/**
  * Image Loader for the Search Engine App
  * @author Robert J Morton
  * @version 12 Dec 2007, 10 April 2012 
  * Modified for encapsulation in jar file Thu 02 Feb 2017 12:51:07 BRST
  * JFramed Sat 04 Mar 2017 12:03:33 BRT  */

import java.awt.*;  // abstract window tool kit for applet 
import java.io.*;   // file input/output handling
import java.net.*;  // for downloading data from the remote server
import javax.imageio.*;
import java.awt.MediaTracker;  // for the new-fangled 1.1 event handling
import java.awt.image.BufferedImage;


public class imgldr {
  private search hf;             // instance reference to the search applet
  private img2panel img2;        // instance reference for message panel
  private MediaTracker tracker;  // to track when the images have been loaded

  private boolean 
    loadingImages = true,  // true while in the process of loading images
    trackerError = false,  // true indicates that tracker encountered an error
    loadFTT = true,        // to avoid an erase and repaint of the loading of
    errorFTT = true;       // load-error message once per refresh cycle

  private int ls;     // load switch 0=file, 1=jar, 2=server
  private String cb;  // code base [URL path to image files on server]
  private String[] S = {"local directory", "jar file", "remote server"};


  imgldr(search hf, img2panel img2, int ls, String cb) {
    this.hf = hf;      // instance reference to the movmap app
    this.img2 = img2;  // instance of message panel
    this.ls = ls;      // load switch
    this.cb = cb;      // code base [URL path]

    /* Create a media tracker and register images with it. Media tracker
    monitors the progress of loading process for each image files. */

    tracker = new MediaTracker(hf); 

    System.out.println("Loading images...");
    img2.showMsg("Loading images...", false);
    search.IMG0 = getImg("map-s0.png");  // try to load the image file
    if(search.IMG0 != null)
      tracker.addImage(search.IMG0,0);
    search.IMG1 = getImg("map-s1.png");  // try to load the image file
    if(search.IMG1 != null)
       tracker.addImage(search.IMG1,0);
    search.IMG2 = getImg("map-s2.png");  // try to load the image file
    if(search.IMG2 != null)
       tracker.addImage(search.IMG2,0);
    search.IMG3 = getImg("map-s3.png");  // try to load the image file
    if(search.IMG3 != null) {
      tracker.addImage(search.IMG3,0);
    }
  }


  private BufferedImage getImg(String F) {
    BufferedImage I = null;
    try {
      switch(ls) {
        case 0: I = ImageIO.read(new File(F)); break;
        case 1: I = ImageIO.read(getClass().getResourceAsStream(F)); break;
        case 2: I = ImageIO.read(new URL(cb + F));
      }
    } catch (IOException e) {
      System.out.println("Couldn't load " + F + " from " + S[ls] + ".");
      System.out.println(e);
    }
    return I;
  }


  boolean awaitingImages() {
    if(tracker == null)
      return false;
    if(loadFTT) {       // if this is the first time through here
      System.out.println("Tracking progress...");
      loadFTT = false;  // avoid repeating display every cycle      
    }
    try {

      /* Keep checking the tracker for a signalIf the tracker does not say
      anything, return without servicing the app's run() thread, otherwise,
      will drop thru when tracker gives a completion signal. */
      tracker.waitForAll();

    } catch (InterruptedException e) {
      return true;
    }
    return false;
  }


  // Returns true when image loading has terminated.
   boolean imagesLoaded() {
     if(tracker == null)
       return true;

     /* If the image loading process still running,
     get the status of the image loading process. */

     if(loadingImages) {
       int ts = tracker.statusAll(false);

       /* if the loading process has completed with
       an error, set the image loading failure flag */

       if((ts & MediaTracker.ERRORED) != 0) {
         trackerError = true;

         /* If this is the first time through on this image loading
         attempt, show the error message and set the error display
         flag false to avoid re-displaying the message each pass. */

         if(errorFTT) {
           img2.showMsg("Error: couldn't load image.", true);
           System.out.println("Error: couldn't load images.");
           errorFTT = false;
         }
       }

       /* if tracker has completed its task, set flag to set to indicate that
       image loading has terminated successfully. */

       if(ts == MediaTracker.COMPLETE)
         loadingImages = false;
    }

    /* else, image the loading process has just finished,
    so dispense with this instance of the Media Tracker
    and refresh message display if not already done. */

    else {
      killTracker();
      System.out.println("Images ready.");
    }
    return false;
  }


  /* If this instance of the Media Tracker still exists, remove 
  (de-register) the image from it and then destroy (garbage) it. */

  void killTracker() {
    if(tracker != null) {
      tracker.removeImage(search.IMG1, 0);
      tracker = null;
    }
  }

  boolean TrackerError() {return trackerError;}
}