lots of important stuff (#1883)

* lots of important stuff

* Update Constants.js

src/rest/RESTManager.js

@@ -0,0 +1,73 @@
+const UserAgentManager = require('./UserAgentManager');
+const handlers = require('./handlers');
+const APIRequest = require('./APIRequest');
+const routeBuilder = require('./APIRouter');
+const { Error } = require('../errors');
+const Constants = require('../util/Constants');
+
+class RESTManager {
+  constructor(client, tokenPrefix = 'Bot') {
+    this.client = client;
+    this.handlers = {};
+    this.userAgentManager = new UserAgentManager(this);
+    this.rateLimitedEndpoints = {};
+    this.globallyRateLimited = false;
+    this.tokenPrefix = tokenPrefix;
+    this.versioned = true;
+  }
+
+  get api() {
+    return routeBuilder(this);
+  }
+
+  getAuth() {
+    const token = this.client.token || this.client.accessToken;
+    const prefixed = !!this.client.application || (this.client.user && this.client.user.bot);
+    if (token && prefixed) return `${this.tokenPrefix} ${token}`;
+    else if (token) return token;
+    throw new Error('TOKEN_MISSING');
+  }
+
+  get cdn() {
+    return Constants.Endpoints.CDN(this.client.options.http.cdn);
+  }
+
+  destroy() {
+    for (const handler of Object.values(this.handlers)) {
+      if (handler.destroy) handler.destroy();
+    }
+  }
+
+  push(handler, apiRequest) {
+    return new Promise((resolve, reject) => {
+      handler.push({
+        request: apiRequest,
+        resolve,
+        reject,
+      });
+    });
+  }
+
+  getRequestHandler() {
+    const method = this.client.options.apiRequestMethod;
+    if (typeof method === 'function') return method;
+    const handler = handlers[method];
+    if (!handler) throw new Error('RATELIMIT_INVALID_METHOD');
+    return handler;
+  }
+
+  request(method, url, options = {}) {
+    const apiRequest = new APIRequest(this, method, url, options);
+    if (!this.handlers[apiRequest.route]) {
+      this.handlers[apiRequest.route] = new handlers.RequestHandler(this, this.getRequestHandler());
+    }
+
+    return this.push(this.handlers[apiRequest.route], apiRequest);
+  }
+
+  set endpoint(endpoint) {
+    this.client.options.http.api = endpoint;
+  }
+}
+
+module.exports = RESTManager;