Usync: Barebones Usync Protocol support (#960)

* feature(feature/usync-mex): initial commit

* chore: fix merge commit

* chore:lint

src/Socket/usync.ts

@@ -0,0 +1,81 @@
+import { Boom } from '@hapi/boom'
+import { SocketConfig } from '../Types'
+import { BinaryNode, S_WHATSAPP_NET } from '../WABinary'
+import { USyncQuery } from '../WAUSync'
+import { makeSocket } from './socket'
+
+export const makeUSyncSocket = (config: SocketConfig) => {
+	const sock = makeSocket(config)
+
+	const {
+		generateMessageTag,
+		query,
+	} = sock
+
+	const executeUSyncQuery = async(usyncQuery: USyncQuery) => {
+		if(usyncQuery.protocols.length === 0) {
+			throw new Boom('USyncQuery must have at least one protocol')
+		}
+
+		// todo: validate users, throw WARNING on no valid users
+		// variable below has only validated users
+		const validUsers = usyncQuery.users
+
+		const userNodes = validUsers.map((user) => {
+			return {
+				tag: 'user',
+				attrs: {
+					jid: !user.phone ? user.id : undefined,
+				},
+				content: usyncQuery.protocols
+					.map((a) => a.getUserElement(user))
+					.filter(a => a !== null)
+			} as BinaryNode
+		})
+
+		const listNode: BinaryNode = {
+			tag: 'list',
+			attrs: {},
+			content: userNodes
+		}
+
+		const queryNode: BinaryNode = {
+			tag: 'query',
+			attrs: {},
+			content: usyncQuery.protocols.map((a) => a.getQueryElement())
+		}
+		const iq = {
+			tag: 'iq',
+			attrs: {
+				to: S_WHATSAPP_NET,
+				type: 'get',
+				xmlns: 'usync',
+			},
+			content: [
+				{
+					tag: 'usync',
+					attrs: {
+						context: usyncQuery.context,
+						mode: usyncQuery.mode,
+						sid: generateMessageTag(),
+						last: 'true',
+						index: '0',
+					},
+					content: [
+						queryNode,
+						listNode
+					]
+				}
+			],
+		}
+
+		const result = await query(iq)
+
+		return usyncQuery.parseUSyncQueryResult(result)
+	}
+
+	return {
+		...sock,
+		executeUSyncQuery,
+	}
+}