utils.js

const AWS = require('@serverless/aws-sdk-extra')
const fs = require('fs')
const path = require('path')
const klawSync = require('klaw-sync')
const mime = require('mime-types')
const https = require('https')
const { parseDomain } = require('parse-domain')
const agent = new https.Agent({
  keepAlive: true
})

const log = (msg) => console.log(msg) // eslint-disable-line

const sleep = async (wait) => new Promise((resolve) => setTimeout(() => resolve(), wait))

const generateId = () =>
  Math.random()
    .toString(36)
    .substring(6)

const getClients = (credentials, region) => {
  // this error message assumes that the user is running via the CLI though...
  if (!credentials || !credentials.accessKeyId || !credentials.secretAccessKey) {
    const msg = `AWS credentials not found. Make sure you have a .env file in the cwd. - Docs: https://git.io/JvArp`
    throw new Error(msg)
  }

  AWS.config.update({
    httpOptions: {
      agent
    }
  })

  const params = {
    region,
    credentials
  }

  return {
    s3: {
      // we need two S3 clients because creating/deleting buckets
      // is not available with the acceleration feature.
      regular: new AWS.S3(params),
      accelerated: new AWS.S3({ ...params, endpoint: `s3-accelerate.amazonaws.com` })
    },
    cf: new AWS.CloudFront(params),
    route53: new AWS.Route53(params),
    extras: new AWS.Extras(params),
    acm: new AWS.ACM({
      credentials,
      region: 'us-east-1' // ACM must be in us-east-1
    })
  }
}

const getNakedDomain = (domain) => {
  const parsedDomain = parseDomain(domain)

  if (!parsedDomain.topLevelDomains) {
    throw new Error(`"${domain}" is not a valid domain.`)
  }

  const nakedDomain = `${parsedDomain.domain}.${parsedDomain.topLevelDomains.join('.')}`
  return nakedDomain
}

const shouldConfigureNakedDomain = (domain) => {
  if (!domain) {
    return false
  }
  if (domain.startsWith('www')) {
    return true
  }
  return false
}

const getConfig = (inputs, state) => {
  const config = {}
  config.indexDocument = inputs.indexDocument || 'index.html'
  config.errorDocument = inputs.errorDocument || 'index.html'
  config.bucketName = inputs.bucketName || state.bucketName || `website-${generateId()}`
  config.region = inputs.region || state.region || 'us-east-1'
  config.bucketUrl = `http://${config.bucketName}.s3-website-${config.region}.amazonaws.com`
  config.src = inputs.src

  config.distributionId = state.distributionId
  config.distributionUrl = state.distributionUrl
  config.distributionArn = state.distributionArn
  config.distributionOrigins = [config.bucketUrl] // todo remove this as it's no longer used. Just saved to state.
  config.distributionDescription =
    inputs.distributionDescription || `Website distribution for bucket ${config.bucketName}`
  config.distributionDefaults = inputs.distributionDefaults

  // in case user specified protocol
  config.domain = inputs.domain
    ? inputs.domain.replace('https://', '').replace('http://', '')
    : null
  config.nakedDomain = config.domain ? getNakedDomain(config.domain) : null
  config.domainHostedZoneId = config.domain ? state.domainHostedZoneId : null
  config.certificateArn = state.certificateArn

  // for alternate cloudfront CNAME domains
  config.alternateDomainNames = inputs.alternateDomainNames
    ? inputs.alternateDomainNames.split(',')
    : null

  // if user input example.com, make sure we also setup www.example.com
  if (config.domain && config.domain === config.nakedDomain) {
    config.domain = `www.${config.domain}`
  }

  return config
}

const accelerateBucket = async (clients, bucketName) => {
  try {
    await clients.s3.regular
      .putBucketAccelerateConfiguration({
        AccelerateConfiguration: {
          Status: 'Enabled'
        },
        Bucket: bucketName
      })
      .promise()

    // sleep for a a second for propagation
    // otherwise we'd get "S3 Transfer Acceleration is not configured on this bucket" error
    await sleep(1000)
  } catch (e) {
    if (e.code === 'NoSuchBucket') {
      await sleep(2000)
      return accelerateBucket(clients, bucketName)
    }
    throw e
  }
}

const bucketCreation = async (clients, Bucket) => {
  try {
    await clients.s3.regular.headBucket({ Bucket }).promise()
  } catch (e) {
    if (e.code === 'NotFound' || e.code === 'NoSuchBucket') {
      await sleep(2000)
      return bucketCreation(clients, Bucket)
    }
    throw new Error(e)
  }
}

const ensureBucket = async (clients, bucketName, instance) => {
  try {
    log(`Checking if bucket ${bucketName} exists.`)
    await clients.s3.regular.headBucket({ Bucket: bucketName }).promise()
  } catch (e) {
    if (e.code === 'NotFound') {
      log(`Bucket ${bucketName} does not exist. Creating...`)
      await clients.s3.regular.createBucket({ Bucket: bucketName }).promise()
      // there's a race condition when using acceleration
      // so we need to sleep for a couple seconds. See this issue:
      // https://github.com/serverless/components/issues/428
      log(`Bucket ${bucketName} created. Confirming it's ready...`)
      await bucketCreation(clients, bucketName)

      // only accelerate if bucketName does not contain dots due to DNS limits
      if (!bucketName.includes('.')) {
        log(`Bucket ${bucketName} creation confirmed. Accelerating...`)
        await accelerateBucket(clients, bucketName)
      }
    } else if (e.code === 'Forbidden' && e.message === null) {
      throw Error(`Forbidden: Invalid credentials or this AWS S3 bucket name may already be taken`)
    } else if (e.code === 'Forbidden') {
      throw Error(`Bucket name "${bucketName}" is already taken.`)
    } else {
      throw e
    }
  }
}

// Attempts to call S3 method with "accelerated" and falls back
// onto "regular", if bucket is not accelerated.
const callAcceleratedOrRegular = async (clients, method, params) => {
  return new Promise(async (resolve, reject) => {
    try {
      const result = await clients.s3.accelerated[method](params).promise()
      resolve(result)
    } catch (e) {
      // if acceleration settings are still not ready
      // use the regular client
      if (
        e.message.includes('Transfer Acceleration is not configured') ||
        e.message.includes('Inaccessible host: `s3-accelerate.amazonaws.com')
      ) {
        const result = await clients.s3.regular[method](params).promise()
        resolve(result)
      }
      reject(e)
    }
  })
}

const upload = async (clients, params) => {
  return callAcceleratedOrRegular(clients, 'upload', params)
}

const uploadDir = async (clients, bucketName, zipPath, instance) => {
  // upload a simple website by default
  let dirPath = path.join(__dirname, '_src')

  // but if user provided src code, upload that instead
  if (zipPath) {
    dirPath = await instance.unzip(zipPath)
  }

  const items = await new Promise((resolve, reject) => {
    try {
      resolve(klawSync(dirPath))
    } catch (error) {
      reject(error)
    }
  })

  const uploadItems = []
  items.forEach((item) => {
    if (item.stats.isDirectory()) {
      return
    }

    let key = path.relative(dirPath, item.path)
    // convert backslashes to forward slashes on windows
    if (path.sep === '\\') {
      key = key.replace(/\\/g, '/')
    }

    const itemParams = {
      Bucket: bucketName,
      Key: key,
      Body: fs.readFileSync(item.path),
      ContentType: mime.lookup(path.basename(item.path)) || 'application/octet-stream'
    }

    uploadItems.push(upload(clients, itemParams))
  })

  await Promise.all(uploadItems)
}

const configureBucketForHosting = async (clients, bucketName, indexDocument, errorDocument) => {
  const s3BucketPolicy = {
    Version: '2012-10-17',
    Statement: [
      {
        Sid: 'PublicReadGetObject',
        Effect: 'Allow',
        Principal: {
          AWS: '*'
        },
        Action: ['s3:GetObject'],
        Resource: [`arn:aws:s3:::${bucketName}/*`]
      }
    ]
  }
  const staticHostParams = {
    Bucket: bucketName,
    WebsiteConfiguration: {
      ErrorDocument: {
        Key: errorDocument
      },
      IndexDocument: {
        Suffix: indexDocument
      }
    }
  }

  const putPostDeleteHeadRule = {
    AllowedMethods: ['PUT', 'POST', 'DELETE', 'HEAD'],
    AllowedOrigins: ['https://*.amazonaws.com'],
    AllowedHeaders: ['*'],
    MaxAgeSeconds: 0
  }
  const getRule = {
    AllowedMethods: ['GET'],
    AllowedOrigins: ['*'],
    AllowedHeaders: ['*'],
    MaxAgeSeconds: 0
  }

  try {
    await clients.s3.regular
      .putBucketPolicy({
        Bucket: bucketName,
        Policy: JSON.stringify(s3BucketPolicy)
      })
      .promise()

    await clients.s3.regular
      .putBucketCors({
        Bucket: bucketName,
        CORSConfiguration: {
          CORSRules: [putPostDeleteHeadRule, getRule]
        }
      })
      .promise()

    await clients.s3.regular.putBucketWebsite(staticHostParams).promise()
  } catch (e) {
    if (e.code === 'NoSuchBucket') {
      await sleep(2000)
      return configureBucketForHosting(clients, bucketName)
    }
    throw e
  }
}

const clearBucket = async (clients, bucketName) => {
  try {
    const data = await callAcceleratedOrRegular(clients, 'listObjects', { Bucket: bucketName })

    const items = data.Contents
    const promises = []

    for (var i = 0; i < items.length; i += 1) {
      var deleteParams = { Bucket: bucketName, Key: items[i].Key }
      const delObj = callAcceleratedOrRegular(clients, 'deleteObject', deleteParams)
      promises.push(delObj)
    }

    await Promise.all(promises)
  } catch (error) {
    if (error.code !== 'NoSuchBucket') {
      throw error
    }
  }
}

const deleteBucket = async (clients, bucketName) => {
  try {
    await clients.s3.regular.deleteBucket({ Bucket: bucketName }).promise()
  } catch (error) {
    if (error.code !== 'NoSuchBucket') {
      throw error
    }
  }
}

const getDomainHostedZoneId = async (clients, config) => {
  const hostedZonesRes = await clients.route53.listHostedZonesByName().promise()

  const hostedZone = hostedZonesRes.HostedZones.find(
    // Name has a period at the end, so we're using includes rather than equals
    (zone) => zone.Name.includes(config.nakedDomain)
  )

  if (!hostedZone) {
    log(`Domain ${config.nakedDomain} was not found in your AWS account. Skipping DNS operations.`)
    return
  }

  return hostedZone.Id.replace('/hostedzone/', '') // hosted zone id is always prefixed with this :(
}

const getCertificateArnByDomain = async (clients, config) => {
  const listRes = await clients.acm.listCertificates().promise()
  const certificate = listRes.CertificateSummaryList.find(
    (cert) => cert.DomainName === config.nakedDomain
  )
  return certificate && certificate.CertificateArn ? certificate.CertificateArn : null
}

const getCertificateValidationRecord = (certificate, domain) => {
  if (!certificate.DomainValidationOptions) {
    return null
  }
  const domainValidationOption = certificate.DomainValidationOptions.find(
    (option) => option.DomainName === domain
  )

  return domainValidationOption.ResourceRecord
}

const describeCertificateByArn = async (clients, certificateArn, domain) => {
  const res = await clients.acm.describeCertificate({ CertificateArn: certificateArn }).promise()
  const certificate = res && res.Certificate ? res.Certificate : null

  if (
    certificate.Status === 'PENDING_VALIDATION' &&
    !getCertificateValidationRecord(certificate, domain)
  ) {
    await sleep(1000)
    return describeCertificateByArn(clients, certificateArn, domain)
  }

  return certificate
}

const ensureCertificate = async (clients, config, instance) => {
  const wildcardSubDomain = `*.${config.nakedDomain}`

  const params = {
    DomainName: config.nakedDomain,
    SubjectAlternativeNames: [config.nakedDomain, wildcardSubDomain],
    ValidationMethod: 'DNS'
  }

  log(`Checking if a certificate for the ${config.nakedDomain} domain exists`)
  let certificateArn = await getCertificateArnByDomain(clients, config)

  if (!certificateArn) {
    log(`Certificate for the ${config.nakedDomain} domain does not exist. Creating...`)
    certificateArn = (await clients.acm.requestCertificate(params).promise()).CertificateArn
  }

  const certificate = await describeCertificateByArn(clients, certificateArn, config.nakedDomain)

  log(`Certificate for ${config.nakedDomain} is in a "${certificate.Status}" status`)

  if (certificate.Status === 'PENDING_VALIDATION') {
    const certificateValidationRecord = getCertificateValidationRecord(
      certificate,
      config.nakedDomain
    )
    // only validate if domain/hosted zone is found in this account
    if (config.domainHostedZoneId) {
      log(`Validating the certificate for the ${config.nakedDomain} domain.`)

      const recordParams = {
        HostedZoneId: config.domainHostedZoneId,
        ChangeBatch: {
          Changes: [
            {
              Action: 'UPSERT',
              ResourceRecordSet: {
                Name: certificateValidationRecord.Name,
                Type: certificateValidationRecord.Type,
                TTL: 300,
                ResourceRecords: [
                  {
                    Value: certificateValidationRecord.Value
                  }
                ]
              }
            }
          ]
        }
      }
      await clients.route53.changeResourceRecordSets(recordParams).promise()
      log(
        `Your certificate was created and is being validated. It may take a few mins to validate.`
      )
      log(
        `Please deploy again after few mins to use your newly validated certificate and activate your domain.`
      )
    } else {
      // if domain is not in account, let the user validate manually
      log(
        `Certificate for the ${config.nakedDomain} domain was created, but not validated. Please validate it manually.`
      )
      log(`Certificate Validation Record Name: ${certificateValidationRecord.Name} `)
      log(`Certificate Validation Record Type: ${certificateValidationRecord.Type} `)
      log(`Certificate Validation Record Value: ${certificateValidationRecord.Value} `)
    }
  } else if (certificate.Status === 'ISSUED') {
    // if certificate status is ISSUED, mark it a as valid for CloudFront to use
    config.certificateValid = true
  } else if (certificate.Status === 'SUCCESS') {
    // nothing to do here. We just need to wait a min until the status changes to ISSUED
  } else if (certificate.Status === 'VALIDATION_TIMED_OUT') {
    // if 72 hours passed and the user did not validate the certificate
    // it will timeout and the user will need to recreate and validate the certificate manulaly
    log(
      `Certificate validation timed out after 72 hours. Please recreate and validate the certifcate manually.`
    )
    log(`Your domain will not work until your certificate is created and validated .`)
  } else {
    // something else happened?!
    throw new Error(
      `Failed to validate ACM certificate. Unsupported ACM certificate status ${certificate.Status}`
    )
  }

  return certificateArn
}

const createCloudFrontDistribution = async (clients, config) => {
  const params = {
    DistributionConfig: {
      CallerReference: String(Date.now()),
      DefaultRootObject: 'index.html',
      CustomErrorResponses: {
        Quantity: 2,
        Items: [
          {
            ErrorCode: 404,
            ErrorCachingMinTTL: 300,
            ResponseCode: '200',
            ResponsePagePath: '/index.html'
          },
          {
            ErrorCode: 403,
            ErrorCachingMinTTL: 300,
            ResponseCode: '200',
            ResponsePagePath: '/index.html'
          }
        ]
      },
      Comment: config.distributionDescription,
      Aliases: {
        Quantity: 0,
        Items: []
      },
      Origins: {
        Quantity: 0,
        Items: []
      },
      PriceClass: 'PriceClass_All',
      Enabled: true,
      HttpVersion: 'http2',
      Origins: {
        Quantity: 1,
        Items: [
          {
            Id: config.bucketName,
            DomainName: `${config.bucketName}.s3.${config.region}.amazonaws.com`,
            CustomHeaders: {
              Quantity: 0,
              Items: []
            },
            OriginPath: '',
            S3OriginConfig: {
              OriginAccessIdentity: ''
            }
          }
        ]
      },
      DefaultCacheBehavior: {
        TargetOriginId: config.bucketName,
        ForwardedValues: {
          QueryString: false,
          Cookies: {
            Forward: 'none'
          },
          Headers: {
            Quantity: 0,
            Items: []
          },
          QueryStringCacheKeys: {
            Quantity: 0,
            Items: []
          }
        },
        TrustedSigners: {
          Enabled: false,
          Quantity: 0,
          Items: []
        },
        ViewerProtocolPolicy: 'redirect-to-https',
        MinTTL: 0,
        AllowedMethods: {
          Quantity: 2,
          Items: ['HEAD', 'GET'],
          CachedMethods: {
            Quantity: 2,
            Items: ['HEAD', 'GET']
          }
        },
        SmoothStreaming: false,
        DefaultTTL: 0,
        MaxTTL: 31536000,
        Compress: false,
        LambdaFunctionAssociations: {
          Quantity: 0,
          Items: []
        },
        FieldLevelEncryptionId: ''
      },
      CacheBehaviors: {
        Quantity: 0,
        Items: []
      }
    }
  }

  const distributionConfig = params.DistributionConfig

  // add domain and certificate config if certificate is valid and ISSUED
  if (config.certificateValid) {
    log(`Adding "${config.nakedDomain}" certificate to CloudFront distribution`)
    distributionConfig.ViewerCertificate = {
      ACMCertificateArn: config.certificateArn,
      SSLSupportMethod: 'sni-only',
      MinimumProtocolVersion: 'TLSv1.1_2016',
      Certificate: config.certificateArn,
      CertificateSource: 'acm'
    }

    log(`Adding domain "${config.domain}" to CloudFront distribution`)
    distributionConfig.Aliases = {
      Quantity: 1,
      Items: [config.domain]
    }

    if (shouldConfigureNakedDomain(config.domain)) {
      log(`Adding domain "${config.nakedDomain}" to CloudFront distribution`)
      distributionConfig.Aliases.Quantity = 2
      distributionConfig.Aliases.Items.push(config.nakedDomain)
    }

    if (Array.isArray(config.alternateDomainNames)) {
      config.alternateDomainNames.forEach((domain) => {
        distributionConfig.Aliases.Quantity += 1
        distributionConfig.Aliases.Items.push(domain)
      })
    }
  }

  try {
    const res = await clients.cf.createDistribution(params).promise()

    return {
      distributionId: res.Distribution.Id,
      distributionArn: res.Distribution.ARN,
      distributionUrl: res.Distribution.DomainName,
      distributionOrigins: config.distributionOrigins,
      distributionDefaults: config.distributionDefaults,
      distributionDescription: config.distributionDescription
    }
  } catch (e) {
    // throw a friendly error if trying to use an existing domain
    if (e.message.includes('One or more of the CNAMEs')) {
      throw new Error(
        `The domain "${config.domain}" is already in use by another website or CloudFront Distribution.`
      )
    }
    throw e
  }
}

const updateCloudFrontDistribution = async (clients, config) => {
  try {
    // Update logic is a bit weird...
    // https://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/CloudFront.html#updateDistribution-property

    // 1. we gotta get the config first...
    // todo what if id does not exist?
    const params = await clients.cf.getDistributionConfig({ Id: config.distributionId }).promise()

    // 2. then add this property
    params.IfMatch = params.ETag

    // 3. then delete this property
    delete params.ETag

    // 4. then set this property
    params.Id = config.distributionId

    // 5. then make our changes
    params.DistributionConfig.Enabled = true // make sure it's enabled

    params.DistributionConfig.Comment = config.distributionDescription

    // add domain and certificate config if certificate is valid and ISSUED
    if (config.certificateValid) {
      log(`Adding "${config.nakedDomain}" certificate to CloudFront distribution`)
      params.DistributionConfig.ViewerCertificate = {
        ACMCertificateArn: config.certificateArn,
        SSLSupportMethod: 'sni-only',
        MinimumProtocolVersion: 'TLSv1.1_2016',
        Certificate: config.certificateArn,
        CertificateSource: 'acm'
      }

      log(`Adding domain "${config.domain}" to CloudFront distribution`)
      params.DistributionConfig.Aliases = {
        Quantity: 1,
        Items: [config.domain]
      }

      if (shouldConfigureNakedDomain(config.domain)) {
        log(`Adding domain "${config.nakedDomain}" to CloudFront distribution`)
        params.DistributionConfig.Aliases.Quantity = 2
        params.DistributionConfig.Aliases.Items.push(config.nakedDomain)
      }

      if (Array.isArray(config.alternateDomainNames)) {
        config.alternateDomainNames.forEach((domain) => {
          params.DistributionConfig.Aliases.Quantity += 1
          params.DistributionConfig.Aliases.Items.push(domain)
        })
      }
    }
    // 6. then finally update!
    const res = await clients.cf.updateDistribution(params).promise()

    return {
      distributionId: res.Distribution.Id,
      distributionArn: res.Distribution.ARN,
      distributionUrl: res.Distribution.DomainName,
      distributionOrigins: config.distributionOrigins,
      distributionDefaults: config.distributionDefaults,
      distributionDescription: config.distributionDescription
    }
  } catch (e) {
    if (e.code === 'NoSuchDistribution') {
      return null
    }

    if (e.message.includes('One or more of the CNAMEs')) {
      throw new Error(
        `The domain "${config.domain}" is already in use by another website or CloudFront Distribution.`
      )
    }

    throw e
  }
}

const invalidateCloudfrontDistribution = async (clients, config) => {
  const params = {
    DistributionId: config.distributionId,
    InvalidationBatch: {
      CallerReference: String(Date.now()),
      Paths: {
        Quantity: 3,
        Items: ['/', '/index.html', '/*']
      }
    }
  }
  await clients.cf.createInvalidation(params).promise()
}

const configureDnsForCloudFrontDistribution = async (clients, config) => {
  const dnsRecordParams = {
    HostedZoneId: config.domainHostedZoneId,
    ChangeBatch: {
      Changes: [
        {
          Action: 'UPSERT',
          ResourceRecordSet: {
            Name: config.domain,
            Type: 'A',
            AliasTarget: {
              HostedZoneId: 'Z2FDTNDATAQYW2', // this is a constant that you can get from here https://docs.aws.amazon.com/general/latest/gr/rande.html#s3_region
              DNSName: config.distributionUrl,
              EvaluateTargetHealth: false
            }
          }
        }
      ]
    }
  }

  if (shouldConfigureNakedDomain(config.domain)) {
    dnsRecordParams.ChangeBatch.Changes.push({
      Action: 'UPSERT',
      ResourceRecordSet: {
        Name: config.nakedDomain,
        Type: 'A',
        AliasTarget: {
          HostedZoneId: 'Z2FDTNDATAQYW2', // this is a constant that you can get from here https://docs.aws.amazon.com/general/latest/gr/rande.html#s3_region
          DNSName: config.distributionUrl,
          EvaluateTargetHealth: false
        }
      }
    })
  }

  return clients.route53.changeResourceRecordSets(dnsRecordParams).promise()
}

const disableCloudFrontDistribution = async (clients, distributionId) => {
  const params = await clients.cf.getDistributionConfig({ Id: distributionId }).promise()

  params.IfMatch = params.ETag

  delete params.ETag

  params.Id = distributionId

  params.DistributionConfig.Enabled = false

  const res = await clients.cf.updateDistribution(params).promise()

  return {
    id: res.Distribution.Id,
    arn: res.Distribution.ARN,
    url: `https://${res.Distribution.DomainName}`
  }
}

const deleteCloudFrontDistribution = async (clients, distributionId) => {
  try {
    const res = await clients.cf.getDistributionConfig({ Id: distributionId }).promise()

    const params = { Id: distributionId, IfMatch: res.ETag }
    await clients.cf.deleteDistribution(params).promise()
  } catch (e) {
    if (e.code === 'DistributionNotDisabled') {
      await disableCloudFrontDistribution(clients, distributionId)
    } else if (e.code === 'NoSuchDistribution') {
      return
    } else {
      throw e
    }
  }
}

const removeDomainFromCloudFrontDistribution = async (clients, config) => {
  try {
    const params = await clients.cf.getDistributionConfig({ Id: config.distributionId }).promise()

    params.IfMatch = params.ETag

    delete params.ETag

    params.Id = config.distributionId

    params.DistributionConfig.Aliases = {
      Quantity: 0,
      Items: []
    }

    params.DistributionConfig.ViewerCertificate = {
      SSLSupportMethod: 'sni-only',
      MinimumProtocolVersion: 'TLSv1.1_2016'
    }
    const res = await clients.cf.updateDistribution(params).promise()

    return {
      distributionId: res.Distribution.Id,
      distributionArn: res.Distribution.ARN,
      distributionUrl: res.Distribution.DomainName,
      distributionOrigins: config.distributionOrigins,
      distributionDefaults: config.distributionDefaults,
      distributionDescription: config.distributionDescription
    }
  } catch (e) {
    if (e.code === 'NoSuchDistribution') {
      return null
    }
    throw e
  }
}

const removeCloudFrontDomainDnsRecords = async (clients, config) => {
  const params = {
    HostedZoneId: config.domainHostedZoneId,
    ChangeBatch: {
      Changes: [
        {
          Action: 'DELETE',
          ResourceRecordSet: {
            Name: config.domain,
            Type: 'A',
            AliasTarget: {
              HostedZoneId: 'Z2FDTNDATAQYW2', // this is a constant that you can get from here https://docs.aws.amazon.com/general/latest/gr/rande.html#s3_region
              DNSName: config.distributionUrl,
              EvaluateTargetHealth: false
            }
          }
        }
      ]
    }
  }

  if (shouldConfigureNakedDomain(config.domain)) {
    params.ChangeBatch.Changes.push({
      Action: 'UPSERT',
      ResourceRecordSet: {
        Name: config.nakedDomain,
        Type: 'A',
        AliasTarget: {
          HostedZoneId: 'Z2FDTNDATAQYW2', // this is a constant that you can get from here https://docs.aws.amazon.com/general/latest/gr/rande.html#s3_region
          DNSName: config.distributionUrl,
          EvaluateTargetHealth: false
        }
      }
    })
  }

  try {
    await clients.route53.changeResourceRecordSets(params).promise()
  } catch (e) {
    if (e.code !== 'InvalidChangeBatch' && e.code !== 'NoSuchHostedZone') {
      throw e
    }
  }
}

/*
 * Ensure the Meta IAM Role exists
 */
const createOrUpdateMetaRole = async (instance, inputs, clients, serverlessAccountId) => {
  // Create or update Meta Role for monitoring and more, if option is enabled.  It's enabled by default.
  if (inputs.monitoring || typeof inputs.monitoring === 'undefined') {
    console.log('Creating or updating the meta IAM Role...');

    const roleName = `${instance.name}-meta-role`;

    const assumeRolePolicyDocument = {
      Version: '2012-10-17',
      Statement: {
        Effect: 'Allow',
        Principal: {
          AWS: `arn:aws:iam::${serverlessAccountId}:root`, // Serverless's Components account
        },
        Action: 'sts:AssumeRole',
      },
    };

    // Create a policy that only can access APIGateway and Lambda metrics, logs from CloudWatch...
    const policy = {
      Version: '2012-10-17',
      Statement: [
        {
          Effect: 'Allow',
          Resource: '*',
          Action: [
            'cloudwatch:Describe*',
            'cloudwatch:Get*',
            'cloudwatch:List*',
            'logs:Get*',
            'logs:List*',
            'logs:Describe*',
            'logs:TestMetricFilter',
            'logs:FilterLogEvents',
          ],
        },
      ],
    };

    const roleDescription = `The Meta Role for the Serverless Framework App: ${instance.name} Stage: ${instance.stage}`;

    const result = await clients.extras.deployRole({
      roleName,
      roleDescription,
      policy,
      assumeRolePolicyDocument,
    });

    instance.state.metaRoleName = roleName;
    instance.state.metaRoleArn = result.roleArn;

    console.log(`Meta IAM Role created or updated with ARN ${instance.state.metaRoleArn}`);
  }
};

/*
 * Removes the Function & Meta Roles from aws according to the provided config
 *
 * @param ${object} clients - an object containing aws sdk clients
 * @param ${object} config - the component config
 */
const removeAllRoles = async (instance, clients) => {
  // Delete Meta Role
  if (instance.state.metaRoleName) {
    console.log('Deleting the Meta Role...');
    await clients.extras.removeRole({
      roleName: instance.state.metaRoleName,
    });
  }
};


/**
 * Get metrics from cloudwatch
 * @param {*} clients
 * @param {*} rangeStart MUST be a moment() object
 * @param {*} rangeEnd MUST be a moment() object
 */
const getMetrics = async (
  region,
  metaRoleArn,
  distributionId,
  rangeStart,
  rangeEnd
) => {
  /**
   * Create AWS STS Token via the meta role that is deployed with the Express Component
   */

  // Assume Role
  const assumeParams = {};
  assumeParams.RoleSessionName = `session${Date.now()}`;
  assumeParams.RoleArn = metaRoleArn;
  assumeParams.DurationSeconds = 900;

  const sts = new AWS.STS({ region })
  const resAssume = await sts.assumeRole(assumeParams).promise();

  const roleCreds = {};
  roleCreds.accessKeyId = resAssume.Credentials.AccessKeyId;
  roleCreds.secretAccessKey = resAssume.Credentials.SecretAccessKey;
  roleCreds.sessionToken = resAssume.Credentials.SessionToken;

  /**
   * Instantiate a new Extras instance w/ the temporary credentials
   */

  const extras = new AWS.Extras({
    credentials: roleCreds,
    region,
  })

  const resources = [
    {
      type: 'aws_cloudfront',
      distributionId,
    },
  ];

  return await extras.getMetrics({
    rangeStart,
    rangeEnd,
    resources,
  });
};

module.exports = {
  log,
  generateId,
  getClients,
  getConfig,
  createOrUpdateMetaRole,
  bucketCreation,
  accelerateBucket,
  ensureBucket,
  uploadDir,
  configureBucketForHosting,
  clearBucket,
  deleteBucket,
  getDomainHostedZoneId,
  ensureCertificate,
  createCloudFrontDistribution,
  updateCloudFrontDistribution,
  invalidateCloudfrontDistribution,
  configureDnsForCloudFrontDistribution,
  deleteCloudFrontDistribution,
  removeDomainFromCloudFrontDistribution,
  removeCloudFrontDomainDnsRecords,
  removeAllRoles,
  getMetrics,
}