Add experimental assistant feature

src/lib/structures/AssistantSwitcher.js

@@ -0,0 +1,49 @@
+const constants = require("../constants")
+const collectors = require("../collectors")
+const Assistant = require("./Assistant")
+const db = require("../db")
+
+class AssistantSwitcher {
+	constructor() {
+		this.assistants = constants.assistant.origins.map(origin => new Assistant(origin))
+	}
+
+	enabled() {
+		return constants.assistant.enabled && this.assistants.length
+	}
+
+	getAvailableAssistants() {
+		return this.assistants.filter(assistant => assistant.available()).sort((a, b) => (a.lastRequest - b.lastRequest))
+	}
+
+	requestUser(username) {
+		return new Promise(async (resolve, reject) => {
+			const assistants = this.getAvailableAssistants()
+			while (assistants.length) {
+				const assistant = assistants.shift()
+				try {
+					const user = await assistant.requestUser(username)
+					return resolve(user)
+				} catch (e) {
+					// that assistant broke. try the next one.
+				}
+			}
+			return reject(constants.symbols.NO_ASSISTANTS_AVAILABLE)
+		}).then(user => {
+			const bind = {...user}
+			bind.created = Date.now()
+			bind.updated = Date.now()
+			bind.updated_version = constants.database_version
+			bind.is_private = +user.is_private
+			bind.is_verified = +user.is_verified
+			db.prepare(
+				"REPLACE INTO Users (username,  user_id,  created,  updated,  updated_version,  biography,  post_count,  following_count,  followed_by_count,  external_url,  full_name,  is_private,  is_verified,  profile_pic_url) VALUES "
+									  +"(@username, @user_id, @created, @updated, @updated_version, @biography, @post_count, @following_count, @followed_by_count, @external_url, @full_name, @is_private, @is_verified, @profile_pic_url)"
+			).run(bind)
+			collectors.userRequestCache.cache.delete(`user/${username}`)
+			return collectors.fetchUserFromSaved(user)
+		})
+	}
+}
+
+module.exports = AssistantSwitcher