const simpleWebauthn = require('@simplewebauthn/server')
const base64url = require('base64url')
const _ = require('lodash/fp')

const credentials = require('../../../../hardware-credentials')
const T = require('../../../../time')
const users = require('../../../../users')

const devMode = require('minimist')(process.argv.slice(2)).dev

const REMEMBER_ME_AGE = 90 * T.day

const generateAttestationOptions = (session, options) => {
  return credentials.getHardwareCredentials().then(devices => {
    const opts = simpleWebauthn.generateAttestationOptions({
      rpName: 'Lamassu',
      rpID: options.domain,
      userName: `Usernameless user created at ${new Date().toISOString()}`,
      userID: options.userId,
      timeout: 60000,
      attestationType: 'direct',
      excludeCredentials: devices.map(dev => ({
        id: dev.data.credentialID,
        type: 'public-key',
        transports: ['usb', 'ble', 'nfc', 'internal'],
      })),
      authenticatorSelection: {
        authenticatorAttachment: 'cross-platform',
        userVerification: 'discouraged',
        requireResidentKey: false,
      },
    })

    session.webauthn = {
      attestation: {
        challenge: opts.challenge,
      },
    }

    return opts
  })
}

const generateAssertionOptions = (session, options) => {
  return credentials.getHardwareCredentials().then(devices => {
    const opts = simpleWebauthn.generateAssertionOptions({
      timeout: 60000,
      allowCredentials: devices.map(dev => ({
        id: dev.data.credentialID,
        type: 'public-key',
        transports: ['usb', 'ble', 'nfc', 'internal'],
      })),
      userVerification: 'discouraged',
      rpID: options.domain,
    })

    session.webauthn = {
      assertion: {
        challenge: opts.challenge,
      },
    }
    return opts
  })
}

const validateAttestation = (session, options) => {
  const webauthnData = session.webauthn.attestation
  const expectedChallenge = webauthnData.challenge

  return Promise.all([
    users.getUserById(options.userId),
    simpleWebauthn.verifyAttestationResponse({
      credential: options.attestationResponse,
      expectedChallenge: `${expectedChallenge}`,
      expectedOrigin: `https://${options.domain}${devMode ? `:3001` : ``}`,
      expectedRPID: options.domain,
    }),
  ]).then(([user, verification]) => {
    const { verified, attestationInfo } = verification

    if (!(verified || attestationInfo)) {
      session.webauthn = null
      return verified
    }

    const {
      fmt,
      counter,
      aaguid,
      credentialPublicKey,
      credentialID,
      credentialType,
      userVerified,
      attestationObject,
    } = attestationInfo

    return credentials
      .getHardwareCredentialsByUserId(user.id)
      .then(userDevices => {
        const existingDevice = userDevices.find(
          device => device.data.credentialID === credentialID,
        )

        if (!existingDevice) {
          const newDevice = {
            fmt,
            counter,
            aaguid,
            credentialPublicKey,
            credentialID,
            credentialType,
            userVerified,
            attestationObject,
          }
          credentials.createHardwareCredential(user.id, newDevice)
        }

        session.webauthn = null
        return verified
      })
  })
}

const validateAssertion = (session, options) => {
  const expectedChallenge = session.webauthn.assertion.challenge

  return credentials.getHardwareCredentials().then(devices => {
    const dbAuthenticator = _.find(dev => {
      return (
        Buffer.from(dev.data.credentialID).compare(
          base64url.toBuffer(options.assertionResponse.rawId),
        ) === 0
      )
    }, devices)

    if (!dbAuthenticator.data) {
      throw new Error(
        `Could not find authenticator matching ${options.assertionResponse.id}`,
      )
    }

    const convertedAuthenticator = _.merge(dbAuthenticator.data, {
      credentialPublicKey: Buffer.from(
        dbAuthenticator.data.credentialPublicKey,
      ),
    })

    let verification
    try {
      verification = simpleWebauthn.verifyAssertionResponse({
        credential: options.assertionResponse,
        expectedChallenge: `${expectedChallenge}`,
        expectedOrigin: `https://${options.domain}${devMode ? `:3001` : ``}`,
        expectedRPID: options.domain,
        authenticator: convertedAuthenticator,
      })
    } catch (err) {
      console.error(err)
      return false
    }

    const { verified, assertionInfo } = verification

    if (!verified) {
      session.webauthn = null
      return false
    }

    dbAuthenticator.data.counter = assertionInfo.newCounter
    return Promise.all([
      credentials.updateHardwareCredential(dbAuthenticator),
      users.getUserById(dbAuthenticator.user_id),
    ]).then(([, user]) => {
      const finalUser = {
        id: user.id,
        username: user.username,
        role: user.role,
      }
      session.user = finalUser
      session.cookie.maxAge = REMEMBER_ME_AGE

      session.webauthn = null
      return verified
    })
  })
}

module.exports = {
  generateAttestationOptions,
  generateAssertionOptions,
  validateAttestation,
  validateAssertion,
}