ADD : controller call Firestore database accesser

Sources/dafl_project_flutter/lib/controller/controller.dart

@@ -29,6 +29,10 @@ class Controller {
     _messageAccess.sendMessage(message, idSender, idReceiver);
   }
 
+  Stream<List<Message>> getMessage(String chatId){
+    return _messageAccess.getMessage(chatId);
+  }
+
   void save(User userToSave) {
     saver.save(userToSave);
   }

Sources/dafl_project_flutter/lib/firebase_services/message_database_services.dart

@@ -4,8 +4,10 @@ import 'package:cloud_firestore/cloud_firestore.dart';
 
 class MessageDatabaseServices{
 
+  // Make an unique chat ID between 2 client. Look like 'User1-User2'
+  static String getChatId(String idSender, String idReceiver){
 
-  String _getChatId(String idSender, String idReceiver){
+      // Test to always have the same id
       if (idSender.hashCode <= idReceiver.hashCode)
         return '$idSender-${idReceiver}';
       else
@@ -13,8 +15,10 @@ class MessageDatabaseServices{
 
   }
 
+
+  // Send a message from an user to an other
   void sendMessage(Message message, String idSender, String idReceiver) {
-    String chatId = _getChatId(idSender, idReceiver);
+    String chatId = getChatId(idSender, idReceiver);
 
     var documentReference = FirebaseFirestore.instance
         .collection('messages')
@@ -27,6 +31,7 @@ class MessageDatabaseServices{
     });
   }
 
+  // Get a message from a snapshot Firestore
   Message _getMessage(DocumentSnapshot<Map<String, dynamic>> snapshot) {
     var data = snapshot.data();
     if (data == null)
@@ -35,13 +40,14 @@ class MessageDatabaseServices{
     return Message.fromMap(data);
   }
 
-
+  // Get a list of messages from Firestore
   List<Message> _getAllMessages(QuerySnapshot<Map<String, dynamic>> snapshot) {
     return snapshot.docs.map((doc) {
       return _getMessage(doc);
     }).toList();
   }
 
+  // Get the massages from Firestore
   Stream<List<Message>> getMessage(String chatId) {
     return FirebaseFirestore.instance
         .collection('messages')