import java.awt.image.BufferedImage;
import java.awt.Color;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.ImageIcon;
import javax.swing.JScrollPane;

/** This utility class contains static methods to translate between images and 2-D arrays.
 * 
 * <p>
 * To convert a image's filename or URL to an array of int:<br></br>
 *   <code>  int[][] myPixels =  imageToPixelsBW( "http://www.radford.edu/~itec120/2007fall-ibarland/Lectures/lect01-ufo/muse.jpeg" );  </code>
 *   <code>  displayPixels( myPixels );   // Bring up a window with the image. </code>
 *   <code>  myPixels[13][23] = 255;      // Set location (13,23) to white</code>
 *   <code>  displayPixels( myPixels );   // Look for the modified pixel.</code>
 * </p>
 * 
 *<p>
 * Note that once you have displayed an image, modifying the array won't
 * retroactively change that image; you'll have to call <code>displayPixels</code> again
 * after making any modifications to see a new image.
 * </p>
 * 
 * <p>
 * Optional/Challenge: <br></br>
 * If you want to deal with color images, you can use <code>imageToPixelsColor</code>,
 * which will return an array of <code>java.awt.Color</code> objects.  See the Java API
 * for details, but the most useful color methods are <code>getRed()</code>, <code>setRed(int)</code>,
 * and similarly for green and blue.  To display a color image (if you have
 * a 2-D array of <code>Color</code>s), call <code>displayPixels( Color[][] )</code>.
 * </p>
 */
public class Pict {
    
    private static int displayCount = 0;
    private static final int MAX_WINDOW_WIDTH  = 500;
    private static final int MAX_WINDOW_HEIGHT = 500;
    
    /** Given an array of grayscale values in [0,256),
     *  draw it as a black-and-white image.
     *  (Of course, subsequent changes to the array won't
     *  retroactively change this image.)
     *  @param pixels A 2-D array of grayscale values in [0,256).
     */
    public static void displayPixels( int[][] pixels ) {
        // To show an image:
        // the image is inside of a Icon which is inside of a label inside of a frame
        // (sigh, why must it be so roundabout?)

        ++displayCount;
        javax.swing.JFrame f = new javax.swing.JFrame( "image #" + displayCount );
        //f.setDefaultCloseOperation(javax.swing.JFrame.EXIT_ON_CLOSE);
    
        // Bug: rather than use the image's width and height,
        // we should also account for the frame's title bar etc.
        //
        f.setSize( Math.min(pixels.length,MAX_WINDOW_WIDTH),
                   Math.min(pixels[0].length,MAX_WINDOW_HEIGHT) );
    
        JLabel l = new JLabel();
        l.setIcon(new ImageIcon(pixelsToImage(pixels)));
        f.add( new JScrollPane(l) );
        f.setVisible(true);
    }

        
    /** Given an array of Colors, draw it as a Color image.
     *  (Of course, subsequent changes to the array won't
     *  retroactively change this image.)
     *  @param pixels A 2-D array of java.awt.Colors.
     */
    public static void displayPixels( Color[][] pixels ) {
        // Ugh -- this is EXACTLY the same code as displayPixels(int[][]).
        
        // To show an image:
        // the image is in a Icon in a label in a frame
        // (sigh, why must it be so roundabout?)

        ++displayCount;
        javax.swing.JFrame f = new javax.swing.JFrame( "image #" + displayCount );
        //f.setDefaultCloseOperation(javax.swing.JFrame.EXIT_ON_CLOSE);
    
        // Bug: rather than use the image's width and height,
        // we should also account for the frame's title bar etc.
        //
        f.setSize( Math.min(pixels.length,MAX_WINDOW_WIDTH),
                   Math.min(pixels[0].length,MAX_WINDOW_HEIGHT) );
    
        JLabel l = new JLabel();
        l.setIcon(new ImageIcon(pixelsToImage(pixels)));
        f.add( new JScrollPane(l) );
        f.setVisible(true);
    }
        
    
    /** Return a java.awt.Image.BufferedImage from a given array of grayscale values,
     *  suitable for interacting with other Java awt classes.
     *  @param pixels A 2-D array of grayscale values in [0,256).
     *  @return the image corresponding to the array of pixels.
     */
    private static BufferedImage pixelsToImage( int[][] pixels ) {
        int width = pixels.length > 0 ? pixels[0].length : 0;
        BufferedImage img = new BufferedImage( width, pixels.length, BufferedImage.TYPE_INT_ARGB );
        for (int r=0;  r<pixels.length;  ++r) {
            for (int c=0;  c<width;  ++c) {
                int grayValue = pixels[r][c];
                try {
                    Color col = new Color( grayValue, grayValue, grayValue );
                    img.setRGB( c, r, col.getRGB() );
                } catch (IllegalArgumentException e) {
                    // Improve the error message:
                    throw new IllegalArgumentException( "pixelsToImage: pixels["+r+"]["+c+"] = "
                                                      + grayValue + ", but must be in 0..255" );
                }
                
            }
        }
        return img;
    }


    /** Return a java.awt.Image.BufferedImage from a given array of grayscale values,
     *  suitable for interacting with other Java awt classes.
     *  @param pixels A 2-D array of java.awt.Colors.
     *  @return the image corresponding to the array of pixels.
     */
    private static BufferedImage pixelsToImage( Color[][] pixels ) {
        int width = pixels.length > 0 ? pixels[0].length : 0;
        BufferedImage img = new BufferedImage( width, pixels.length, BufferedImage.TYPE_INT_ARGB );
        for (int r=0;  r<pixels.length;  ++r) {
            for (int c=0;  c<width;  ++c) {
                img.setRGB( c, r, pixels[r][c].getRGB() );
            }
        }
        return img;
    }
        

    /** Given a filename or URL, return a 2-D array of grayscale values in [0,256).
     * @param filenameOrURL A string like "H:\MyFile.jpeg" or "http://www.radford.edu/someUser/somePict.jpg"
     * @return The 2-D array of grayscale values representing the indicated picture.
     *          Will cause a run-time exception if the file/URL can't be opened.
     */
    public static int[][] fileToPixelsBW( String filenameOrURL )
    {
       java.awt.image.BufferedImage img = fileOrURLToImage(filenameOrURL);
        int[][] answer = new int[img.getHeight()][img.getWidth()];
        
        for (int r=0; r < img.getHeight(); ++r) {
            for (int c=0; c < img.getWidth(); ++c) {
                java.awt.Color pixel = new java.awt.Color( img.getRGB(c,r) );
                answer[r][c] = (pixel.getRed() + pixel.getGreen() + pixel.getBlue()) / 3;
            }
        }
        return answer;
    }

 
    /** Given a filename or URL, return a 2-D array of java.awt.Colors.
     * @param filenameOrURL A string like "H:\MyFile.jpeg" or "http://www.radford.edu/someUser/somePict.jpg"
     * @return The 2-D array of grayscale values representing the indicated picture.
     *          Will cause a run-time exception if the file/URL can't be opened.
     */
    public static Color[][] fileToPixelsColor( String filenameOrURL )
    {
       java.awt.image.BufferedImage img = fileOrURLToImage(filenameOrURL);
        Color[][] answer = new Color[img.getHeight()][img.getWidth()];
        
        for (int r=0; r < img.getHeight(); ++r) {
            for (int c=0; c < img.getWidth(); ++c) {
                answer[r][c] = new Color( img.getRGB(c,r) );
            }
        }
        return answer;
    }
    
    
    /** Return a java.awt.Image.BufferedImage from a given filename or URL.
     *  @param filenameOrURL A filename or URL for a standard image type (.jpg, .gif, etc)
     *  @return the image corresponding to the filename.
     *          Will cause a run-time exception if the file/URL can't be opened.
     */
    private static java.awt.image.BufferedImage fileOrURLToImage( String filenameOrURL )
    {
        java.awt.image.BufferedImage img;
        // Get the underlying ImageIO object:
        try {
            if (filenameOrURL.startsWith("http://")) {
                img = javax.imageio.ImageIO.read( new java.net.URL(filenameOrURL) );
                if (img==null) throw new java.io.IOException( "Reading from URL doesn't return an image"
                                                                + "; "   + "is the web request being intercepted by Clean Access or other firewall?"
                                                                + "\n  " + filenameOrURL );
            }
            else {
                img = javax.imageio.ImageIO.read( new java.io.File(filenameOrURL) );
            }
        } catch (java.io.IOException e) {
            // Convert the exception into one which doesn't need to be declared.
            // This is BAD PRACTICE, but we don't want 120 students to have to handle exceptions.
            throw new RuntimeException( e.toString() );
        }
        return img;
    }


    /** A test method, which just displays three images:
     * A color version, a black-and-white version, 
     * and a tiny 4x3 image.
     */
    public static void main( String[] args ) {
        String aFileURL = "http://www.radford.edu/~itec120/2007fall-ibarland/Lectures/lect01-ufo/muse.jpeg";

        // Color pixels created from a file, then displayed:
        Color[][] data3 = fileToPixelsColor( aFileURL );
        displayPixels( data3 );
        
        // int pixels created from a file, then displayed:
        int[][] data2 = fileToPixelsBW( aFileURL );
        // System.out.println( java.util.Arrays.deepToString( data2 ) );
        displayPixels( data2 );
        
        // int pixels as a literal array, then displayed:
        int[][] data1 = { {30,  30, 30, 128},
                          {40, 200, 40, 128},
                          {50,  90, 50, 128} };
        displayPixels( data1 );
    }
    
}