Add reading server domain name from SQLite3 DB

It is annoying to type the server domain name on every app start. This
should be way more ergonomic.

As a minimal first step reading from the database is implemented and
tested with an externally injected database.

2 files changed, 43 insertions, 2 deletions

diff --git a/lib/data.dart b/lib/data.dart
index 365f5bc..302908c 100644
--- a/lib/data.dart
+++ b/lib/data.dart
@@ -1,6 +1,11 @@
+import 'dart:io';
+
 import 'package:flutter/foundation.dart';
 import 'package:mqtt_client/mqtt_client.dart';
 import 'package:mqtt_client/mqtt_server_client.dart';
+import 'package:path_provider/path_provider.dart';
+import 'package:sqlite3/sqlite3.dart';
+import 'package:path/path.dart' as p;
 
 const int brokerPort = 1883;
 const String topicPrefix = 'sia';
@@ -46,9 +51,36 @@ class AppState with ChangeNotifier {
   Map<String, bool> contacts = <String, bool>{};
   late MqttServerClient _client;
 
+  late Directory supportDir;
   String fqdn = '';
 
-  AppState();
+  AppState() {
+    loadPersistence();
+  }
+
+  void loadPersistence() async {
+    supportDir = await getApplicationSupportDirectory();
+    String dbPath = p.join(supportDir.path, 'main.sqlite3');
+
+    final Database db = sqlite3.open(dbPath);
+    try {
+      final ResultSet result = db.select(
+        'SELECT value FROM key_value WHERE key = \'server_fqdn\';'
+      );
+      if (result.length == 1) {
+        fqdn = result[0]['value'];
+        notifyListeners();
+      }
+    } catch (e) {
+      // loading persistence is optional
+    } finally {
+      db.close();
+    }
+  }
+
+  void setFqdn(String value) {
+    fqdn = value;
+  }
 
   void process(MachineEvent event) {
     MachineState lastState = state;
diff --git a/lib/ui.dart b/lib/ui.dart
index 9603562..3a98be9 100644
--- a/lib/ui.dart
+++ b/lib/ui.dart
@@ -41,8 +41,17 @@ class _ConnectionPageState extends State<ConnectionPage> {
     final AppState provider = context.read<AppState>();
     controller = TextEditingController(text: provider.fqdn);
 
+    provider.addListener(() {
+      if (controller.text != provider.fqdn) {
+        controller.text = provider.fqdn;
+        controller.selection = TextSelection.fromPosition(
+          TextPosition(offset: controller.text.length),
+        );
+      }
+    });
+
     controller.addListener(() {
-      provider.fqdn = controller.text;
+      provider.setFqdn(controller.text);
     });
   }