[Refactoring] convert serve/index.js to typescript code (#1873)

* serve/index.js to typescript

* convert serve/index js to typescript code

* change require to import

* change export serve and fix relative source

* convert arrow function

* function serve return type

* add jsdoc

* refactoring  remove `const target `

src/commands/serve.js

@@ -9,7 +9,7 @@ var utils = require("../utils");
 var { requirePermissions } = require("../requirePermissions");
 var requireConfig = require("../requireConfig");
 var checkDupHostingKeys = require("../checkDupHostingKeys");
-var serve = require("../serve/index");
+var { serve } = require("../serve/index");
 var filterTargets = require("../filterTargets");
 var getProjectNumber = require("../getProjectNumber");
 

src/serve/index.ts

@@ -0,0 +1,45 @@
+import { EmulatorServer } from "../emulator/emulatorServer";
+import * as _ from "lodash";
+import * as logger from "../logger";
+
+const TARGETS: {
+  [key: string]:
+    | EmulatorServer
+    | { start: (o: any) => void; stop: (o: any) => void; connect: () => void };
+} = {
+  hosting: require("./hosting"),
+  functions: require("./functions"),
+  database: require("./database"),
+  firestore: require("./firestore"),
+};
+
+/**
+ * Serve runs the emulators for a set of targets provided in options.
+ * @param options Firebase CLI options.
+ */
+export async function serve(options: any): Promise<void> {
+  const targetNames = options.targets;
+  options.port = parseInt(options.port, 10);
+  await Promise.all(
+    _.map(targetNames, (targetName: string) => {
+      return TARGETS[targetName].start(options);
+    })
+  );
+  await Promise.all(
+    _.map(targetNames, (targetName: string) => {
+      return TARGETS[targetName].connect();
+    })
+  );
+  await new Promise((resolve) => {
+    process.on("SIGINT", () => {
+      logger.info("Shutting down...");
+      return Promise.all(
+        _.map(targetNames, (targetName: string) => {
+          return TARGETS[targetName].stop(options);
+        })
+      )
+        .then(resolve)
+        .catch(resolve);
+    });
+  });
+}