/*
 * File: gbufferedimage.h
 * ----------------------
 * This file exports the GBufferedImage class for per-pixel graphics.
 * See gbufferedimage.cpp for implementation of each member.
 *
 * @author Marty Stepp
 * @version 2016/10/16
 * - refactored to/fromGrid to use static pixelString methods (so we can reuse
 *   the pixel functionality in GWindow)
 * @version 2016/07/30
 * - added constructor that takes a file name
 * - converted all occurrences of string parameters to const string&
 * - added operators ==, !=
 * @version 2015/10/08
 * - bug fixes and refactoring for pixel-based functions such as fromGrid, load
 *   to help fix bugs with Base64 encoding/decoding
 * @version 2015/08/12
 * - added toGrid, fromGrid, createRgbPixel, getRed, getGreen, getBlue functions
 * - perf.optimizations to per-pixel stuff; now almost tolerable speed
 * @version 2014/10/22
 * - added save, load methods
 * - added three-argument constructor (w, h, background)
 * - added diff methods
 * @version 2014/10/07
 * - added inBounds method, private resize, zero-arg ctor; slight refactor
 * @since 2014/08/04
 */

#ifndef _gbufferedimage_h
#define _gbufferedimage_h

#include "grid.h"
#include "ginteractors.h"
#include "gobjects.h"
#include "gtypes.h"

// default color used to highlight pixels that do not match between two images
#define GBUFFEREDIMAGE_DEFAULT_DIFF_PIXEL_COLOR 0xdd00dd

/*
 * This class implements a 2D region of colored pixels that can be read/set
 * individually, not unlike the <code>BufferedImage</code> class in Java.
 * The color of each pixel in a <code>GBufferedImage</code> is represented
 * as a 32-bit integer as described by the <code>GWindow</code> function
 * <code>convertRGBToColor</code></a>, where:
 *
 * - bits 0-7 are unused;
 * - bits 8-15 represent the redness of the color, from 0 (none) through 255 (full);
 * - bits 16-23 represent the greenness of the color, from 0 (none) through 255 (full);
 * - and bits 24-31 represent the blueness of the color, from 0 (none) through 255 (full).
 *
 * For example, the integer <code>0xff00cc</code> is a purple color, while
 * <code>0x770000</code> is a dark red.
 * A <code>GBufferedImage</code> will also let you represent colors as hex strings
 * such as <code>"#ff00cc"</code> instead of as integers.
 * String colors are always converted to integer colors internally by calling the
 * <code>GWindow</code> function <code>convertColorToRGB</code>.
 * Therefore some common color names like "black" can be passed successfully
 * in lieu of the usual hex format; see that function for more details.
 *
 * Though the x, y, width, and height parameters to the constructor and several
 * methods are received as type <code>double</code> for maximum compatibility
 * with other classes in this library, they should be thought of as
 * integer coordinates.  Any real numbers passed will be internally truncated
 * into integers by discarding any fractional component (by type-casting from
 * <code>double</code> to <code>int</code>).
 *
 * Note that per-pixel graphics operations using the Stanford C++ library are
 * relatively slow.  A call to the <code>fill</code> method is relatively
 * efficient, and a call to <code>getRGB</code> is also efficient since pixels'
 * colors are cached locally.  But calling <code>setRGB</code> repeatedly over
 * a large range of pixels is likely to yield poor performance.
 * This is due to the fact that the graphics are implemented using a background
 * Java process to which all graphical commands are forwarded.
 * The <code>GBufferedImage</code> class is not performant enough to be used
 * for rapidly advancing animations or extremely complex graphical effects.
 * It also does not provide any drawing primitives other than filling
 * individual pixels and rectangular regions.
 * If you want to draw shapes and lines, use other classes from this library
 * such as GRect, GLine, and so on.
 * </p>
 * 
 * <p class="since">
 *     Available since: 2014/08/04 version of C++ library
 * </p>
 */
class GBufferedImage : public GInteractor {
public:
    /*
     * Largest value that an image's width and/or height can have.
     * Error will be thrown if you try to make/resize an image larger than this.
     */
    static const int WIDTH_HEIGHT_MAX;

    /*
     * Creates a single RGB integer from the given R-G-B components from 0-255.
     */
    static int createRgbPixel(int red, int green, int blue);

    /*
     * Extracts the alpha component from 0-255 of the given ARGB integer.
     * The red component comes from bits 24-31 (most significant) of the integer.
     */
    static int getAlpha(int argb);

    /*
     * Extracts the blue component from 0-255 of the given RGB integer.
     * The red component comes from bits 0-7 (least significant) of the integer.
     */
    static int getBlue(int rgb);

    /*
     * Extracts the green component from 0-255 of the given RGB integer.
     * The red component comes from bits 8-15 of the integer.
     */
    static int getGreen(int rgb);

    /*
     * Extracts the red component from 0-255 of the given RGB integer.
     * The red component comes from bits 16-23 of the integer.
     */
    static int getRed(int rgb);

    /*
     * Extracts the red, green, and blue components from 0-255
     * of the given RGB integer, filling by reference.
     */
    static void getRedGreenBlue(int rgb, int& red, int& green, int& blue);

    /*
     * Functions for converting grids of pixels into strings for sending to
     * the Java back-end.
     * Private; clients should not use these functions.
     */
    static std::string gridToPixelString(const Grid<int>& grid);
    static Grid<int> pixelStringToGrid(const std::string& base64text);
    static void pixelStringToGrid(const std::string& base64text, Grid<int>& grid);

    /*
     * Constructs an image with the specified location, size, and optional
     * background color.
     * You can also pass a filename instead to read the image from that file.
     * If no size is passed, the default size of 0x0 pixels is used.
     * If no location is passed, the default of (x=0, y=0) is used.
     * If no background color is passed, the default of black (0x0) is used.
     * Throws an error if the given width/height ranges are negative.
     * Throws an error if the given rgb value is invalid or out of range.
     */
    GBufferedImage();
    GBufferedImage(const std::string& filename);
    GBufferedImage(double width, double height,
                   int rgbBackground = 0x000000);
    GBufferedImage(double x, double y, double width, double height,
                   int rgbBackground = 0x000000);
    GBufferedImage(double x, double y, double width, double height,
                   const std::string& rgbBackground);
    
    /* Prototypes for the virtual methods */
    virtual GRectangle getBounds() const;
    virtual std::string getType() const;
    virtual std::string toString() const;

    /* unique GBufferedImage behavior */

    /*
     * Sets all pixels to be the original background RGB passed to the constructor.
     */
    void clear();
    
    /*
     * Returns the total number of pixels that are not the same color
     * between this image and the given other image.
     * If the images are not the same size, any pixels in the range of one image
     * but out of the bounds of the other are considered to be differing.
     */
    int countDiffPixels(GBufferedImage& image) const;
    
    /*
     * Generates a new image whose content is equal to that of this image but with
     * any pixels that don't match those in parameter 'image' colored in the given
     * color (default purple) to highlight differences between the two.
     */
    GBufferedImage* diff(GBufferedImage& image, int diffPixelColor = GBUFFEREDIMAGE_DEFAULT_DIFF_PIXEL_COLOR) const;
    
    /*
     * Sets the color of every pixel in the image to the given color value.
     * Throws an error if the given rgb value is not a valid color.
     */
    void fill(int rgb);
    void fill(const std::string& rgb);

    /*
     * Sets the color of every pixel in the given rectangular range of the image
     * to the given color value.
     * Specifically, the pixels in the rectangular range (x, y) through
     * (x + width - 1, y + height - 1) become filled with the given color.
     * Throws an error if the given x/y/width/height range goes outside the bounds
     * of the image.
     * Throws an error if the given rgb value is not a valid color.
     */
    void fillRegion(double x, double y, double width, double height, int rgb);
    void fillRegion(double x, double y, double width, double height,
                    const std::string& rgb);
    
    /*
     * Replaces the entire contents of this image with the contents of the
     * given grid of RGB pixel values.
     * If this image is not the same size as the grid, the image is resized.
     * Any existing contents of the image are lost.
     */
    void fromGrid(const Grid<int>& grid);

    /*
     * Returns the height of the image in pixels.
     */
    double getHeight() const;

    /*
     * Returns the color of the pixel at the given x/y coordinates of the image
     * as an integer such as 0xff00cc.
     * Throws an error if the given x/y values are out of bounds.
     */
    int getRGB(double x, double y) const;

    /*
     * Returns the color of the pixel at the given x/y coordinates of the image
     * as a string such as "#ff00cc".
     * The string that is returned comes from the <code>GWindow</code> function
     * <code>convertRGBToColor</code>; see documentation of that function.
     * Throws an error if the given x/y values are out of bounds.
     */
    std::string getRGBString(double x, double y) const;

    /*
     * Returns the width of the image in pixels.
     */
    double getWidth() const;
    
    /*
     * Returns true if the given x/y position is within the range of pixels
     * occupied by this buffered image, namely (0, 0) through (width-1, height-1)
     * inclusive.
     */
    bool inBounds(double x, double y) const;
    
    /*
     * Reads the image's contents from the given image file.
     * Throws an error if the given file is not a valid image file.
     */
    void load(const std::string& filename);
    
    /*
     * Changes this image's bounds to be the given size.
     * This does not scale the image but rather just changes the max x/y that
     * can be painted onto this image.
     * If the 'retain' parameter is not passed or is set to true,
     * any existing pixel values will be kept during the resize.
     * If 'retain' is false, the contents will be wiped and set to the default.
     * Any existing pixel contents are discarded and revert to defaults.
     * Throws an error if the given width/height ranges are negative.
     */
    void resize(double width, double height, bool retain = true);
    
    /*
     * Saves the image's contents to the given image file.
     * Throws an error if the given file is not writeable.
     */
    void save(const std::string& filename) const;

    /*
     * Sets the color of the pixel at the given x/y coordinates of the image
     * to the given value.
     * Implementation/performance note: Each call to this method produces a
     * call to the Java graphical back-end.  Calling this method many times
     * in a tight loop can lead to poor performance.  If you need to fill a
     * large rectangular region, consider calling fill or fillRegion instead.
     * Throws an error if the given x/y values are out of bounds.
     * Throws an error if the given rgb value is not a valid color.
     */
    void setRGB(double x, double y, int rgb);
    void setRGB(double x, double y, const std::string& rgb);
    
    /*
     * Converts this image into a grid of RGB pixels.
     * The grid's first index is a row or y-index, and its second index
     * is the column or x-index.
     * So for example, grid[y][x] returns the RGB int value at that pixel.
     * The grid can either be returned or filled by reference.
     */
    Grid<int> toGrid() const;
    void toGrid(Grid<int>& grid) const;

private:
    double m_width;          // really, these are treated as integers
    double m_height;
    int m_backgroundColor;
    Grid<int> m_pixels;      // row-major; [y][x]

    /*
     * Throws an error if the given rgb value is not a valid color.
     */
    void checkColor(const std::string& member, int rgb) const;

    /*
     * Throws an error if the given x/y values are out of bounds.
     */
    void checkIndex(const std::string& member, double x, double y) const;

    /*
     * Throws an error if the given width/height values are out of bounds.
     */
    void checkSize(const std::string& member, double width, double height) const;

    /*
     * Initializes private member variables; called by all constructors.
     */
    void init(double x, double y, double width, double height, int rgb);

    // allow operators to see private data inside image
    friend bool operator ==(const GBufferedImage& img1, const GBufferedImage& img2);
    friend bool operator !=(const GBufferedImage& img1, const GBufferedImage& img2);
};

bool operator ==(const GBufferedImage& img1, const GBufferedImage& img2);
bool operator !=(const GBufferedImage& img1, const GBufferedImage& img2);

#include "private/init.h"   // ensure that Stanford C++ lib is initialized

#endif
