AddressBook.java: add recover command

docs/UserGuide.adoc

@@ -101,6 +101,12 @@ Deletes the 2nd person in the address book.
 `delete 1` +
 Deletes the 1st person in the results of the `find` command.
 
+=== Recovering a person: `recover`
+
+Recovers the specified version from the address book. +
+Format: `recover`
+
+
 === Clearing all entries: `clear`
 
 Clears all entries from the address book. +

src/seedu/addressbook/AddressBook.java

@@ -66,6 +66,7 @@ public class AddressBook {
      * =========================================================================
      */
     private static final String MESSAGE_ADDED = "New person added: %1$s, Phone: %2$s, Email: %3$s";
+    private static final String MESSAGE_ADDRESSBOOK_RECOVERED = "Latest deleted person has been recovered!";
     private static final String MESSAGE_ADDRESSBOOK_CLEARED = "Address book has been cleared!";
     private static final String MESSAGE_COMMAND_HELP = "%1$s: %2$s";
     private static final String MESSAGE_COMMAND_HELP_PARAMETERS = "\tParameters: %1$s";
@@ -115,6 +116,10 @@ public class AddressBook {
     private static final String COMMAND_LIST_DESC = "Displays all persons as a list with index numbers.";
     private static final String COMMAND_LIST_EXAMPLE = COMMAND_LIST_WORD;
 
+    private static final String COMMAND_RECOVER_WORD = "recover";
+    private static final String COMMAND_RECOVER_DESC = "Recover the latest deleted people.";
+    private static final String COMMAND_RECOVER_EXAMPLE = COMMAND_RECOVER_WORD;
+
     private static final String COMMAND_DELETE_WORD = "delete";
     private static final String COMMAND_DELETE_DESC = "Deletes a person identified by the index number used in "
                                                     + "the last find/list call.";
@@ -183,6 +188,7 @@ public class AddressBook {
      */
     private static final ArrayList<String[]> ALL_PERSONS = new ArrayList<>();
 
+    private static  String LAST_DELETE_PERSON;
     /**
      * Stores the most recent list of persons shown to the user as a result of a user command.
      * This is a subset of the full list. Deleting persons in the pull list does not delete
@@ -377,6 +383,8 @@ private static String executeCommand(String userInputString) {
             return executeListAllPersonsInAddressBook();
         case COMMAND_DELETE_WORD:
             return executeDeletePerson(commandArgs);
+        case COMMAND_RECOVER_WORD:
+            return executeRecoverAddressBook();
         case COMMAND_CLEAR_WORD:
             return executeClearAddressBook();
         case COMMAND_HELP_WORD:
@@ -558,6 +566,18 @@ private static String getMessageForSuccessfulDelete(String[] deletedPerson) {
         return String.format(MESSAGE_DELETE_PERSON_SUCCESS, getMessageForFormattedPersonData(deletedPerson));
     }
 
+
+    /**
+     * Clears all persons in the address book.
+     *
+     * @return feedback display message for the operation result
+     */
+    private static String executeRecoverAddressBook() {
+        recoverPersonToAddressBook();
+        return MESSAGE_ADDRESSBOOK_RECOVERED;
+    }
+
+
     /**
      * Clears all persons in the address book.
      *
@@ -786,6 +806,14 @@ private static void addPersonToAddressBook(String[] person) {
         ALL_PERSONS.add(person);
         savePersonsToFile(getAllPersonsInAddressBook(), storageFilePath);
     }
+    /**
+     * Recovers the latest deleted person to the address book. Saves changes to storage file.
+     *
+     */
+    private static void recoverPersonToAddressBook() {
+        ALL_PERSONS.add(decodePersonFromString(LAST_DELETE_PERSON ).get());
+        savePersonsToFile(getAllPersonsInAddressBook(), storageFilePath);
+    }
 
     /**
      * Deletes the specified person from the addressbook if it is inside. Saves any changes to storage file.
@@ -795,6 +823,7 @@ private static void addPersonToAddressBook(String[] person) {
      */
     private static boolean deletePersonFromAddressBook(String[] exactPerson) {
         final boolean changed = ALL_PERSONS.remove(exactPerson);
+        LAST_DELETE_PERSON = encodePersonToString(exactPerson);
         if (changed) {
             savePersonsToFile(getAllPersonsInAddressBook(), storageFilePath);
         }
@@ -1086,6 +1115,7 @@ private static String getUsageInfoForAllCommands() {
                 + getUsageInfoForFindCommand() + LS
                 + getUsageInfoForViewCommand() + LS
                 + getUsageInfoForDeleteCommand() + LS
+                + getUsageInfoForRecoverCommand() + LS
                 + getUsageInfoForClearCommand() + LS
                 + getUsageInfoForExitCommand() + LS
                 + getUsageInfoForHelpCommand();
@@ -1105,6 +1135,12 @@ private static String getUsageInfoForFindCommand() {
                 + String.format(MESSAGE_COMMAND_HELP_EXAMPLE, COMMAND_FIND_EXAMPLE) + LS;
     }
 
+    /** Returns the string for showing 'recover' command usage instruction */
+    private static String getUsageInfoForRecoverCommand() {
+        return String.format(MESSAGE_COMMAND_HELP, COMMAND_RECOVER_WORD, COMMAND_RECOVER_DESC) + LS
+                + String.format(MESSAGE_COMMAND_HELP_EXAMPLE, COMMAND_RECOVER_EXAMPLE) + LS;
+    }
+
     /** Returns the string for showing 'delete' command usage instruction */
     private static String getUsageInfoForDeleteCommand() {
         return String.format(MESSAGE_COMMAND_HELP, COMMAND_DELETE_WORD, COMMAND_DELETE_DESC) + LS

test/expected.txt

@@ -66,6 +66,9 @@
 || 	Parameters: INDEX
 || 	Example: delete 1
 || 
+|| recover: Recover the latest deleted people.
+|| 	Example: recover
+|| 
 || clear: Clears address book permanently.
 || 	Example: clear
 ||