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


module AppOpticsAPM
  class XTraceOptions

    attr_reader :options, :signature, :trigger_trace, :timestamp
    attr_reader :pd_keys, :custom_kvs, :ignored # used in tests
    ##
    # Params:
    # +options+ : An X-Trace-Options @options string
    # +signature+ : hmac signature to pass on for verification
    #
    # populates:
    # - @force_trace (true|false)
    # - @app_id (as given by Pingdom)
    # - @probe_id (as given by Pingdom)
    # - @loc (2 characters given by Pingdom)
    # - @custom_kvs (hash)
    # - @ignored (array)
    #
    # split it up by ';' separator
    # kv assignment by '='
    # currently valid keys:
    # - force_trace (valid: 0,1) unless we use just a kv
    # - application_id (format defined by pingdom (no validation))
    # - probe_id
    # - custom_* (';=' not allowed in key), value (validate max. length)
    # - ts (unix timestamp)
    # - other keys will be reported in the response options as ignored

    def initialize(options, signature = nil)
      @options = options.dup
      @signature = signature.dup
      @trigger_trace = false
      @custom_kvs = {}
      @pd_keys = nil
      @ignored = []
      @timestamp = 0

      options&.split(/;+/)&.each do |val|
        k = val.split('=', 2)

        next unless k[0] # it can be nil, eg when the header starts with ';'

        k[0]&.strip!
        case k[0]
        when 'trigger-trace'
          if k[1]
            @ignored << 'trigger-trace'
          else
            @trigger_trace = true
          end
        when 'pd-keys'
          if @pd_keys
            AppOpticsAPM.logger.info "[appoptics_apm/x-trace-options] Duplicate key: #{k[0]}"
          else
            @pd_keys = k[1].strip
          end
        when /^custom-[^\s]*$/
          if @custom_kvs[k[0]]
            AppOpticsAPM.logger.info "[appoptics_apm/x-trace-options] Duplicate key: #{k[0]}"
          else
            @custom_kvs[k[0]] = k[1].strip
          end
        when 'ts'
          if @timestamp > 0
            AppOpticsAPM.logger.info "[appoptics_apm/x-trace-options] Duplicate key: #{k[0]}"
          else
            @timestamp = k[1].to_i
          end
        else
          @ignored << k[0]
        end
      end
      unless @ignored.empty?
        msg = "[appoptics_apm/x-trace-options] Some keys were ignored: #{@ignored.join(',' )}"
        AppOpticsAPM.logger.info(msg)
      end
    end

    def add_kvs(kvs, settings)
      return unless settings.auth_ok?

      @custom_kvs.each { |k,v| kvs[k] = v } unless @custom_kvs.empty?
      kvs['PDKeys'] = @pd_keys if @pd_keys
      kvs['TriggeredTrace'] = true if settings.triggered_trace?
    end

    def add_response_header(headers, settings)
      return unless options

      response = []
      response << "auth=#{settings.auth_msg}" if @signature
      if settings.auth_ok?
        if @trigger_trace
          trigger_msg = !settings.xtrace.empty? && settings.type == 0 ? 'ignored' : settings.status_msg
        else
          trigger_msg = 'not-requested'
        end
        response << "trigger-trace=#{trigger_msg}"
        response << "ignored=#{@ignored.join(',')}" unless @ignored.empty?
      end

      headers['X-Trace-Options-Response'] = response.join(';')
    end

  end
end