module RequestLogAnalyzer::FileFormat
  # FileFormat for Amazon S3 access logs.
  #
  # Access logs are disabled by default on Amazon S3. To enable logging, see
  # http://docs.amazonwebservices.com/AmazonS3/latest/index.html?ServerLogs.html
  class AmazonS3 < Base
    extend CommonRegularExpressions

    line_definition :access do |line|
      line.header = true
      line.footer = true
      line.regexp = /^([^\ ]+) ([^\ ]+) \[(#{timestamp('%d/%b/%Y:%H:%M:%S %z')})?\] (#{ip_address}) ([^\ ]+) ([^\ ]+) (\w+(?:\.\w+)*) ([^\ ]+) "([^"]+)" (\d+) ([^\ ]+) ([^\ ]+) (\d+) (\d+) ([^\ ]+) "([^"]*)" "([^"]*)"/

      line.capture(:bucket_owner)
      line.capture(:bucket)
      line.capture(:timestamp).as(:timestamp)
      line.capture(:remote_ip)
      line.capture(:requester)
      line.capture(:request_id)
      line.capture(:operation)
      line.capture(:key).as(:nillable_string)
      line.capture(:request_uri)
      line.capture(:http_status).as(:integer)
      line.capture(:error_code).as(:nillable_string)
      line.capture(:bytes_sent).as(:traffic, unit: :byte)
      line.capture(:object_size).as(:traffic, unit: :byte)
      line.capture(:total_time).as(:duration, unit: :msec)
      line.capture(:turnaround_time).as(:duration, unit: :msec)
      line.capture(:referer).as(:referer)
      line.capture(:user_agent).as(:user_agent)
    end

    report do |analyze|
      analyze.timespan
      analyze.hourly_spread

      analyze.frequency category: lambda { |r| "#{r[:bucket]}/#{r[:key]}" }, title: 'Most popular items'
      analyze.duration duration: :total_time, category: lambda { |r| "#{r[:bucket]}/#{r[:key]}" }, title: 'Request duration'
      analyze.traffic traffic: :bytes_sent,  category: lambda { |r| "#{r[:bucket]}/#{r[:key]}" }, title: 'Traffic'
      analyze.frequency category: :http_status, title: 'HTTP status codes'
      analyze.frequency category: :error_code, title: 'Error codes'
    end

    class Request < RequestLogAnalyzer::Request
      MONTHS = { 'Jan' => '01', 'Feb' => '02', 'Mar' => '03', 'Apr' => '04', 'May' => '05', 'Jun' => '06',
                'Jul' => '07', 'Aug' => '08', 'Sep' => '09', 'Oct' => '10', 'Nov' => '11', 'Dec' => '12' }

      # Do not use DateTime.parse, but parse the timestamp ourselves to return a integer
      # to speed up parsing.
      def convert_timestamp(value, _definition)
        "#{value[7, 4]}#{MONTHS[value[3, 3]]}#{value[0, 2]}#{value[12, 2]}#{value[15, 2]}#{value[18, 2]}".to_i
      end

      # Make sure that the string '-' is parsed as a nil value.
      def convert_nillable_string(value, _definition)
        value == '-' ? nil : value
      end

      # Can be implemented in subclasses for improved categorizations
      def convert_referer(value, _definition)
        value == '-' ? nil : value
      end

      # Can be implemented in subclasses for improved categorizations
      def convert_user_agent(value, _definition)
        value == '-' ? nil : value
      end
    end
  end
end