Show changelog on upgrade if available

lib/changelog.dart

@@ -0,0 +1,16 @@
+const contents = [
+  // v1
+  null,
+  // v2
+  null,
+  // v3
+  null,
+  // v4
+  null,
+  // v5
+  null,
+  // v6
+  null,
+  // v7
+  null,
+];

lib/k.dart

@@ -1,5 +1,6 @@
 /// Version string shown in settings page
-const version = "6.0-c4da14";
+const versionStr = "6.0-c4da14";
+const version = 6;
 
 /// Show a snack bar for a short amount of time
 const snackBarDurationShort = const Duration(seconds: 4);

lib/l10n/app_en.arb

@@ -344,6 +344,10 @@
 	"@downloadFailureNoPermissionNotification": {
 		"description": "Inform user that the file cannot be downloaded due to missing storage permission"
 	},
+	"changelogTitle": "Changelog",
+	"@changelogTitle": {
+		"description": "Title of the changelog dialog"
+	},
 	"errorUnauthenticated": "Unauthenticated access. Please sign-in again if the problem continues",
 	"@errorUnauthenticated": {
 		"description": "Error message when server responds with HTTP401"

lib/main.dart

@@ -6,6 +6,7 @@ import 'package:flutter/material.dart';
 import 'package:flutter_bloc/flutter_bloc.dart';
 import 'package:kiwi/kiwi.dart';
 import 'package:logging/logging.dart';
+import 'package:nc_photos/k.dart' as k;
 import 'package:nc_photos/metadata_task_manager.dart';
 import 'package:nc_photos/mobile/platform.dart'
     if (dart.library.html) 'package:nc_photos/web/platform.dart' as platform;
@@ -51,7 +52,18 @@ void _initLog() {
   });
 }
 
-Future<void> _initPref() => Pref.init();
+Future<void> _initPref() async {
+  await Pref.init();
+  if (Pref.inst().getLastVersion(null) == null) {
+    if (Pref.inst().getSetupProgress(null) == null) {
+      // new install
+      await Pref.inst().setLastVersion(k.version);
+    } else {
+      // v6 is the last version without saving the version number in pref
+      await Pref.inst().setLastVersion(6);
+    }
+  }
+}
 
 void _initBloc() {
   Bloc.observer = _BlocObserver();

lib/pref.dart

@@ -51,6 +51,11 @@ class Pref {
   Future<bool> setSetupProgress(int value) =>
       _pref.setInt("setupProgress", value);
 
+  /// Return the version number when the app last ran
+  int getLastVersion([int def = 0]) => _pref.getInt("lastVersion") ?? def;
+
+  Future<bool> setLastVersion(int value) => _pref.setInt("lastVersion", value);
+
   Pref._();
 
   static final _inst = Pref._();

lib/widget/settings.dart

@@ -79,7 +79,7 @@ class _SettingsState extends State<Settings> {
                   AppLocalizations.of(context).settingsAboutSectionTitle),
               ListTile(
                 title: Text(AppLocalizations.of(context).settingsVersionTitle),
-                subtitle: const Text(k.version),
+                subtitle: const Text(k.versionStr),
               ),
               ListTile(
                 title:

lib/widget/splash.dart

@@ -1,13 +1,15 @@
 import 'package:flutter/material.dart';
 import 'package:flutter/widgets.dart';
 import 'package:flutter_gen/gen_l10n/app_localizations.dart';
+import 'package:logging/logging.dart';
+import 'package:nc_photos/changelog.dart' as changelog;
+import 'package:nc_photos/k.dart' as k;
 import 'package:nc_photos/pref.dart';
 import 'package:nc_photos/theme.dart';
 import 'package:nc_photos/widget/home.dart';
 import 'package:nc_photos/widget/setup.dart';
 import 'package:nc_photos/widget/sign_in.dart';
 
-/// A useless widget
 class Splash extends StatefulWidget {
   static const routeName = "/splash";
 
@@ -22,17 +24,11 @@ class _SplashState extends State<Splash> {
   initState() {
     super.initState();
     WidgetsBinding.instance.addPostFrameCallback((timeStamp) {
-      Future.delayed(const Duration(seconds: 1)).then((_) {
-        final account = Pref.inst().getCurrentAccount();
-        if (isNeedSetup()) {
-          Navigator.pushReplacementNamed(context, Setup.routeName);
-        } else if (account == null) {
-          Navigator.pushReplacementNamed(context, SignIn.routeName);
-        } else {
-          Navigator.pushReplacementNamed(context, Home.routeName,
-              arguments: HomeArguments(account));
-        }
-      });
+      if (_shouldUpgrade()) {
+        _handleUpgrade();
+      } else {
+        _initTimedExit();
+      }
     });
   }
 
@@ -69,4 +65,70 @@ class _SplashState extends State<Splash> {
       ),
     );
   }
+
+  void _initTimedExit() {
+    Future.delayed(const Duration(seconds: 1)).then((_) {
+      final account = Pref.inst().getCurrentAccount();
+      if (isNeedSetup()) {
+        Navigator.pushReplacementNamed(context, Setup.routeName);
+      } else if (account == null) {
+        Navigator.pushReplacementNamed(context, SignIn.routeName);
+      } else {
+        Navigator.pushReplacementNamed(context, Home.routeName,
+            arguments: HomeArguments(account));
+      }
+    });
+  }
+
+  bool _shouldUpgrade() {
+    final lastVersion = Pref.inst().getLastVersion(k.version);
+    return lastVersion < k.version;
+  }
+
+  void _handleUpgrade() {
+    final lastVersion = Pref.inst().getLastVersion(k.version);
+    // ...
+
+    final change = _gatherChangelog(lastVersion);
+    if (change.isNotEmpty) {
+      showDialog(
+        context: context,
+        builder: (context) => AlertDialog(
+          title: Text(AppLocalizations.of(context).changelogTitle),
+          content: SingleChildScrollView(
+            child: Text(change),
+          ),
+          actions: <Widget>[
+            TextButton(
+              onPressed: () {
+                Navigator.of(context).pop();
+              },
+              child: Text(MaterialLocalizations.of(context).okButtonLabel),
+            )
+          ],
+        ),
+      ).whenComplete(() {
+        _initTimedExit();
+        Pref.inst().setLastVersion(k.version);
+      });
+    } else {
+      _initTimedExit();
+      Pref.inst().setLastVersion(k.version);
+    }
+  }
+
+  String _gatherChangelog(int from) {
+    try {
+      return changelog.contents
+          .sublist(from)
+          .reversed
+          .where((element) => element != null)
+          .join("\n\n");
+    } catch (e, stacktrace) {
+      _log.severe("[_gatherChangelog] Failed", e, stacktrace);
+      return "";
+    }
+  }
+
+  static final _log = Logger("widget.splash._SplashState");
 }