Fix to show correct url even for IPv6

Author: ohakutsu

src/commands/preview.ts

@@ -1,6 +1,7 @@
 import { config } from "../lib/config";
 import { getFileSystemRepo } from "../lib/get-file-system-repo";
 import { getQiitaApiInstance } from "../lib/get-qiita-api-instance";
+import { resolveUrlFromAddress } from "../lib/resolve-url-from-address";
 import { syncArticlesFromQiita } from "../lib/sync-articles-from-qiita";
 import { startLocalChangeWatcher, startServer } from "../server/app";
 
@@ -13,9 +14,10 @@ export const preview = async () => {
   const server = await startServer();
 
   const address = server.address();
-  if (address && typeof address !== "string") {
+  const url = resolveUrlFromAddress(address);
+  if (url) {
     const open = (await import("open")).default;
-    await open(`http://${address.address}:${address.port}`);
+    await open(url);
   }
 
   startLocalChangeWatcher({

src/lib/resolve-url-from-address.test.ts

@@ -0,0 +1,48 @@
+import type { AddressInfo } from "node:net";
+import { resolveUrlFromAddress } from "./resolve-url-from-address";
+
+describe("resolveUrlFromAddress", () => {
+  describe("when null is passed", () => {
+    it("returns null", () => {
+      const url = resolveUrlFromAddress(null);
+
+      expect(url).toBeNull();
+    });
+  });
+
+  describe("when string is passed", () => {
+    it("returns null", () => {
+      const url = resolveUrlFromAddress("foobar");
+
+      expect(url).toBeNull();
+    });
+  });
+
+  describe("when AddressInfo is passed", () => {
+    describe("when IPv4 family", () => {
+      it("returns url", () => {
+        const address: AddressInfo = {
+          address: "0.0.0.0",
+          family: "IPv4",
+          port: 8888,
+        };
+        const url = resolveUrlFromAddress(address);
+
+        expect(url).toEqual(`http://${address.address}:${address.port}`);
+      });
+    });
+
+    describe("when IPv6 family", () => {
+      it("returns url", () => {
+        const address: AddressInfo = {
+          address: "::",
+          family: "IPv6",
+          port: 8888,
+        };
+        const url = resolveUrlFromAddress(address);
+
+        expect(url).toEqual(`http://[${address.address}]:${address.port}`);
+      });
+    });
+  });
+});

src/lib/resolve-url-from-address.ts

@@ -0,0 +1,19 @@
+import type { AddressInfo } from "node:net";
+
+export const resolveUrlFromAddress = (address: string | AddressInfo | null) => {
+  if (!address || typeof address === "string") return null;
+
+  let hostname;
+  switch (address.family) {
+    case "IPv6":
+      hostname = `[${address.address}]`;
+      break;
+    case "IPv4":
+      hostname = address.address;
+      break;
+    default:
+      throw new Error("Unknown address family");
+  }
+
+  return `http://${hostname}:${address.port}`;
+};

src/server/app.ts

@@ -10,6 +10,7 @@ import { EmojiRouter } from "./api/emoji";
 import { ItemsRouter } from "./api/items";
 import { ReadmeRouter } from "./api/readme";
 import { config } from "../lib/config";
+import { resolveUrlFromAddress } from "../lib/resolve-url-from-address";
 
 export async function startServer() {
   const app = express();
@@ -39,7 +40,11 @@ export async function startServer() {
     server
       .listen(port, host)
       .once("listening", () => {
-        console.log(`Preview: http://${host}:${port}`);
+        const address = server.address();
+        const url = resolveUrlFromAddress(address);
+        if (url) {
+          console.log(`Preview: ${url}`);
+        }
 
         resolve(server);
       })