const base64 = require('base-64');
const sha512 = require('js-sha512');
const shortid = require('shortid');
const db = require('./db');

const buildSessionCookie = ({ username, sessionToken, isLogout }) => {
  if (!isLogout) {
    const tokenData = {
      username,
      sessionToken,
    };
    const tokenDataStr = JSON.stringify(tokenData);
    const encodedToken = base64.encode(tokenDataStr);
    return `sessionCookie=${encodedToken}; Domain=localhost; HttpOnly; SameSite=strict;`;
  } else {
    return `sessionCookie=deleted; Domain=localhost; Expires=Thu, 01 Jan 1970 00:00:00 GMT; HttpOnly; SameSite=strict;`;
  }
};

const authMiddleware = async (req, res, next) => {
  const cookies = req.cookies;
  const encodedCookie = cookies.sessionCookie;

  if (!encodedCookie) {
    res.status(403);
    return res.json({
      message: 'Log in first!',
    });
  }
  const sessionCookieStr = base64.decode(encodedCookie);
  const sessionCookie = JSON.parse(sessionCookieStr);

  const { username, sessionToken } = sessionCookie;

  const user = await db('users').where({ username }).first();
  if (!user) {
    res.status(400);
    res.set('Set-Cookie', buildSessionCookie({ isLogout: true }));
    return res.json({
      message: 'Invalid session token.',
      sessionCookie,
    });
  }

  const salt = user.salt;

  const sessionTokenHash = sha512(salt + sessionToken);
  const token = await db('tokens').where({ type: 'session', value: sessionTokenHash });
  if (!token) {
    res.status(400);
    res.set('Set-Cookie', buildSessionCookie({ isLogout: true }));
    return res.json({
      message: 'Invalid session token.',
      sessionCookie,
    });
  }

  req.sessionTokenHash = sessionTokenHash;
  req.user = user;

  next();
};

const registerRoute = async (req, res) => {
  const { username, password } = req.body;
  if (!username || !password) {
    res.status(400);
    return res.json({
      error: 'Username or password missing.',
    });
  }

  const existingUser = await db('users').where({ username }).first();
  if (existingUser) {
    res.status(400);
    return res.json({
      error: 'Username already taken.',
    });
  }

  const salt = shortid.generate();
  const pwHash = sha512(salt + password);

  const sessionToken = shortid.generate();
  const sessionTokenHash = sha512(salt + sessionToken);

  const user = (await db('users').insert({ username, password: pwHash, salt }).returning('*'))[0];
  await db('tokens').insert({ user_id: user.id, type: 'session', value: sessionTokenHash });

  res.set('Set-Cookie', buildSessionCookie({ username, sessionToken, remember: false, isLogout: false }));
  return res.json({
    username,
  });
};

const loginRoute = async (req, res) => {
  const { username, password, remember } = req.body;
  if (!username || !password) {
    res.status(400);
    return res.json({
      error: 'Username or password missing.',
    });
  }

  const user = await db('users').where({ username }).first();

  if (user) {
    const sessionToken = shortid.generate();
    const sessionTokenHash = sha512(user.salt + sessionToken);

    await db('tokens').insert({ user_id: user.id, type: 'session', value: sessionTokenHash });

    res.set('Set-Cookie', buildSessionCookie({ username, sessionToken, remember, isLogout: false }));

    return res.json({
      username,
    });
  }

  res.status(403);
  res.json({
    error: 'Wrong username or password',
  });
};

const logoutRoute = async (req, res) => {
  await db('tokens').where({ type: 'session', user_id: req.user.id, value: req.sessionTokenHash }).delete();
  res.status(204);
  res.set('Set-Cookie', buildSessionCookie({ isLogout: true }));
  res.send();
};

module.exports = {
  buildSessionCookie,
  authMiddleware,
  registerRoute,
  loginRoute,
  logoutRoute,
};