground Flag whether the background should be drawn.
	\return Pointer to the created list box. Returns 0 if an error occurred.
	This pointer should not be dropped. See IReferenceCounted::drop() for
	more information. */
	virtual IGUIListBox *addListBox(const core::rect<s32> &rectangle,
			IGUIElement *parent = 0, s32 id = -1, bool drawBackground = false) = 0;

	//! Adds a file open dialog.
	/** \param title Text to be displayed as the title of the dialog.
	\param modal Defines if the dialog is modal. This means, that all other
	gui elements which were created before the message box cannot be used
	until this messagebox is removed.
	\param parent Parent gui element of the dialog.
	\param id Id to identify the gui element.
	\param restoreCWD If set to true, the current working directory will be
	restored after the dialog is closed in some way. Otherwise the working
	directory will be the one that the file dialog was last showing.
	\param startDir Optional path for which the file dialog will be opened.
	\return Pointer to the created file open dialog. Returns 0 if an error
	occurred. This pointer should not be dropped. See
	IReferenceCounted::drop() for more information. */
	virtual IGUIFileOpenDialog *addFileOpenDialog(const wchar_t *title = 0,
			bool modal = true, IGUIElement *parent = 0, s32 id = -1,
			bool restoreCWD = false, io::path::char_type *startDir = 0) = 0;

	//! Adds a static text.
	/** \param text Text to be displayed. Can be altered after creation by SetText().
	\param rectangle Rectangle specifying the borders of the static text
	\param border Set to true if the static text should have a 3d border.
	\param wordWrap Enable if the text should wrap into multiple lines.
	\param parent Parent item of the element, e.g. a window.
	\param id The ID of the element.
	\param fillBackground Enable if the background shall be filled.
	Defaults to false.
	\return Pointer to the created static text. Returns 0 if an error
	occurred. This pointer should not be dropped. See
	IReferenceCounted::drop() for more information. */
	virtual IGUIStaticText *addStaticText(const wchar_t *text, const core::rect<s32> &rectangle,
			bool border = false, bool wordWrap = true, IGUIElement *parent = 0, s32 id = -1,
			bool fillBackground = false) = 0;

	//! Adds an edit box.
	/** Supports Unicode input from every keyboard around the world,
	scrolling, copying and pasting (exchanging data with the clipboard
	directly), maximum character amount, marking, and all shortcuts like
	ctrl+X, ctrl+V, ctrl+C, shift+Left, shift+Right, Home, End, and so on.
	\param text Text to be displayed. Can be altered after creation
	by setText().
	\param rectangle Rectangle specifying the borders of the edit box.
	\param border Set to true if the edit box should have a 3d border.
	\param parent Parent item of the element, e.g. a window.
	Set it to 0 to place the edit box directly in the environment.
	\param id The ID of the element.
	\return Pointer to the created edit box. Returns 0 if an error occurred.
	This pointer should not be dropped. See IReferenceCounted::drop() for
	more information. */
	virtual IGUIEditBox *addEditBox(const wchar_t *text, const core::rect<s32> &rectangle,
			bool border = true, IGUIElement *parent = 0, s32 id = -1) = 0;

	//! Adds a tab control to the environment.
	/** \param rectangle Rectangle specifying the borders of the tab control.
	\param parent Parent item of the element, e.g. a window.
	Set it to 0 to place the tab control directly in the environment.
	\param fillbackground Specifies if the background of the tab control
	should be drawn.
	\param border Specifies if a flat 3d border should be drawn. This is
	usually not necessary unless you place the control directly into
	the environment without a window as parent.
	\param id An identifier for the tab control.
	\return Pointer to the created tab control element. Returns 0 if an
	error occurred. This pointer should not be dropped. See
	IReferenceCounted::drop() for more information. */
	virtual IGUITabControl *addTabControl(const core::rect<s32> &rectangle,
			IGUIElement *parent = 0, bool fillbackground = false,
			bool border = true, s32 id = -1) = 0;

	//! Adds tab to the environment.
	/** You can use this element to group other elements. This is not used
	for creating tabs on tab controls, please use IGUITabControl::addTab()
	for this instead.
	\param rectangle Rectangle specifying the borders of the tab.
	\param parent Parent item of the element, e.g. a window.
	Set it to 0 to place the tab directly in the environment.
	\param id An identifier for the tab.
	\return Pointer to the created tab. Returns 0 if an
	error occurred. This pointer should not be dropped. See
	IReferenceCounted::drop() for more information. */
	virtual IGUITab *addTab(const core::rect<s32> &rectangle,
			IGUIElement *parent = 0, s32 id = -1) = 0;

	//! Adds a combo box to the environment.
	/** \param rectangle Rectangle specifying the borders of the combo box.
	\param parent Parent item of the element, e.g. a window.
	Set it to 0 to place the combo box directly in the environment.
	\param id An identifier for the combo box.
	\return Pointer to the created combo box. Returns 0 if an
	error occurred. This pointer should not be dropped. See
	IReferenceCounted::drop() for more information. */
	virtual IGUIComboBox *addComboBox(const core::rect<s32> &rectangle,
			IGUIElement *parent = 0, s32 id = -1) = 0;

	//! Find the next element which would be selected when pressing the tab-key
	/** If you set the focus for the result you can manually force focus-changes like they
	would happen otherwise by the tab-keys.
	\param reverse When true it will search backward (toward lower TabOrder numbers, like shift+tab)
	\param group When true it will search for the next tab-group (like ctrl+tab)
	*/
	virtual IGUIElement *getNextElement(bool reverse = false, bool group = false) = 0;

	//! Set the way the gui will handle automatic focus changes
	/** The default is (EFF_SET_ON_LMOUSE_DOWN | EFF_SET_ON_TAB).
	with the left mouse button.
	This does not affect the setFocus function itself - users can still call that whenever they want on any element.
	\param flags A bitmask which is a combination of ::EFOCUS_FLAG flags.*/
	virtual void setFocusBehavior(u32 flags) = 0;

	//! Get the way the gui does handle focus changes
	/** \returns A bitmask which is a combination of ::EFOCUS_FLAG flags.*/
	virtual u32 getFocusBehavior() const = 0;

	//! Adds a IGUIElement to deletion queue.
	/** Queued elements will be removed at the end of each drawAll call.
	Or latest in the destructor of the GUIEnvironment.
	This can be used to allow an element removing itself safely in a function
	iterating over gui elements, like an overloaded	IGUIElement::draw or
	IGUIElement::OnPostRender function.
	Note that in general just calling IGUIElement::remove() is enough.
	Unless you create your own GUI elements removing themselves you won't need it.
	\param element: Element to remove */
	virtual void addToDeletionQueue(IGUIElement *element) = 0;
};

} // end namespace gui
