Merge pull request #214 from charlesliyifeng/refactor-undoable-as-int…

…erface

Refactor undoable as interface and implement undo for import

docs/DeveloperGuide.md

@@ -126,7 +126,7 @@ The `Model` component,
 * stores the address book data i.e., all `Person` objects (which are contained in a `UniquePersonList` object).
 * stores the currently 'selected' `Person` objects (e.g., results of a search query) as a separate _filtered_ list which is exposed to outsiders as an unmodifiable `ObservableList<Person>` that can be 'observed' e.g. the UI can be bound to this list so that the UI automatically updates when the data in the list change.
 * stores a `UserPref` object that represents the user’s preferences. This is exposed to the outside as a `ReadOnlyUserPref` objects.
-* stores a history of concrete commands (commands that can be undone) executed successfully by the user, which allows the user to undo commands.
+* stores a history of undoable commands executed successfully by the user, which allows the user to undo commands.
 * only depends on the Logic component due to the undo feature.
 
 <box type="info" seamless>
@@ -163,12 +163,12 @@ This section describes some noteworthy details on how certain features are imple
 
 #### Implementation
 
-The undo mechanism is facilitated by the abstract class `ConcreteCommand`. 
-It extends `Command` and has the `undo()` method. The `undo()` method is called when the user executes the `undo` command. 
+The undo mechanism is facilitated by the interface `Undoable`.
+It has the `undo()` method. The `undo()` method is called when the user executes the `undo` command. 
 The `undo()` method reverses the effects of the command that was previously executed.
-The `undo()` method is implemented in the concrete command classes, such as `AddCommand`, `DeleteCommand`, `EditCommand`, etc.
+The `undo()` method is implemented in the undoable command classes, such as `AddCommand`, `DeleteCommand`, `EditCommand`, etc.
 
-The `Model` component stores a history of executed concrete commands in a stack.
+The `Model` component stores a history of executed undoable commands in a stack.
 When a command is executed successfully, the command is pushed onto the stack.
 When the user executes the `undo` command, the `Model` component pops the last command from the stack and calls the `undo()` method of the command.
 
@@ -236,7 +236,7 @@ _{more aspects and alternatives to be added}_
 
 #### Implementation
 
-The `clean` command extends `ConcreteCommand`. The `clean` command deletes the contacts whose `GradYear` field is earlier
+The `clean` command extends `Command` and implements `Undoable`. The `clean` command deletes the contacts whose `GradYear` field is earlier
 than the current year, deleting contacts who have graduated from the address book.
 The `clean` command is undoable.
 

docs/UserGuide.md

@@ -240,7 +240,7 @@ This deletes all students who graduate in 2023 or earlier.
 
 Undoes the previous command that changes the data in the address book.
 
-Commands that can be undone are `add`, `delete`, `edit`, `clear`, `clean`.
+Commands that can be undone are `add`, `delete`, `edit`, `clear`, `clean`, `import`.
 
 Format: `undo`
 

docs/diagrams/LogicClassDiagram.puml

@@ -10,10 +10,11 @@ package "Parser Classes" as ParserClasses{
 }
 Class A_Command
 Class B_Command
-Class C_Command
+Class ImportCommand
+Class ExportCommand
 Class CommandResult
 Class "{abstract}\nCommand" as Command
-Class "{abstract}\nConcreteCommand" as ConcreteCommand
+Class "<<interface>>\nUndoable" as Undoable
 Class "{abstract}\nFileAccessCommand" as FileAccessCommand
 
 
@@ -35,14 +36,14 @@ LogicManager .right.|> Logic
 LogicManager -right->"1" ParserClasses
 ParserClasses ..> A_Command : <<create>>
 ParserClasses ..> B_Command : <<create>>
-ParserClasses ..> C_Command : <<create>>
 
-ConcreteCommand -up-|> Command
 FileAccessCommand -up-|> Command
-A_Command -up-|> ConcreteCommand
+A_Command .up.|> Undoable
+A_Command -up-|> Command
 B_Command -up-|> Command
-C_Command -up-|> FileAccessCommand
-A_Command .[hidden]right.> C_Command
+ExportCommand -up-|> FileAccessCommand
+ImportCommand -up-|> FileAccessCommand
+ImportCommand .up.|> Undoable
 LogicManager .left.> Command : <<call>>
 
 LogicManager --> Model
@@ -51,10 +52,9 @@ FileAccessCommand .up.> Storage
 Storage --[hidden] Model
 Command .[hidden]up.> Storage
 Command .right.> Model
+Model ..> Undoable
 note bottom of A_Command: Commands that can be undone: \nAddCommand, DeleteCommand, etc.
 note right of B_Command: Commands that cannot be undone: \nListCommand, UndoCommand, etc.
-note right of C_Command: Commands that access Storage: \nExportCommand, ImportCommand, etc.
-
 
 Logic ..> CommandResult
 LogicManager .down.> CommandResult

src/main/java/seedu/address/logic/LogicManager.java

@@ -10,9 +10,8 @@
 import seedu.address.commons.core.LogsCenter;
 import seedu.address.logic.commands.Command;
 import seedu.address.logic.commands.CommandResult;
-import seedu.address.logic.commands.ConcreteCommand;
 import seedu.address.logic.commands.FileAccessCommand;
-import seedu.address.logic.commands.ImportCommand;
+import seedu.address.logic.commands.Undoable;
 import seedu.address.logic.commands.exceptions.CommandException;
 import seedu.address.logic.parser.AddressBookParser;
 import seedu.address.logic.parser.exceptions.ParseException;
@@ -59,12 +58,10 @@ public CommandResult execute(String commandText) throws CommandException, ParseE
         assert command.isExecuted() : "Command should be executed.";
         assert commandResult != null : "CommandResult should not be null.";
 
-        // Push the command to the undo stack if it is a ConcreteCommand and successfully executed
+        // Push the command to the undo stack if it is undoable and successfully executed
         // No need to check for success as the command will exit through an exception if it fails
-        if (command instanceof ConcreteCommand) {
-            model.pushToUndoStack((ConcreteCommand) command);
-        } else if (command instanceof ImportCommand) {
-            model.clearUndoStack();
+        if (command instanceof Undoable) {
+            model.pushToUndoStack((Undoable) command);
         }
 
         try {

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

@@ -17,7 +17,7 @@
 /**
  * Adds a person to the address book.
  */
-public class AddCommand extends ConcreteCommand {
+public class AddCommand extends Command implements Undoable {
 
     public static final String COMMAND_WORD = "add";
 

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

@@ -20,7 +20,7 @@
 /**
  * Deletes all people whose graduation date has passed.
  */
-public class CleanCommand extends ConcreteCommand {
+public class CleanCommand extends Command implements Undoable {
 
     public static final String COMMAND_WORD = "clean";
 

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

@@ -8,7 +8,7 @@
 /**
  * Clears the address book.
  */
-public class ClearCommand extends ConcreteCommand {
+public class ClearCommand extends Command implements Undoable {
 
     public static final String COMMAND_WORD = "clear";
     public static final String MESSAGE_SUCCESS = "Address book has been cleared!";

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

@@ -20,7 +20,7 @@
 /**
  * Deletes a person identified using its displayed index from the address book.
  */
-public class DeleteCommand extends ConcreteCommand {
+public class DeleteCommand extends Command implements Undoable {
 
     public static final String COMMAND_WORD = "delete";
     public static final String MESSAGE_USAGE = COMMAND_WORD

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

@@ -39,7 +39,7 @@
 /**
  * Edits the details of an existing person in the address book.
  */
-public class EditCommand extends ConcreteCommand {
+public class EditCommand extends Command implements Undoable {
 
     public static final String COMMAND_WORD = "edit";
 

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

@@ -9,16 +9,18 @@
 import seedu.address.commons.exceptions.DataLoadingException;
 import seedu.address.commons.util.ToStringBuilder;
 import seedu.address.logic.commands.exceptions.CommandException;
+import seedu.address.model.AddressBook;
 import seedu.address.model.Model;
 import seedu.address.model.ReadOnlyAddressBook;
 import seedu.address.storage.Storage;
 
 /**
  * Imports the contacts from a file to the address book.
  */
-public class ImportCommand extends FileAccessCommand {
+public class ImportCommand extends FileAccessCommand implements Undoable {
     public static final String COMMAND_WORD = "import";
     public static final String MESSAGE_SUCCESS = "Address book from %s has been imported!";
+    public static final String MESSAGE_UNDO_SUCCESS = "Address book has been restored to version before import!";
     public static final String MESSAGE_USAGE = COMMAND_WORD
             + ": Imports the contacts found in the provided file into the address book. \n"
             + "Parameters: " + PREFIX_FILE_PATH + "FILE_PATH\n"
@@ -27,6 +29,7 @@ public class ImportCommand extends FileAccessCommand {
             "Could not read data from file %s due to inability to find or access the file.";
 
     private final Path filePath;
+    private AddressBook initialAddressBook;
 
     /**
      * @param filePath of the json file to be imported
@@ -42,11 +45,12 @@ public CommandResult execute(Model model, Storage storage) throws CommandExcepti
         requireNotExecuted();
         requireNonNull(model);
         requireNonNull(storage);
-        isExecuted = true;
 
         Optional<ReadOnlyAddressBook> addressBookOptional;
         ReadOnlyAddressBook importedData;
 
+        initialAddressBook = new AddressBook(model.getAddressBook());
+
         try {
             addressBookOptional = storage.readAddressBook(filePath);
             importedData = addressBookOptional.orElseGet(model::getAddressBook);
@@ -55,9 +59,20 @@ public CommandResult execute(Model model, Storage storage) throws CommandExcepti
         }
 
         model.setAddressBook(importedData);
+        isExecuted = true;
         return new CommandResult(String.format(MESSAGE_SUCCESS, this.filePath));
     }
 
+    @Override
+    public CommandResult undo(Model model) {
+        requireExecuted();
+        requireNonNull(model);
+        requireNonNull(initialAddressBook);
+        model.setAddressBook(initialAddressBook);
+        isExecuted = false;
+        return new CommandResult(MESSAGE_UNDO_SUCCESS);
+    }
+
     @Override
     public boolean equals(Object other) {
         if (other == this) {

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

@@ -6,7 +6,7 @@
 import seedu.address.model.Model;
 
 /**
- * Undoes the previous concrete command.
+ * Undoes the previous undoable command.
  */
 public class UndoCommand extends Command {
     public static final String COMMAND_WORD = "undo";

src/main/java/seedu/address/logic/commands/ConcreteCommand.java → src/main/java/seedu/address/logic/commands/Undoable.java

@@ -5,12 +5,12 @@
 /**
  * Represents a command which can be undone by the undo command.
  */
-public abstract class ConcreteCommand extends Command {
+public interface Undoable {
     /**
      * Undoes the effects of the command and returns the result message.
      *
      * @param model {@code Model} which the command should operate on.
      * @return feedback message of the operation result for display
      */
-    public abstract CommandResult undo(Model model);
+    CommandResult undo(Model model);
 }

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

@@ -7,7 +7,7 @@
 import seedu.address.commons.core.GuiSettings;
 import seedu.address.commons.core.index.Index;
 import seedu.address.logic.commands.CommandResult;
-import seedu.address.logic.commands.ConcreteCommand;
+import seedu.address.logic.commands.Undoable;
 import seedu.address.model.person.Person;
 
 /**
@@ -116,12 +116,12 @@ public interface Model {
     void updateFilteredPersonList(Predicate<Person> predicate);
 
     /**
-     * Pushes a concrete command to the undo stack.
+     * Pushes an undoable command to the undo stack.
      */
-    void pushToUndoStack(ConcreteCommand command);
+    void pushToUndoStack(Undoable command);
 
     /**
-     * Undoes the most recent concrete command.
+     * Undoes the most recent undoable command.
      */
     CommandResult undoAddressBook();
 

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

@@ -14,7 +14,7 @@
 import seedu.address.commons.core.LogsCenter;
 import seedu.address.commons.core.index.Index;
 import seedu.address.logic.commands.CommandResult;
-import seedu.address.logic.commands.ConcreteCommand;
+import seedu.address.logic.commands.Undoable;
 import seedu.address.model.person.Person;
 
 /**
@@ -26,7 +26,7 @@ public class ModelManager implements Model {
     private final AddressBook addressBook;
     private final UserPrefs userPrefs;
     private final FilteredList<Person> filteredPersons;
-    private final Stack<ConcreteCommand> undoStack;
+    private final Stack<Undoable> undoStack;
 
     /**
      * Initializes a ModelManager with the given addressBook and userPrefs.
@@ -182,7 +182,7 @@ public boolean equals(Object other) {
     //=========== Undo ================================================================================
 
     @Override
-    public void pushToUndoStack(ConcreteCommand command) {
+    public void pushToUndoStack(Undoable command) {
         assert command != null;
         undoStack.push(command);
     }
@@ -192,7 +192,7 @@ public CommandResult undoAddressBook() {
         if (undoStack.isEmpty()) {
             return null;
         }
-        ConcreteCommand command = undoStack.pop();
+        Undoable command = undoStack.pop();
         return command.undo(this);
     }
 

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

@@ -232,7 +232,7 @@ public void updateFilteredPersonList(Predicate<Person> predicate) {
         }
 
         @Override
-        public void pushToUndoStack(ConcreteCommand command) {
+        public void pushToUndoStack(Undoable command) {
             throw new AssertionError("This method should not be called.");
         }