Added methods for inserting games and groups into the db

lib/data/dao/game_dao.dart

@@ -41,6 +41,27 @@ class GameDao extends DatabaseAccessor<AppDatabase> with _$GameDaoMixin {
     );
   }
 
+  Future<void> addGame(Game game) async {
+    await db.transaction(() async {
+      for (final p in game.players ?? []) {
+        await db.playerDao.addPlayer(p);
+        await db.playerGameDao.addPlayerToGame(game.id, p.id);
+      }
+      if (game.group != null) {
+        await db.groupDao.addGroup(game.group!);
+        await db.groupGameDao.addGroupToGame(game.id, game.group!.id);
+      }
+      await into(gameTable).insert(
+        GameTableCompanion.insert(
+          id: game.id,
+          name: game.name,
+          winnerId: Value(game.winner),
+        ),
+        mode: InsertMode.insertOrReplace,
+      );
+    });
+  }
+
   /// Retrieves the number of games in the database.
   Future<int> getGameCount() async {
     final count =

lib/data/dao/group_dao.dart

@@ -32,11 +32,26 @@ class GroupDao extends DatabaseAccessor<AppDatabase> with _$GroupDaoMixin {
   }
 
   /// Adds a new group with the given [id] and [name] to the database.
-  /// Returns `true` if more than 0 rows were affected, otherwise `false`.
-  Future<void> addGroup(String id, String name) async {
-    await into(
-      groupTable,
-    ).insert(GroupTableCompanion.insert(id: id, name: name));
+  /// This method also adds the group's members to the [PlayerGroupTable].
+  Future<void> addGroup(Group group) async {
+    await db.transaction(() async {
+      await into(
+        groupTable,
+      ).insert(GroupTableCompanion.insert(id: group.id, name: group.name));
+      await db.batch(
+        (b) => b.insertAll(
+          db.playerGroupTable,
+          group.members
+              .map(
+                (member) => PlayerGroupTableCompanion.insert(
+                  playerId: member.id,
+                  groupId: group.id,
+                ),
+              )
+              .toList(),
+        ),
+      );
+    });
   }
 
   /// Deletes the group with the given [id] from the database.

lib/data/dao/group_game_dao.dart

@@ -30,4 +30,12 @@ class GroupGameDao extends DatabaseAccessor<AppDatabase>
     final group = await db.groupDao.getGroupById(result.groupId);
     return group;
   }
+
+  /// Associates a group with a game by inserting a record into the
+  /// [GroupGameTable].
+  Future<void> addGroupToGame(String gameId, String groupId) async {
+    await into(
+      groupGameTable,
+    ).insert(GroupGameTableCompanion.insert(groupId: groupId, gameId: gameId));
+  }
 }

lib/data/dao/player_game_dao.dart

@@ -37,4 +37,12 @@ class PlayerGameDao extends DatabaseAccessor<AppDatabase>
     final players = await Future.wait(futures);
     return players.whereType<Player>().toList();
   }
+
+  /// Associates a player with a game by inserting a record into the
+  /// [PlayerGameTable].
+  Future<void> addPlayerToGame(String gameId, String playerId) async {
+    await into(playerGameTable).insert(
+      PlayerGameTableCompanion.insert(playerId: playerId, gameId: gameId),
+    );
+  }
 }

lib/data/db/tables/game_table.dart

@@ -3,6 +3,7 @@ import 'package:drift/drift.dart';
 class GameTable extends Table {
   TextColumn get id => text()();
   TextColumn get name => text()();
+  // todo: winner id needs to be deleted when corresponding player gets deleted
   TextColumn get winnerId => text().nullable()();
 
   @override