EditCommand: Store Person to be edited

EditCommand only stores the `Index` of the `Person`
in the current `filteredPersonList` to be edited.

This could cause the wrong `Person` to be edited during the
re-execution of the same command during `redo()` due to
different indexing in different `filteredPersonList` views.

Let's update `EditCommand` to store the `Person` to be
edited before its first execution.

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

@@ -50,9 +50,13 @@ public class EditCommand extends UndoableCommand {
     public static final String MESSAGE_NOT_EDITED = "At least one field to edit must be provided.";
     public static final String MESSAGE_DUPLICATE_PERSON = "This person already exists in the address book.";
 
-    private final Index index;
+    private final Index targetIndex;
     private final EditPersonDescriptor editPersonDescriptor;
 
+    private ReadOnlyPerson personToEdit;
+    private boolean isFirstExecution;
+
+
     /**
      * @param index of the person in the filtered person list to edit
      * @param editPersonDescriptor details to edit the person with
@@ -61,19 +65,20 @@ public EditCommand(Index index, EditPersonDescriptor editPersonDescriptor) {
         requireNonNull(index);
         requireNonNull(editPersonDescriptor);
 
-        this.index = index;
         this.editPersonDescriptor = new EditPersonDescriptor(editPersonDescriptor);
+        targetIndex = index;
+        isFirstExecution = true;
+        personToEdit = null;
     }
 
     @Override
     public CommandResult executeUndoableCommand() throws CommandException {
-        List<ReadOnlyPerson> lastShownList = model.getFilteredPersonList();
 
-        if (index.getZeroBased() >= lastShownList.size()) {
-            throw new CommandException(Messages.MESSAGE_INVALID_PERSON_DISPLAYED_INDEX);
+        if (isFirstExecution) {
+            preprocessEditCommand();
+            isFirstExecution = false;
         }
 
-        ReadOnlyPerson personToEdit = lastShownList.get(index.getZeroBased());
         Person editedPerson = createEditedPerson(personToEdit, editPersonDescriptor);
 
         try {
@@ -104,6 +109,21 @@ private static Person createEditedPerson(ReadOnlyPerson personToEdit,
         return new Person(updatedName, updatedPhone, updatedEmail, updatedAddress, updatedTags);
     }
 
+    /**
+     * Preprocess the command before its first execution by finding and storing
+     * the {@code personToEdit}
+     */
+    private void preprocessEditCommand() throws CommandException {
+
+        List<ReadOnlyPerson> lastShownList = model.getFilteredPersonList();
+
+        if (targetIndex.getZeroBased() >= lastShownList.size()) {
+            throw new CommandException(Messages.MESSAGE_INVALID_PERSON_DISPLAYED_INDEX);
+        }
+
+        personToEdit = lastShownList.get(targetIndex.getZeroBased());
+    }
+
     @Override
     public boolean equals(Object other) {
         // short circuit if same object
@@ -118,7 +138,7 @@ public boolean equals(Object other) {
 
         // state check
         EditCommand e = (EditCommand) other;
-        return index.equals(e.index)
+        return targetIndex.equals(e.targetIndex)
                 && editPersonDescriptor.equals(e.editPersonDescriptor);
     }
 

src/test/java/systemtests/EditCommandSystemTest.java

@@ -101,6 +101,7 @@ public void edit() throws Exception {
         /* ------------------ Performing edit operation while a filtered list is being shown ------------------------ */
 
         /* Case: filtered person list, edit index within bounds of address book and person list -> edited */
+        model  = getModel();
         showPersonsWithName(KEYWORD_MATCHING_MEIER);
         index = INDEX_FIRST_PERSON;
         assertTrue(index.getZeroBased() < getModel().getFilteredPersonList().size());
@@ -109,6 +110,17 @@ public void edit() throws Exception {
         editedPerson = new PersonBuilder(personToEdit).withName(VALID_NAME_BOB).build();
         assertCommandSuccess(command, index, editedPerson);
 
+        /* Case: undo editing the first person in the filtered list -> first person in filtered list restored */
+        command = UndoCommand.COMMAND_WORD;
+        expectedResultMessage = UndoCommand.MESSAGE_SUCCESS;
+        assertCommandSuccess(command, model, expectedResultMessage);
+
+        /* Case: redo editing the first person in the filtered list -> first person in filtered list edited again */
+        command = RedoCommand.COMMAND_WORD;
+        expectedResultMessage = RedoCommand.MESSAGE_SUCCESS;
+        model.updatePerson(personToEdit, editedPerson);
+        assertCommandSuccess(command, model, expectedResultMessage);
+
         /* Case: filtered person list, edit index within bounds of address book but out of bounds of person list
          * -> rejected
          */