/** 
  * Web Site Hits Count Graph Generator
  * @author Robert John Morton UK-YE572246C
  * @version 27 April 2000 */


import java.applet.*;  // all the gubbins to make the applet work
import java.awt.*;     // for graphics operations (GUI)
import java.net.*;     // for downloading data from the remote server
import java.io.*;      // for stream handling for the above


public class hc extends Applet implements Runnable {

  AppletContext ac; // get details of HTML document this applet is running in
  InputStream I;    // input stream for downloading index or current HTML file
  URL url;          // url of current HTML file 
  int
    L = 0,    // length of the remote item being loaded
    l = 0,    // number of bytes of the above successfully downloaded
    w,        // weeks counter used on horizontal axis of graph
    X = 30,   // horizontal bias from left edge of applet to start of x-axis
    Y = 145,  // vertical bias from top edge of applet to start of y-axis
    n = 25,   // off-set from start mark of year to start of its name
    lp = 1,   // indicates current and previous download phases 
    LP = 1,
    weeks[] = {52,52,52,52,52,52,52};  // weeks per year

  String
    year[] = {"1998","1999","2000","2001","2002","2003","2004"},
    hits[] = {"0","20","40","60","80","100","110"},  // hits scale
    cb;  // code base URL - where this applet's class file came from

  byte B[];  // gigantic byte array to hold the downloaded index data

  Thread TH;  // reference for a separate Internet Data Transfer thread
  String E;   // for Exception during downloading + method where it occurred

  Color
    bg1 = new Color(210,210,210),  // main background colour
    bg2 = new Color(210,195,195),  // graph background colour
    bg3 = new Color(180,180,180);  // graticule colour


  public void init() {
    bg1 = getBackground();  // Get HTML page's backround colour and
    setBackground(bg1);     // set it as the applet's background colour.

    /* Get the details of the HTML document this applet is running in and
    its codebase: the URL (less file name) from where this applet came.*/

    ac = getAppletContext();
    cb = getCodeBase().toString();

    if(!cb.endsWith("/")) {          // Workaround re Hotjava re Microsoft
      int x = cb.lastIndexOf('/');   // intranet machine names where
      if(x != -1)                    // getCodeBase() wrongly returns
        cb = cb.substring(0,x + 1);  // the document base (cira Nov 1999).
    }
    TH = new Thread(this);  // a thread for downloading data from server
  }


  public void paint(Graphics g) {
    g.setColor(bg1);          // Clear the panel and the graph area
    g.fillRect(0,0,450,170);  // to respective background colours.
    g.setColor(bg2);
    g.fillRect(X,Y-120,364,120);

    w = 0;  // total number of weeks

    for(int i = 0; i < weeks.length; i++) {     // for each year shown
      g.setColor(Color.black);                  // set to paint in black
      g.drawString(year[i],X + 13 + w,Y + 20);  // show year number 
      g.drawLine(X + w,Y + 5,X + w,Y + 10);     // and boundary mark
      g.setColor(bg3);                          // set appropriate colour
      g.drawLine(X + w,Y,X + w,Y - 120);        // and show annotation mark
      w += weeks[i];                            // accumulated number of weeks
    }
    g.setColor(bg3);  // Show final annotation mark
    g.drawLine(X + w,Y,X + w,Y - 120);

    g.setColor(Color.black);               // Display in black
    g.drawLine(X + w,Y + 5,X + w,Y + 10);  // the final year boundary
    g.drawLine(X,Y + 5,X + w,Y + 5);       // and the horizontal axis.

    int z = 0;
    for(int i = 0; i < hits.length; i++) {      // for each 10-hit graduation
      rightString(g,hits[i],X - 10,Y + 5 - z);  // annotation
      g.drawLine(X - 10,Y - z,X - 5,Y - z);     // annotation mark

      g.setColor(bg3);  // Show final annotation mark
      g.drawLine(X,Y - z,X + w,Y - z);

      z += 20;  // accumulated number of hits

      g.setColor(Color.black);
    }
    g.drawLine(X - 5,Y,X - 5,Y - 120);   //vertical axis
    g.drawString("Hits per week:",X - n,Y - 130);
    g.drawString("Year:",X - n,Y + 20);

    update(g);  // paint/repaint the graph bars
  }


  public void update(Graphics g) {

    if(lp == 3) {   //provided hit count data download completed
      w = X;       //initial x-bias for week number
      int
        h = 0,   //number of hits for a given week
        W = 0,   //number of weeks for which there is valid data
        H = 0;   //hits total accumulator

      g.setColor(Color.blue);   //set trace colour to blue

      for(int i = 0; i < L; i++) {   /* For every week covered by graph

        Provided the number of hits is not zero [to avoid displaying
        zero values before start date]: */

        if((h = (int)B[i]) > 0) {
          g.drawLine(w,Y,w,Y - h);  // display it as a vertical bar on chart, 
          H += h;                   // this week's hits to the total
          W++;                      // increment the number of weeks for
        }                           // which there is valid data
        w++;                        // increment the week number
      }
      g.setColor(Color.black);
      g.drawString("Total to Date " + H,105,15);
      g.drawString("Weekly Average " + (H / W),230,15);
    }
  }


  // Start execution of the Internet data transfer thread. 
  public void start() { TH.start(); }


  // MANAGE THE INTERNET DATA TRANSFERS ON A SEPARATE THREAD
  public void run() {
    while(TH != null) {   // while this thread exists
      switch(lp) {        // THE 2 DOWNLOADING PHASES:
        case 1:
          fileConnect();  // connect to index resource on server
          break; 
        case 2:
          fileLoad();     // manage the downloading of its content
      }
      if(lp != LP) {  // if loading of hits data has finished
        LP = lp;      // latch the current load state
        repaint();    // display the bars
      }

      /* Put the thread to sleep for 250 milliseconds.
      Catch any exceptions which may occur while the
      thread is asleep but take no action. */

      try { TH.sleep(250); } catch (InterruptedException e) { }
    }
  }


  // Freeze execution of thread while away from host HTML page.
  public void stop() {TH = null;}


  /* Called after stop() before applet is removed from memory.
  If the Internet data transfer thread object still exists and
  jettison its object into limbo. */

  public void destroy() { if(TH != null) { TH = null; } }


  void fileConnect() {  // CONNECT TO THE HITS DATA FILE ON THE SERVER
    try {               // for loading from a jar file
      I = getClass().getResourceAsStream("hc.dat");
      L = 512;          // cannot find the current file length easily
      l = 0;            // number of bytes so far successfully downloaded
      B = new byte[L];  // create the gigantic buffer for the data
      lp = 2;           // advance to the index loading phase
    }

    /* If an exception occurs while connecting, set unrecoverable error
    status and note the type of exception and where it occurred. */

    catch(Exception e) { lp = 0; E = "fileConnect() " + e; } 
  }


  void fileLoad() {  // DOWNLOAD THE HITS DATA
    int k;           //current byte being read()
    try {

      /* While read() hasn't hit current end of input stream
      and the entire file has not yet been downloaded: */

      while((k = I.read()) != -1)
        B[l++] = (byte)k;  // add its new byte to the big byte array

      I.close();  // close the URL Connection's input stream
      lp = 3;     // indicate file loading completed successfully
    } 

    /* If an exception occurs while loading, set unrecoverable error
    status and note the type of exception and where it occurred. */

    catch(Exception e) { lp = 0; E = "fileLoad() " + e + L + " " + l; }
  }


  // DRAW A RIGHT-JUSTIFIED STRING
  void rightString(Graphics g, String s, int x, int y) {
    FontMetrics                               // get character dimensions
      fm = g.getFontMetrics();                // for current font
    g.drawString(s,x - fm.stringWidth(s),y);  // display the string
  }
}