add /prestiges

also fix inconsistency with checking groups

src/main/java/sh/okx/rankup/commands/PrestigesCommand.java

@@ -0,0 +1,47 @@
+package sh.okx.rankup.commands;
+
+import lombok.RequiredArgsConstructor;
+import org.bukkit.command.Command;
+import org.bukkit.command.CommandExecutor;
+import org.bukkit.command.CommandSender;
+import org.bukkit.entity.Player;
+import sh.okx.rankup.Rankup;
+import sh.okx.rankup.messages.Message;
+import sh.okx.rankup.prestige.Prestige;
+import sh.okx.rankup.prestige.Prestiges;
+import sh.okx.rankup.ranks.Rank;
+
+@RequiredArgsConstructor
+public class PrestigesCommand implements CommandExecutor {
+  private final Rankup plugin;
+
+  @Override
+  public boolean onCommand(CommandSender sender, Command command, String label, String[] args) {
+    Prestiges prestiges = plugin.getPrestiges();
+    Prestige playerRank = null;
+    if (sender instanceof Player) {
+      playerRank = prestiges.getByPlayer((Player) sender);
+    }
+
+    plugin.sendHeaderFooter(sender, playerRank, Message.PRESTIGES_HEADER);
+
+    Message message = playerRank == null ? Message.PRESTIGES_INCOMPLETE : Message.PRESTIGES_COMPLETE;
+    Prestige prestige = prestiges.getFirst();
+    if(!prestige.isLast()) {
+      prestige = prestiges.next(prestige);
+      while (!prestige.isLast()) {
+        Prestige next = prestiges.next(prestige);
+        if (prestige.equals(playerRank)) {
+          plugin.sendMessage(sender, Message.PRESTIGES_CURRENT, prestige, next);
+          message = Message.PRESTIGES_INCOMPLETE;
+        } else {
+          plugin.sendMessage(sender, message, prestige, next);
+        }
+        prestige = next;
+      }
+    }
+
+    plugin.sendHeaderFooter(sender, playerRank, Message.PRESTIGES_FOOTER);
+    return true;
+  }
+}