Start working on the changepassword api method

TODO: fix unit testing

src/main/java/fr/xephi/authme/process/changepassword/AsyncChangePassword.java

@@ -9,6 +9,7 @@ import fr.xephi.authme.process.AsynchronousProcess;
 import fr.xephi.authme.service.CommonService;
 import fr.xephi.authme.security.PasswordSecurity;
 import fr.xephi.authme.security.crypts.HashedPassword;
+import org.bukkit.command.CommandSender;
 import org.bukkit.entity.Player;
 
 import javax.inject.Inject;
@@ -30,7 +31,13 @@ public class AsyncChangePassword implements AsynchronousProcess {
     AsyncChangePassword() {
     }
 
-
+    /**
+     * Change password for an online player
+     *
+     * @param player the player
+     * @param oldPassword the old password used by the player
+     * @param newPassword the new password chosen by the player
+     */
     public void changePassword(final Player player, String oldPassword, String newPassword) {
         final String name = player.getName().toLowerCase();
         PlayerAuth auth = playerCache.getAuth(name);
@@ -50,5 +57,38 @@ public class AsyncChangePassword implements AsynchronousProcess {
             commonService.send(player, MessageKey.WRONG_PASSWORD);
         }
     }
-}
 
+    /**
+     * Change a user's password as an administrator, without asking for the previous one
+     *
+     * @param sender who is performing the operation, null if called by other plugins
+     * @param playerName the player name
+     * @param newPassword the new password chosen for the player
+     */
+    public void changePasswordAsAdmin(CommandSender sender, final String playerName, String newPassword) {
+        final String lowerCaseName = playerName.toLowerCase();
+        if (!(playerCache.isAuthenticated(lowerCaseName) || dataSource.isAuthAvailable(lowerCaseName))) {
+            if(sender == null) {
+                ConsoleLogger.warning("Tried to change password for user " + lowerCaseName + " but it doesn't exist!");
+            } else {
+                commonService.send(sender, MessageKey.UNKNOWN_USER);
+            }
+            return;
+        }
+
+        HashedPassword hashedPassword = passwordSecurity.computeHash(newPassword, lowerCaseName);
+        if (dataSource.updatePassword(lowerCaseName, hashedPassword)) {
+            if(sender != null) {
+                commonService.send(sender, MessageKey.PASSWORD_CHANGED_SUCCESS);
+                ConsoleLogger.info(sender.getName() + " changed password of " + lowerCaseName);
+            } else {
+                ConsoleLogger.info("Changed password of " + lowerCaseName);
+            }
+        } else {
+            if(sender != null) {
+                commonService.send(sender, MessageKey.ERROR);
+            }
+            ConsoleLogger.warning("An error occurred while changing password for user " + lowerCaseName + "!");
+        }
+    }
+}