Refactor code for delete task feature

src/main/java/seedu/address/logic/commands/DeleteTaskCommand.java

@@ -2,28 +2,35 @@
 
 import static java.util.Objects.requireNonNull;
 
+import seedu.address.commons.core.index.Index;
 import seedu.address.commons.util.ToStringBuilder;
 import seedu.address.logic.commands.exceptions.CommandException;
 import seedu.address.model.Model;
+import seedu.address.model.task.Task;
 
 /**
  * Deletes a task in the task list.
  */
 public class DeleteTaskCommand extends Command {
 
     public static final String COMMAND_WORD = "deletetask";
-    public static final String MESSAGE_USAGE = COMMAND_WORD + "<index> : Deletes a task in the task list.";
-    public static final String MESSAGE_SUCCESS = "Task number %1$s has been deleted.";
+    public static final String MESSAGE_USAGE = COMMAND_WORD
+            + ": Deletes the task identified by the index number used in the displayed task list.\n"
+            + "Parameters: INDEX (must be a positive integer)\n"
+            + "Example: " + COMMAND_WORD + " 1";
+    public static final String MESSAGE_SUCCESS = "Deleted Task: %1$s";
     public static final String MESSAGE_INDEX_TOO_LARGE = "The index is not valid, use \"list task\" to "
             + "display all tasks.";
+
+
     public static final String MESSAGE_INDEX_BELOW_ONE = "The index must be greater than 0.";
 
-    private final Integer taskIndexToDelete;
+    private final Index taskIndexToDelete;
 
     /**
      * Creates an DeleteTaskCommand to add the specified {@code index}
      */
-    public DeleteTaskCommand(int index) {
+    public DeleteTaskCommand(Index index) {
         taskIndexToDelete = index;
     }
 
@@ -38,22 +45,18 @@ public DeleteTaskCommand(int index) {
     public CommandResult execute(Model model) throws CommandException {
         requireNonNull(model);
 
-        if (taskIndexToDelete <= 0) {
-            throw new CommandException(MESSAGE_INDEX_BELOW_ONE);
-        }
-
         if (!model.isValidTaskIndex(taskIndexToDelete)) {
             throw new CommandException(MESSAGE_INDEX_TOO_LARGE);
-        }
+        }        
 
-        model.deleteTask(taskIndexToDelete);
-        return new CommandResult(String.format(MESSAGE_SUCCESS, taskIndexToDelete));
+        Task deletedTask = model.deleteTask(taskIndexToDelete);
+        return new CommandResult(String.format(MESSAGE_SUCCESS, deletedTask.getDescription()));
     }
 
     @Override
     public String toString() {
         return new ToStringBuilder(this)
-                .add("toDelete", taskIndexToDelete)
+                .add("toDelete", taskIndexToDelete.getOneBased())
                 .toString();
     }
 }

src/main/java/seedu/address/logic/parser/DeleteTaskCommandParser.java

@@ -2,6 +2,7 @@
 
 import static seedu.address.logic.Messages.MESSAGE_INVALID_COMMAND_FORMAT;
 
+import seedu.address.commons.core.index.Index;
 import seedu.address.logic.commands.DeleteTaskCommand;
 import seedu.address.logic.parser.exceptions.ParseException;
 
@@ -22,9 +23,9 @@ public DeleteTaskCommand parse(String userInput) throws ParseException {
             throw new ParseException(String.format(MESSAGE_INVALID_COMMAND_FORMAT, DeleteTaskCommand.MESSAGE_USAGE));
         }
         try {
-            int taskIndexToDelete = Integer.parseInt(userInput.trim());
+            Index taskIndexToDelete = ParserUtil.parseIndex(userInput.trim());
             return new DeleteTaskCommand(taskIndexToDelete);
-        } catch (NumberFormatException e) {
+        } catch (ParseException pe) {
             throw new ParseException(String.format(MESSAGE_INVALID_COMMAND_FORMAT, DeleteTaskCommand.MESSAGE_USAGE));
         }
 

src/main/java/seedu/address/model/Model.java

@@ -5,6 +5,7 @@
 
 import javafx.collections.ObservableList;
 import seedu.address.commons.core.GuiSettings;
+import seedu.address.commons.core.index.Index;
 import seedu.address.model.person.Person;
 import seedu.address.model.task.Task;
 
@@ -107,7 +108,7 @@ static void setTaskList(TaskList taskList) {}
      * Deletes the given task.
      * {@code index} the index must exist in the task list.
      */
-    void deleteTask(int index);
+    Task deleteTask(Index index);
 
     /**
      * Returns true if a task has the same description as a {@code task} in the task list.
@@ -117,7 +118,7 @@ static void setTaskList(TaskList taskList) {}
     /**
      * Returns true if the {@code index} is within the task list.
      */
-    boolean isValidTaskIndex(int index);
+    boolean isValidTaskIndex(Index index);
 
     /** Returns an unmodifiable view of the filtered person list */
     ObservableList<Person> getFilteredPersonList();

src/main/java/seedu/address/model/ModelManager.java

@@ -11,6 +11,7 @@
 import javafx.collections.transformation.FilteredList;
 import seedu.address.commons.core.GuiSettings;
 import seedu.address.commons.core.LogsCenter;
+import seedu.address.commons.core.index.Index;
 import seedu.address.model.person.Person;
 import seedu.address.model.task.Task;
 
@@ -141,8 +142,8 @@ public void addTask(Task task) {
     }
 
     @Override
-    public void deleteTask(int index) {
-        taskList.deleteTask(index);
+    public Task deleteTask(Index index) {
+        return taskList.deleteTask(index);
     }
 
     @Override
@@ -152,7 +153,7 @@ public boolean hasTask(Task task) {
     }
 
     @Override
-    public boolean isValidTaskIndex(int index) {
+    public boolean isValidTaskIndex(Index index) {
         return taskList.isValidTaskIndex(index);
     }
     /**

src/main/java/seedu/address/model/TaskList.java

@@ -5,6 +5,7 @@
 
 import javafx.collections.FXCollections;
 import javafx.collections.ObservableList;
+import seedu.address.commons.core.index.Index;
 import seedu.address.model.task.Task;
 
 /**
@@ -34,13 +35,25 @@ public void addTask(Task task) {
         taskList.add(task);
     }
 
+    /**
+     * Returns a task based on the index of list.
+     *
+     * @param index The index of the task to be returned.
+     */
+    public Task getTask(Index index) {
+        Task task = taskList.get(index.getZeroBased());
+        return task;
+    }
+
     /**
      * Deletes a task based on the index of list.
      *
      * @param index The index of the task to be deleted in the list.
      */
-    public void deleteTask(int index) {
-        taskList.remove(index - 1);
+    public Task deleteTask(Index index) {
+        Task task = taskList.get(index.getZeroBased());
+        taskList.remove(index.getZeroBased());
+        return task;
     }
 
     public ObservableList<Task> getSerializeTaskList() {
@@ -51,8 +64,8 @@ public boolean hasTask(Task task) {
         return taskList.contains(task);
     }
 
-    public boolean isValidTaskIndex(int index) {
-        return taskList.size() > index;
+    public boolean isValidTaskIndex(Index index) {
+        return index.getZeroBased() < taskList.size();
     }
 
 }

src/test/java/seedu/address/logic/commands/AddCommandTest.java

@@ -16,6 +16,7 @@
 
 import javafx.collections.ObservableList;
 import seedu.address.commons.core.GuiSettings;
+import seedu.address.commons.core.index.Index;
 import seedu.address.logic.Messages;
 import seedu.address.logic.commands.exceptions.CommandException;
 import seedu.address.model.AddressBook;
@@ -193,7 +194,7 @@ public void addTask(Task task) {
          * @param index The index of the task to be deleted in the list.
          */
         @Override
-        public void deleteTask(int index) {
+        public Task deleteTask(Index index) {
             throw new AssertionError("This method should not be called.");
         }
 
@@ -214,7 +215,7 @@ public boolean hasTask(Task task) {
          * @param index
          */
         @Override
-        public boolean isValidTaskIndex(int index) {
+        public boolean isValidTaskIndex(Index index) {
             throw new AssertionError("This method should not be called.");
         }