server/src/operations.ts


1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56

import { Context } from "./context.model";
import { SubscriptionRequest } from "../../lib/subscription-req.model";
import { WriteRequest } from "../../lib/write-req.model";
import { DatabaseChange } from "../../lib/database-change.model";

import { DatabaseInterface } from "naive-core";

import express, { RequestHandler } from "express";
import bodyParser from "body-parser";

export const bindOperations = (
  ctx: Context,
  db: DatabaseInterface,
  send: (e: DatabaseChange) => Promise<any>
) => {
  const unsubs: { [key: string]: () => any } = {};

  const writeHandler: RequestHandler = async (req, res) => {
    const { path, toWrite } = req.body as WriteRequest;
    await db.write(path, toWrite);
    res.status(200).end();
  };

  const addSubHandler: RequestHandler = async (req, res) => {
    const { path } = req.body as SubscriptionRequest;
    // only allow users to subscribe
    // to a given path once
    // TODO return a better error
    if (unsubs[path]) {
      res.status(500).end();
      return;
    }
    unsubs[path] = db.subscribe(path, async (change: Object) => {
      await send({
        path,
        change
      });
    });
    res.status(200).end();
  };

  const removeSubHandler: RequestHandler = async (req, res) => {
    const { path } = req.body as SubscriptionRequest;
    const unsub = unsubs[path];
    if (unsub) unsub();
  };

  const router = express();
  router.use(bodyParser.json());
  router.post("/write", writeHandler);
  router
    .route("/subscribe")
    .post(addSubHandler)
    .delete(removeSubHandler);
  router.listen(ctx.httpPort, () => ctx.logger("HTTPS server started"));
};