cuubot/src/utils/database.ts

import {
  createWriteStream,
  createReadStream,
  promises,
  ReadStream,
} from 'fs';
import readline from 'readline';

export type Item = {
  url: string,
  reactions?: string[],
}

export const save = async (userId: string, item: Item): Promise<void> => {
  try {
    await promises.stat('.data');
  } catch {
    await promises.mkdir('.data');
  }

  return new Promise((resolve, reject) => {
    const ws = createWriteStream(`.data/${userId}.txt`, { flags: 'a' });
    ws.on('error', reject);
    ws.on('finish', resolve);
    ws.end(`${[item.url, ...(item.reactions || [])].join(' ')}\n`);
  });
};

export const load = async (userId: string, count = 1): Promise<Item[]> => {
  try {
    await promises.stat('.data');
  } catch {
    await promises.mkdir('.data');
  }

  return new Promise<Item[]>((resolve, reject) => {
    let rs: ReadStream;
    const items: Item[] = [];
    try {
      rs = createReadStream(`.data/${userId}.txt`, { flags: 'r' });
      rs.on('error', reject);
      const rl = readline.createInterface(rs);
      rl.on('line', (line) => {
        if (items.length >= count) {
          return;
        }
        const [url, ...reactions] = line.split(' ');
        items.push({
          url,
          reactions,
        });
      });
      rl.on('close', () => {
        resolve(items);
      });
    } catch {
      // noop
    }
  });
};

export const remove = async (userId: string, count = 1): Promise<void> => {
  try {
    await promises.stat('.data');
  } catch {
    await promises.mkdir('.data');
  }

  return new Promise((resolve, reject) => {
    let rs: ReadStream;
    let lines = 0;
    try {
      rs = createReadStream(`.data/${userId}.txt`, { flags: 'r' });
      rs.on('error', reject);
      const rl = readline.createInterface(rs);
      const ws = createWriteStream(`.data/${userId}.txt.tmp`, { flags: 'w' });
      // eslint-disable-next-line @typescript-eslint/no-misused-promises
      ws.on('close', async () => {
        await promises.unlink(`.data/${userId}.txt`);
        await promises.rename(`.data/${userId}.txt.tmp`, `.data/${userId}.txt`);
        resolve();
      });
      rl.on('line', (line) => {
        lines += 1;
        if (lines <= count) {
          return;
        }
        ws.write(`${line}\n`);
      });
      rl.on('close', () => {
        ws.close();
      });
    } catch (e) {
      // noop
      reject(e);
    }
  });
};