const { isAfter, subDays, subHours, addMilliseconds } = require("date-fns");
const { body, param } = require("express-validator");
const promisify = require("util").promisify;
const bcrypt = require("bcryptjs");
const dns = require("dns");
const URL = require("url");
const ms = require("ms");

const query = require("../queries");
const utils = require("../utils");
const knex = require("../knex");
const env = require("../env");

const dnsLookup = promisify(dns.lookup);

const checkUser = (value, { req }) => !!req.user;
const sanitizeCheckbox = value => value === true || value === "on" || value;

const createLink = [
  body("target")
    .exists({ checkNull: true, checkFalsy: true })
    .withMessage("Target is missing.")
    .isString()
    .trim()
    .isLength({ min: 1, max: 2040 })
    .withMessage("Maximum URL length is 2040.")
    .customSanitizer(utils.addProtocol)
    .custom(value => utils.urlRegex.test(value) || /^(?!https?|ftp)(\w+:|\/\/)/.test(value))
    .withMessage("URL is not valid.")
    .custom(value => utils.removeWww(URL.parse(value).host) !== env.DEFAULT_DOMAIN)
    .withMessage(`${env.DEFAULT_DOMAIN} URLs are not allowed.`),
  body("password")
    .optional({ nullable: true, checkFalsy: true })
    .custom(checkUser)
    .withMessage("Only users can use this field.")
    .isString()
    .isLength({ min: 3, max: 64 })
    .withMessage("Password length must be between 3 and 64."),
  body("customurl")
    .optional({ nullable: true, checkFalsy: true })
    .custom(checkUser)
    .withMessage("Only users can use this field.")
    .isString()
    .trim()
    .isLength({ min: 1, max: 64 })
    .withMessage("Custom URL length must be between 1 and 64.")
    .custom(value => /^[a-zA-Z0-9-_]+$/g.test(value))
    .withMessage("Custom URL is not valid.")
    .custom(value => !utils.preservedURLs.some(url => url.toLowerCase() === value))
    .withMessage("You can't use this custom URL."),
  body("reuse")
    .optional({ nullable: true })
    .custom(checkUser)
    .withMessage("Only users can use this field.")
    .isBoolean()
    .withMessage("Reuse must be boolean."),
  body("description")
    .optional({ nullable: true, checkFalsy: true })
    .isString()
    .trim()
    .isLength({ min: 1, max: 2040 })
    .withMessage("Description length must be between 1 and 2040."),
  body("expire_in")
    .optional({ nullable: true, checkFalsy: true })
    .isString()
    .trim()
    .custom(value => {
      try {
        return !!ms(value);
      } catch {
        return false;
      }
    })
    .withMessage("Expire format is invalid. Valid examples: 1m, 8h, 42 days.")
    .customSanitizer(ms)
    .custom(value => value >= ms("1m"))
    .withMessage("Expire time should be more than 1 minute.")
    .customSanitizer(value => addMilliseconds(new Date(), value).toISOString()),
  body("domain")
    .optional({ nullable: true, checkFalsy: true })
    .custom(checkUser)
    .withMessage("Only users can use this field.")
    .isString()
    .withMessage("Domain should be string.")
    .customSanitizer(value => value.toLowerCase())
    .custom(async (address, { req }) => {
      if (address === env.DEFAULT_DOMAIN) {
        req.body.domain = null;
        return;
      }

      const domain = await query.domain.find({
        address,
        user_id: req.user.id
      });
      req.body.fetched_domain = domain || null;

      if (!domain) return Promise.reject();
    })
    .withMessage("You can't use this domain.")
];

const editLink = [
  body("target")
    .optional({ checkFalsy: true, nullable: true })
    .isString()
    .trim()
    .isLength({ min: 1, max: 2040 })
    .withMessage("Maximum URL length is 2040.")
    .customSanitizer(utils.addProtocol)
    .custom(value => utils.urlRegex.test(value) || /^(?!https?|ftp)(\w+:|\/\/)/.test(value))
    .withMessage("URL is not valid.")
    .custom(value => utils.removeWww(URL.parse(value).host) !== env.DEFAULT_DOMAIN)
    .withMessage(`${env.DEFAULT_DOMAIN} URLs are not allowed.`),
  body("password")
    .optional({ nullable: true, checkFalsy: true })
    .isString()
    .isLength({ min: 3, max: 64 })
    .withMessage("Password length must be between 3 and 64."),
  body("address")
    .optional({ checkFalsy: true, nullable: true })
    .isString()
    .trim()
    .isLength({ min: 1, max: 64 })
    .withMessage("Custom URL length must be between 1 and 64.")
    .custom(value => /^[a-zA-Z0-9-_]+$/g.test(value))
    .withMessage("Custom URL is not valid")
    .custom(value => !utils.preservedURLs.some(url => url.toLowerCase() === value))
    .withMessage("You can't use this custom URL."),
  body("expire_in")
    .optional({ nullable: true, checkFalsy: true })
    .isString()
    .trim()
    .custom(value => {
      try {
        return !!ms(value);
      } catch {
        return false;
      }
    })
    .withMessage("Expire format is invalid. Valid examples: 1m, 8h, 42 days.")
    .customSanitizer(ms)
    .custom(value => value >= ms("1m"))
    .withMessage("Expire time should be more than 1 minute.")
    .customSanitizer(value => addMilliseconds(new Date(), value).toISOString()),
  body("description")
    .optional({ nullable: true, checkFalsy: true })
    .isString()
    .trim()
    .isLength({ min: 0, max: 2040 })
    .withMessage("Description length must be between 0 and 2040."),
  param("id", "ID is invalid.")
    .exists({ checkFalsy: true, checkNull: true })
    .isLength({ min: 36, max: 36 })
];

const redirectProtected = [
  body("password", "Password is invalid.")
    .exists({ checkFalsy: true, checkNull: true })
    .isString()
    .isLength({ min: 3, max: 64 })
    .withMessage("Password length must be between 3 and 64."),
  param("id", "ID is invalid.")
    .exists({ checkFalsy: true, checkNull: true })
    .isLength({ min: 36, max: 36 })
];

const addDomain = [
  body("address", "Domain is not valid.")
    .exists({ checkFalsy: true, checkNull: true })
    .isLength({ min: 3, max: 64 })
    .withMessage("Domain length must be between 3 and 64.")
    .trim()
    .customSanitizer(utils.addProtocol)
    .custom(value => utils.urlRegex.test(value))
    .customSanitizer(value => {
      const parsed = URL.parse(value);
      return utils.removeWww(parsed.hostname || parsed.href);
    })
    .custom(value => value !== env.DEFAULT_DOMAIN)
    .withMessage("You can't use the default domain.")
    .custom(async value => {
      const domain = await query.domain.find({ address: value });
      if (domain?.user_id || domain?.banned) return Promise.reject();
    })
    .withMessage("You can't add this domain."),
  body("homepage")
    .optional({ checkFalsy: true, nullable: true })
    .customSanitizer(utils.addProtocol)
    .custom(value => utils.urlRegex.test(value) || /^(?!https?|ftp)(\w+:|\/\/)/.test(value))
    .withMessage("Homepage is not valid.")
];

const removeDomain = [
  param("id", "ID is invalid.")
    .exists({
      checkFalsy: true,
      checkNull: true
    })
    .isLength({ min: 36, max: 36 })
];

const deleteLink = [
  param("id", "ID is invalid.")
    .exists({
      checkFalsy: true,
      checkNull: true
    })
    .isLength({ min: 36, max: 36 })
];

const reportLink = [
  body("link", "No link has been provided.")
    .exists({
      checkFalsy: true,
      checkNull: true
    })
    .customSanitizer(utils.addProtocol)
    .custom(
      value => utils.removeWww(URL.parse(value).host) === env.DEFAULT_DOMAIN
    )
    .withMessage(`You can only report a ${env.DEFAULT_DOMAIN} link.`)
];

const banLink = [
  param("id", "ID is invalid.")
    .exists({
      checkFalsy: true,
      checkNull: true
    })
    .isLength({ min: 36, max: 36 }),
  body("host", '"host" should be a boolean.')
    .optional({
      nullable: true
    })
    .customSanitizer(sanitizeCheckbox)
    .isBoolean(),
  body("user", '"user" should be a boolean.')
    .optional({
      nullable: true
    })
    .customSanitizer(sanitizeCheckbox)
    .isBoolean(),
  body("userLinks", '"userLinks" should be a boolean.')
    .optional({
      nullable: true
    })
    .customSanitizer(sanitizeCheckbox)
    .isBoolean(),
  body("domain", '"domain" should be a boolean.')
    .optional({
      nullable: true
    })
    .customSanitizer(sanitizeCheckbox)
    .isBoolean()
];

const getStats = [
  param("id", "ID is invalid.")
    .exists({
      checkFalsy: true,
      checkNull: true
    })
    .isLength({ min: 36, max: 36 })
];

const signup = [
  body("password", "Password is not valid.")
    .exists({ checkFalsy: true, checkNull: true })
    .isLength({ min: 8, max: 64 })
    .withMessage("Password length must be between 8 and 64."),
  body("email", "Email is not valid.")
    .exists({ checkFalsy: true, checkNull: true })
    .trim()
    .isEmail()
    .isLength({ min: 0, max: 255 })
    .withMessage("Email length must be max 255.")
    .custom(async (value, { req }) => {
      const user = await query.user.find({ email: value });

      if (user)
        req.user = user;

      if (user?.verified) 
        return Promise.reject();
    })
    .withMessage("You can't use this email address.")
];

const login = [
  body("password", "Password is not valid.")
    .exists({ checkFalsy: true, checkNull: true })
    .isLength({ min: 8, max: 64 })
    .withMessage("Password length must be between 8 and 64."),
  body("email", "Email is not valid.")
    .exists({ checkFalsy: true, checkNull: true })
    .trim()
    .isEmail()
    .isLength({ min: 1, max: 255 })
    .withMessage("Email length must be max 255.")
];

const changePassword = [
  body("currentpassword", "Password is not valid.")
    .exists({ checkFalsy: true, checkNull: true })
    .isLength({ min: 8, max: 64 })
    .withMessage("Password length must be between 8 and 64."),
  body("newpassword", "Password is not valid.")
    .exists({ checkFalsy: true, checkNull: true })
    .isLength({ min: 8, max: 64 })
    .withMessage("Password length must be between 8 and 64.")
];

const changeEmail = [
  body("password", "Password is not valid.")
    .exists({ checkFalsy: true, checkNull: true })
    .isLength({ min: 8, max: 64 })
    .withMessage("Password length must be between 8 and 64."),
  body("email", "Email address is not valid.")
    .exists({ checkFalsy: true, checkNull: true })
    .trim()
    .isEmail()
    .isLength({ min: 1, max: 255 })
    .withMessage("Email length must be max 255.")
];

const resetPassword = [
  body("email", "Email is not valid.")
    .exists({ checkFalsy: true, checkNull: true })
    .trim()
    .isEmail()
    .isLength({ min: 0, max: 255 })
    .withMessage("Email length must be max 255.")
];

const deleteUser = [
  body("password", "Password is not valid.")
    .exists({ checkFalsy: true, checkNull: true })
    .isLength({ min: 8, max: 64 })
    .custom(async (password, { req }) => {
      const isMatch = await bcrypt.compare(password, req.user.password);
      if (!isMatch) return Promise.reject();
    })
    .withMessage("Password is not correct.")
];

// TODO: if user has posted malware should do something better
function cooldown(user) {
  if (!env.GOOGLE_SAFE_BROWSING_KEY || !user || !user.cooldowns) return;

  // If has active cooldown then throw error
  const hasCooldownNow = user.cooldowns.some(cooldown =>
    isAfter(subHours(new Date(), 12), new Date(cooldown))
  );

  if (hasCooldownNow) {
    throw new utils.CustomError("Cooldown because of a malware URL. Wait 12h");
  }
}

// TODO: if user or non-user has posted malware should do something better
async function malware(user, target) {
  if (!env.GOOGLE_SAFE_BROWSING_KEY) return;

  const isMalware = await fetch(
    `https://safebrowsing.googleapis.com/v4/threatMatches:find?key=${env.GOOGLE_SAFE_BROWSING_KEY}`,
    {
      method: "post",
      body: JSON.stringify({
        client: {
          clientId: 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 }]
        }
      })
    }
  ).then(res => res.json());
  if (!isMalware.data || !isMalware.data.matches) return;

  if (user) {
    const [updatedUser] = await query.user.update(
      { id: user.id },
      {
        cooldowns: knex.raw("array_append(cooldowns, ?)", [
          new Date().toISOString()
        ])
      }
    );

    // Ban if too many cooldowns
    if (updatedUser.cooldowns.length > 2) {
      await query.user.update({ id: user.id }, { banned: true });
      throw new utils.CustomError("Too much malware requests. You are now banned.");
    }
  }

  throw new utils.CustomError(
    user ? "Malware detected! Cooldown for 12h." : "Malware detected!"
  );
};

async function linksCount(user) {
  if (!user) return;

  const count = await query.link.total({
    user_id: user.id,
    "links.created_at": [">", subDays(new Date(), 1).toISOString()]
  });

  if (count > env.USER_LIMIT_PER_DAY) {
    throw new utils.CustomError(
      `You have reached your daily limit (${env.USER_LIMIT_PER_DAY}). Please wait 24h.`
    );
  }
};

async function bannedDomain(domain) {
  const isBanned = await query.domain.find({
    address: domain,
    banned: true
  });

  if (isBanned) {
    throw new utils.CustomError("URL is containing malware/scam.", 400);
  }
};

async function bannedHost(domain) {
  let isBanned;

  try {
    const dnsRes = await dnsLookup(domain);

    if (!dnsRes || !dnsRes.address) return;

    isBanned = await query.host.find({
      address: dnsRes.address,
      banned: true
    });
  } catch (error) {
    isBanned = null;
  }

  if (isBanned) {
    throw new utils.CustomError("URL is containing malware/scam.", 400);
  }
};

module.exports = {
  addDomain,
  banLink,
  bannedDomain,
  bannedHost,
  changeEmail,
  changePassword,
  checkUser,
  cooldown,
  createLink,
  deleteLink,
  deleteUser,
  editLink,
  getStats,
  linksCount,
  login, 
  malware,
  redirectProtected,
  removeDomain,
  reportLink,
  resetPassword,
  signup,
}