# frozen_string_literal: true

require "datadog/tracing/contrib/integration"
require "datadog/tracing/contrib/configuration/settings"
require "datadog/tracing/contrib/patcher"

module Datadog::Tracing
  module Contrib
    module HTTPX
      DATADOG_VERSION = defined?(::DDTrace) ? ::DDTrace::VERSION : ::Datadog::VERSION

      METADATA_MODULE = Datadog::Tracing::Metadata

      TYPE_OUTBOUND = Datadog::Tracing::Metadata::Ext::HTTP::TYPE_OUTBOUND

      TAG_BASE_SERVICE = if Gem::Version.new(DATADOG_VERSION::STRING) < Gem::Version.new("1.15.0")
        "_dd.base_service"
      else
        Datadog::Tracing::Contrib::Ext::Metadata::TAG_BASE_SERVICE
      end
      TAG_PEER_HOSTNAME = Datadog::Tracing::Metadata::Ext::TAG_PEER_HOSTNAME

      TAG_KIND = Datadog::Tracing::Metadata::Ext::TAG_KIND
      TAG_CLIENT = Datadog::Tracing::Metadata::Ext::SpanKind::TAG_CLIENT
      TAG_COMPONENT = Datadog::Tracing::Metadata::Ext::TAG_COMPONENT
      TAG_OPERATION = Datadog::Tracing::Metadata::Ext::TAG_OPERATION
      TAG_URL = Datadog::Tracing::Metadata::Ext::HTTP::TAG_URL
      TAG_METHOD = Datadog::Tracing::Metadata::Ext::HTTP::TAG_METHOD
      TAG_TARGET_HOST = Datadog::Tracing::Metadata::Ext::NET::TAG_TARGET_HOST
      TAG_TARGET_PORT = Datadog::Tracing::Metadata::Ext::NET::TAG_TARGET_PORT

      TAG_STATUS_CODE = Datadog::Tracing::Metadata::Ext::HTTP::TAG_STATUS_CODE

      # HTTPX Datadog Plugin
      #
      # Enables tracing for httpx requests.
      #
      # A span will be created for each request transaction; the span is created lazily only when
      # buffering a request, and it is fed the start time stored inside the tracer object.
      #
      module Plugin
        module RequestTracer
          extend Contrib::HttpAnnotationHelper

          module_function

          SPAN_REQUEST = "httpx.request"

          # initializes tracing on the +request+.
          def call(request)
            return unless configuration(request).enabled

            span = nil

            # request objects are reused, when already buffered requests get rerouted to a different
            # connection due to connection issues, or when they already got a response, but need to
            # be retried. In such situations, the original span needs to be extended for the former,
            # while a new is required for the latter.
            request.on(:idle) do
              span = nil
            end
            # the span is initialized when the request is buffered in the parser, which is the closest
            # one gets to actually sending the request.
            request.on(:headers) do
              next if span

              span = initialize_span(request, now)
            end

            request.on(:response) do |response|
              span = initialize_span(request, request.init_time) if !span && request.init_time

              finish(response, span)
            end
          end

          def finish(response, span)
            if response.is_a?(::HTTPX::ErrorResponse)
              span.set_error(response.error)
            else
              span.set_tag(TAG_STATUS_CODE, response.status.to_s)

              span.set_error(::HTTPX::HTTPError.new(response)) if response.status >= 400 && response.status <= 599

              span.set_tags(
                Datadog.configuration.tracing.header_tags.response_tags(response.headers.to_h)
              ) if Datadog.configuration.tracing.respond_to?(:header_tags)
            end

            span.finish
          end

          # return a span initialized with the +@request+ state.
          def initialize_span(request, start_time)
            verb = request.verb
            uri = request.uri

            config = configuration(request)

            span = create_span(request, config, start_time)

            span.resource = verb

            # Tag original global service name if not used
            span.set_tag(TAG_BASE_SERVICE, Datadog.configuration.service) if span.service != Datadog.configuration.service

            span.set_tag(TAG_KIND, TAG_CLIENT)

            span.set_tag(TAG_COMPONENT, "httpx")
            span.set_tag(TAG_OPERATION, "request")

            span.set_tag(TAG_URL, request.path)
            span.set_tag(TAG_METHOD, verb)

            span.set_tag(TAG_TARGET_HOST, uri.host)
            span.set_tag(TAG_TARGET_PORT, uri.port)

            span.set_tag(TAG_PEER_HOSTNAME, uri.host)

            # Tag as an external peer service
            # span.set_tag(TAG_PEER_SERVICE, span.service)

            if config[:distributed_tracing]
              propagate_trace_http(
                Datadog::Tracing.active_trace,
                request.headers
              )
            end

            # Set analytics sample rate
            if Contrib::Analytics.enabled?(config[:analytics_enabled])
              Contrib::Analytics.set_sample_rate(span, config[:analytics_sample_rate])
            end

            span.set_tags(
              Datadog.configuration.tracing.header_tags.request_tags(request.headers.to_h)
            ) if Datadog.configuration.tracing.respond_to?(:header_tags)

            span
          rescue StandardError => e
            Datadog.logger.error("error preparing span for http request: #{e}")
            Datadog.logger.error(e.backtrace)
          end

          def now
            ::Datadog::Core::Utils::Time.now.utc
          end

          def configuration(request)
            Datadog.configuration.tracing[:httpx, request.uri.host]
          end

          if Gem::Version.new(DATADOG_VERSION::STRING) >= Gem::Version.new("2.0.0")
            def propagate_trace_http(trace, headers)
              Datadog::Tracing::Contrib::HTTP.inject(trace, headers)
            end

            def create_span(request, configuration, start_time)
              Datadog::Tracing.trace(
                SPAN_REQUEST,
                service: service_name(request.uri.host, configuration),
                type: TYPE_OUTBOUND,
                start_time: start_time
              )
            end
          else
            def propagate_trace_http(trace, headers)
              Datadog::Tracing::Propagation::HTTP.inject!(trace.to_digest, headers)
            end

            def create_span(request, configuration, start_time)
              Datadog::Tracing.trace(
                SPAN_REQUEST,
                service: service_name(request.uri.host, configuration),
                span_type: TYPE_OUTBOUND,
                start_time: start_time
              )
            end
          end
        end

        module RequestMethods
          attr_accessor :init_time

          # intercepts request initialization to inject the tracing logic.
          def initialize(*)
            super

            @init_time = nil

            return unless Datadog::Tracing.enabled?

            RequestTracer.call(self)
          end

          def response=(*)
            # init_time should be set when it's send to a connection.
            # However, there are situations where connection initialization fails.
            # Example is the :ssrf_filter plugin, which raises an error on
            # initialize if the host is an IP which matches against the known set.
            # in such cases, we'll just set here right here.
            @init_time ||= ::Datadog::Core::Utils::Time.now.utc

            super
          end
        end

        module ConnectionMethods
          def initialize(*)
            super

            @init_time = ::Datadog::Core::Utils::Time.now.utc
          end

          def send(request)
            request.init_time ||= @init_time

            super
          end
        end
      end

      module Configuration
        # Default settings for httpx
        #
        class Settings < Datadog::Tracing::Contrib::Configuration::Settings
          DEFAULT_ERROR_HANDLER = lambda do |response|
            Datadog::Ext::HTTP::ERROR_RANGE.cover?(response.status)
          end

          option :service_name, default: "httpx"
          option :distributed_tracing, default: true
          option :split_by_domain, default: false

          if Gem::Version.new(DATADOG_VERSION::STRING) >= Gem::Version.new("1.13.0")
            option :enabled do |o|
              o.type :bool
              o.env "DD_TRACE_HTTPX_ENABLED"
              o.default true
            end

            option :analytics_enabled do |o|
              o.type :bool
              o.env "DD_TRACE_HTTPX_ANALYTICS_ENABLED"
              o.default false
            end

            option :analytics_sample_rate do |o|
              o.type :float
              o.env "DD_TRACE_HTTPX_ANALYTICS_SAMPLE_RATE"
              o.default 1.0
            end
          else
            option :enabled do |o|
              o.default { env_to_bool("DD_TRACE_HTTPX_ENABLED", true) }
              o.lazy
            end

            option :analytics_enabled do |o|
              o.default { env_to_bool(%w[DD_TRACE_HTTPX_ANALYTICS_ENABLED DD_HTTPX_ANALYTICS_ENABLED], false) }
              o.lazy
            end

            option :analytics_sample_rate do |o|
              o.default { env_to_float(%w[DD_TRACE_HTTPX_ANALYTICS_SAMPLE_RATE DD_HTTPX_ANALYTICS_SAMPLE_RATE], 1.0) }
              o.lazy
            end
          end

          if defined?(Datadog::Tracing::Contrib::SpanAttributeSchema)
            option :service_name do |o|
              o.default do
                Datadog::Tracing::Contrib::SpanAttributeSchema.fetch_service_name(
                  "DD_TRACE_HTTPX_SERVICE_NAME",
                  "httpx"
                )
              end
              o.lazy unless Gem::Version.new(DATADOG_VERSION::STRING) >= Gem::Version.new("1.13.0")
            end
          else
            option :service_name do |o|
              o.default do
                ENV.fetch("DD_TRACE_HTTPX_SERVICE_NAME", "httpx")
              end
              o.lazy unless Gem::Version.new(DATADOG_VERSION::STRING) >= Gem::Version.new("1.13.0")
            end
          end

          option :distributed_tracing, default: true

          if Gem::Version.new(DATADOG_VERSION::STRING) >= Gem::Version.new("1.15.0")
            option :error_handler do |o|
              o.type :proc
              o.default_proc(&DEFAULT_ERROR_HANDLER)
            end
          elsif Gem::Version.new(DATADOG_VERSION::STRING) >= Gem::Version.new("1.13.0")
            option :error_handler do |o|
              o.type :proc
              o.experimental_default_proc(&DEFAULT_ERROR_HANDLER)
            end
          else
            option :error_handler, default: DEFAULT_ERROR_HANDLER
          end
        end
      end

      # Patcher enables patching of 'httpx' with datadog components.
      #
      module Patcher
        include Datadog::Tracing::Contrib::Patcher

        module_function

        def target_version
          Integration.version
        end

        # loads a session instannce with the datadog plugin, and replaces the
        # base HTTPX::Session with the patched session class.
        def patch
          datadog_session = ::HTTPX.plugin(Plugin)

          ::HTTPX.send(:remove_const, :Session)
          ::HTTPX.send(:const_set, :Session, datadog_session.class)
        end
      end

      # Datadog Integration for HTTPX.
      #
      class Integration
        include Contrib::Integration

        MINIMUM_VERSION = Gem::Version.new("0.10.2")

        register_as :httpx

        def self.version
          Gem.loaded_specs["httpx"] && Gem.loaded_specs["httpx"].version
        end

        def self.loaded?
          defined?(::HTTPX::Request)
        end

        def self.compatible?
          super && version >= MINIMUM_VERSION
        end

        def new_configuration
          Configuration::Settings.new
        end

        def patcher
          Patcher
        end
      end
    end
  end
end
