/** 
  * Semi-Generic Loader
  * @author Robert J Morton YE572246C
  * @version 04 December 2007
  * @copyright Robert J Morton (all rights reserved) */

import java.io.*;   // file input/output handling
import java.net.*;  // for downloading data from the remote server

class loader {  // TO LOAD AND DISPLAY ROUTE NAMES AND GEOGRAPHIC FEATURES

  private boolean 
    connectFTT = true,   // first-time-through flag
    loadingFTT = true,   // first-time-through flag
    dataLoaded = false;  // hits data not yet loaded

  private int
    ls = 0,  // load switch [see navstart.java]
    lp = 0,  // 0=idle 1=connecting 2=loading 3=connect error 4=load error
    l = 0;   // number of bytes of the above successfully downloaded

  int L = 0;  // length of the remote item being loaded
  byte B[];   // gigantic byte array to hold the downloaded index data

  private String 
    loadFile = "hc.dat",  // name of the route names file
    cb;                   // URL path to data files

  private BufferedReader R;  // for reading data from files
  private InputStream I;     // input stream for downloading data file


  // CONSTRUCTOR
  loader(int ls, String cb) {
    this.ls = ls;  // load switch
    this.cb = cb;  // URL (less file name) from where this applet came
    lp = 1;        // start the route names loading process
  }


  // RUN THE AUXILIARY THREAD
  boolean dataLoaded() {
    switch(lp) {        // THE 2 DOWNLOADING PHASES
      case 1:
        fileConnect();  // connect to data resource on server
        break;
      case 2:
        fileLoad();     // manage the downloading of its content
    }
    return dataLoaded;
  }


  // CONNECT TO APPROPRIATE DATA FILE ON SERVER
  private void fileConnect() {
    if(!connectFTT)
      return;
    System.out.println("Connecting to server...");
    connectFTT = false;
    try {  // set to capture any exceptions locally

      switch(ls) {
        case 0: // Create an input stream to load from local file
          L = (int)(new File(loadFile)).length();
          I = new FileInputStream(loadFile);
          break;

        case 1: // Create an input stream to load from jar file
          L = 512; //default maximum content length
          I = getClass().getResourceAsStream(loadFile);
          break;

        case 2: // Create an input stream to load ile from server
          URLConnection u = new URL(cb + loadFile).openConnection();
          I = u.getInputStream();
          L = (int)u.getContentLength();
      }

      B = new byte[L];  // create the gigantic buffer for the data
      l = 0;            // number of bytes so far successfully downloaded
      lp = 2;           // advance to the index loading phase
    }

    /* If any exception at all occurs, note what kind
    of exception it was and where it occurred. */

    catch(Exception e) {
      System.out.println("fileConnect() " + e);
      System.out.println("Couldn't find hits data file.");
      lp = 4;  // reset loader to its idle state
    }
  }


  // DOWNLOAD THE APPROPRIATE DATA FILE
  private void fileLoad() {
    if(loadingFTT) {
      System.out.println("Loading hits data...");
      loadingFTT = false;
    }
    int k;  // content of current byte being read()

    /* NOTE: Multiple passes of this fileLoad() are only necessary for
    downloading across the Internet [ls = 2]. Loading from a file 
    in the local directory or from a jar file only need to pass once
    through this method.*/

    try {
      if(ls == 1) {  // L is unknown for jar files

        /* While the entire file has not yet been down-
        loaded add each new byte to the big byte array. */

        while((k = I.read()) != -1)
          B[l++] = (byte)k;
        L = l;  // marks the end point of the data
      }
      else  // L is known for server connections and local files

        while(l < L && (k = I.read()) != -1)
          B[l++] = (byte)k;

      if(l >= L) {
        I.close();  // close URL Connection [or local file]
        lp = 3;     // go to post-loading phase
        dataLoaded = true;
        System.out.println("Hits data loaded.");
      }
    }

    /* Catch any data transmission or file loading error
    conditions and note the kind of exception and where
    it occurred then display it in the terminal. */

    catch(Exception e) {
      System.out.println("fileLoad() " + e + L + " " + l);
      System.out.println("Couldn't load hits data.");
      lp = 5;  // reset loader to its idle state
    }
  }
}