App refactor (#140)

* Add additional types
* Split components from single index module into smaller modules
* Misc smaller changes

app/src/daemon.ts

@@ -0,0 +1,61 @@
+"use strict";
+
+import { spawn } from "child_process";
+import { Readable } from "stream";
+
+import minimist from "minimist";
+import WebSocket from "ws";
+
+import { DecodeTransform
+       , EncodeTransform } from "./transforms";
+
+
+export function init (port: number) {
+    process.stdout.write("Starting WebSocket server... ");
+
+    const wss = new WebSocket.Server({ port }, () => {
+        console.log("Done!");
+    });
+
+    wss.on("error", (err) => {
+        console.log("Failed!");
+        console.error(err);
+    });
+
+
+    wss.on("connection", socket => {
+        // Stream for incoming WebSocket messages
+        const messageStream = new Readable({ objectMode: true });
+        messageStream._read = () => {};
+
+        socket.on("message", (message: string) => {
+            messageStream.push(JSON.parse(message));
+        });
+
+
+        /**
+         * Daemon and bridge are the same binary, so spawn a new
+         * version of self in bridge mode.
+         */
+        const bridge = spawn(process.execPath, [ process.argv[1] ]);
+
+        // socket -> bridge.stdin
+        messageStream
+            .pipe(new EncodeTransform())
+            .pipe(bridge.stdin);
+
+        // bridge.stdout -> socket
+        bridge.stdout
+            .pipe(new DecodeTransform())
+            .on("data", data => {
+                // Socket can be CLOSING here
+                if (socket.readyState === WebSocket.OPEN) {
+                    socket.send(JSON.stringify(data));
+                }
+            });
+
+        // Handle termination
+        socket.on("close", () => bridge.kill());
+        bridge.on("exit", () => socket.close());
+    });
+}