ditto/src/controllers/api/trends.ts

import { z } from 'zod';

import { type AppController } from '@/app.ts';
import { Conf } from '@/config.ts';
import { Time } from '@/utils.ts';
import { stripTime } from '@/utils/time.ts';
import { TrendsWorker } from '@/workers/trends.ts';
import { Context } from 'hono';

await TrendsWorker.open('data/trends.sqlite3');

const limitSchema = z.coerce.number().catch(10).transform((value) => Math.min(Math.max(value, 0), 20));

const trendingTagsController: AppController = async (c: Context) => {
  const limit = limitSchema.parse(c.req.query('limit'));
  if (limit < 1) return c.json([]);

  const now = new Date();
  const yesterday = new Date(now.getTime() - Time.days(1));
  const lastWeek = new Date(now.getTime() - Time.days(7));

  /** Most used hashtags within the past 24h. */
  const tags = await TrendsWorker.getTrendingTags({
    since: yesterday,
    until: now,
    limit,
  });

  return c.json(
    await Promise.all(tags.map(async ({ tag, uses, accounts }) => ({
      tag,
      url: Conf.local(`/tags/${tag}`),
      history: [
        // Use the full 24h query for the current day. Then use `offset: 1` to adjust for this below.
        // This result is more accurate than what Mastodon returns.
        {
          day: String(Math.floor(stripTime(now).getTime() / 1000)),
          accounts: String(accounts),
          uses: String(uses),
        },
        ...(await TrendsWorker.getTagHistory({
          tag,
          since: lastWeek,
          until: now,
          limit: 6,
          offset: 1,
        })).map((history) => ({
          // For some reason, Mastodon wants these to be strings... oh well.
          day: String(Math.floor(history.day.getTime() / 1000)),
          accounts: String(history.accounts),
          uses: String(history.uses),
        })),
      ],
    }))),
  );
};

export { trendingTagsController };