feat: remove datastores and implement Managers (#3696)

* Initial commit: add 5 initial managers

- Base manager
- GuildChannelManager
- MessageManager
- PresenceManager
- Reaction Manager
- Added LimitedCollection

* Add GuildEmojiManager, various fixes

* Modify some managers and add guildmembermanager

* Initial integration

* Delete old stores

* Integration part two, removed LRUCollection

- Most of the integration has been finished
- TODO typings
- Removed LRUCollection, needless sweeping

* Typings + stuff i somehow missed in ChannelManager

* LimitedCollection typings/ final changes

* Various jsdoc and syntactical fixes, Removed Util.mixin()

* tslint fix

* Grammatical and logical changes

* Delete temporary file placed by mistake

* Grammatical changes

* Add missing type

* Update jsdoc examples

* fix: ChannelManager#remove should call cache#delete not cache#remove

* fix recursive require

* Fix missed cache in util

* fix: more missed cache

* Remove accidental _fetchMany change from #3645

* fix: use .cache.delete() over .remove()

* fix: missing cache in ReactionCollector

* fix: missed cache in client

* fix: members is a collection not a manager

Co-Authored-By: Sugden <28943913+NotSugden@users.noreply.github.com>

* fix: various docs and cache fixes

* fix: missed cache

* fix: missing _roles

* Final testing and debugging

* LimitedCollection: return the Collection instead of undefined on .set

* Add cache to BaseManager in typings

* Commit fixes i forgot to stage yesterday

* Update invite events

* Account for new commit

* fix: MessageReactionRemoveAll should call .cache.clear()

* fix: add .cache at various places, correct return type

* docs: remove mentions of 'store'

* Add extra documented properties to typings

Co-authored-by: Sugden <28943913+NotSugden@users.noreply.github.com>
Co-authored-by: SpaceEEC <spaceeec@yahoo.com>

src/managers/UserManager.js

@@ -0,0 +1,69 @@
+'use strict';
+
+const BaseManager = require('./BaseManager');
+const User = require('../structures/User');
+const GuildMember = require('../structures/GuildMember');
+const Message = require('../structures/Message');
+
+/**
+ * Manages API methods for users and stores their cache.
+ * @extends {BaseManager}
+ */
+class UserManager extends BaseManager {
+  constructor(client, iterable) {
+    super(client, iterable, User);
+  }
+
+  /**
+   * The cache of this manager
+   * @property {Collection<Snowflake, User>} cache
+   * @memberof UserManager
+   * @instance
+   */
+
+  /**
+   * Data that resolves to give a User object. This can be:
+   * * A User object
+   * * A Snowflake
+   * * A Message object (resolves to the message author)
+   * * A GuildMember object
+   * @typedef {User|Snowflake|Message|GuildMember} UserResolvable
+   */
+
+  /**
+   * Resolves a UserResolvable to a User object.
+   * @param {UserResolvable} user The UserResolvable to identify
+   * @returns {?User}
+   */
+  resolve(user) {
+    if (user instanceof GuildMember) return user.user;
+    if (user instanceof Message) return user.author;
+    return super.resolve(user);
+  }
+
+  /**
+   * Resolves a UserResolvable to a user ID string.
+   * @param {UserResolvable} user The UserResolvable to identify
+   * @returns {?Snowflake}
+   */
+  resolveID(user) {
+    if (user instanceof GuildMember) return user.user.id;
+    if (user instanceof Message) return user.author.id;
+    return super.resolveID(user);
+  }
+
+  /**
+   * Obtains a user from Discord, or the user cache if it's already available.
+   * @param {Snowflake} id ID of the user
+   * @param {boolean} [cache=true] Whether to cache the new user object if it isn't already
+   * @returns {Promise<User>}
+   */
+  async fetch(id, cache = true) {
+    const existing = this.cache.get(id);
+    if (existing && !existing.partial) return existing;
+    const data = await this.client.api.users(id).get();
+    return this.add(data, cache);
+  }
+}
+
+module.exports = UserManager;