✨ #38 ねこのIDからねこの名前を取り出す関数を実装

src/app/chat/[catId]/layout.tsx

@@ -1,4 +1,4 @@
-import type { CatId } from '@/features';
+import { extractCatNameById, type CatId } from '@/features';
 import type { Metadata, ResolvingMetadata } from 'next';
 import { Noto_Sans_JP } from 'next/font/google';
 import type { JSX, ReactNode } from 'react';
@@ -21,8 +21,10 @@ export const generateMetadata = async (
   parent: ResolvingMetadata
 ): Promise<Metadata> => {
   return {
-    title: 'AI Cat もこちゃん🐱',
-    description: 'ねこのAI（もこちゃん）とお話しよう🐱',
+    title: `AI Cat ${extractCatNameById(params.catId)}ちゃん🐱`,
+    description: `ねこのAI（${extractCatNameById(
+      params.catId
+    )}）とお話しよう🐱`,
   };
 };
 

src/features/cat.ts

@@ -1,4 +1,12 @@
-export type CatId = 'moko';
+import { ExhaustiveError } from '@/utils';
+
+const catIds = ['moko'] as const;
+
+export type CatId = (typeof catIds)[number];
+
+const catNames = ['もこ'] as const;
+
+type CatName = (typeof catNames)[number];
 
 export type FetchCatMessageDto = {
   catId: CatId;
@@ -13,3 +21,12 @@ export type FetchCatMessageResponse = {
 export type FetchCatMessage = (
   dto: FetchCatMessageDto
 ) => Promise<FetchCatMessageResponse>;
+
+export const extractCatNameById = (catId: CatId): CatName => {
+  switch (catId) {
+    case 'moko':
+      return 'もこ';
+    default:
+      throw new ExhaustiveError(catId);
+  }
+};

src/features/index.ts

@@ -4,3 +4,5 @@ export type {
   FetchCatMessageResponse,
   FetchCatMessage,
 } from './cat';
+
+export { extractCatNameById } from './cat';