Config Help

Hi guys, I'm working on a chat plugin and I don't really understand how to get and set stuff from the config.

Exampe: $this->config->exists("ranks")[$this->getRank($player->username)] doesnt work as it says "cant use exists on a non-object"

Code:

PHP:

<?php

/*
__PocketMine Plugin__
name=MultiCbat
version=1.0
description=Separate chat for each world
author=Lambo
class=multichat
apiversion=11
*/

class multichat implements Plugin{
        private $api;

        public function __construct(ServerAPI $api, $server = false){
            $this->api = $api;
        }

        public function __destruct(){}

        public function init(){
            $this->api->addHandler("player.chat", array($this,"onChat"));
            $this->config = new Config($this->api->plugin->configPath($this)."config.yml", CONFIG_YAML, array(
                    "ranks"=> array(
                        "default"=> array(
                            "world"=> array(
                               "tag"=>"Player","chat-format"=>"|@tag|@player: @message"
                            )
                        ),
                        "moderator"=> array(
                            "world"=>array(
                               "tag"=>"Mod","chat-format"=>"|@tag|@player: @message"
                            )
                        ),
                        "admin"=> array(
                            "world"=>array(
                               "tag"=>"Admin","chat-format"=>"|@tag|@player: @message"
                            )
                        ),
                       "owner"=>array(
                          "world"=>array(
                             "tag"=>"Owner","chat-format"=>"|@tag|@player: @message"
                          )
                       ),
                        "vip"=> array(
                            "world"=>array(
                               "tag"=>"ViP","chat-format"=>"|@tag|@player: @message"
                            )
                        )
                    ),
                    "in-ranks"=>array(
                        "ranks" => array(
                           "moderator"=>array(),
                           "admin"=>array(),
                           "owner"=>array(),
                           "vip"=>array()
                       )
                    )
               )
            );
        }

        public function onChat($data){
            $player = $data["player"];
            $message = $data["message"];
            $level = $player->level->getName();
            $tag = $this->config->get("ranks")[$this->getRank($player->username)]["tag"];
            $format = $this->config->get("ranks")[$this->getRank($player->username)]["chat-format"];
            $username = $player->username;
            foreach($this->api->player->getAll($level) as $players){
                if($this->config->exists("ranks")[$this->getRank($player->username)][$level]){
                    $players->sendChat(str_replace(array("@tag","@player"),array($tag,$username),$format));
                }else{
                    $this->config->set("ranks")[$this->getRank($player->username)][$level][$this->config->get("ranks")[$this->getRank($player->username)]["tag"]];//basically creates the other world in the config
                    $this->config->set("ranks")[$this->getRank($player->username)][$level][$this->config->get("ranks")[$this->getRank($player->username)]["chat-format"]];
                    $players->sendChat(str_replace(array("@tag","@player"),array($tag,$username),$format));
                }
            }
        }

So can you guys teach me how to use configs like the way im using them in my code?

PS: I have the function $this->getRank defined in my code

Thanks.

No help? :/

Can i help you in a private conversation?

Sure.

Anyone help?

...