asclass DynServerAwareDiscordBot<A extends DynServerAwareDiscordBot.ByServer> extends DynDiscordHopper {

  new Map<Long, A> dataByServer;

  int guildCount;

  transient IF0<A> makeByServer; // mandatory

  void startMe {

    super.startMe();

    dm_vmBus_onMessage_q incomingDiscordReaction(voidfunc(Map map) {

      if (!enabled) ret;

      O module = map.get('module);

      if (!dm_isMe(module)) ret;

      MessageReaction reaction = cast map.get('reaction);

      Guild guild = reaction.getGuild();

      if (guild == null) ret with print("Ignoring reaction without guild");

      getByServer(guild).onMessageReaction(map, true);

    });

    dm_vmBus_onMessage_q discordReactionRemoved(voidfunc(Map map) {

      if (!enabled) ret;

      O module = map.get('module);

      if (!dm_isMe(module)) ret;

      MessageReaction reaction = cast map.get('reaction);

      Guild guild = reaction.getGuild();

      if (guild == null) ret with print("Ignoring reaction remove without guild");

      getByServer(guild).onMessageReaction(map, false);

    });

  }

  class ByServer extends DynamicObject {

    long guildID;

    bool isGuild;

    transient Guild guild;

    S answer(S s, Map map) { null; }

    bool setField(S name, O value) {

      if (set_trueIfChanged(this, name, value)) false;

      ret true with _change();

    }

    Member getSelfMember(Guild guild) {

      ret guild.getMember(getSelfUser());

    }

    void onMessageReaction(Map map, bool added) {

      print("onMessageReaction " + added);

    }

  }

  @Override S answer(S input, Map map) {

    try answer super.answer(input, map); // discord hopping

    long guildID = toLong(map.get('guildID));

    Guild guild = cast map.get('guild);

    long id = guildID;

    print("Guild ID: " + guildID);

    if (id == 0) {

      id = toLong(map.get('userID));

      print("User ID: " + id);

    }

    // config by guild or user

    A data = guild != null ? getByServer(guild) : getByServer(id, id == guildID);

    Message msg = cast map.get('msg);

    if (msg != null && nempty(msg.getAttachments()))

      ret data.answer(input, map);

    else

      ret lines_rtrim(nempties(

        map(s -> data.answer(s, map), splitIntoLines(input))));

  }

  A getByServer(long id, bool isGuild) {

    ret pairA(getByServer2(id, isGuild));

  }

  Pair<A, Bool> getByServer2(long id, bool isGuild) {

    A data, bool isNew = unpair syncGetOrCreate2(dataByServer, id, makeByServer);

    data.isGuild = isGuild;

    if (isGuild && data.guildID == 0) {

      data.guildID = id;

      change();

    }

    if (isNew) {

      if (data.isGuild) ++guildCount;

      change();

    }

    ret pair(data, isNew);

  }

  A getByServer(Guild guild) {

    if (guild == null) null;

    A a = getByServer(guild.getIdLong(), true);

    a.guild = guild;

    ret a;

  }

  start {

    if (guildCount == 0)

      setField(guildCount := countValuesWhere_sync(dataByServer, isGuild := true));

  }

  int liveGuildCount() {

    ret l(discord.getGuilds());

  }

  long idForByServer(ByServer bs) {

    ret bs == null ? 0 : toLong(keyForValue_sync(dataByServer, (A) bs));

  }

  LS splitIntoLines(S s) {

    ret tlft(s);

  }

}