# Copyright (c) 2019 SolarWinds, LLC.
# All rights reserved.

require 'singleton'

module AppOpticsAPM

  class OboeInitOptions
    include Singleton

    attr_reader :reporter, :host, :service_name  # exposing these mainly for testing

    # TODO decide if these globals are useful when testing
    # OBOE_HOSTNAME_ALIAS = 0
    # OBOE_DEBUG_LEVEL = 1
    # OBOE_LOGFILE = 2
    #
    # OBOE_MAX_TRANSACTIONS = 3
    # OBOE_FLUSH_MAX_WAIT_TIME = 4
    # OBOE_EVENTS_FLUSH_INTERVAL = 5
    # OBOE_EVENTS_FLUSH_BATCH_SIZE = 6
    #
    # OBOE_REPORTER = 7
    # OBOE_COLLECTOR = 8
    # OBOE_SERVICE_KEY = 9
    # OBOE_TRUSTEDPATH = 10
    #
    # OBOE_BUFSIZE = 11
    # OBOE_TRACE_METRICS = 12
    # OBOE_HISTOGRAM_PRECISION = 13
    # OBOE_TOKEN_BUCKET_CAPACITY = 14
    # OBOE_TOKEN_BUCKET_RATE = 15
    # OBOE_FILE_SINGLE = 16

    def initialize
      # optional hostname alias
      @hostname_alias = ENV['APPOPTICS_HOSTNAME_ALIAS'] || AppOpticsAPM::Config[:hostname_alias] || ''
      # level at which log messages will be written to log file (0-6)
      @debug_level = (ENV['APPOPTICS_DEBUG_LEVEL'] || AppOpticsAPM::Config[:debug_level] || 3).to_i
      # file name including path for log file
      # TODO eventually find better way to combine ruby and oboe logs
      @log_file_path = ENV['APPOPTICS_LOGFILE'] || ''
      # maximum number of transaction names to track
      @max_transactions = (ENV['APPOPTICS_MAX_TRANSACTIONS'] || -1).to_i
      # maximum wait time for flushing data before terminating in milli seconds
      @max_flush_wait_time = (ENV['APPOPTICS_FLUSH_MAX_WAIT_TIME'] || -1).to_i
      # events flush timeout in seconds (threshold for batching messages before sending off)
      @events_flush_interval = (ENV['APPOPTICS_EVENTS_FLUSH_INTERVAL'] || -1).to_i
      # events flush batch size in KB (threshold for batching messages before sending off)
      @event_flush_batch_size = (ENV['APPOPTICS_EVENTS_FLUSH_BATCH_SIZE'] || -1).to_i

      # the reporter to be used (ssl, upd, file, null)
      # collector endpoint (reporter=ssl), udp address (reporter=udp), or file path (reporter=file)
      @reporter, @host = reporter_and_host

      # the service key
      @service_key = read_and_validate_service_key
      # path to the SSL certificate (only for ssl)
      @trusted_path = ENV['APPOPTICS_TRUSTEDPATH'] || ''
      # size of the message buffer
      @buffer_size = (ENV['APPOPTICS_BUFSIZE'] || -1).to_i
      # flag indicating if trace metrics reporting should be enabled (default) or disabled
      @trace_metrics = (ENV['APPOPTICS_TRACE_METRICS'] || -1).to_i
      # the histogram precision (only for ssl)
      @histogram_precision = (ENV['APPOPTICS_HISTOGRAM_PRECISION'] || -1).to_i
      # custom token bucket capacity
      @token_bucket_capacity = (ENV['APPOPTICS_TOKEN_BUCKET_CAPACITY'] || -1).to_i
      # custom token bucket rate
      @token_bucket_rate = (ENV['APPOPTICS_TOKEN_BUCKET_RATE'] || -1).to_i
      # use single files in file reporter for each event
      @file_single = (ENV['APPOPTICS_REPORTER_FILE_SINGLE'].to_s.downcase == 'true') ? 1 : 0
    end

    def re_init # for testing with changed ENV vars
      initialize
    end

    def array_for_oboe
      [
        @hostname_alias,
        @debug_level,
        @log_file_path,
        @max_transactions,
        @max_flush_wait_time,
        @events_flush_interval,
        @event_flush_batch_size,

        @reporter,
        @host,
        @service_key,
        @trusted_path,
        @buffer_size,
        @trace_metrics,
        @histogram_precision,
        @token_bucket_capacity,
        @token_bucket_rate,
        @file_single
      ]
    end

    def service_key_ok?
      return !@service_key.empty? || @reporter != 'ssl'
    end

    private

    def reporter_and_host

      reporter = ENV['APPOPTICS_REPORTER'] || 'ssl'
      # override with 'file', e.g. when running tests
      # changed my mind => set the right reporter in the env when running tests !!!
      # reporter = 'file' if ENV.key?('APPOPTICS_GEM_TEST')

      host = ''
      case reporter
      when 'ssl', 'file'
        host = ENV['APPOPTICS_COLLECTOR'] || ''
      when 'udp'
        host = ENV['APPOPTICS_COLLECTOR'] ||
                "#{AppOpticsAPM::Config[:reporter_host]}:#{AppOpticsAPM::Config[:reporter_port]}"
        # TODO decide what to do
        # ____ AppOpticsAPM::Config[:reporter_host] and
        # ____ AppOpticsAPM::Config[:reporter_port] were moved here from
        # ____ oboe_metal.rb and are not documented anywhere
        # ____ udp is for internal use only
      when 'null'
        host = ''
      end

      [reporter, host]
    end

    def read_and_validate_service_key
      return '' unless @reporter == 'ssl'

      service_key = ENV['APPOPTICS_SERVICE_KEY'] || AppOpticsAPM::Config[:service_key]
      unless service_key
        AppOpticsAPM.logger.error "[appoptics_apm/oboe_options] APPOPTICS_SERVICE_KEY not configured."
        return ''
      end

      match = service_key.match( /([^:]+)(:{0,1})(.*)/ )
      token = match[1]
      service_name = match[3]

      return '' unless validate_token(token)
      return '' unless validate_transform_service_name(service_name)

      return "#{token}:#{service_name}"
    end

    def validate_token(token)
      if (token !~ /^[0-9a-fA-F]{64}|[0-9a-zA-Z_\-]{71}$/) && ENV['APPOPTICS_COLLECTOR'] != "sslcollector:12222"
        masked = "#{token[0..3]}...#{token[-4..-1]}"
        AppOpticsAPM.logger.error "[appoptics_apm/oboe_options] APPOPTICS_SERVICE_KEY problem. API Token in wrong format. Masked token: #{masked}"
        return false
      end

      true
    end

    def validate_transform_service_name(service_name)
      service_name = 'test_ssl_collector' if ENV['APPOPTICS_COLLECTOR'] == "sslcollector:12222"
      if service_name.empty?
        AppOpticsAPM.logger.error "[appoptics_apm/oboe_options] APPOPTICS_SERVICE_KEY problem. Service Name is missing"
        return false
      end

      name = service_name.dup
      name.downcase!
      name.gsub!(/[^a-z0-9.:_-]/, '')
      name = name[0..254]

      if name != service_name
        AppOpticsAPM.logger.warn "[appoptics_apm/oboe_options] APPOPTICS_SERVICE_KEY problem. Service Name transformed from #{service_name} to #{name}"
        service_name = name
      end
      @service_name = service_name # instance variable used in testing
      true
    end
  end
end