module Stripe

def self._uname_uname
  (`uname -a 2>/dev/null` || '').strip
rescue Errno::ENOMEM # couldn't create subprocess
  "uname lookup failed"
end

def self._uname_ver
  (`ver` || '').strip
rescue Errno::ENOMEM # couldn't create subprocess
  "uname lookup failed"
end

def self.api_error(error, resp, error_obj)
  APIError.new(error[:message], resp.code, resp.body, error_obj, resp.headers)
end

def self.api_url(url='', api_base_url=nil)
  (api_base_url || @api_base) + url
end

def self.authentication_error(error, resp, error_obj)
  AuthenticationError.new(error[:message], resp.code, resp.body, error_obj,
                          resp.headers)
end

def self.ca_bundle_path
  @ca_bundle_path
end

def self.ca_bundle_path=(path)
  @ca_bundle_path = path
end

def self.card_error(error, resp, error_obj)
  CardError.new(error[:message], error[:param], error[:code],
                resp.code, resp.body, error_obj, resp.headers)
end

def self.execute_request(opts)
  RestClient::Request.execute(opts)
end

def self.execute_request_with_rescues(request_opts, api_base_url, retry_count = 0)
  begin
    response = execute_request(request_opts)
  rescue SocketError => e
    response = handle_restclient_error(e, request_opts, retry_count, api_base_url)
  rescue NoMethodError => e
    # Work around RestClient bug
    if e.message =~ /\WRequestFailed\W/
      e = APIConnectionError.new('Unexpected HTTP response code')
      response = handle_restclient_error(e, request_opts, retry_count, api_base_url)
    else
      raise
    end
  rescue RestClient::ExceptionWithResponse => e
    if e.response
      handle_api_error(e.response)
    else
      response = handle_restclient_error(e, request_opts, retry_count, api_base_url)
    end
  rescue RestClient::Exception, Errno::ECONNREFUSED => e
    response = handle_restclient_error(e, request_opts, retry_count, api_base_url)
  end
  response
end

def self.general_api_error(rcode, rbody)
  APIError.new("Invalid response object from API: #{rbody.inspect} " +
               "(HTTP response code was #{rcode})", rcode, rbody)
end

def self.get_uname
  if File.exist?('/proc/version')
    File.read('/proc/version').strip
  else
    case RbConfig::CONFIG['host_os']
    when /linux|darwin|bsd|sunos|solaris|cygwin/i
      _uname_uname
    when /mswin|mingw/i
      _uname_ver
    else
      "unknown platform"
    end
  end
end

def self.handle_api_error(resp)
  begin
    error_obj = JSON.parse(resp.body)
    error_obj = Util.symbolize_names(error_obj)
    error = error_obj[:error]
    raise StripeError.new unless error && error.is_a?(Hash)
  rescue JSON::ParserError, StripeError
    raise general_api_error(resp.code, resp.body)
  end
  case resp.code
  when 400, 404
    raise invalid_request_error(error, resp, error_obj)
  when 401
    raise authentication_error(error, resp, error_obj)
  when 402
    raise card_error(error, resp, error_obj)
  when 429
    raise rate_limit_error(error, resp, error_obj)
  else
    raise api_error(error, resp, error_obj)
  end
end

def self.handle_restclient_error(e, request_opts, retry_count, api_base_url=nil)
  if should_retry?(e, retry_count)
    retry_count = retry_count + 1
    sleep sleep_time(retry_count)
    response = execute_request_with_rescues(request_opts, api_base_url, retry_count)
    return response
  end
  api_base_url = @api_base unless api_base_url
  connection_message = "Please check your internet connection and try again. " \
      "If this problem persists, you should check Stripe's service status at " \
      "https://twitter.com/stripestatus, or let us know at support@stripe.com."
  case e
  when RestClient::RequestTimeout
    message = "Could not connect to Stripe (#{api_base_url}). #{connection_message}"
  when RestClient::ServerBrokeConnection
    message = "The connection to the server (#{api_base_url}) broke before the " \
      "request completed. #{connection_message}"
  when RestClient::SSLCertificateNotVerified
    message = "Could not verify Stripe's SSL certificate. " \
      "Please make sure that your network is not intercepting certificates. " \
      "(Try going to https://api.stripe.com/v1 in your browser.) " \
      "If this problem persists, let us know at support@stripe.com."
  when SocketError
    message = "Unexpected error communicating when trying to connect to Stripe. " \
      "You may be seeing this message because your DNS is not working. " \
      "To check, try running 'host stripe.com' from the command line."
  else
    message = "Unexpected error communicating with Stripe. " \
      "If this problem persists, let us know at support@stripe.com."
  end
  if retry_count > 0
    message += " Request was retried #{retry_count} times."
  end
  raise APIConnectionError.new(message + "\n\n(Network error: #{e.message})")
end

def self.invalid_request_error(error, resp, error_obj)
  InvalidRequestError.new(error[:message], error[:param], resp.code,
                          resp.body, error_obj, resp.headers)
end

def self.max_network_retries
  @max_network_retries
end

def self.max_network_retries=(val)
  @max_network_retries = val.to_i
end

def self.parse(response)
  begin
    # Would use :symbolize_names => true, but apparently there is
    # some library out there that makes symbolize_names not work.
    response = JSON.parse(response.body)
  rescue JSON::ParserError
    raise general_api_error(response.code, response.body)
  end
  Util.symbolize_names(response)
end

def self.rate_limit_error(error, resp, error_obj)
  RateLimitError.new(error[:message], resp.code, resp.body, error_obj,
                     resp.headers)
end

def self.request(method, url, api_key, params={}, headers={}, api_base_url=nil)
  api_base_url = api_base_url || @api_base
  unless api_key ||= @api_key
    raise AuthenticationError.new('No API key provided. ' \
      'Set your API key using "Stripe.api_key = <API-KEY>". ' \
      'You can generate API keys from the Stripe web interface. ' \
      'See https://stripe.com/api for details, or email support@stripe.com ' \
      'if you have any questions.')
  end
  if api_key =~ /\s/
    raise AuthenticationError.new('Your API key is invalid, as it contains ' \
      'whitespace. (HINT: You can double-check your API key from the ' \
      'Stripe web interface. See https://stripe.com/api for details, or ' \
      'email support@stripe.com if you have any questions.)')
  end
  if verify_ssl_certs
    request_opts = {:verify_ssl => OpenSSL::SSL::VERIFY_PEER,
                    :ssl_ca_file => @ca_bundle_path}
  else
    request_opts = {:verify_ssl => false}
    unless @verify_ssl_warned
      @verify_ssl_warned = true
      $stderr.puts("WARNING: Running without SSL cert verification. " \
        "You should never do this in production. " \
        "Execute 'Stripe.verify_ssl_certs = true' to enable verification.")
    end
  end
  params = Util.objects_to_ids(params)
  url = api_url(url, api_base_url)
  case method.to_s.downcase.to_sym
  when :get, :head, :delete
    # Make params into GET parameters
    url += "#{URI.parse(url).query ? '&' : '?'}#{Util.encode_parameters(params)}" if params && params.any?
    payload = nil
  else
    if headers[:content_type] && headers[:content_type] == "multipart/form-data"
      payload = params
    else
      payload = Util.encode_parameters(params)
    end
  end
  request_opts.update(:headers => request_headers(api_key, method).update(headers),
                      :method => method, :open_timeout => open_timeout,
                      :payload => payload, :url => url, :timeout => read_timeout)
  response = execute_request_with_rescues(request_opts, api_base_url)
  [parse(response), api_key]
end

def self.request_headers(api_key, method)
  headers = {
    :user_agent => "Stripe/v1 RubyBindings/#{Stripe::VERSION}",
    :authorization => "Bearer #{api_key}",
    :content_type => 'application/x-www-form-urlencoded'
  }
  # It is only safe to retry network failures on post and delete
  # requests if we add an Idempotency-Key header
  if [:post, :delete].include?(method) && self.max_network_retries > 0
    headers[:idempotency_key] ||= SecureRandom.uuid 
  end
  headers[:stripe_version] = api_version if api_version
  begin
    headers.update(:x_stripe_client_user_agent => JSON.generate(user_agent))
  rescue => e
    headers.update(:x_stripe_client_raw_user_agent => user_agent.inspect,
                   :error => "#{e} (#{e.class})")
  end
end

def self.should_retry?(e, retry_count)
  return false if retry_count >= self.max_network_retries
  return false if e.is_a?(RestClient::SSLCertificateNotVerified)
  return true
end

def self.sleep_time(retry_count)
  # This method was adapted from https://github.com/ooyala/retries/blob/master/lib/retries.rb
  # The sleep time is an exponentially-increasing function of base_sleep_seconds. But, it never exceeds
  # max_sleep_seconds.
  sleep_seconds = [initial_network_retry_delay * (2 ** (retry_count - 1)), max_network_retry_delay].min
  # Randomize to a random value in the range sleep_seconds/2 .. sleep_seconds
  sleep_seconds = sleep_seconds * (0.5 * (1 + rand()))
  # But never sleep less than base_sleep_seconds
  sleep_seconds = [initial_network_retry_delay, sleep_seconds].max
  sleep_seconds
end

def self.uri_encode(params)
  Util.encode_parameters(params)
end

def self.user_agent
  @uname ||= get_uname
  lang_version = "#{RUBY_VERSION} p#{RUBY_PATCHLEVEL} (#{RUBY_RELEASE_DATE})"
  {
    :bindings_version => Stripe::VERSION,
    :lang => 'ruby',
    :lang_version => lang_version,
    :platform => RUBY_PLATFORM,
    :engine => defined?(RUBY_ENGINE) ? RUBY_ENGINE : '',
    :publisher => 'stripe',
    :uname => @uname,
    :hostname => Socket.gethostname,
  }
end