discordeno/plugins/cache/src/setupCacheRemovals.ts

import {
Bot,
  Channel,
  Collection,
  GuildBanAddRemove,
  GuildEmojisUpdate,
  GuildMemberRemove,
  GuildRoleDelete,
  MessageDelete,
  MessageDeleteBulk,
} from "../deps.ts";
import { SnakeCasedPropertiesDeep, UnavailableGuild } from "../deps.ts";
import { BotWithCache } from "./addCacheCollections.ts";

export function setupCacheRemovals<B extends Bot>(bot: BotWithCache<B>) {
  const {
    CHANNEL_DELETE,
    GUILD_BAN_ADD,
    GUILD_DELETE,
    GUILD_EMOJIS_UPDATE,
    GUILD_MEMBER_REMOVE,
    GUILD_ROLE_DELETE,
    MESSAGE_DELETE_BULK,
  } = bot.handlers;

  bot.handlers.GUILD_DELETE = function (_, data, shardId) {
    const payload = data.d as SnakeCasedPropertiesDeep<UnavailableGuild>;
    const id = bot.transformers.snowflake(payload.id);

    bot.guilds.delete(id);
    bot.channels.forEach((channel) => {
      if (channel.guildId === id) bot.channels.delete(channel.id);
    });
    bot.members.forEach((member) => {
      if (member.guildId === id) bot.members.delete(member.id);
    });
    bot.messages.forEach((message) => {
      if (message.guildId === id) bot.messages.delete(message.id);
    });
    GUILD_DELETE(bot, data, shardId);
  };

  bot.handlers.CHANNEL_DELETE = function (_, data, shardId) {
    const payload = data.d as SnakeCasedPropertiesDeep<Channel>;
    // HANDLER BEFORE DELETING, BECAUSE HANDLER RUNS TRANSFORMER WHICH RECACHES
    CHANNEL_DELETE(bot, data, shardId);

    const id = bot.transformers.snowflake(payload.id);
    bot.channels.delete(id);
    bot.messages.forEach((message) => {
      if (message.channelId === id) bot.messages.delete(message.id);
    });
  };

  bot.handlers.GUILD_MEMBER_REMOVE = function (_, data, shardId) {
    const payload = data.d as SnakeCasedPropertiesDeep<GuildMemberRemove>;
    bot.members.delete(bot.transformers.snowflake(payload.user.id));
    GUILD_MEMBER_REMOVE(bot, data, shardId);
  };

  bot.handlers.GUILD_BAN_ADD = function (_, data, shardId) {
    const payload = data.d as SnakeCasedPropertiesDeep<GuildBanAddRemove>;
    bot.members.delete(bot.transformers.snowflake(payload.user.id));
    GUILD_BAN_ADD(bot, data, shardId);
  };

  bot.handlers.GUILD_EMOJIS_UPDATE = function (_, data, shardId) {
    const payload = data.d as SnakeCasedPropertiesDeep<GuildEmojisUpdate>;

    const guild = bot.guilds.get(bot.transformers.snowflake(payload.guild_id));
    if (guild) {
      guild.emojis = new Collection(payload.emojis.map((e) => {
        const emoji = bot.transformers.emoji(bot, e);
        return [emoji.id!, emoji];
      }));
    }

    GUILD_EMOJIS_UPDATE(bot, data, shardId);
  };

  bot.handlers.MESSAGE_DELETE = function (_, data) {
    const payload = data.d as SnakeCasedPropertiesDeep<MessageDelete>;
    const id = bot.transformers.snowflake(payload.id);
    const message = bot.messages.get(id);
    bot.events.messageDelete(bot, {
      id,
      channelId: bot.transformers.snowflake(payload.channel_id),
      guildId: payload.guild_id
        ? bot.transformers.snowflake(payload.guild_id)
        : undefined,
    }, message);
    bot.messages.delete(id);
  };

  bot.handlers.MESSAGE_DELETE_BULK = function (_, data, shardId) {
    const payload = data.d as SnakeCasedPropertiesDeep<MessageDeleteBulk>;
    payload.ids.forEach((id) =>
      bot.messages.delete(bot.transformers.snowflake(id))
    );
    MESSAGE_DELETE_BULK(bot, data, shardId);
  };

  bot.handlers.GUILD_ROLE_DELETE = function (_, data, shardId) {
    const payload = data.d as SnakeCasedPropertiesDeep<GuildRoleDelete>;
    const guild = bot.guilds.get(
      bot.transformers.snowflake(payload.guild_id),
    );
    const id = bot.transformers.snowflake(payload.role_id);

    if (guild) {
      guild.roles.delete(id);
      bot.members.forEach((member) => {
        // SKIP MEMBERS IN OTHER GUILDS
        if (member.guildId !== guild.id) return;
        // SKIP MEMBERS WHO DON'T HAVE ROLE
        if (!member.roles.includes(id)) return;
        // EDIT THE MEMBERS ROLES
        member.roles = member.roles.filter((roleId) => roleId !== id);
      });
    }

    GUILD_ROLE_DELETE(bot, data, shardId);
  };
}