feat: basic database functionality

lib/data/dao/statistic_group_dao.dart

@@ -0,0 +1,66 @@
+import 'package:drift/drift.dart';
+import 'package:tallee/data/db/database.dart';
+import 'package:tallee/data/db/tables/group_table.dart';
+import 'package:tallee/data/db/tables/statistic_group_table.dart';
+import 'package:tallee/data/models/group.dart';
+
+part 'statistic_group_dao.g.dart';
+
+@DriftAccessor(tables: [StatisticGroupTable, GroupTable])
+class StatisticGroupDao extends DatabaseAccessor<AppDatabase>
+    with _$StatisticGroupDaoMixin {
+  StatisticGroupDao(super.db);
+
+  /// Retrieves a list of groups associated with a specific statistic.
+  Future<List<Group>> getGroupsForStatistic(String statisticId) async {
+    final query = select(statisticGroupTable).join([
+      innerJoin(
+        groupTable,
+        groupTable.id.equalsExp(statisticGroupTable.groupId),
+      ),
+    ])..where(statisticGroupTable.statisticId.equals(statisticId));
+
+    final results = await query.map((row) => row.readTable(groupTable)).get();
+    final groups = await Future.wait(
+      results.map((result) async {
+        final groupMembers = await db.playerGroupDao.getPlayersOfGroup(
+          groupId: result.id,
+        );
+        return Group(
+          id: result.id,
+          createdAt: result.createdAt,
+          name: result.name,
+          description: result.description,
+          members: groupMembers,
+        );
+      }),
+    );
+
+    return groups;
+  }
+
+  Future<bool> addStatisticGroups({
+    required String statisticId,
+    required List<Group> groups,
+  }) async {
+    final entries = groups
+        .map(
+          (group) => StatisticGroupTableCompanion.insert(
+            statisticId: statisticId,
+            groupId: group.id,
+          ),
+        )
+        .toList();
+
+    return batch((batch) {
+      batch.insertAll(
+        statisticGroupTable,
+        entries,
+        mode: InsertMode.insertOrReplace,
+      );
+    }).then((_) => true).catchError((error) {
+      print('Error adding statistic groups: $error');
+      return false;
+    });
+  }
+}