+import * as Bluebird from 'bluebird'
+import { AccessDeniedError } from 'oauth2-server'
+import { logger } from '../helpers/logger'
+import { UserModel } from '../models/account/user'
+import { OAuthClientModel } from '../models/oauth/oauth-client'
+import { OAuthTokenModel } from '../models/oauth/oauth-token'
+import { LRU_CACHE } from '../initializers/constants'
+import { Transaction } from 'sequelize'
+import { CONFIG } from '../initializers/config'
+import * as LRUCache from 'lru-cache'
+import { MOAuthTokenUser } from '@server/typings/models/oauth/oauth-token'
+
+type TokenInfo = { accessToken: string, refreshToken: string, accessTokenExpiresAt: Date, refreshTokenExpiresAt: Date }
+
+const accessTokenCache = new LRUCache<string, MOAuthTokenUser>({ max: LRU_CACHE.USER_TOKENS.MAX_SIZE })
+const userHavingToken = new LRUCache<number, string>({ max: LRU_CACHE.USER_TOKENS.MAX_SIZE })