Commit 5e2243e

@@ -0,0 +1,62 @@
+import 'dart:async';
+
+import 'package:path/path.dart';
+import 'package:sqflite/sqflite.dart';
+
+/// The config database has the following tables:
+///
+/// settings
+/// profile_id: INTEGER PRIMARY KEY, settings_json: STRING
+///
+/// exportStrings
+/// internalColumnName STRING PRIMARY KEY, columnTitle STRING, formatPattern STRING
+class ConfigDB {
+  ConfigDB._create();
+
+  late final Database _database;
+
+  /// The meaning of the arguments is the same as in the create constructor.
+  Future<void> _asyncInit(String? dbPath, bool isFullPath) async {
+    dbPath ??= await getDatabasesPath();
+    if (dbPath != inMemoryDatabasePath && !isFullPath) {
+      dbPath = join(dbPath, 'config.db');
+    }
+
+    _database = await openDatabase(
+      dbPath,
+      onCreate: _onDBCreate,
+      onUpgrade: _onDBUpgrade,
+      // When increasing the version an update procedure from every other possible version is needed
+      version: 2,
+    );
+  }
+
+  FutureOr<void> _onDBCreate(Database db, int version) {
+    db.execute(
+        'CREATE TABLE exportStrings(internalColumnName STRING PRIMARY KEY, columnTitle STRING, formatPattern STRING)');
+    db.execute('CREATE TABLE settings(profile_id: INTEGER PRIMARY KEY, settings_json: STRING)');
+  }
+
+  FutureOr<void> _onDBUpgrade(Database db, int oldVersion, int newVersion) async {
+    // When adding more versions the upgrade procedure proposed in https://stackoverflow.com/a/75153875/21489239
+    // might be useful, to avoid duplicated code. Currently this would only lead to complexity, without benefits.
+    if (oldVersion == 1 && newVersion == 2) {
+      db.execute('CREATE TABLE settings(profile_id: INTEGER PRIMARY KEY, settings_json: STRING)');
+      db.database.setVersion(2);
+    } else {
+      assert(false, 'Unexpected version upgrade from $oldVersion to $newVersion.');
+    }
+  }
+
+  /// Factory method that either opens an existing db file or creates a new one if no file is present.
+  ///
+  /// [dbPath] is the path to the folder the database is in. When [dbPath] is left empty the default database file is
+  /// used. The [isFullPath] option tells the constructor not to add the default filename at the end of [dbPath].
+  Future<ConfigDB> open({String? dbPath, bool isFullPath = false}) async {
+    final instance = ConfigDB._create();
+    await instance._asyncInit(dbPath, isFullPath);
+    return instance;
+  }
+
+  Database get database => _database;
+}

@@ -34,9 +34,9 @@ class BloodPressureModel extends ChangeNotifier {
 
     _database = await openDatabase(
       dbPath,
-      // runs when the database is first created
       onCreate: _onDBCreate,
       onUpgrade: _onDBUpgrade,
+      // When increasing the version an update procedure from every other possible version is needed
       version: 2,
     );
   }
@@ -61,9 +61,12 @@ class BloodPressureModel extends ChangeNotifier {
     }
   }
 
-  // factory method, to allow for async constructor
+  /// Factory method to create a BloodPressureModel for a database file. This is needed to allow an async constructor.
+  ///
+  /// [dbPath] is the path to the folder the database is in. When [dbPath] is left empty the default database file is
+  /// used. The [isFullPath] option tells the constructor not to add the default filename at the end of [dbPath].
   static Future<BloodPressureModel> create({String? dbPath, bool isFullPath = false}) async {
-    if (Platform.isWindows || Platform.isLinux) {
+    if (Platform.isWindows || Platform.isLinux) { // TODO: drop desktop support
       sqfliteFfiInit();
       databaseFactory = databaseFactoryFfi;
     }

@@ -17,6 +17,8 @@ class ExportFields {
 }
 
 class ExportConfigurationModel {
+  // TODO: remove database functionality and use configDB, this should not touch the file, because it would be read by
+  // 2 sources.
   static ExportConfigurationModel? _instance;
 
   final Settings settings;