import { user, type User } from './user';

export interface FollowingPage {
  data: {
    Page: {
      pageInfo: {
        hasNextPage: boolean;
      };
      following: Partial<User>[];
    };
  };
}

const followingPage = async (page: number, id: number): Promise<FollowingPage> =>
  await (
    await fetch('https://graphql.anilist.co', {
      method: 'POST',
      headers: {
        'Content-Type': 'application/json',
        Accept: 'application/json'
      },
      body: JSON.stringify({
        query: `{
					Page(page: ${page}) {
    				pageInfo { hasNextPage }
						following(userId: ${id}) { name id }
					}
				}`
      })
    })
  ).json();

export const followers = async (name: string): Promise<Partial<User>[]> => {
  const activities = [];
  let page = 1;
  const userData = await user(name);

  if (!userData) throw new Error(`User not found: ${name}`);

  const id = userData.id;
  let currentPage = await followingPage(page, id);

  for (const activity of currentPage.data.Page.following) activities.push(activity);

  while (currentPage['data']['Page']['pageInfo']['hasNextPage']) {
    for (const activity of currentPage.data.Page.following) activities.push(activity);

    page += 1;
    currentPage = await followingPage(page, id);
  }

  for (const activity of currentPage.data.Page.following) activities.push(activity);

  for (let i = activities.length - 1; i > 0; i--) {
    const j = Math.floor(Math.random() * (i + 1));
    [activities[i], activities[j]] = [activities[j], activities[i]];
  }

  return activities;
};