/**
 * Encapsulation for easy picture reading.
 * CIS 120 HW4: Simple Machine Learning
 * @author Kuzman Ganchev (2006)
 */

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.awt.image.WritableRaster;
import java.io.File;
import java.io.FileNotFoundException;
import javax.imageio.*;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;

public class SimplePicture {

  /** the image in a format easy for displaying */
  protected BufferedImage bufferedImage;
  /** a raster for the image */
  protected WritableRaster raster;
  /** the name of the file used to create the SimplePicture */
  private String name;
 
  /** creates a new SimplePicture object of the specified type by reading in
   * the given file. 
   * @param filename the location of the image file to read */ 
  SimplePicture(String filename) throws FileNotFoundException,
    	NotAPictureException {
    load(filename);
    name=filename;
  }

  /** get the width of the image */ 
  public int getWidth() { return bufferedImage.getWidth(); }
  /** get the height of the image */ 
  public int getHeight() { return bufferedImage.getHeight(); }
  /** get the name used to create this picture */
  public String getName() { return name;}
  
  /** load the image from the specified image into this Picture object 
   * @param filename the location of the file
   * @throws FileNotFoundException if the file does not exist
   * @throws NotAPictureException if the file exists but we could not
   * load it.*/ 
  public void load(String filename) throws FileNotFoundException,
	 NotAPictureException {
    ImageIcon icon;
    if ((new File(filename)).exists()) icon = new ImageIcon(filename);
    else throw new FileNotFoundException(filename);
    Image image = icon.getImage();
    if (image.getHeight(null)<0 || image.getWidth(null)<0){
      throw new NotAPictureException();
    }
    bufferedImage = new BufferedImage(image.getWidth(null),
                                      image.getHeight(null),
                                      BufferedImage.TYPE_BYTE_GRAY);
    Graphics g = bufferedImage.getGraphics();
    g.drawImage(image, 0, 0, null);
    g.dispose();
    raster = bufferedImage.getRaster();
  }
 
  /** get the greyscale value for this picture at the specified
   * location. The value is in the range 0-255. 
   * @param x the x-coordinate
   * @param y the y-coordinate
   */
  public int getValue(int x, int y){
    int val = 0;
    int[] pix = raster.getPixel(x, y, (int [])null);
    for (int i=0; i<pix.length; i++){
      val+=pix[i];
    }
    return val/pix.length;
  }

  /** open a window with the image */
  public void display(){
    JFrame frame = new JFrame("FrameDemo");
    /* Put the Picture in an ImageIcon */
    ImageIcon icon = new ImageIcon();
    icon.setImage(bufferedImage);
    
    /* Put the Image Icon in a JLabel */
    JLabel imageLabel = new JLabel(icon);
    imageLabel.setIcon(icon);
    
    /* Put the JLabel in a JPanel */
    JPanel imagePanel = new JPanel();
    imagePanel.setBackground(Color.black);
    imagePanel.add(imageLabel);
    
    /* Add the JPanel to the PictureFrame */
    frame.getContentPane().add(imagePanel, BorderLayout.CENTER);
    
    //5. Size the frame.
    frame.pack();
    
    //6. Show it.
    frame.setVisible(true);
  }
  
  /** save the image to a file 
   * @param name the location to save the image. It is overwritten if
   * it already exists.  
   */
  public void save(String name){
    File f = new File(name);
    try {
      ImageIO.write(bufferedImage, "JPEG", f);
      System.out.println("Written " + f);
    } catch(Exception e) {
      System.err.println(e);
    }
  }
}