/* ScummVM - Graphic Adventure Engine
 *
 * ScummVM is the legal property of its developers, whose names
 * are too numerous to list here. Please refer to the COPYRIGHT
 * file distributed with this source distribution.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#ifndef GRAPHICS_CURSORMAN_H
#define GRAPHICS_CURSORMAN_H

#include "common/scummsys.h"
#include "common/stack.h"
#include "common/singleton.h"
#include "graphics/cursor.h"
#include "graphics/surface.h"

namespace Graphics {

/**
 * @defgroup graphics_cursorman Cursor manager
 * @ingroup graphics
 *
 * @brief  The CursorManager class for managing the behavior of the mouse cursor.
 *
 * @{
 */

class CursorManager : public Common::Singleton<CursorManager> {
public:
	/** Return whether the mouse cursor is visible. */
	bool isVisible();

	/**
	 * Show or hide the mouse cursor.
	 *
	 * This function does not call OSystem::updateScreen, when visible is true.
	 * You may need to call OSystem::updateScreen after a call to showMouse(true)
	 * to ensure that the mouse cursor becomes visible.
	 *
	 * @todo We might want to reconsider this behavior, it might be confusing
	 * for the user to call OSystem::updateScreen separately, on the other
	 * hand OSystem::updateScreen might as well display unwanted changes on
	 * the screen. Another alternative would be to let the backend worry
	 * about this on OSystem::showMouse call.
	 *
	 * @see OSystem::showMouse.
	 */
	bool showMouse(bool visible);

	/**
	 * Push a new cursor onto the stack, and set it in the backend.
	 *
	 * A local copy of the cursor data will be made, so the original buffer
	 * can be safely freed afterwards.
	 *
	 * @param buf		New cursor data.
	 * @param w			Width.
	 * @param h			Height.
	 * @param hotspotX	Hotspot X coordinate.
	 * @param hotspotY	Hotspot Y coordinate.
	 * @param keycolor	Color value for the transparent color. This cannot exceed
	 *                  the maximum color value as defined by format.
	 *                  Does nothing if mask is set.
	 * @param dontScale	Whether the cursor should never be scaled. An exception are high PPI displays, where the cursor
	 *                  would be too small to notice otherwise. These are allowed to scale the cursor anyway.
	 * @param format	Pointer to the pixel format that the cursor graphic uses.
	 *					CLUT8 will be used if this is null or not specified.
	 * @param mask      Optional pointer to cursor mask containing values from the CursorMaskValue enum.
	 *
	 * @note It is acceptable for the buffer to be a null pointer. It is sometimes
	 *       useful to push a "dummy" cursor and modify it later. The
	 *       cursor will be added to the stack, but not to the backend.
	 */
	void pushCursor(const void *buf, uint w, uint h, int hotspotX, int hotspotY, uint32 keycolor, bool dontScale = false, const Graphics::PixelFormat *format = NULL, const byte *mask = nullptr);

	/**
	 * Push a new cursor onto the stack, and set it in the backend.
	 *
	 * A local copy of the cursor data will be made, so the original surface
	 * can be safely freed afterwards.
	 *
	 * @param surf		New cursor surface.
	 * @param hotspotX	Hotspot X coordinate.
	 * @param hotspotY	Hotspot Y coordinate.
	 * @param keycolor	Color value for the transparent color. This cannot exceed
	 *                  the maximum color value as defined by format.
	 *                  Does nothing if mask is set.
	 * @param dontScale	Whether the cursor should never be scaled. An exception are high PPI displays, where the cursor
	 *                  would be too small to notice otherwise. These are allowed to scale the cursor anyway.
	 * @param mask      Optional pointer to cursor mask containing values from the CursorMaskValue enum.
	 *
	 * @note It is acceptable for the surface to be empty. It is sometimes
	 *       useful to push a "dummy" cursor and modify it later. The
	 *       cursor will be added to the stack, but not to the backend.
	 */
	void pushCursor(const Surface &surf, int hotspotX, int hotspotY, uint32 keycolor, bool dontScale = false, const byte *mask = nullptr);

	/**
	 * Pop a cursor from the stack, and restore the previous one to the
	 * backend.
	 *
	 * If there is no previous cursor, the cursor is hidden.
	 */
	void popCursor();

	/**
	 * Replace the current cursor on the stack.
	 *
	 * If the stack is empty, the cursor is pushed instead. This is a slightly
	 * more optimized way of popping the old cursor before pushing the new one.
	 *
	 * @param buf		New cursor data.
	 * @param mask		New cursor mask data.
	 * @param w			Width.
	 * @param h			Height.
	 * @param hotspotX	Hotspot X coordinate.
	 * @param hotspotY	Hotspot Y coordinate.
	 * @param keycolor	Color value for the transparent color. This cannot exceed
	 *                  the maximum color value as defined by format.
	 *                  Does nothing if mask is set.
	 * @param dontScale	Whether the cursor should never be scaled. An exception are high PPI displays, where the cursor
	 *                  would be too small to notice otherwise. These are allowed to scale the cursor anyway.
	 * @param format	Pointer to the pixel format that the cursor graphic uses,
	 *					CLUT8 will be used if this is null or not specified.
	 * @param mask      Optional pointer to cursor mask containing values from the CursorMaskValue enum.
	 */
	void replaceCursor(const void *buf, uint w, uint h, int hotspotX, int hotspotY, uint32 keycolor, bool dontScale = false, const Graphics::PixelFormat *format = nullptr, const byte *mask = nullptr);

	/**
	 * Replace the current cursor on the stack.
	 *
	 * If the stack is empty, the cursor is pushed instead. This is a slightly
	 * more optimized way of popping the old cursor before pushing the new one.
	 *
	 * @param surf		New cursor surface.
	 * @param mask		New cursor mask data.
	 * @param hotspotX	Hotspot X coordinate.
	 * @param hotspotY	Hotspot Y coordinate.
	 * @param keycolor	Color value for the transparent color. This cannot exceed
	 *                  the maximum color value as defined by format.
	 *                  Does nothing if mask is set.
	 * @param dontScale	Whether the cursor should never be scaled. An exception are high PPI displays, where the cursor
	 *                  would be too small to notice otherwise. These are allowed to scale the cursor anyway.
	 * @param mask      Optional pointer to cursor mask containing values from the CursorMaskValue enum.
	 */
	void replaceCursor(const Surface &surf, int hotspotX, int hotspotY, uint32 keycolor, bool dontScale = false, const byte *mask = nullptr);

	/**
	 * Replace the current cursor on the stack.
	 *
	 * If the stack is empty, the cursor is pushed instead. This is a slightly
	 * more optimized way of popping the old cursor before pushing the new one.
	 *
	 * @param cursor	New cursor.
	 */
	void replaceCursor(const Graphics::Cursor *cursor);

	/**
	 * Pop all cursors and cursor palettes from their respective stacks.
	 *
	 * The purpose is to ensure that all unnecessary cursors are removed from the
	 * stack when returning to the launcher from an engine.
	 *
	 */
	void popAllCursors();

	/**
	 * Test whether cursor palettes are supported.
	 *
	 * This is just a convenience wrapper for checking whether
	 * OSystem::kFeatureCursorPalette is supported by OSystem.
	 *
	 * @see OSystem::kFeatureCursorPalette
	 * @see OSystem::hasFeature
	 */
	bool supportsCursorPalettes();

	/**
	 * Enable or disable the current cursor palette.
	 *
	 * @param disable
	 */
	void disableCursorPalette(bool disable);

	/**
	 * Push a new cursor palette onto the stack, and set it in the backend.
	 *
	 * The palette entries from @p start until @c (start+num-1) will be replaced
	 * so a full palette update is accomplished via start=0, num=256.
	 *
	 * The palette data is specified in the same interleaved RGB format as
	 * used by all backends.
	 *
	 * @param colors	New palette data, in interleaved RGB format.
	 * @param start		First palette entry to be updated.
	 * @param num		Number of palette entries to be updated.
	 *
	 * @note If num is zero, the cursor palette is disabled.
	 */
	void pushCursorPalette(const byte *colors, uint start, uint num);

	/**
	 * Pop a cursor palette from the stack, and restore the previous one to
	 * the backend.
	 *
	 * If there is no previous palette, the cursor palette is disabled instead.
	 */
	void popCursorPalette();

	/**
	 * Replace the current cursor palette on the stack.
	 *
	 * If the stack is empty, the palette is pushed instead. This is a slightly
	 * more optimized way of popping the old palette before pushing the new one.
	 *
	 * @param colors	New palette data, in interleaved RGB format.
	 * @param start		First palette entry to be updated.
	 * @param num		Number of palette entries to be updated.
	 *
	 * @note If num is zero, the cursor palette is disabled.
	 */
	void replaceCursorPalette(const byte *colors, uint start, uint num);

	/**
	 * Lock or unlock the visibility state of the cursor.
	 *
	 * When the cursor is locked, calling showMouse(bool) does nothing
	 * and returns false.
	 */
	void lock(bool locked);
private:
	/**
	* Generic class for implementing the singleton design pattern.
	*/
	friend class Common::Singleton<SingletonBaseType>;
	// Even though this is basically the default constructor we implement it
	// ourselves, so it is private and thus there is no way to create this class
	// except from the Singleton code.
	CursorManager() {
		_locked = false;
	}
	~CursorManager();

	struct Cursor {
		Surface _surf;
		byte *_mask;
		bool _visible;
		int _hotspotX;
		int _hotspotY;
		uint32 _keycolor;
		bool _dontScale;

		uint _size;

		// _surf set to default by Graphics::Surface default constructor
		Cursor() : _mask(0), _visible(false), _hotspotX(0), _hotspotY(0), _keycolor(0), _dontScale(false), _size(0) {}

		Cursor(const Surface &surf, int hotspotX, int hotspotY, uint32 keycolor, bool dontScale, const byte *mask);
		~Cursor();
	};

	struct Palette {
		byte *_data;
		uint _start;
		uint _num;
		uint _size;

		bool _disabled;

		Palette() : _data(0), _start(0), _num(0), _size(0), _disabled(false) {}

		Palette(const byte *colors, uint start, uint num);
		~Palette();
	};
	Common::Stack<Cursor *> _cursorStack;
	Common::Stack<Palette *> _cursorPaletteStack;
	bool _locked;
};
/** @} */
} // End of namespace Graphics

#define CursorMan	(::Graphics::CursorManager::instance())

#endif