class ElasticAPM::ContextBuilder

def apply_to_request(context, rack_env:, for_type:)
  req = rails_req?(rack_env) ? rack_env : Rack::Request.new(rack_env)
  context.request = Context::Request.new unless context.request
  request = context.request
  request.socket = Context::Request::Socket.new(req)
  request.http_version = build_http_version req
  request.method = req.request_method
  request.url = Context::Request::Url.new(req)
  request.body = should_capture_body?(for_type) ? get_body(req) : SKIPPED
  headers, env = get_headers_and_env(rack_env)
  request.headers = headers if config.capture_headers?
  request.env = env if config.capture_env?
  request.cookies = req.cookies.dup
  unless request.cookies.empty?
    request.headers['Cookie'] = SKIPPED if request.headers.has_key?('Cookie')
  end
  context
end

def build(rack_env:, for_type:)
  Context.new.tap do |context|
    apply_to_request(context, rack_env: rack_env, for_type: for_type)
  end
end

def build_http_version(req)
  return unless (http_version = req.env['HTTP_VERSION'])
  http_version.gsub(%r{HTTP/}, '')
end

def camel_key(key)
  key.gsub(/^HTTP_/, '').split('_').map(&:capitalize).join('-')
end

def get_body(req)
  case req.media_type
  when 'application/x-www-form-urlencoded', 'multipart/form-data'
    req.POST.dup
  else
    body = req.body.read
    req.body.rewind
    body.byteslice(0, MAX_BODY_LENGTH).force_encoding('utf-8').scrub
  end
end

def get_headers_and_env(rack_env)
  # In Rails < 5 ActionDispatch::Request inherits from Hash
  headers =
    rack_env.respond_to?(:headers) ? rack_env.headers : rack_env
  headers.each_with_object([{}, {}]) do |(key, value), (http, env)|
    next unless key == key.upcase
    if key.start_with?('HTTP_')
      http[camel_key(key)] = value
    else
      env[key] = value
    end
  end
end

def initialize(config)
  @config = config
end

def rails_req?(env)
  defined?(ActionDispatch::Request) && env.is_a?(ActionDispatch::Request)
end

def should_capture_body?(for_type)
  option = config.capture_body
  return true if option == 'all'
  return true if option == 'transactions' && for_type == :transaction
  return true if option == 'errors' && for_type == :error
  false
end