import { RequestHandler } from 'express';
import { promisify } from 'util';
import dns from 'dns';
import axios from 'axios';
import URL from 'url';
import urlRegex from 'url-regex';
import validator from 'express-validator/check';
import { differenceInMinutes, subHours, subDays } from 'date-fns';
import { validationResult } from 'express-validator/check';

import { IUser } from '../models/user';
import { addCooldown, banUser } from '../db/user';
import { getIP } from '../db/ip';
import { getUserLinksCount } from '../db/link';
import { getDomain } from '../db/domain';
import { getHost } from '../db/host';
import { addProtocol } from '../utils';

const dnsLookup = promisify(dns.lookup);

export const validationCriterias = [
  validator
    .body('email')
    .exists()
    .withMessage('Email must be provided.')
    .isEmail()
    .withMessage('Email is not valid.')
    .trim()
    .normalizeEmail(),
  validator
    .body('password', 'Password must be at least 8 chars long.')
    .exists()
    .withMessage('Password must be provided.')
    .isLength({ min: 8 }),
];

export const validateBody = (req, res, next) => {
  const errors = validationResult(req);
  if (!errors.isEmpty()) {
    const errorsObj = errors.mapped();
    const emailError = errorsObj.email && errorsObj.email.msg;
    const passwordError = errorsObj.password && errorsObj.password.msg;
    return res.status(400).json({ error: emailError || passwordError });
  }
  return next();
};

export const preservedUrls = [
  'login',
  'logout',
  'signup',
  'reset-password',
  'resetpassword',
  'url-password',
  'url-info',
  'settings',
  'stats',
  'verify',
  'api',
  '404',
  'static',
  'images',
  'banned',
  'terms',
  'privacy',
  'report',
  'pricing',
];

export const validateUrl: RequestHandler = async (req, res, next) => {
  // Validate URL existence
  if (!req.body.target)
    return res.status(400).json({ error: 'No target has been provided.' });

  // validate URL length
  if (req.body.target.length > 3000) {
    return res.status(400).json({ error: 'Maximum URL length is 3000.' });
  }

  // Validate URL
  const isValidUrl = urlRegex({ exact: true, strict: false }).test(
    req.body.target
  );
  if (!isValidUrl && !/^\w+:\/\//.test(req.body.target))
    return res.status(400).json({ error: 'URL is not valid.' });

  // If target is the URL shortener itself
  const { host } = URL.parse(addProtocol(req.body.target));
  if (host === process.env.DEFAULT_DOMAIN) {
    return res
      .status(400)
      .json({ error: `${process.env.DEFAULT_DOMAIN} URLs are not allowed.` });
  }

  // Validate password length
  if (req.body.password && req.body.password.length > 64) {
    return res.status(400).json({ error: 'Maximum password length is 64.' });
  }

  // Custom URL validations
  if (req.user && req.body.customurl) {
    // Validate custom URL
    if (!/^[a-zA-Z0-9-_]+$/g.test(req.body.customurl.trim())) {
      return res.status(400).json({ error: 'Custom URL is not valid.' });
    }

    // Prevent from using preserved URLs
    if (preservedUrls.some(url => url === req.body.customurl)) {
      return res
        .status(400)
        .json({ error: "You can't use this custom URL name." });
    }

    // Validate custom URL length
    if (req.body.customurl.length > 64) {
      return res
        .status(400)
        .json({ error: 'Maximum custom URL length is 64.' });
    }
  }

  return next();
};

export const cooldownCheck = async (user: IUser) => {
  if (user && user.cooldowns) {
    if (user.cooldowns.length > 4) {
      await banUser(user._id);
      throw new Error('Too much malware requests. You are now banned.');
    }
    const hasCooldownNow = user.cooldowns.some(
      cooldown => cooldown.toJSON() > subHours(new Date(), 12).toJSON()
    );
    if (hasCooldownNow) {
      throw new Error('Cooldown because of a malware URL. Wait 12h');
    }
  }
};

export const ipCooldownCheck: RequestHandler = async (req, res, next) => {
  const cooldownConfig = Number(process.env.NON_USER_COOLDOWN);
  if (req.user || !cooldownConfig) return next();
  const ip = await getIP(req.realIP);
  if (ip) {
    const timeToWait =
      cooldownConfig - differenceInMinutes(new Date(), ip.createdAt);
    return res.status(400).json({
      error:
        `Non-logged in users are limited. Wait ${timeToWait} ` +
        'minutes or log in.',
    });
  }
  next();
};

export const malwareCheck = async (user: IUser, target: string) => {
  const isMalware = await axios.post(
    `https://safebrowsing.googleapis.com/v4/threatMatches:find?key=${
      process.env.GOOGLE_SAFE_BROWSING_KEY
    }`,
    {
      client: {
        clientId: process.env.DEFAULT_DOMAIN.toLowerCase().replace('.', ''),
        clientVersion: '1.0.0',
      },
      threatInfo: {
        threatTypes: [
          'THREAT_TYPE_UNSPECIFIED',
          'MALWARE',
          'SOCIAL_ENGINEERING',
          'UNWANTED_SOFTWARE',
          'POTENTIALLY_HARMFUL_APPLICATION',
        ],
        platformTypes: ['ANY_PLATFORM', 'PLATFORM_TYPE_UNSPECIFIED'],
        threatEntryTypes: [
          'EXECUTABLE',
          'URL',
          'THREAT_ENTRY_TYPE_UNSPECIFIED',
        ],
        threatEntries: [{ url: target }],
      },
    }
  );
  if (isMalware.data && isMalware.data.matches) {
    if (user) {
      await addCooldown(user._id);
    }
    throw new Error(
      user ? 'Malware detected! Cooldown for 12h.' : 'Malware detected!'
    );
  }
};

export const urlCountsCheck = async (user: IUser) => {
  const count = await getUserLinksCount({
    user: user._id,
    date: subDays(new Date(), 1),
  });
  if (count > Number(process.env.USER_LIMIT_PER_DAY)) {
    throw new Error(
      `You have reached your daily limit (${
        process.env.USER_LIMIT_PER_DAY
      }). Please wait 24h.`
    );
  }
};

export const checkBannedDomain = async (domain: string) => {
  const bannedDomain = await getDomain({ name: domain, banned: true });
  if (bannedDomain) {
    throw new Error('URL is containing malware/scam.');
  }
};

export const checkBannedHost = async (domain: string) => {
  let isHostBanned;
  try {
    const dnsRes = await dnsLookup(domain);
    isHostBanned = await getHost({
      address: dnsRes && dnsRes.address,
      banned: true,
    });
  } catch (error) {
    isHostBanned = null;
  }
  if (isHostBanned) {
    throw new Error('URL is containing malware/scam.');
  }
};