Implemented the email change command

src/main/java/fr/xephi/authme/command/CommandManager.java

@@ -4,6 +4,7 @@ import fr.xephi.authme.command.executable.*;
 import fr.xephi.authme.command.executable.authme.*;
 import fr.xephi.authme.command.executable.changepassword.ChangePasswordCommand;
 import fr.xephi.authme.command.executable.email.AddEmailCommand;
+import fr.xephi.authme.command.executable.email.ChangeEmailCommand;
 import fr.xephi.authme.command.executable.login.LoginCommand;
 import fr.xephi.authme.command.executable.logout.LogoutCommand;
 
@@ -483,7 +484,7 @@ public class CommandManager {
                 "E-mail command",
                 "The AuthMe Reloaded E-mail command. The root for all E-mail commands.", null);
 
-        // Register the help command
+        // Register the add command
         CommandDescription addEmailCommand = new CommandDescription(
                 new AddEmailCommand(),
                 new ArrayList<String>() {{
@@ -492,11 +493,25 @@ public class CommandManager {
                     add("addmail");
                 }},
                 "Add E-mail",
-                "Add a new E-Mail address to your account.",
+                "Add an new E-Mail address to your account.",
                 emailBaseCommand);
         addEmailCommand.addArgument(new CommandArgumentDescription("email", "Email address", false));
         addEmailCommand.addArgument(new CommandArgumentDescription("verifyEmail", "Email address verification", false));
 
+        // Register the change command
+        CommandDescription changeEmailCommand = new CommandDescription(
+                new ChangeEmailCommand(),
+                new ArrayList<String>() {{
+                    add("change");
+                    add("changeemail");
+                    add("changemail");
+                }},
+                "Change E-mail",
+                "Change an E-Mail address of your account.",
+                emailBaseCommand);
+        changeEmailCommand.addArgument(new CommandArgumentDescription("oldEmail", "Old email address", false));
+        changeEmailCommand.addArgument(new CommandArgumentDescription("newEmail", "New email address", false));
+
         // Register the help command
         CommandDescription emailHelpCommand = new CommandDescription(
                 new HelpCommand(),

src/main/java/fr/xephi/authme/command/executable/email/ChangeEmailCommand.java

@@ -0,0 +1,88 @@
+package fr.xephi.authme.command.executable.email;
+
+import fr.xephi.authme.AuthMe;
+import fr.xephi.authme.cache.auth.PlayerAuth;
+import fr.xephi.authme.cache.auth.PlayerCache;
+import fr.xephi.authme.command.CommandParts;
+import fr.xephi.authme.command.ExecutableCommand;
+import fr.xephi.authme.settings.Messages;
+import fr.xephi.authme.settings.Settings;
+import org.bukkit.command.CommandSender;
+import org.bukkit.entity.Player;
+
+import java.util.Arrays;
+
+public class ChangeEmailCommand extends ExecutableCommand {
+
+    /**
+     * Execute the command.
+     *
+     * @param sender The command sender.
+     * @param commandReference The command reference.
+     * @param commandArguments The command arguments.
+     *
+     * @return True if the command was executed successfully, false otherwise.
+     */
+    @Override
+    public boolean executeCommand(CommandSender sender, CommandParts commandReference, CommandParts commandArguments) {
+        // AuthMe plugin instance
+        final AuthMe plugin = AuthMe.getInstance();
+
+        // Messages instance
+        final Messages m = Messages.getInstance();
+
+        // Get the parameter values
+        String playerMailOld = commandArguments.get(0);
+        String playerMailNew = commandArguments.get(1);
+
+        // Make sure the current command executor is a player
+        if(!(sender instanceof Player)) {
+            return true;
+        }
+
+        // Get the player instance and name
+        final Player player = (Player) sender;
+        final String playerName = player.getName();
+
+        // Command logic
+        if (Settings.getmaxRegPerEmail > 0) {
+            if (!plugin.authmePermissible(sender, "authme.allow2accounts") && plugin.database.getAllAuthsByEmail(playerMailNew).size() >= Settings.getmaxRegPerEmail) {
+                m.send(player, "max_reg");
+                return true;
+            }
+        }
+        if (PlayerCache.getInstance().isAuthenticated(playerName)) {
+            PlayerAuth auth = PlayerCache.getInstance().getAuth(playerName);
+            if (auth.getEmail() == null || auth.getEmail().equals("your@email.com") || auth.getEmail().isEmpty()) {
+                m.send(player, "usage_email_add");
+                return true;
+            }
+            if (!playerMailOld.equals(auth.getEmail())) {
+                m.send(player, "old_email_invalid");
+                return true;
+            }
+            if (!Settings.isEmailCorrect(playerMailNew)) {
+                m.send(player, "new_email_invalid");
+                return true;
+            }
+            auth.setEmail(playerMailNew);
+            if (!plugin.database.updateEmail(auth)) {
+                m.send(player, "error");
+                return true;
+            }
+            PlayerCache.getInstance().updatePlayer(auth);
+            m.send(player, "email_changed");
+            player.sendMessage(Arrays.toString(m.send("email_defined")) + auth.getEmail());
+        } else if (PlayerCache.getInstance().isAuthenticated(playerName)) {
+            m.send(player, "email_confirm");
+        } else {
+            if (!plugin.database.isAuthAvailable(playerName)) {
+                m.send(player, "login_msg");
+            } else {
+                m.send(player, "reg_email_msg");
+            }
+        }
+
+        return true;
+    }
+}