/** 
  * Web Site Hits and TLI Sales 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 tlisales extends Applet implements Runnable {
   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
     lp = 1,   // indicates current download phase 
     LP = 1,   // indicates previous download phase
     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
     weeks[] = {52,52,52,52,52,52,52};   // weeks in year

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

  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

  String   // Year names and "hits scale".
    year[] = {"1998","1999","2000","2001","2002","2003","2004"},
    hits[] = {"0","20","40","60","80","100","110"},
    cb,  // code base URL - where this applet's class file came from
    E;   // for Exception during downloading + method where it occurred

  AppletContext ac;  // ref to 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 
  Thread TH;  // reference for a separate Internet Data Transfer thread


  public void init() {
    bg1 = getBackground();
    setBackground(bg1);
    ac = getAppletContext();        // get applet's context reference
    cb = getCodeBase().toString();  // URL path from where this applet came

    /* Workaround re Hotjava re Microsoft intranet machine names where
    getCodeBase() wrongly returns the document base (cira Nov 1999). */

    if(!cb.endsWith("/")) {
      int x = cb.lastIndexOf('/');
      if(x != -1) 
      cb = cb.substring(0,x + 1);
    }
    TH = new Thread(this);  // create a thread for downloading data
    setBackground(bg1);     // set the applet's background colour
  }


  public void paint(Graphics g) { 
    g.setColor(bg1); g.fillRect(0,0,450,170);      // clear graph panel
    g.setColor(bg2); g.fillRect(X,Y-120,364,120);  // clear graph area
    w = 0;
    for(int i = 0; i < weeks.length; i++) {  // for each year shown

      g.setColor(Color.black);
      g.drawString(year[i],X + 13 + w,Y + 20);  // year number
      g.drawLine(X + w,Y + 5,X + w,Y + 10);     // year boundary mark

      g.setColor(bg3);
      g.drawLine(X + w,Y,X + w,Y - 120);  // annotation mark
      w += weeks[i];                      // accumulated number of weeks
    }
    g.setColor(bg3);
    g.drawLine(X + w,Y,X + w,Y - 120);  // annotation mark

    g.setColor(Color.black);
    g.drawLine(X + w, Y + 5,X + w,Y + 10);  // final year boundary mark
    g.drawLine(X,Y + 5,X + w,Y + 5);        // 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);
      g.drawLine(X,Y - z,X + w,Y - z);  // annotation mark
      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) {

    g.setColor(Color.blue);  // set trace colour to blue
    int h = 0;               // number of hits for a given week

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

      for(int i = 0; i < L; i++) {  // For each weekly hits figure ...

        /* Provided the hits count > zero [to avoid displaying zero values
        before start date], display it as a vertical bar on the chart: */

        if((h = (int)B[i]) > 0) {
          g.drawLine(w,Y,w,Y - h);
          H += h;  // add this week's hits to the total
          W++;     // increment number of weeks for which there's 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/resume execution of 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 the hits data loading process has just finished,
        LP = lp;      // latch the current load state
        repaint();    // and display the histogram bars.
      }
      /* Put the thread to sleep for 250 milliseconds. Catch any exceptions
      which may occur during this time but take no action as they are not
      relevant to this program. */

      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 existsand
  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("tlisales.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 the current end of input stream
      and the entire file has not yet been downloaded, add its
      new byte to the array big byte array. */

      while((k = I.read()) != -1)
        B[l++] = (byte)k;
      I.close();  // close the URL Connection's input stream
      lp = 3;     // indicate file loading completed successfully
    }
    /* 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 = "fileLoad() " + e + L + " " + l; }
  }


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