room can create a unique code

Assets/Scripts/RoomManager.cs

@@ -2,7 +2,10 @@
 using System.Collections.Generic;
 using Firebase;
 using Firebase.Database;
+using Firebase.Extensions;
+using TMPro;
 using UnityEngine;
+using System;
 
 public class RoomManager : MonoBehaviour
 {
@@ -30,6 +33,11 @@ public class RoomManager : MonoBehaviour
 
     DatabaseReference realtimeDB;
 
+    /// <summary>
+    /// TextMeshPro that show the value of the current rooom code
+    /// </summary>
+    public TextMeshProUGUI roomCodeLabel;
+
     private void Awake()
     {
         FirebaseInitializer.Instance.onFirebaseReady += Initialize;
@@ -41,8 +49,6 @@ private void Start()
 
         propositionCurrentTime = propositionTime;
         votingCurrentTime = votingTime;
-
-        //we need to call CreateNewRoom. but not yet
     }
 
     private void OnApplicationQuit()
@@ -57,6 +63,33 @@ private void Initialize()
         FirebaseInitializer.Instance.onFirebaseReady -= Initialize;
         realtimeDB = FirebaseDatabase.DefaultInstance.RootReference;
         Debug.Log("Realtime DB initialized");
+        CreateNewRoom();
+    }
+
+    /// <summary>
+    /// Check all the rooms in the server and give back the number already taken
+    /// </summary>
+    private void WhichCodesAreAlreadyUsed(Action<List<int>> callback_OnCodesChecked)
+    {
+        List<int> alreadyUsedCodes = new List<int>();
+        realtimeDB.Child("rooms").GetValueAsync().ContinueWithOnMainThread(task =>
+        {
+            if (task.IsFaulted)
+            {
+                Debug.LogException(task.Exception);
+            }
+            else if (task.IsCompleted)
+            {
+                DataSnapshot snapshot = task.Result;
+                List<Room> onlineRooms = JsonUtility.FromJson<List<Room>>(snapshot.GetRawJsonValue());
+                foreach (Room r in onlineRooms)
+                {
+                    alreadyUsedCodes.Add(int.Parse(r.code));
+                }
+            }
+            callback_OnCodesChecked?.Invoke(alreadyUsedCodes);
+        });
+
     }
 
     /// <summary>
@@ -65,11 +98,39 @@ private void Initialize()
     [ContextMenu("Create New Room")]
     public void CreateNewRoom()
     {
-        Room newRoom = new Room(Random.Range(0, 1000).ToString("D4"));
-        currentRoom = newRoom;
-        string JSON = JsonUtility.ToJson(newRoom);
-        realtimeDB.Child("rooms").Child(newRoom.code).SetRawJsonValueAsync(JSON);
-        Debug.Log($"room {currentRoom.code} has been created on the server");
+        WhichCodesAreAlreadyUsed(codes =>
+        {
+            Room newRoom = new Room(GenerateRandomAvailableCode(codes).ToString("D4"));
+            currentRoom = newRoom;
+            string JSON = JsonUtility.ToJson(newRoom);
+            realtimeDB.Child("rooms").Child(newRoom.code).SetRawJsonValueAsync(JSON).ContinueWithOnMainThread(task =>
+            {
+                Debug.Log($"room {currentRoom.code} has been created on the server");
+                //TODO MARINE : uncomment and reference the correct game object
+                //roomCodeLabel.text = currentRoom.code;
+            });
+        });
+    }
+
+    /// <summary>
+    /// Generate a code between 0 and 1000 that is not in the list
+    /// </summary>
+    /// <param name="_impossibleCodes">the list of code you don"t want to get</param>
+    /// <returns></returns>
+    private int GenerateRandomAvailableCode(List<int> _impossibleCodes)
+    {
+        int random = UnityEngine.Random.Range(0, 1000);
+        while (_impossibleCodes.Contains(random))
+        {
+            Debug.Log($"{random} is already taken, choosing another room code", this);
+            random = UnityEngine.Random.Range(0, 1000);
+        }
+        return random;
+    }
+
+    private void DisplayRoomCode()
+    {
+
     }
 
     public void PlayerSendProposition(Proposition _proposition)