Change firebase configs in select

ionic-v1
1

Hi, I have multiple databases firebase, but I want to load the firebase configuration specific about the selected city in my home, for example:
I Have a list of citys

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when I select a city, I want to capture in this button the value, and change my firebase configuration
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my html:

	<ion-list>
		<div class="item item-divider">Selecione sua cidade</div>
		<div class="item item-select" fancy-select ng-model="single1" items="selectable" item-label="fname">
			{{single1.fname || 'Cidade selecionada'}}
		</div>
	<button class="button button-full" ng-click="vm.submit()">Enviar</button>  
	</ion-list>

my configuration:

"use strict";

 angular.module('config', [])

.constant('ENV',
{
    name:'development',
dataProvider:'FIREBASE',
firebaseConfig:{
    apiKey:'AIzaSyCfE-kOfvtPs8D7mDa7Mq8ykHXS08jkSY0',
    authDomain:'achou-cidades.firebaseapp.com',
    databaseURL:'https://achou-cidades.firebaseio.com'
},
    firebaseConfig2:{
    apiKey:'AIzaSyB-6HEg5PMvAA3YKwx7xgRAiaJTqKFQzg4',
    authDomain:'achou-tubarao.firebaseapp.com',
    databaseURL:'https://achou-tubarao.firebaseio.com'
},
    youtubeKey:'AIzaSyDael5MmCQa1GKQNKQYypmBeB08GATgSEo',
    ionicPrivateKey:'a9265eaf15a20cc8516c770e8748aeed4891b28f453ce755',
    ionicPublicKey:'e30d4d540b8c75d1f167bbf242423c3fb23fe10275d1c016',
    ionicAppId:'241b6d37',
    gcmId:'228071472080'
    },
)
;

(firebaseConf1 is a city, and firebaseConfig2 is other city, for example.

here is where I call the configuration:

angular
		.module('listing.common')
		.factory('db', ['ENV', function(ENV) {
			firebase.initializeApp(ENV.firebaseConfig);
			return firebase.database().ref()
		}])
		.factory('firebaseDataService', firebaseDataService);

So… I want to change de firebase.initializeApp when I change de select for example… if (selected city = 1) ENV.firebaseConfig… else if (selected city = 2) ENV.firebaseConfig2… Any idea? or other solution for case? Thanks!