feat(transport_helper: add "ref" to Segments for journeyDetails later

lib/transport_helper.dart

@@ -309,7 +309,9 @@ class Route {
 class Segment {
   static const String tableName = "segment";
 
+  // TODO: add attribute for departures on the way?
   int? id;
+  String ref;
   Station startPoint;
   Station endPoint;
   DateTime startTime;
@@ -318,6 +320,7 @@ class Segment {
 
   Segment({
     this.id, // might throw errors - needs testing, I guess
+    required this.ref,
     required this.startPoint,
     required this.endPoint,
     required this.startTime,
@@ -327,6 +330,7 @@ class Segment {
 
   Map<String, Object?> toMap() {
     return {
+      "ref": ref,
       "startpoint": startPoint.id,
       "endpoint": endPoint.id,
       "starttime": startTime,
@@ -338,6 +342,7 @@ class Segment {
   factory Segment.fromMap(Map<String, Object?> map) {
     return Segment(
       id: map["id"] as int,
+      ref: map["ref"] as String,
       startPoint: map["startPoint"] as Station,
       endPoint: map["endPoint"] as Station,
       startTime: map["startTime"] as DateTime,
@@ -348,6 +353,7 @@ class Segment {
 
   factory Segment.fromJson(Map<String, dynamic> json) {
     Segment tmp = Segment(
+      ref: json["JourneyDetail"]["ref"],
       startPoint: Station.fromJson(json["Origin"]),
       endPoint: Station.fromJson(json["Destination"]),
       startTime: json["Origin"]["rtTime"],
@@ -372,6 +378,8 @@ class Segment {
     String vehicle = Vehicle.tableName;
     database.execute("""
     CREATE TABLE IF NOT EXISTS $tableName(
+    id          INTEGER PRIMARY KEY AUTOINCREMENT,
+    ref         TEXT,
     startpoint  TEXT,
     endpoint    TEXT,
     starttime   TEXT,
@@ -943,4 +951,4 @@ enum VehicleType {
   subway,
   regionalTrain,
   PLACEHOLDER,
-}
+}