Feat: add user header with follow info

src/hooks/data-fetching/user-follows/useGetUsersFollowingUser.ts

@@ -0,0 +1,64 @@
+import FollowInfoSchema from '@/services/UserFollows/schema/FollowInfoSchema';
+import APIResponseValidationSchema from '@/validation/APIResponseValidationSchema';
+import useSWRInfinite from 'swr/infinite';
+import { z } from 'zod';
+
+const useGetUsersFollowingUser = ({
+  pageSize,
+  userId,
+}: {
+  pageSize: number;
+  userId: string;
+}) => {
+  const fetcher = async (url: string) => {
+    const response = await fetch(url);
+    if (!response.ok) {
+      throw new Error(response.statusText);
+    }
+
+    const json = await response.json();
+    const count = response.headers.get('X-Total-Count');
+
+    const parsed = APIResponseValidationSchema.safeParse(json);
+    if (!parsed.success) {
+      throw new Error('API response validation failed');
+    }
+
+    const parsedPayload = z.array(FollowInfoSchema).safeParse(parsed.data.payload);
+    if (!parsedPayload.success) {
+      throw new Error('API response validation failed');
+    }
+
+    const pageCount = Math.ceil(parseInt(count as string, 10) / pageSize);
+
+    return { followers: parsedPayload.data, pageCount, followerCount: count };
+  };
+
+  const { data, error, isLoading, setSize, size } = useSWRInfinite(
+    (index) =>
+      `/api/users/${userId}/followers?page_num=${index + 1}&page_size=${pageSize}`,
+    fetcher,
+    { parallel: true },
+  );
+
+  const followers = data?.flatMap((d) => d.followers) ?? [];
+  const followerCount = data?.[0].followerCount ?? 0;
+
+  const pageCount = data?.[0].pageCount ?? 0;
+  const isLoadingMore = size > 0 && data && typeof data[size - 1] === 'undefined';
+  const isAtEnd = !(size < data?.[0].pageCount!);
+
+  return {
+    followers,
+    followerCount,
+    pageCount,
+    size,
+    setSize,
+    isLoading,
+    isLoadingMore,
+    isAtEnd,
+    error: error as unknown,
+  };
+};
+
+export default useGetUsersFollowingUser;