import Settings from '@overleaf/settings'
import { User } from '../../models/User.mjs'
import { db, ObjectId } from '../../infrastructure/mongodb.mjs'
import bcrypt from 'bcrypt'
import EmailHelper from '../Helpers/EmailHelper.mjs'

import {
  InvalidEmailError,
  InvalidPasswordError,
  ParallelLoginError,
  PasswordMustBeDifferentError,
  PasswordReusedError,
} from './AuthenticationErrors.mjs'

import { callbackify, callbackifyMultiResult } from '@overleaf/promise-utils'
import HaveIBeenPwned from './HaveIBeenPwned.mjs'
import UserAuditLogHandler from '../User/UserAuditLogHandler.mjs'
import logger from '@overleaf/logger'
import DiffHelper from '../Helpers/DiffHelper.mjs'
import Metrics from '@overleaf/metrics'

const BCRYPT_ROUNDS = Settings.security.bcryptRounds || 12
const BCRYPT_MINOR_VERSION = Settings.security.bcryptMinorVersion || 'a'
const MAX_SIMILARITY = 0.7

function _exceedsMaximumLengthRatio(password, maxSimilarity, value) {
  const passwordLength = password.length
  const lengthBoundSimilarity = (maxSimilarity / 2) * passwordLength
  const valueLength = value.length
  return (
    passwordLength >= 10 * valueLength && valueLength < lengthBoundSimilarity
  )
}

const _checkWriteResult = function (result) {
  // for MongoDB
  return !!(result && result.modifiedCount === 1)
}

function _validatePasswordNotTooLong(password) {
  // bcrypt has a hard limit of 72 characters.
  if (password.length > 72) {
    return new InvalidPasswordError({
      message: 'password is too long',
      info: { code: 'too_long' },
    })
  }
  return null
}

function _metricsForSuccessfulPasswordMatch(password) {
  const validationResult = AuthenticationManager.validatePassword(password)
  const status =
    validationResult === null ? 'success' : validationResult?.info?.code
  Metrics.inc('check-password', { status })
  return null
}

const AuthenticationManager = {
  async _checkUserPassword(query, password) {
    // Using Mongoose for legacy reasons here. The returned User instance
    // gets serialized into the session and there may be subtle differences
    // between the user returned by Mongoose vs mongodb (such as default values)
    const user = await User.findOne(query).exec()

    if (!user || !user.hashedPassword) {
      return { user: null, match: null }
    }

    let rounds = 0
    try {
      rounds = bcrypt.getRounds(user.hashedPassword)
    } catch (err) {
      let prefix, suffix, length
      if (typeof user.hashedPassword === 'string') {
        length = user.hashedPassword.length
        if (user.hashedPassword.length > 50) {
          // A full bcrypt hash is 60 characters long.
          prefix = user.hashedPassword.slice(0, '$2a$12$x'.length)
          suffix = user.hashedPassword.slice(-4)
        } else if (user.hashedPassword.length > 20) {
          prefix = user.hashedPassword.slice(0, 4)
          suffix = user.hashedPassword.slice(-4)
        } else {
          prefix = user.hashedPassword.slice(0, 4)
        }
      }
      logger.warn(
        {
          err,
          userId: user._id,
          hashedPassword: {
            type: typeof user.hashedPassword,
            length,
            prefix,
            suffix,
          },
        },
        'unexpected user.hashedPassword value'
      )
    }
    Metrics.inc('bcrypt', 1, {
      method: 'compare',
      path: rounds,
    })

    const match = await bcrypt.compare(password, user.hashedPassword)

    if (match) {
      _metricsForSuccessfulPasswordMatch(password)
    }

    return { user, match }
  },

  async authenticate(query, password, auditLog, { enforceHIBPCheck = true }) {
    const { user, match } = await AuthenticationManager._checkUserPassword(
      query,
      password
    )

    if (!user) {
      return { user: null }
    }

    const update = { $inc: { loginEpoch: 1 } }
    if (!match) {
      update.$set = { lastFailedLogin: new Date() }
    }

    const result = await User.updateOne(
      { _id: user._id, loginEpoch: user.loginEpoch },
      update,
      {}
    ).exec()

    if (result.modifiedCount !== 1) {
      throw new ParallelLoginError()
    }

    if (!match) {
      if (!auditLog) {
        return { user: null }
      } else {
        try {
          await UserAuditLogHandler.promises.addEntry(
            user._id,
            'failed-password-match',
            user._id,
            auditLog.ipAddress,
            auditLog.info
          )
        } catch (err) {
          logger.error(
            { userId: user._id, err, info: auditLog.info },
            'Error while adding AuditLog entry for failed-password-match'
          )
        }
        return { user: null }
      }
    }
    await AuthenticationManager.checkRounds(user, user.hashedPassword, password)

    let isPasswordReused
    try {
      isPasswordReused =
        await HaveIBeenPwned.promises.checkPasswordForReuse(password)
    } catch (err) {
      logger.err({ err }, 'cannot check password for re-use')
    }

    if (isPasswordReused && enforceHIBPCheck) {
      throw new PasswordReusedError()
    }

    return { user, isPasswordReused }
  },

  validateEmail(email) {
    const parsed = EmailHelper.parseEmail(email)
    if (!parsed) {
      return new InvalidEmailError({ message: 'email not valid' })
    }
    return null
  },

  // validates a password based on a similar set of rules previously used by `passfield.js` on the frontend
  // note that `passfield.js` enforced more rules than this, but these are the most commonly set.
  // returns null on success, or an error object.
  validatePassword(password, email) {
    if (password == null) {
      return new InvalidPasswordError({
        message: 'password not set',
        info: { code: 'not_set' },
      })
    }

    Metrics.inc('try-validate-password')

    let allowAnyChars, min, max
    if (Settings.passwordStrengthOptions) {
      allowAnyChars = Settings.passwordStrengthOptions.allowAnyChars === true
      if (Settings.passwordStrengthOptions.length) {
        min = Settings.passwordStrengthOptions.length.min
        max = Settings.passwordStrengthOptions.length.max
      }
    }
    allowAnyChars = !!allowAnyChars
    min = min || 8
    max = max || 72

    // we don't support passwords > 72 characters in length, because bcrypt truncates them
    if (max > 72) {
      max = 72
    }

    if (password.length < min) {
      return new InvalidPasswordError({
        message: 'password is too short',
        info: { code: 'too_short' },
      })
    }
    if (password.length > max) {
      return new InvalidPasswordError({
        message: 'password is too long',
        info: { code: 'too_long' },
      })
    }
    const passwordLengthError = _validatePasswordNotTooLong(password)
    if (passwordLengthError) {
      return passwordLengthError
    }
    if (
      !allowAnyChars &&
      !AuthenticationManager._passwordCharactersAreValid(password)
    ) {
      return new InvalidPasswordError({
        message: 'password contains an invalid character',
        info: { code: 'invalid_character' },
      })
    }
    if (typeof email === 'string' && email !== '') {
      const startOfEmail = email.split('@')[0]
      if (
        password.includes(email) ||
        password.includes(startOfEmail) ||
        email.includes(password)
      ) {
        return new InvalidPasswordError({
          message: 'password contains part of email address',
          info: { code: 'contains_email' },
        })
      }
      try {
        const passwordTooSimilarError =
          AuthenticationManager._validatePasswordNotTooSimilar(password, email)
        if (passwordTooSimilarError) {
          Metrics.inc('password-too-similar-to-email')
          return new InvalidPasswordError({
            message: 'password is too similar to email address',
            info: { code: 'too_similar' },
          })
        }
      } catch (error) {
        logger.error(
          { error },
          'error while checking password similarity to email'
        )
      }
      // TODO: remove this check once the password-too-similar checks are active?
    }
    return null
  },

  async setUserPassword(user, password) {
    return await AuthenticationManager.setUserPasswordInV2(user, password)
  },

  async checkRounds(user, hashedPassword, password) {
    // Temporarily disable this function, TODO: re-enable this
    if (Settings.security.disableBcryptRoundsUpgrades) {
      Metrics.inc('bcrypt_check_rounds', 1, { status: 'disabled' })
      return
    }
    // check current number of rounds and rehash if necessary
    const currentRounds = bcrypt.getRounds(hashedPassword)
    if (currentRounds < BCRYPT_ROUNDS) {
      Metrics.inc('bcrypt_check_rounds', 1, { status: 'upgrade' })
      return await AuthenticationManager._setUserPasswordInMongo(user, password)
    } else {
      Metrics.inc('bcrypt_check_rounds', 1, { status: 'success' })
    }
  },

  async hashPassword(password) {
    // Double-check the size to avoid truncating in bcrypt.
    const error = _validatePasswordNotTooLong(password)
    if (error) {
      throw error
    }

    const salt = await bcrypt.genSalt(BCRYPT_ROUNDS, BCRYPT_MINOR_VERSION)

    Metrics.inc('bcrypt', 1, {
      method: 'hash',
      path: BCRYPT_ROUNDS,
    })
    return await bcrypt.hash(password, salt)
  },

  async setUserPasswordInV2(user, password) {
    if (!user || !user.email || !user._id) {
      throw new Error('invalid user object')
    }
    const validationError = this.validatePassword(password, user.email)
    if (validationError) {
      throw validationError
    }
    // check if we can log in with this password. In which case we should reject it,
    // because it is the same as the existing password.
    const { match } = await AuthenticationManager._checkUserPassword(
      { _id: user._id },
      password
    )

    if (match) {
      throw new PasswordMustBeDifferentError()
    }

    let isPasswordReused
    try {
      isPasswordReused =
        await HaveIBeenPwned.promises.checkPasswordForReuse(password)
    } catch (error) {
      logger.err({ error }, 'cannot check password for re-use')
    }

    if (isPasswordReused) {
      throw new PasswordReusedError()
    }

    // password is strong enough or the validation with the service did not happen
    return await this._setUserPasswordInMongo(user, password)
  },

  async _setUserPasswordInMongo(user, password) {
    const hash = await this.hashPassword(password)
    const result = await db.users.updateOne(
      { _id: new ObjectId(user._id.toString()) },
      {
        $set: {
          hashedPassword: hash,
        },
        $unset: {
          password: true,
        },
      }
    )

    return _checkWriteResult(result)
  },

  _passwordCharactersAreValid(password) {
    let digits, letters, lettersUp, symbols
    if (
      Settings.passwordStrengthOptions &&
      Settings.passwordStrengthOptions.chars
    ) {
      digits = Settings.passwordStrengthOptions.chars.digits
      letters = Settings.passwordStrengthOptions.chars.letters
      lettersUp = Settings.passwordStrengthOptions.chars.letters_up
      symbols = Settings.passwordStrengthOptions.chars.symbols
    }
    digits = digits || '1234567890'
    letters = letters || 'abcdefghijklmnopqrstuvwxyz'
    lettersUp = lettersUp || 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
    symbols = symbols || '@#$%^&*()-_=+[]{};:<>/?!£€.,'

    for (let charIndex = 0; charIndex <= password.length - 1; charIndex++) {
      if (
        digits.indexOf(password[charIndex]) === -1 &&
        letters.indexOf(password[charIndex]) === -1 &&
        lettersUp.indexOf(password[charIndex]) === -1 &&
        symbols.indexOf(password[charIndex]) === -1
      ) {
        return false
      }
    }
    return true
  },

  /**
   * Check if the password is similar to (parts of) the email address.
   * For now, this merely sends a metric when the password and
   * email address are deemed to be too similar to each other.
   * Later we will reject passwords that fail this check.
   *
   * This logic was borrowed from the django project:
   * https://github.com/django/django/blob/fa3afc5d86f1f040922cca2029d6a34301597a70/django/contrib/auth/password_validation.py#L159-L214
   */
  _validatePasswordNotTooSimilar(password, email) {
    password = password.toLowerCase()
    email = email.toLowerCase()
    const stringsToCheck = [email]
      .concat(email.split(/\W+/))
      .concat(email.split(/@/))
    for (const emailPart of stringsToCheck) {
      if (!_exceedsMaximumLengthRatio(password, MAX_SIMILARITY, emailPart)) {
        const similarity = DiffHelper.stringSimilarity(password, emailPart)
        if (similarity > MAX_SIMILARITY) {
          return new Error('password is too similar to email')
        }
      }
    }
  },

  getMessageForInvalidPasswordError(error, req) {
    const errorCode = error?.info?.code
    const message = {
      type: 'error',
    }
    switch (errorCode) {
      case 'not_set':
        message.key = 'password-not-set'
        message.text = req.i18n.translate('invalid_password_not_set')
        break
      case 'invalid_character':
        message.key = 'password-invalid-character'
        message.text = req.i18n.translate('invalid_password_invalid_character')
        break
      case 'contains_email':
        message.key = 'password-contains-email'
        message.text = req.i18n.translate('invalid_password_contains_email')
        break
      case 'too_similar':
        message.key = 'password-too-similar'
        message.text = req.i18n.translate('invalid_password_too_similar')
        break
      case 'too_short':
        message.key = 'password-too-short'
        message.text = req.i18n.translate('invalid_password_too_short', {
          minLength: Settings.passwordStrengthOptions?.length?.min || 8,
        })
        break
      case 'too_long':
        message.key = 'password-too-long'
        message.text = req.i18n.translate('invalid_password_too_long', {
          maxLength: Settings.passwordStrengthOptions?.length?.max || 72,
        })
        break
      default:
        logger.error({ err: error }, 'Unknown password validation error code')
        message.text = req.i18n.translate('invalid_password')
        break
    }
    return message
  },
}

export default {
  _validatePasswordNotTooSimilar:
    AuthenticationManager._validatePasswordNotTooSimilar, // Private function exported for tests
  validateEmail: AuthenticationManager.validateEmail,
  validatePassword: AuthenticationManager.validatePassword,
  getMessageForInvalidPasswordError:
    AuthenticationManager.getMessageForInvalidPasswordError,
  authenticate: callbackifyMultiResult(AuthenticationManager.authenticate, [
    'user',
    'isPasswordReused',
  ]),
  setUserPassword: callbackify(AuthenticationManager.setUserPassword),
  checkRounds: callbackify(AuthenticationManager.checkRounds),
  hashPassword: callbackify(AuthenticationManager.hashPassword),
  setUserPasswordInV2: callbackify(AuthenticationManager.setUserPasswordInV2),
  promises: AuthenticationManager,
}