Abstract Messages into two layers; move to new 'output' package

- Abstract Messages into two layers: the top layer 'Messages' is how Messages can be retrieved and sent as before. In the background, package-private, MessagesManager actually does the file read and worries about I/O while Messages takes care of higher-level things (such as joining two lines or checking the current language).

src/main/java/fr/xephi/authme/output/Messages.java

@@ -0,0 +1,72 @@
+package fr.xephi.authme.output;
+
+import fr.xephi.authme.settings.Settings;
+import fr.xephi.authme.util.StringUtils;
+import org.bukkit.command.CommandSender;
+
+/**
+ * Class for retrieving and sending translatable messages to players.
+ */
+public class Messages {
+
+    private static Messages singleton;
+    private final String language;
+    private MessagesManager manager;
+
+
+    private Messages(String language, MessagesManager manager) {
+        this.language = language;
+        this.manager = manager;
+    }
+
+    public static Messages getInstance() {
+        if (singleton == null) {
+            MessagesManager manager = new MessagesManager(Settings.messageFile);
+            singleton = new Messages(Settings.messagesLanguage, manager);
+        }
+        return singleton;
+    }
+
+    /**
+     * Send the given message code to the player.
+     *
+     * @param sender The entity to send the message to
+     * @param key The key of the message to send
+     */
+    public void send(CommandSender sender, MessageKey key) {
+        String[] lines = manager.retrieve(key.getKey());
+        for (String line : lines) {
+            sender.sendMessage(line);
+        }
+    }
+
+    /**
+     * Retrieve the message from the text file and return it split by new line as an array.
+     *
+     * @param key The message key to retrieve
+     *
+     * @return The message split by new lines
+     */
+    public String[] retrieve(MessageKey key) {
+        if (!Settings.messagesLanguage.equalsIgnoreCase(language)) {
+            reloadManager();
+        }
+        return manager.retrieve(key.getKey());
+    }
+
+    /**
+     * Retrieve the message from the text file.
+     *
+     * @param key The message key to retrieve
+     *
+     * @return The message from the file
+     */
+    public String retrieveSingle(MessageKey key) {
+        return StringUtils.join("\n", retrieve(key));
+    }
+
+    public void reloadManager() {
+        manager = new MessagesManager(Settings.messageFile);
+    }
+
+}