[Marshaller] - Enhance data structure

[LeadcodeDev]

Context

The addition of category support within server channels has created a serialisation problem linked to non-existent channels within the cache.

Proposal

Cache structure

├── root
│  └── user-[user_id]
│  └── server-[server_id]
│  └── server-[server_id]/emoji-[emoji_id]
│  └── server-[server_id]/member-[emoji_id]

final class Marshaller {
  // Cache structure
  Map<String, dynamic> _cache = {};

  Future<void> putServer(Server server) async {
    final rawServer = serializers.servers.deserialize(server);
    _cache.put('server-${server.id}', rawServer);
    
    for (final role in server.roles.list) {
      final rawRole = await serializers.roles.deserialize(role)
      _cache.put('server-${server.id}/role-${role.id}', rawRole);
    }

    for (final emoji in emojis.list) {
      final rawEmoji = await serializers.emojis.deserialize(emoji)
      _cache.put('server-${server.id}/emoji-${emoji.id}', rawEmoji);
    }
  }

  Future<({ Server? instance, Map<String, dynamic>? struct })> getServer(String id) async {
    final cachedServer = await _cache.getOrFail('server-$id');
    
    return (
      instance: cachedServer != null 
        ? await serializers.servers.cacheSerializer(cachedServer) 
        : null,
      struct: cachedServer
    );
  }
}

Cached data structures

Channel

├── <channel>
│  └── id
│  └── name
│  └── Map<Snowflake, User> users

Server

├── Server
│  └── id
│  └── name
│  └── List<Snowflake> members
│  └── List<Snowflake> channels

Serializers

abstract interface class Serializer<T> {
  T remoteSerializer(Map<String, dynamic>);
  T cacheSerializer(Map<String, dynamic>);
  Map<String, dynamic> deserialize(T);
}