App refactor (#140)

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

app/src/bridge/components/discovery.ts

@@ -0,0 +1,111 @@
+"use strict";
+
+import mdns from "mdns";
+
+import StatusListener from "./chromecast/StatusListener";
+import { ReceiverStatus } from "../types";
+import { sendMessage } from "../lib/messaging";
+
+
+const browser = mdns.createBrowser(mdns.tcp("googlecast"), {
+    resolverSequence: [
+        mdns.rst.DNSServiceResolve()
+      , "DNSServiceGetAddrInfo" in mdns.dns_sd
+            ? mdns.rst.DNSServiceGetAddrInfo()
+              // Some issues on Linux with IPv6, so restrict to IPv4
+            : mdns.rst.getaddrinfo({ families: [ 4 ] })
+      , mdns.rst.makeAddressesUnique()
+    ]
+});
+
+function onBrowserServiceUp (service: mdns.Service) {
+    sendMessage({
+        subject: "main:/serviceUp"
+      , data: {
+            host: service.addresses[0]
+          , port: service.port
+          , id: service.txtRecord.id
+          , friendlyName: service.txtRecord.fn
+        }
+    });
+}
+
+function onBrowserServiceDown (service: mdns.Service) {
+    sendMessage({
+        subject: "main:/serviceDown"
+      , data: {
+            id: service.txtRecord.id
+        }
+    });
+}
+
+browser.on("serviceUp", onBrowserServiceUp);
+browser.on("servicedown", onBrowserServiceDown);
+
+
+interface InitializeOptions {
+    shouldWatchStatus?: boolean;
+}
+
+export function startDiscovery (options: InitializeOptions) {
+    if (options.shouldWatchStatus) {
+        browser.on("serviceUp", onStatusBrowserServiceUp);
+        browser.on("serviceDown", onStatusBrowserServiceDown);
+    }
+
+    browser.start();
+
+    // Receiver status listeners for status mode
+    const statusListeners = new Map<string, StatusListener>();
+
+    function onStatusBrowserServiceUp (service: mdns.Service) {
+        const { id } = service.txtRecord;
+
+        const listener = new StatusListener(
+                service.addresses[0]
+              , service.port);
+
+        listener.on("receiverStatus", (status: ReceiverStatus) => {
+            const receiverStatusMessage: any = {
+                subject: "main:/receiverStatus"
+              , data: {
+                    id
+                  , status: {
+                        volume: {
+                            level: status.volume.level
+                          , muted: status.volume.muted
+                        }
+                    }
+                }
+            };
+
+            if (status.applications && status.applications.length) {
+                const application = status.applications[0];
+
+                receiverStatusMessage.data.status.application = {
+                    appId: application.appId
+                  , displayName: application.displayName
+                  , isIdleScreen: application.isIdleScreen
+                  , statusText: application.statusText
+                };
+            }
+
+            sendMessage(receiverStatusMessage);
+        });
+
+        statusListeners.set(id, listener);
+    }
+
+    function onStatusBrowserServiceDown (service: mdns.Service) {
+        const { id } = service.txtRecord;
+
+        if (statusListeners.has(id)) {
+            statusListeners.get(id)!.deregister();
+            statusListeners.delete(id);
+        }
+    }
+}
+
+export function stopDiscovery () {
+    browser.stop();
+}