import {promises as fsp} from 'fs';
import {join} from 'path';
import cheerio from 'cheerio';
import got, {Response} from 'got';

export interface OfficialTopic {
  date: Date;
  id: string;
  title: string;
  url: string;
}

async function entry(): Promise<void> {
  const timeout = 250;
  const officialTopics: OfficialTopic[] = [];
  const baseURL = 'https://tildes.net/~tildes.official?order=new&per_page=100';

  let hasNextButton = true;

  while (hasNextButton) {
    // Set the URL to be downloaded, on the first iteration we won't have an ID for
    // `&after=` yet so we make sure to check for that.
    let getURL: string = baseURL;
    if (officialTopics.length > 0) {
      getURL += `&after=${officialTopics[officialTopics.length - 1].id}`;
    }

    // Download the page and load the HTML into Cheerio.
    const response: Response<string> = await got(getURL, {
      headers: {
        'User-Agent': 'Tildes Issue Log scraping Official Topics'
      }
    });
    const html: CheerioStatic = cheerio.load(response.body);

    // Grab all topics from the listing.
    const topics: CheerioElement[] = html(
      '.topic-listing > li > article'
    ).toArray();

    for (const topic of topics) {
      const $topic: CheerioStatic = cheerio.load(topic);

      // Topic IDs in the listing will start with `topic-` so remove that first.
      const id: string = topic.attribs.id.slice(6);

      officialTopics.push({
        date: new Date($topic('time').attr('datetime')!),
        id,
        title: $topic('.topic-title > a').text(),
        url: `https://tild.es/${id}`
      });
    }

    const paginationButtons: CheerioElement[] = html('.pagination')
      .find('.page-item.btn')
      .toArray();

    // If all pagination buttons are "previous" buttons, stop the loop.
    if (
      paginationButtons.every((value) =>
        value.firstChild.data?.toLowerCase().includes('prev')
      )
    ) {
      hasNextButton = false;
    }

    await wait(timeout);
  }

  await fsp.mkdir(join(__dirname, '../pages/data/'), {recursive: true});
  await fsp.writeFile(
    join(__dirname, '../pages/data/official-topics.json'),
    JSON.stringify(officialTopics, null, 2)
  );
}

export async function wait(timeout: number): Promise<void> {
  return new Promise((resolve) => setTimeout(resolve, timeout));
}

export async function getTopicsFromMonth(
  data: OfficialTopic[],
  year: number,
  month: number
): Promise<OfficialTopic[]> {
  const topics: OfficialTopic[] = [];
  for (const topic of data) {
    topic.date = new Date(topic.date);
    if (
      topic.date.getFullYear() === year &&
      topic.date.getMonth() + 1 === month
    ) {
      topics.push(topic);
    }
  }

  topics.sort((a, b) => a.date.getDate() - b.date.getDate());
  return topics;
}

if (require.main === module) {
  void entry();
}