hw3: use iterator pattern for iterating through list

hw3/src/PhotoAlbumApp.java

@@ -1,11 +1,12 @@
 import controller.PhotoAlbumController;
 import model.PhotoAlbumModel;
+import strategy.SortByDate;
 import view.PhotoAlbumView;
 
 public class PhotoAlbumApp {
     public static void main(String[] args) {
         // Create MVC components
-        PhotoAlbumModel model = new PhotoAlbumModel();
+        PhotoAlbumModel model = new PhotoAlbumModel(new SortByDate());
         PhotoAlbumView view = new PhotoAlbumView();
         PhotoAlbumController controller = new PhotoAlbumController(model, view);
 

hw3/src/controller/PhotoAlbumController.java

@@ -1,7 +1,5 @@
 package controller;
 
-import iterator.AlbumIterator;
-import iterator.PhotoIterator;
 import model.Photo;
 import model.PhotoAlbumModel;
 import strategy.SortByDate;
@@ -56,26 +54,14 @@ public class PhotoAlbumController {
     }
 
     public void handleNext() {
-        List<Photo> photos = model.getPhotos();
-        if (photos.isEmpty()) return;
-
-        Photo current = model.getCurrentPhoto();
-        int index = photos.indexOf(current);
-
-        if (index < photos.size() - 1) {
-            model.setCurrentPhoto(photos.get(index + 1));
+        if (model.hasNext()) {
+            model.next();
         }
     }
 
     public void handlePrevious() {
-        List<Photo> photos = model.getPhotos();
-        if (photos.isEmpty()) return;
-
-        Photo current = model.getCurrentPhoto();
-        int index = photos.indexOf(current);
-
-        if (index > 0) {
-            model.setCurrentPhoto(photos.get(index - 1));
+        if (model.hasPrevious()) {
+            model.previous();
         }
     }
 
@@ -94,9 +80,10 @@ public class PhotoAlbumController {
     }
 
     public void handlePhotoSelection(int index) {
+        // Reset iterator and loop to the selected index
         List<Photo> photos = model.getPhotos();
-        if (index >= 0 && index < photos.size()) {
-            model.setCurrentPhoto(photos.get(index));
+        for (int i = 0; i < index; i++) {
+            model.next();
         }
     }
 }

hw3/src/model/PhotoAlbumModel.java

@@ -2,36 +2,40 @@ package model;
 
 import strategy.SortingStrategy;
 import iterator.AlbumIterator;
+import iterator.PhotoIterator;
 import java.util.*;
 
 public class PhotoAlbumModel {
     private List<Photo> photos;
     private SortingStrategy<Photo> sortingStrategy;
     private final List<ModelChangeListener> listeners;
-    private Photo currentPhoto;
+    private AlbumIterator iterator;
 
     public interface ModelChangeListener {
         void onModelChanged();
     }
 
-    public PhotoAlbumModel() {
+    public PhotoAlbumModel(SortingStrategy<Photo> sortingStrategy) {
         photos = new ArrayList<>();
         listeners = new ArrayList<>();
+        iterator = new PhotoIterator(photos);
+        this.sortingStrategy = sortingStrategy;
     }
 
     public void addPhoto(Photo photo) {
         photos.add(photo);
-        if (photos.size() == 1) {
-            currentPhoto = photo;
-        }
         sortPhotos();
+        iterator = new PhotoIterator(photos);
         notifyListeners();
     }
 
     public void deletePhoto(String name) {
+        Photo currentPhoto = iterator.current();
         photos.removeIf(photo -> photo.name().equals(name));
-        if (currentPhoto != null && currentPhoto.name().equals(name)) {
-            currentPhoto = photos.isEmpty() ? null : photos.getFirst();
+        if (photos.isEmpty()) {
+            iterator = new PhotoIterator(photos);
+        } else if (currentPhoto != null && currentPhoto.name().equals(name)) {
+            iterator = new PhotoIterator(photos);
         }
         notifyListeners();
     }
@@ -39,13 +43,12 @@ public class PhotoAlbumModel {
     public void setSortingStrategy(SortingStrategy<Photo> strategy) {
         this.sortingStrategy = strategy;
         sortPhotos();
+        iterator = new PhotoIterator(photos);
         notifyListeners();
     }
 
     private void sortPhotos() {
-        if (sortingStrategy != null) {
-            photos = sortingStrategy.sort(photos);
-        }
+        photos = sortingStrategy.sort(photos);
     }
 
     public void addListener(ModelChangeListener listener) {
@@ -63,13 +66,38 @@ public class PhotoAlbumModel {
     }
 
     public Photo getCurrentPhoto() {
-        return currentPhoto;
+        try {
+            return iterator.current();
+        } catch (NoSuchElementException e) {
+            return null;
+        }
     }
 
-    public void setCurrentPhoto(Photo photo) {
-        if (photos.contains(photo)) {
-            currentPhoto = photo;
+    public boolean hasNext() {
+        return iterator.hasNext();
+    }
+
+    public boolean hasPrevious() {
+        return iterator.hasPrevious();
+    }
+
+    public Photo next() {
+        try {
+            Photo next = iterator.next();
             notifyListeners();
+            return next;
+        } catch (NoSuchElementException e) {
+            return null;
+        }
+    }
+
+    public Photo previous() {
+        try {
+            Photo prev = iterator.previous();
+            notifyListeners();
+            return prev;
+        } catch (NoSuchElementException e) {
+            return null;
         }
     }
 }