# Copyright (c) 2023 Contrast Security, Inc. See https://www.contrastsecurity.com/enduser-terms-0317a for more details.
# frozen_string_literal: true

require 'net/http'
require 'contrast/utils/net_http_base'
require 'contrast/components/logger'
require 'contrast/utils/object_share'
require 'contrast/agent/version'
require 'json'

module Contrast
  module Agent
    module Telemetry
      # This module creates a Net::HTTP client and initiates a connection to the provided result
      class Client < Contrast::Utils::NetHttpBase
        include Contrast::Components::Logger::InstanceMethods
        ENDPOINT = 'api/v1/telemetry/metrics' # /TelemetryEvent.path
        EXCEPTIONS = 'api/v1/telemetry/exceptions' # /Telemetry::Exception::Event.path
        SERVICE_NAME = 'Telemetry'
        # This method initializes the Net::HTTP client we'll need. it will validate
        # the connection and make the first request. If connection is valid and response
        # is available then the open connection is returned.
        #
        # @param url [String]
        # @return [Net::HTTP, nil] Return open connection or nil
        def initialize_connection url
          super(SERVICE_NAME, url, use_proxy: false, use_custom_cert: false)
        end

        # This method will be responsible for building the request. Because the telemetry collector expects to receive
        # multiple events in a single request, we must always wrap the event in an array, even if there is only one.
        #
        # @param event [Contrast::Agent::Telemetry::Event, Array<Contrast::Agent::Telemetry::Exception::Event>]
        # @return [Net::HTTP::Post]
        def build_request event
          return unless valid_event?(event)

          header = {
              'User-Agent' => "<#{ Contrast::Utils::ObjectShare::RUBY }>-<#{ Contrast::Agent::VERSION }>",
              'Content-Type' => 'application/json'
          }
          request = Net::HTTP::Post.new(build_path(event), header)
          request.body = get_event_json(event)
          request
        end

        # This method will create the actual request and send it
        # @param event[Contrast::Agent::Telemetry::Event]
        # @param connection[Net::HTTP]
        def send_request event, connection
          return if connection.nil? || event.nil?
          return unless valid_event?(event)

          req = build_request(event)
          connection.request(req)
        end

        # This method will handle the response from the tenant
        # @param res [Net::HTTPResponse]
        # @return sleep_time [Integer, nil]
        def handle_response res
          status_code = res.code.to_i
          ready_after = if res.to_hash.keys.map(&:downcase).include?('ready-after')
                          res['Ready-After']
                        else
                          60
                        end
          ready_after if status_code == 429
        end

        # This method will be responsible for validating the event. Valid if event is of a known
        # Contrast::Agent::Telemetry type
        #
        # @param event [Object]
        def valid_event? event
          return true if event.cs__is_a?(Contrast::Agent::Telemetry::Event)
          return true if event.cs__is_a?(Contrast::Agent::Telemetry::StartupMetricsEvent)
          return true if event.cs__is_a?(Contrast::Agent::Telemetry::Exception::Event)

          false
        end

        private

        # The telemetry instance accepts any path to #{ Contrast::Agent::Telemetry::URL }#{ ENDPOINT }, using the
        # remainder of the path to segregate messages.
        #
        # @param event [Contrast::Agent::Telemetry::Event, Contrast::Agent::Telemetry::Exception::Event]
        # @return [String] the fully qualified path to send the request
        def build_path event
          endpoint = Array(event).all?(Contrast::Agent::Telemetry::Exception::Event) ? EXCEPTIONS : ENDPOINT
          path = endpoint == EXCEPTIONS ? Contrast::Agent::Telemetry::Exception::Event.path : event.path
          "#{ Contrast::Agent::Telemetry::Base::URL }#{ endpoint }#{ path }"
        end

        # Helper Method to get json representation of Telemetry Event data, handles error on to_json
        #
        # @param event [Contrast::Agent::Telemetry::Event, Array<Contrast::Agent::Telemetry::Exception::Event>]
        # @return [String] - JSON
        def get_event_json event
          Array(event.to_controlled_hash).to_json
        rescue Exception => e # rubocop:disable Lint/RescueException
          logger.error('[Telemetry] Unable to convert TelemetryEvent to JSON string', e, hsh)
          raise(e)
        end
      end
    end
  end
end