class Aws::Plugins::S3RegionDetection::DetectRegionHandler

def call(context)
  response = @handler.call(context)
  handle_region_errors(response)
end

def detect_region_and_retry(resp)
  context = resp.context
  updgrade_to_v4(context, 'us-east-1')
  resp = @handler.call(context)
  actual_region = region_from_location_header(context)
  updgrade_to_v4(context, actual_region)
  log_warning(context, actual_region)
  @handler.call(context)
end

def extract_body_region_and_retry(context)
  actual_region = region_from_body(context)
  updgrade_to_v4(context, actual_region)
  log_warning(context, actual_region)
  @handler.call(context)
end

def handle_region_errors(response)
  if requires_sigv4?(response)
    detect_region_and_retry(response)
  elsif wrong_sigv4_region?(response)
    extract_body_region_and_retry(response.context)
  else
    response
  end
end

def log_warning(context, actual_region)
  S3::BUCKET_REGIONS[context.params[:bucket]] = actual_region
  msg = "S3 client configured for #{context.config.region.inspect} " +
    "but the bucket #{context.params[:bucket].inspect} is in " +
    "#{actual_region.inspect}; Please configure the proper region " +
    "to avoid multiple unecessary redirects and signing attempts"
  if logger = context.config.logger
    logger.warn(msg)
  else
    warn(msg)
  end
end

def region_from_body(context)
  context.http_response.body_contents.match(/<Region>(.+?)<\/Region>/)[1]
end

def region_from_location_header(context)
  location = context.http_response.headers['location']
  location.match(/s3.(.+?)\.amazonaws\.com/)[1]
end

def requires_sigv4?(resp)
  resp.context.http_response.status_code == 400 &&
  resp.context.http_response.body_contents.include?('Please use AWS4-HMAC-SHA256') &&
  resp.context.http_response.body.respond_to?(:truncate)
end

def updgrade_to_v4(context, region)
  bucket = context.params[:bucket]
  context.http_response.body.truncate(0)
  context.http_request.headers.delete('authorization')
  context.http_request.headers.delete('x-amz-security-token')
  context.http_request.endpoint.host = new_hostname(context, region)
  signer = Signers::V4.new(context.config.credentials, 's3', region)
  signer.sign(context.http_request)
end

def wrong_sigv4_region?(resp)
  resp.context.http_response.status_code == 400 &&
  resp.context.http_response.body_contents.match(/<Region>.+?<\/Region>/)
end