1 files changed, 90 insertions, 0 deletions
diff --git a/lib/db.dart b/lib/db.dart
new file mode 100644
index 0000000..0b2cf7a
--- /dev/null
+++ b/lib/db.dart
@@ -0,0 +1,90 @@
+import 'dart:io';
+import 'dart:async';
+
+import 'package:path_provider/path_provider.dart';
+import 'package:sqlite3/sqlite3.dart';
+import 'package:path/path.dart' as p;
+
+class DB {
+  final Completer<Database?> _dbCompleter = Completer<Database?>();
+  static const List<String> migrations = <String>[
+    '''
+PRAGMA user_version = 1;
+CREATE TABLE "key_value" (
+	"key"	TEXT NOT NULL UNIQUE,
+	"value"	TEXT,
+	PRIMARY KEY("key")
+);
+    ''',
+  ];
+
+  Future<void> connect() async {
+    String path = await _getDbPath();
+    Database candidate = sqlite3.open(path);
+
+    migrate(candidate);
+
+    _dbCompleter.complete(candidate);
+  }
+
+  void dispose() async {
+    if (_dbCompleter.isCompleted == false) {
+      return;
+    }
+    Database? db = await _dbCompleter.future;
+    if (db == null) return;
+    db.close();
+  }
+
+  static Future<String> _getDbPath() async {
+    Directory supportDir = await getApplicationSupportDirectory();
+    return p.join(supportDir.path, 'main.sqlite3');
+  }
+
+  static void migrate(Database db) {
+    for (int i=0; i<migrations.length; i++) {
+      int? userVersion = _getUserVersion(db);
+      if (userVersion == null) return;
+
+      if (i == userVersion) {
+        db.execute(migrations[i]);
+      }
+    }
+  }
+
+  static int? _getUserVersion(Database db) {
+    ResultSet result = db.select('PRAGMA user_version;');
+    if (result.length != 1) return null;
+    return result.first.values.first as int;
+  }
+
+  Future<String?> getServerFqdn() async {
+    Database? db = await _dbCompleter.future;
+    if (db == null) return null;
+
+    ResultSet result = db.select(
+      'SELECT value FROM key_value WHERE key = \'server_fqdn\';'
+    );
+    if (result.length != 1) return null;
+
+    return result[0]['value'];
+  }
+
+  Future<void> setServerFqdn(String value) async {
+    Database? db = await _dbCompleter.future;
+    if (db == null) return;
+
+    String? current = await getServerFqdn();
+    if (current == null) {
+      db.execute(
+        'INSERT INTO key_value (key, value) VALUES (\'server_fqdn\', ?);',
+        <Object?>[value],
+      );
+    } else {
+      db.execute(
+        'UPDATE key_value SET value = ? WHERE key = \'server_fqdn\';',
+        <Object?>[value],
+      );
+    }
+  }
+}