refactor: separate collection state from UI navigation

app/src/main/java/ru/project/App.java

@@ -21,9 +21,18 @@ public final class App {
     try {
       MultiWindowTextGUI gui = new MultiWindowTextGUI(screen);
 
-      Navigator navigator = new Navigator(gui);
+      // Application state
+      AppState state = new AppState();
 
+      // Controllers
+      CollectionController collectionController = new CollectionController(state);
+
+      // Navigation
+      Navigator navigator = new Navigator(gui, collectionController);
+
+      // Application entry point
       gui.addWindowAndWait(new MainMenu(navigator));
+
     } finally {
       screen.stopScreen();
     }

app/src/main/java/ru/project/AppState.java

@@ -0,0 +1,18 @@
+package ru.project;
+
+public class AppState {
+
+  private DataCollection collection;
+
+  public DataCollection getCollection() {
+    return collection;
+  }
+
+  public void setCollection(DataCollection collection) {
+    this.collection = collection;
+  }
+
+  public boolean hasCollection() {
+    return collection != null;
+  }
+}

app/src/main/java/ru/project/CollectionController.java

@@ -0,0 +1,49 @@
+package ru.project;
+
+public class CollectionController {
+
+  private final AppState state;
+
+  public CollectionController(AppState state) {
+    this.state = state;
+  }
+
+  public void createCollection() {
+    DataCollection collection = new DataCollection();
+
+    collection.add("Charlie");
+    collection.add("Alice");
+    collection.add("Bob");
+    collection.add("Alice");
+
+    state.setCollection(collection);
+  }
+
+  public DataCollection getCollection() {
+    return state.getCollection();
+  }
+
+  public boolean hasCollection() {
+    return state.hasCollection();
+  }
+
+  public void sortCollection() {
+    if (!state.hasCollection()) {
+      return;
+    }
+
+    state.getCollection().sort();
+  }
+
+  public boolean contains(String element) {
+    return state.hasCollection() && state.getCollection().contains(element);
+  }
+
+  public int countOccurrences(String element) {
+    if (!state.hasCollection()) {
+      return 0;
+    }
+
+    return state.getCollection().count(element);
+  }
+}

app/src/main/java/ru/project/DataCollection.java

@@ -0,0 +1,47 @@
+package ru.project;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+public class DataCollection {
+
+  private final List<String> elements = new ArrayList<>();
+
+  public void add(String element) {
+    elements.add(element);
+  }
+
+  public void sort() {
+    Collections.sort(elements);
+  }
+
+  public boolean contains(String element) {
+    return elements.contains(element);
+  }
+
+  public int count(String element) {
+    int count = 0;
+
+    for (String current : elements) {
+      if (current.equals(element)) {
+        count++;
+      }
+    }
+
+    return count;
+  }
+
+  public List<String> getElements() {
+    return Collections.unmodifiableList(elements);
+  }
+
+  @Override
+  public String toString() {
+    if (elements.isEmpty()) {
+      return "Коллекция пуста";
+    }
+
+    return String.join(", ", elements);
+  }
+}

app/src/main/java/ru/project/ui/CollectionView.java

@@ -1,8 +1,10 @@
 package ru.project.ui;
 
+import ru.project.CollectionController;
+
 public class CollectionView extends EmptyMenu {
 
-  public CollectionView() {
+  public CollectionView(CollectionController controller) {
     super("Текущая коллекция");
   }
 }

app/src/main/java/ru/project/ui/CountOccurrencesMenu.java

@@ -1,8 +1,10 @@
 package ru.project.ui;
 
+import ru.project.CollectionController;
+
 public class CountOccurrencesMenu extends EmptyMenu {
 
-  public CountOccurrencesMenu() {
+  public CountOccurrencesMenu(CollectionController controller) {
     super("Подсчёт количества вхождений");
   }
 }

app/src/main/java/ru/project/ui/CreateCollectionMenu.java

@@ -1,8 +1,10 @@
 package ru.project.ui;
 
+import ru.project.CollectionController;
+
 public class CreateCollectionMenu extends EmptyMenu {
 
-  public CreateCollectionMenu() {
+  public CreateCollectionMenu(CollectionController controller) {
     super("Создание новой коллекции");
   }
 }

app/src/main/java/ru/project/ui/Navigator.java

@@ -2,13 +2,16 @@ package ru.project.ui;
 
 import com.googlecode.lanterna.gui2.BasicWindow;
 import com.googlecode.lanterna.gui2.WindowBasedTextGUI;
+import ru.project.CollectionController;
 
 public class Navigator {
 
   private final WindowBasedTextGUI gui;
+  private final CollectionController collectionController;
 
-  public Navigator(WindowBasedTextGUI gui) {
+  public Navigator(WindowBasedTextGUI gui, CollectionController collectionController) {
     this.gui = gui;
+    this.collectionController = collectionController;
   }
 
   public void show(BasicWindow window) {
@@ -16,26 +19,26 @@ public class Navigator {
   }
 
   public void showCollectionView() {
-    show(new CollectionView());
+    show(new CollectionView(collectionController));
   }
 
   public void showCreateCollection() {
-    show(new CreateCollectionMenu());
+    show(new CreateCollectionMenu(collectionController));
   }
 
   public void showSaveCollection() {
-    show(new SaveCollectionMenu());
+    show(new SaveCollectionMenu(collectionController));
   }
 
   public void showSortCollection() {
-    show(new SortCollectionMenu());
+    show(new SortCollectionMenu(collectionController));
   }
 
   public void showSearchElement() {
-    show(new SearchElementMenu());
+    show(new SearchElementMenu(collectionController));
   }
 
   public void showCountOccurrences() {
-    show(new CountOccurrencesMenu());
+    show(new CountOccurrencesMenu(collectionController));
   }
 }

app/src/main/java/ru/project/ui/SaveCollectionMenu.java

@@ -1,8 +1,10 @@
 package ru.project.ui;
 
+import ru.project.CollectionController;
+
 public class SaveCollectionMenu extends EmptyMenu {
 
-  public SaveCollectionMenu() {
+  public SaveCollectionMenu(CollectionController controller) {
     super("Сохранение текущей коллекции");
   }
 }

app/src/main/java/ru/project/ui/SearchElementMenu.java

@@ -1,8 +1,10 @@
 package ru.project.ui;
 
+import ru.project.CollectionController;
+
 public class SearchElementMenu extends EmptyMenu {
 
-  public SearchElementMenu() {
+  public SearchElementMenu(CollectionController controller) {
     super("Поиск элемента");
   }
 }

app/src/main/java/ru/project/ui/SortCollectionMenu.java

@@ -1,8 +1,10 @@
 package ru.project.ui;
 
+import ru.project.CollectionController;
+
 public class SortCollectionMenu extends EmptyMenu {
 
-  public SortCollectionMenu() {
+  public SortCollectionMenu(CollectionController controller) {
     super("Сортировка текущей коллекции");
   }
 }