/* 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 2
 * 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, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 */

#ifndef ZVISION_RENDER_MANAGER_H
#define ZVISION_RENDER_MANAGER_H

#include "common/types.h"
#include "common/rect.h"

#include "graphics/surface.h"

#include "zvision/render_table.h"

class OSystem;

namespace Common {
class String;
class SeekableReadStream;
}

namespace Video {
class VideoDecoder;
}

namespace ZVision {

class RenderManager {
public:
	RenderManager(OSystem *system, const Common::Rect workingWindow, const Graphics::PixelFormat pixelFormat);
	~RenderManager();

private:
	OSystem *_system;
	const Graphics::PixelFormat _pixelFormat;

	// A buffer the exact same size as the workingWindow
	// It's used for panorama/tilt warping and for clearing the workingWindow to a single color
	uint16 *_workingWindowBuffer;

	/** Width of the working window. Saved to prevent extraneous calls to _workingWindow.width() */
	const int _workingWidth;
	/** Height of the working window. Saved to prevent extraneous calls to _workingWindow.height() */
	const int _workingHeight;
	/** Center of the screen in the x direction */
	const int _screenCenterX;
	/** Center of the screen in the y direction */
	const int _screenCenterY;

	/** 
	 * A Rectangle centered inside the actual window. All in-game coordinates
	 * are given in this coordinate space. Also, all images are clipped to the
	 * edges of this Rectangle
	 */
	const Common::Rect _workingWindow;
	/** Used to warp the background image */
	RenderTable _renderTable;

	Graphics::Surface _currentBackground;
	/** The (x1,y1) coordinates of the subRectangle of the background that is currently displayed on the screen */
	Common::Point _backgroundOffset;
	/** The width of the current background image */
	uint16 _backgroundWidth;
	/** The height of the current background image */
	uint16 _backgroundHeight;

	/** 
	 * The "velocity" at which the background image is panning. We actually store the inverse of velocity (ms/pixel instead of pixels/ms)
	 * because it allows you to accumulate whole pixels 'steps' instead of rounding pixels every frame
	 */
	int _backgroundInverseVelocity;
	/** Holds any 'leftover' milliseconds between frames */
	uint _accumulatedVelocityMilliseconds;

	// TODO: Potentially merge this buffer and _workingWindowBuffer
	byte *_scaledVideoFrameBuffer;

public:
	void initialize();
	/**
	 * Rotates the background image in accordance to the current _backgroundInverseVelocity
	 *
	 * @param deltaTimeInMillis    The amount of time that has passed since the last frame
	 */
	void update(uint deltaTimeInMillis);

	/**
	 * Fills the entire workingWindow with the specified color
	 *
	 * @param color    The color to fill the working window with. (In RGB 555)
	 */
	void clearWorkingWindowToColor(uint16 color);

	/**
	 * Blits the image or a portion of the image to the backbuffer. Actual screen updates won't happen until the end of the frame.
	 * The image will be clipped to fit inside the working window. Coords are in working window space, not screen space!
	 *
	 * @param fileName        Name of the image file
	 * @param destinationX    X position where the image should be put. Coords are in working window space, not screen space!
	 * @param destinationY    Y position where the image should be put. Coords are in working window space, not screen space!
	 */
	void renderImageToScreen(const Common::String &fileName, int16 destinationX, int16 destinationY, bool wrap = false);

	/**
	 * Blits the image or a portion of the image to the backbuffer. Actual screen updates won't happen until the end of the frame.
	 * The image will be clipped to fit inside the working window. Coords are in working window space, not screen space!
	 *
	 * @param stream          Surface to read the image data from
	 * @param destinationX    X position where the image should be put. Coords are in working window space, not screen space!
	 * @param destinationY    Y position where the image should be put. Coords are in working window space, not screen space!
	 */
	void renderImageToScreen(Graphics::Surface &surface, int16 destinationX, int16 destinationY, bool wrap = false);

	/**
	 * Sets the current background image to be used by the RenderManager and immediately
	 * blits it to the screen. (It won't show up until the end of the frame)
	 *
	 * @param fileName    The name of the image file
	 */
	void setBackgroundImage(const Common::String &fileName);

	/**
	 * Set the background position (_backgroundOffset). If the current RenderState is PANORAMA, the offset
	 * will be in the horizontal direction. If the current RenderState is TILT, the offset will be in the
	 * vertical direction. 
	 *
	 * This method will not render anything on the screen. So if nothing else is called that renders the 
	 * background, the change won't be seen until next frame.
	 *
	 * @param offset The amount to offset the background
	 */
	void setBackgroundPosition(int offset);
	
	/**
	 * Set the background scroll velocity. Negative velocities correspond to left / up scrolling and 
	 * positive velocities correspond to right / down scrolling
	 *
	 * @param velocity    Velocity
	 */
	void setBackgroundVelocity(int velocity);

	/**
	 * Converts a point in screen coordinate space to image coordinate space
	 *
	 * @param point    Point in screen coordinate space
	 * @return         Point in image coordinate space
	 */
	const Common::Point screenSpaceToImageSpace(const Common::Point &point);

	RenderTable *getRenderTable();
	uint32 getCurrentBackgroundOffset();

private:
	/**
	 * Renders a subRectangle of an image to the backbuffer. The destinationRect and SubRect
	 * will be clipped to image bound and to working window bounds
	 *
	 * @param buffer             Pointer to (0, 0) of the image data
	 * @param imageWidth         The width of the original image (not of the subRectangle)
	 * @param imageHeight        The width of the original image (not of the subRectangle)
	 * @param horizontalPitch    The horizontal pitch of the original image
	 * @param destinationX       The x coordinate (in working window space) of where to put the final image
	 * @param destinationY       The y coordinate (in working window space) of where to put the final image
	 * @param subRectangle       A rectangle representing the part of the image that should be rendered
	 * @param wrap               Should the image wrap (tile) if it doesn't completely fill the screen?
	 */
	void renderSubRectToScreen(Graphics::Surface &surface, int16 destinationX, int16 destinationY, bool wrap);

	void readImageToSurface(const Common::String &fileName, Graphics::Surface &destination);

	void moveBackground(int offset);
};

} // End of namespace ZVision

#endif