/** 
  * Applet to generate a graph of my 'as paid' and my inflation-corrected
    income.
  * @author Robert J Morton <rob@robmorton.20m.com>
  * @version 12 July 2000, 27 April 2012
  * @copyright July 2000 Robert J Morton (all rights reserved) */

//  DATA LOADER


import java.io.*;   // for stream handling for the above
import java.net.*;  // for downloading data from the remote server


public class loader {
  private InputStream I;  // input stream for downloading data files
  private byte B[];       // gigantic byte array to hold the downloaded data

  private int
    lp = 0,   // indicates current download phase
    LP = 0,   // indicates previous download phase
    L = 0,    // length of the remote item being loaded
    l = 0;    // number of bytes of the above successfully downloaded so far

  private boolean jarred = true;

  private String 
    FN,   // filename of current data file
    cb;   // code base URL - where this applet's class file came from

  private graphs ap;   // instance reference to the mail applet
  private trace TR;    // instance reference to the trace panel


  loader(graphs ap, trace TR, boolean jarred) {
    this.ap = ap;
    this.TR = TR;
    this.jarred = jarred;

    // URL (less file name) from where this applet came
    cb = ap.getCodeBase().toString();

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

    if(!cb.endsWith("/")) {
      int x = cb.lastIndexOf('/');
      if(x != -1)
        cb = cb.substring(0, x + 1);
    }
  }


  void runLoop() {
    switch(lp) {  // THE 3 DOWNLOADING PHASES

      // load phase 1: connect to index resource on server
      case 1: fileConnect(); break;

      // load phase 2: manage the downloading of its content
      case 2: fileLoad(); break;

      /* load phase 3: if loading of data has finished, latch the current
      load state and paint all the widgets as well as the graph. */
      case 3: if(lp != LP) { LP = lp; ap.repaint(); }
    }
  }


  void fileConnect() {  // CONNECT TO THE FINANCIAL DATA FILE ON THE SERVER

    ap.showStatus("Connecting to server...");

    try {

      /* If loading from the applet's '.jar' file, create stream
      through which to load the file, use a fixed known length for
      the file because we cannot find the current file length easily */

      if(jarred) { 
        I = getClass().getResourceAsStream(FN + ".dat");
        L = 4096;
      }

      /* Else we're loading directly from the remote server, so form
      the URL of the account balance data file, create an input stream
      object to access the file and get length of the remote file. */

      else {
        URL url = new URL(cb + FN + ".dat");
        URLConnection u = url.openConnection();
        I = u.getInputStream();
        L = u.getContentLength();
      }

      l = 0;            // number of bytes so far successfully downloaded
      B = new byte[L];  // create the gigantic buffer for the data

      DataInputStream D = new DataInputStream(new ByteArrayInputStream(B));

      TR.setD(D);       // inform the trace panel
      lp = 2;           // advance to the file loading phase
    }

    /* Set unrecoverable error status and note the
    type of exception and where it occurred. */

    catch(Exception e) {
      lp = 0; 
      ap.showStatus("fileConnect() " + e);
    } 
  }


  void fileLoad() {  // DOWNLOAD THE DATA
    ap.showStatus("Loading data...");
    int k;                      // current byte being read()
    try {                       // try to load the index file
      if(jarred)                // If loading from the '.jar' file:
        while(                  // then while we have
          (k = I.read()) != -1  // not yet hit current end of input stream
        ) B[l++] = (byte)k;     // add new byte to big byte array.

      else  // else we are loading directly from the remote server

        while(                  // So, while:
          l < L &&              // the entire file not yet downloaded, and
          (k = I.read()) != -1  // not yet hit current end of input stream
        ) B[l++] = (byte)k;     // add its new byte to the big byte array.

        if(jarred || l >= L) {  // If whole index has now been downloaded,
          I.close();            // close the  URL Connection's input stream
          lp = 3;               // and indicate that index file has been
          ap.showStatus("Graph data loaded.");  // loaded successfully.
       }
    } 

    /* If an exception occurs during download, set error condition, note
    the type of exception and where it occurred: it occurred during file
    loading, 'e' contains the kind of error (exception) that occurred,
    show the length of the file (in bytes) and how many bytes had been
    loaded when the error occurred. */

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


  void getData(String FN) {
    this.FN = FN;  // get the name of the required data file
    lp = 1;        // initiate the loading sequence
    LP = 0;        // prime the loading sequence latch
  }
}