Implemented the changepassword command

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

@@ -138,6 +138,21 @@ public class CommandManager {
         registerCommand.addArgument(new CommandArgumentDescription("player", "Player name", false));
         registerCommand.addArgument(new CommandArgumentDescription("password", "Password", false));
 
+        // Register the changepassword command
+        CommandDescription changePasswordCommand = new CommandDescription(
+                new RegisterCommand(),
+                new ArrayList<String>() {{
+                    add("changepassword");
+                    add("changepass");
+                    add("cp");
+                }},
+                "Change player's password",
+                "Change the password of a player.",
+                authMeCommand);
+        changePasswordCommand.setCommandPermissions("authme.admin.changepassword", CommandPermissions.DefaultPermission.OP_ONLY);
+        changePasswordCommand.addArgument(new CommandArgumentDescription("player", "Player name", false));
+        changePasswordCommand.addArgument(new CommandArgumentDescription("password", "New password", false));
+
         // Register the purge command
         CommandDescription lastLoginCommand = new CommandDescription(
                 new LastLoginCommand(),

src/main/java/fr/xephi/authme/command/executable/authme/ChangePasswordCommand.java

@@ -0,0 +1,100 @@
+package fr.xephi.authme.command.executable.authme;
+
+import fr.xephi.authme.AuthMe;
+import fr.xephi.authme.ConsoleLogger;
+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.security.PasswordSecurity;
+import fr.xephi.authme.settings.Messages;
+import fr.xephi.authme.settings.Settings;
+import org.bukkit.Bukkit;
+import org.bukkit.command.CommandSender;
+
+import java.security.NoSuchAlgorithmException;
+
+public class ChangePasswordCommand 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(final CommandSender sender, CommandParts commandReference, CommandParts commandArguments) {
+        // AuthMe plugin instance
+        final AuthMe plugin = AuthMe.getInstance();
+
+        // Messages instance
+        final Messages m = Messages.getInstance();
+
+        // Get the player and password
+        String playerName = commandArguments.get(0);
+        final String playerPass = commandArguments.get(1);
+
+        // Validate the password
+        String playerPassLowerCase = playerPass.toLowerCase();
+        if (playerPassLowerCase.contains("delete") || playerPassLowerCase.contains("where") || playerPassLowerCase.contains("insert") || playerPassLowerCase.contains("modify") || playerPassLowerCase.contains("from") || playerPassLowerCase.contains("select") || playerPassLowerCase.contains(";") || playerPassLowerCase.contains("null") || !playerPassLowerCase.matches(Settings.getPassRegex)) {
+            m.send(sender, "password_error");
+            return true;
+        }
+        if (playerPassLowerCase.equalsIgnoreCase(playerName)) {
+            m.send(sender, "password_error_nick");
+            return true;
+        }
+        if (playerPassLowerCase.length() < Settings.getPasswordMinLen || playerPassLowerCase.length() > Settings.passwordMaxLength) {
+            m.send(sender, "pass_len");
+            return true;
+        }
+        if (!Settings.unsafePasswords.isEmpty()) {
+            if (Settings.unsafePasswords.contains(playerPassLowerCase)) {
+                m.send(sender, "password_error_unsafe");
+                return true;
+            }
+        }
+
+        // Set the password
+        final String playerNameLowerCase = playerName.toLowerCase();
+        Bukkit.getScheduler().runTaskAsynchronously(plugin, new Runnable() {
+
+            @Override
+            public void run() {
+                String hash;
+                try {
+                    hash = PasswordSecurity.getHash(Settings.getPasswordHash, playerPass, playerNameLowerCase);
+                } catch (NoSuchAlgorithmException e) {
+                    m.send(sender, "error");
+                    return;
+                }
+                PlayerAuth auth = null;
+                if (PlayerCache.getInstance().isAuthenticated(playerNameLowerCase)) {
+                    auth = PlayerCache.getInstance().getAuth(playerNameLowerCase);
+                } else if (plugin.database.isAuthAvailable(playerNameLowerCase)) {
+                    auth = plugin.database.getAuth(playerNameLowerCase);
+                }
+                if (auth == null) {
+                    m.send(sender, "unknown_user");
+                    return;
+                }
+                auth.setHash(hash);
+                if (PasswordSecurity.userSalt.containsKey(playerNameLowerCase)) {
+                    auth.setSalt(PasswordSecurity.userSalt.get(playerNameLowerCase));
+                    plugin.database.updateSalt(auth);
+                }
+                if (!plugin.database.updatePassword(auth)) {
+                    m.send(sender, "error");
+                    return;
+                }
+                sender.sendMessage("pwd_changed");
+                ConsoleLogger.info(playerNameLowerCase + "'s password changed");
+            }
+
+        });
+        return true;
+    }
+}