package cse1030;

import java.awt.MediaTracker;
import java.io.File;
import java.util.ArrayList;
import java.util.List;

import javax.swing.ImageIcon;

/**
 * A model for the image viewer app. The model represents a sequence of
 * images. It supports traversal through the sequence of images by providing
 * methods for getting the previous image in the sequence, the current image
 * in the sequence, and the next image in the sequence. Images
 * 
 * @author CSE1030Z
 *
 */
public class ViewerModel {
  private static final ImageIcon EMPTY_IMAGE = new ImageIcon();

  private int currentImageIndex;
  private List<ImageIcon> images;

  /**
   * Create the model.
   */
  public ViewerModel() {
    this.currentImageIndex = -1;
    this.images = new ArrayList<ImageIcon>();
  }

  /**
   * Get the current image in the model. Returns an empty image if the model has no images.
   * 
   * @return the current image if the model has one or more images, or an empty
   *         image otherwise
   */
  public ImageIcon getCurrentImage() {
    if (this.currentImageIndex < 0) {
      return EMPTY_IMAGE;
    }
    return this.images.get(this.currentImageIndex);
  }

  /**
   * Get the next image in the model and makes the next image the current image.
   * Returns the current image if the current image is the last image in the
   * model. Returns an empty image if the model has no images.
   * 
   * @return the next image in the model 
   */
  public ImageIcon getNextImage() {
    if (this.currentImageIndex == this.images.size() - 1) {
      return this.getCurrentImage();
    }
    else if (this.images.isEmpty()) {
      return EMPTY_IMAGE;
    }
    else {
      this.currentImageIndex++;
      return this.images.get(this.currentImageIndex);
    }
  }

  /**
   * Get the previous image in the model and makes the previous image the current image.
   * Returns the current image if the current image is the first image in the
   * model. Returns an empty image if the model has no images.
   * 
   * @return the previous image in the model
   */
  public ImageIcon getPreviousImage() {
    if (this.currentImageIndex == 0) {
      return this.getCurrentImage();
    }
    else if (this.images.isEmpty()) {
      return EMPTY_IMAGE;
    }
    else {
      this.currentImageIndex--;
      return this.images.get(this.currentImageIndex);
    }
  }

  /**
   * Clear the images held by the model.
   */
  public void clearImages() {
    this.currentImageIndex = -1;
    this.images.clear();
  }
  
  /**
   * Read an array of image files into the model. The images are added to the end
   * of the sequence of images in the model. Image file formats supported
   * include JPEG, PNG, and GIF.
   * 
   * @param files an array of <code>File</code> references to open
   */
  public void openImages(File[] files) {
    List<ImageIcon> icons = new ArrayList<ImageIcon>();
    for (File f : files) {
      ImageIcon icon = new ImageIcon(f.getAbsolutePath());
      if (icon.getImageLoadStatus() == MediaTracker.COMPLETE) {
        icons.add(icon);
      }
    }
    if (this.currentImageIndex < 0 && icons.size() > 0) {
      this.currentImageIndex = 0;
    }
    this.images.addAll(icons);
  }

}