added provider class for timer

lib/main.dart

@@ -1,4 +1,6 @@
 import 'package:flutter/material.dart';
+import 'package:provider/provider.dart';
+import 'package:sendtrain/models/activity_timer_model.dart';
 import 'package:sendtrain/screens/activities_screen.dart';
 import 'package:sendtrain/screens/sessions_screen.dart';
 
@@ -88,5 +90,10 @@ class _AppState extends State<App> {
 }
 
 void main() {
-  runApp(const SendTrain());
+  runApp(
+    ChangeNotifierProvider(
+      create: (context) => ActivityTimerModel(),
+      child: const SendTrain(),
+    ),
+  );
 }

lib/models/activity_timer_model.dart

@@ -0,0 +1,60 @@
+import 'dart:async';
+
+import 'package:flutter/material.dart';
+import 'package:sendtrain/models/activity_model.dart';
+
+class ActivityTimerModel with ChangeNotifier {
+  late int _activityId;
+  late int _tickCount;
+  late int _currentSet;
+  late int _totalSets;
+  late int _currentRep;
+  late int _totalReps;
+  late String _currentState;
+  late Timer? _periodicTimer;
+
+  bool _active = false;
+
+  int get tickCount => _tickCount;
+  int get currentSet => _currentSet;
+  int get currentRep => _currentRep;
+  int get totalSets => _totalSets;
+  int get totalReps => _totalReps;
+  bool get active => _active;
+
+  void setupTimer(ActivityModel activity) {
+    _activityId = activity.id;
+    _currentSet = 0;
+    _currentRep = 0;
+    _totalSets = activity.actions[0].activityActionSet.total;
+    _totalReps = activity.actions[0].activityActionSet.reps.amounts[0];
+    _tickCount = activity.actions[0].activityActionSet.rest ~/ 10000;
+  }
+
+  void startTimer(ActivityModel activity) {
+    _active = true;
+    _periodicTimer = Timer.periodic(const Duration(seconds: 1), (Timer timer) {
+      if (_tickCount == 0) {
+        if (_currentRep + 1 ==
+            activity.actions[0].activityActionSet.reps.amounts[_currentSet]) {
+          _currentSet++;
+          if (_currentSet == activity.actions[0].activityActionSet.total) {
+            timer.cancel();
+            _active = false;
+            setupTimer(activity);
+          }
+          _currentRep = 0;
+          _totalReps =
+              activity.actions[0].activityActionSet.reps.amounts[_currentSet];
+          _tickCount = activity.actions[0].activityActionSet.rest ~/ 10000;
+        } else {
+          _currentRep++;
+        }
+      } else {
+        _tickCount--;
+      }
+
+      notifyListeners();
+    });
+  }
+}

lib/widgets/activity_view.dart

@@ -1,9 +1,9 @@
-import 'dart:async';
-
 import 'package:flutter/material.dart';
+import 'package:provider/provider.dart';
 import 'package:sendtrain/classes/activity_action.dart';
 import 'package:sendtrain/classes/media.dart';
 import 'package:sendtrain/models/activity_model.dart';
+import 'package:sendtrain/models/activity_timer_model.dart';
 import 'package:sendtrain/widgets/activity_action_view.dart';
 import 'package:sendtrain/widgets/media_card.dart';
 
@@ -17,44 +17,16 @@ class ActivityView extends StatefulWidget {
 }
 
 class _ActivityViewState extends State<ActivityView> {
-  Timer? _periodicTimer;
-  int _tickCount = 0;
-  int _currentSet = 1;
-  int _currentRep = 1;
-  String _currentState = 'Rep';
-
-  void _startPeriodicTimer() {
-    _tickCount = widget.activity.actions[0].activityActionSet.rest ~/ 10000;
-    const oneSecond = Duration(seconds: 1);
-    _periodicTimer = Timer.periodic(oneSecond, (Timer timer) {
-      setState(() {
-        if (_tickCount == 0) {
-          if (_currentSet ==
-              widget.activity.actions[0].activityActionSet.total) {
-            timer.cancel();
-          }
-
-          if (_currentRep ==
-              widget.activity.actions[0].activityActionSet.reps
-                  .amounts[_currentSet]) {
-            _currentSet++;
-            _currentRep = 1;
-            _tickCount =
-                widget.activity.actions[0].activityActionSet.rest ~/ 10000;
-          } else {
-            _currentRep++;
-          }
-        } else {
-          _tickCount--;
-        }
-      });
-    });
-  }
-
   @override
   Widget build(BuildContext context) {
     ActivityModel activity = widget.activity;
 
+    ActivityTimerModel atm = Provider.of<ActivityTimerModel>(context, listen: false);
+
+    if (atm.active == false) {
+      atm.setupTimer(activity);
+    }
+
     var content = [
       AppBar(
         // surfaceTintColor: ThemeData.dark(useMaterial3: true).colorScheme.primary,
@@ -101,27 +73,34 @@ class _ActivityViewState extends State<ActivityView> {
                 IconButton(
                     iconSize: 30,
                     icon: const Icon(Icons.play_arrow_rounded),
-                    onPressed: _startPeriodicTimer),
+                    onPressed: () =>
+                        atm.startTimer(activity)),
                 IconButton(
-                    iconSize: 30,
+                    iconSize: 36,
                     icon: const Icon(Icons.skip_next_rounded),
                     onPressed: () {})
               ])),
           Expanded(
-            flex: 1,
+              flex: 1,
-            child: Text(
+              child: Consumer<ActivityTimerModel>(
-                style: const TextStyle(fontSize: 25),
+                builder: (context, atm, child) {
-                textAlign: TextAlign.center,
+                  return Text(
-                '$_tickCount'),
+                      style: const TextStyle(fontSize: 25),
-          ),
+                      textAlign: TextAlign.center,
+                      '${atm.tickCount}');
+                },
+              )),
           Expanded(
               flex: 1,
               child: Padding(
                   padding: const EdgeInsets.only(right: 10),
-                  child: Text(
+                  child: Consumer<ActivityTimerModel>(
-                      style: const TextStyle(fontSize: 15),
+                      builder: (context, atm, child) {
-                      textAlign: TextAlign.right,
+                    return Text(
-                      'Set: $_currentSet/3 \nRep: $_currentRep/5'))),
+                        style: const TextStyle(fontSize: 15),
+                        textAlign: TextAlign.right,
+                        'Set: ${atm.currentSet + 1}/${atm.totalSets}\nRep: ${atm.currentRep + 1}/${atm.totalReps}');
+                  }))),
         ])));
     return Column(
         crossAxisAlignment: CrossAxisAlignment.start, children: content);