Do some refactoring for protocol v2

lib/data.dart

@@ -1,5 +1,6 @@
 import 'dart:async';
 import 'dart:convert';
+import 'dart:io';
 import 'dart:math' as math;
 import 'dart:typed_data';
 import 'dart:ui';
@@ -45,6 +46,12 @@ class SessionData {
   static bool IsSavedData = false;
   static String SaveDataType = "";
 
+  /// This indicates whether the app is in a live session.
+  static bool Recording = false;
+
+  /// This is the version number of the recording as specified by the server.
+  static int RecordingVersion = 0;
+
   /// Is true if the try-catch is tripped or if not running on Android
   static bool isWeb = false;
 
@@ -236,6 +243,8 @@ class SessionData {
       );
     }
 
+    await _create();
+
     _listener = Geolocator.getPositionStream(
       locationSettings: TTConsts.LOCATION_SETTINGS,
     ).listen((pos) {
@@ -274,6 +283,50 @@ class SessionData {
     _upload(nbtData);
   }
 
+  /// v2 Create function.
+  ///
+  /// This function sets the Session ID globally. It will also set the Recording flag to true.
+  static Future<void> _create() async {
+    Dio dio = Dio();
+    Map<String, dynamic> payload = {"cmd": "createv2"};
+
+    try {
+      var reply = await dio.post(
+        TTConsts.SESSION_SERVER,
+        data: json.encode(payload),
+      );
+
+      if (reply.statusCode == null) {
+        throw Exception("Fatal error while creating");
+      }
+      if (reply.statusCode! != 200) {
+        throw Exception("Fatal error while creating");
+      }
+
+      Map<String, dynamic> replyJs = json.decode(reply.data as String);
+      if (replyJs["status"] == "created") {
+        print("Successful creation");
+        LastSessionID = replyJs['session'] as String;
+        Recording = true;
+        RecordingVersion = 0;
+        Calls.dispatch();
+      }
+    } catch (E) {
+      // Retry in 2 seconds
+      DisplayError =
+          "Error: Something went wrong during session creation. Retry in 5 seconds...";
+      Calls.dispatch();
+
+      Timer(Duration(seconds: 5), () {
+        _create();
+      });
+    }
+  }
+
+  /// Deprecated: This function uploads using the v1 API, and is intended to be called at the conclusion of data recording.
+  @Deprecated(
+    "This function utilizes the Protocol v1 Create method, which has been replaced by createv2 and patch. This function will be removed.",
+  )
   static Future<void> _upload(List<int> nbtData) async {
     Dio dio = Dio();
 
@@ -325,6 +378,7 @@ class SessionData {
     DisplayError = "";
     IsReadOnly = false;
     ContainsTripTimes = true;
+    Recording = false;
     if (FlutterBackground.isBackgroundExecutionEnabled) {
       FlutterBackground.disableBackgroundExecution();
     }
@@ -367,6 +421,15 @@ class SessionData {
 
   static Future<void> _deserialize(CompoundTag ct) async {
     IsOnTheClock = NbtUtils.readBoolean(ct, "inprog");
+    if (ct.containsKey("record"))
+      Recording = NbtUtils.readBoolean(ct, "record");
+    else
+      Recording = false;
+
+    if (Recording && isWeb) {
+      IsOnTheClock = false;
+      IsReadOnly = true;
+    }
 
     if (IsOnTheClock) {
       await Login();
@@ -416,6 +479,7 @@ class SessionData {
     CompoundTag ct = CompoundTag();
 
     NbtUtils.writeBoolean(ct, "inprog", IsOnTheClock);
+    NbtUtils.writeBoolean(ct, "record", Recording);
     // No need to write the contains trip times flag, it is set during deserialization.  For inprog sessions, it will be set to true by the system.
     ct.put("start", StringTag.valueOf(StartTime.toIso8601String()));
     if (EndTime.year > 2000) {
@@ -603,6 +667,29 @@ class SessionData {
 
     return tm.toString();
   }
+
+  static Future<int> FetchVersion() async {
+    Dio dio = Dio();
+    var packet = json.encode({"cmd": "get_version", "id": LastSessionID});
+
+    var response = await dio.post(TTConsts.SESSION_SERVER, data: packet);
+    if (response.statusCode == null) {
+      DisplayError = "Error: Version retrieval failed";
+      return -1;
+    }
+    if (response.statusCode! != 200) {
+      DisplayError = "Error: Session server HTTP Response code";
+      return -2;
+    }
+
+    var reply = json.decode(response.data as String);
+    if (reply["status"] == "version_back") {
+      return reply["version"] as int;
+    } else {
+      DisplayError = "Error: Unknown get_version reply";
+      return -3;
+    }
+  }
 }
 
 class Delivery {