# This file is distributed under New Relic's license terms.
# See https://github.com/newrelic/newrelic-ruby-agent/blob/main/LICENSE for complete details.
# frozen_string_literal: true

require 'new_relic/agent/error_trace_aggregator'
require 'new_relic/agent/error_event_aggregator'

module NewRelic
  module Agent
    # This class collects errors from the parent application, storing
    # them until they are harvested and transmitted to the server
    class ErrorCollector
      # Maximum possible length of the queue - defaults to 20, may be
      # made configurable in the future. This is a tradeoff between
      # memory and data retention
      MAX_ERROR_QUEUE_LENGTH = 20
      EXCEPTION_TAG_IVAR = :'@__nr_seen_exception'

      attr_reader :error_trace_aggregator, :error_event_aggregator

      # Returns a new error collector
      def initialize(events)
        @error_trace_aggregator = ErrorTraceAggregator.new(MAX_ERROR_QUEUE_LENGTH)
        @error_event_aggregator = ErrorEventAggregator.new(events)

        @error_filter = NewRelic::Agent::ErrorFilter.new

        %w[
          ignore_classes ignore_messages ignore_status_codes
          expected_classes expected_messages expected_status_codes
        ].each do |w|
          Agent.config.register_callback(:"error_collector.#{w}") do |value|
            @error_filter.load_from_config(w, value)
          end
        end
      end

      def enabled?
        error_trace_aggregator.enabled? || error_event_aggregator.enabled?
      end

      def disabled?
        !enabled?
      end

      # We store the passed block in both an ivar on the class, and implicitly
      # within the body of the ignore_filter_proc method intentionally here.
      # The define_method trick is needed to get around the fact that users may
      # call 'return' from within their filter blocks, which would otherwise
      # result in a LocalJumpError.
      #
      # The raw block is also stored in an instance variable so that we can
      # return it later in its original form.
      #
      # This is all done at the class level in order to avoid the case where
      # the user sets up an ignore filter on one instance of the ErrorCollector,
      # and then that instance subsequently gets discarded during agent startup.
      # (For example, if the agent is initially disabled, and then gets enabled
      # via a call to manual_start later on.)
      #
      def self.ignore_error_filter=(block)
        @ignore_filter = block
        if block
          define_method(:ignore_filter_proc, &block)
        elsif method_defined?(:ignore_filter_proc)
          remove_method(:ignore_filter_proc)
        end
        @ignore_filter
      end

      def self.ignore_error_filter
        defined?(@ignore_filter) ? @ignore_filter : nil
      end

      def ignore(errors)
        @error_filter.ignore(errors)
      end

      def ignore?(ex, status_code = nil)
        @error_filter.ignore?(ex, status_code)
      end

      def expect(errors)
        @error_filter.expect(errors)
      end

      def expected?(ex, status_code = nil)
        @error_filter.expected?(ex, status_code)
      end

      def load_error_filters
        @error_filter.load_all
      end

      def reset_error_filters
        @error_filter.reset
      end

      # Checks the provided error against the error filter, if there
      # is an error filter
      def ignored_by_filter_proc?(error)
        respond_to?(:ignore_filter_proc) && !ignore_filter_proc(error)
      end

      # an error is ignored if it is nil or if it is filtered
      def error_is_ignored?(error, status_code = nil)
        error && (@error_filter.ignore?(error, status_code) || ignored_by_filter_proc?(error))
      rescue => e
        NewRelic::Agent.logger.error("Error '#{error}' will NOT be ignored. Exception '#{e}' while determining whether to ignore or not.", e)
        false
      end

      # Calling instance_variable_set on a wrapped Java object in JRuby will
      # generate a warning unless that object's class has already been marked
      # as persistent, so we skip tagging of exception objects that are actually
      # wrapped Java objects on JRuby.
      #
      # See https://github.com/jruby/jruby/wiki/Persistence
      #
      def exception_is_java_object?(exception)
        NewRelic::LanguageSupport.jruby? && exception.respond_to?(:java_class)
      end

      def exception_tagged_with?(ivar, exception)
        return false if exception_is_java_object?(exception)

        exception.instance_variable_defined?(ivar)
      end

      def tag_exception_using(ivar, exception)
        return if exception_is_java_object?(exception) || exception.frozen?

        begin
          exception.instance_variable_set(ivar, true)
        rescue => e
          NewRelic::Agent.logger.warn("Failed to tag exception: #{exception}: ", e)
        end
      end

      def tag_exception(exception)
        return if exception_is_java_object?(exception) || exception.frozen?

        begin
          exception.instance_variable_set(EXCEPTION_TAG_IVAR, true)
        rescue => e
          NewRelic::Agent.logger.warn("Failed to tag exception: #{exception}: ", e)
        end
      end

      def blamed_metric_name(txn, options)
        if options[:metric] && options[:metric] != ::NewRelic::Agent::UNKNOWN_METRIC
          "Errors/#{options[:metric]}"
        else
          "Errors/#{txn.best_name}" if txn
        end
      end

      def aggregated_metric_names(txn)
        metric_names = ['Errors/all']
        return metric_names unless txn

        if txn.recording_web_transaction?
          metric_names << 'Errors/allWeb'
        else
          metric_names << 'Errors/allOther'
        end

        metric_names
      end

      # Increments a statistic that tracks total error rate
      def increment_error_count!(state, exception, options = {})
        txn = state.current_transaction

        metric_names = aggregated_metric_names(txn)
        blamed_metric = blamed_metric_name(txn, options)
        metric_names << blamed_metric if blamed_metric

        stats_engine = NewRelic::Agent.agent.stats_engine
        stats_engine.record_unscoped_metrics(state, metric_names) do |stats|
          stats.increment_count
        end
      end

      def increment_expected_error_count!(state, exception)
        stats_engine = NewRelic::Agent.agent.stats_engine
        stats_engine.record_unscoped_metrics(state, ['ErrorsExpected/all']) do |stats|
          stats.increment_count
        end
      end

      def skip_notice_error?(exception, status_code = nil)
        disabled? ||
          exception.nil? ||
          exception_tagged_with?(EXCEPTION_TAG_IVAR, exception) ||
          error_is_ignored?(exception, status_code)
      end

      # calls a method on an object, if it responds to it - used for
      # detection and soft fail-safe. Returns nil if the method does
      # not exist
      def sense_method(object, method)
        object.__send__(method) if object.respond_to?(method)
      end

      # extracts a stack trace from the exception for debugging purposes
      def extract_stack_trace(exception)
        actual_exception = if defined?(Rails::VERSION::MAJOR) && Rails::VERSION::MAJOR < 5
          sense_method(exception, :original_exception) || exception
        else
          exception
        end
        sense_method(actual_exception, :backtrace) || '<no stack trace>'
      end

      def notice_segment_error(segment, exception, options = {})
        return if skip_notice_error?(exception)

        segment.set_noticed_error(create_noticed_error(exception, options))
        exception
      rescue => e
        ::NewRelic::Agent.logger.warn("Failure when capturing segment error '#{exception}':", e)
        nil
      end

      # See NewRelic::Agent.notice_error for options and commentary
      def notice_error(exception, options = {}, span_id = nil)
        state = ::NewRelic::Agent::Tracer.state
        transaction = state.current_transaction
        status_code = transaction&.http_response_code

        return if skip_notice_error?(exception, status_code)

        tag_exception(exception)

        if options[:expected] || @error_filter.expected?(exception, status_code)
          increment_expected_error_count!(state, exception)
        else
          increment_error_count!(state, exception, options)
        end

        noticed_error = create_noticed_error(exception, options)
        error_trace_aggregator.add_to_error_queue(noticed_error)
        transaction = state.current_transaction
        payload = transaction&.payload
        span_id ||= transaction&.current_segment ? transaction.current_segment.guid : nil
        error_event_aggregator.record(noticed_error, payload, span_id)
        exception
      rescue => e
        ::NewRelic::Agent.logger.warn("Failure when capturing error '#{exception}':", e)
        nil
      end

      def truncate_trace(trace, keep_frames = nil)
        keep_frames ||= Agent.config[:'error_collector.max_backtrace_frames']
        return trace if !keep_frames || trace.length < keep_frames || trace.length == 0

        # If keep_frames is odd, we will split things up favoring the top of the trace
        keep_top = (keep_frames / 2.0).ceil
        keep_bottom = (keep_frames / 2.0).floor

        truncate_frames = trace.length - keep_frames

        truncated_trace = trace[0...keep_top].concat(["<truncated #{truncate_frames.to_s} additional frames>"]).concat(trace[-keep_bottom..-1])
        truncated_trace
      end

      def create_noticed_error(exception, options)
        error_metric = options.delete(:metric) || NewRelic::EMPTY_STR

        noticed_error = NewRelic::NoticedError.new(error_metric, exception)
        noticed_error.request_uri = options.delete(:uri) || NewRelic::EMPTY_STR
        noticed_error.request_port = options.delete(:port)
        noticed_error.attributes = options.delete(:attributes)

        noticed_error.file_name = sense_method(exception, :file_name)
        noticed_error.line_number = sense_method(exception, :line_number)
        noticed_error.stack_trace = truncate_trace(extract_stack_trace(exception))

        noticed_error.expected = !options.delete(:expected).nil? || expected?(exception)

        noticed_error.attributes_from_notice_error = options.delete(:custom_params) || {}

        # Any options that are passed to notice_error which aren't known keys
        # get treated as custom attributes, so merge them into that hash.
        noticed_error.attributes_from_notice_error.merge!(options)

        update_error_group_name(noticed_error, exception, options)

        noticed_error
      end

      # *Use sparingly for difficult to track bugs.*
      #
      # Track internal agent errors for communication back to New Relic.
      # To use, make a specific subclass of NewRelic::Agent::InternalAgentError,
      # then pass an instance of it to this method when your problem occurs.
      #
      # Limits are treated differently for these errors. We only gather one per
      # class per harvest, disregarding (and not impacting) the app error queue
      # limit.
      def notice_agent_error(exception)
        @error_trace_aggregator.notice_agent_error(exception)
      end

      def drop_buffered_data
        @error_trace_aggregator.reset!
        @error_event_aggregator.reset!
        nil
      end

      private

      def update_error_group_name(noticed_error, exception, options)
        return unless error_group_callback

        callback_hash = build_customer_callback_hash(noticed_error, exception, options)
        result = error_group_callback.call(callback_hash)
        noticed_error.error_group = result
      rescue StandardError => e
        NewRelic::Agent.logger.error("Failed to obtain error group from customer callback: #{e.class} - #{e.message}")
      end

      def build_customer_callback_hash(noticed_error, exception, options)
        {error: exception,
         customAttributes: noticed_error.custom_attributes,
         'request.uri': noticed_error.request_uri,
         'http.statusCode': noticed_error.agent_attributes[:'http.statusCode'],
         'http.method': noticed_error.intrinsic_attributes[:'http.method'],
         'error.expected': noticed_error.expected,
         options: options}
      end

      def error_group_callback
        NewRelic::Agent.error_group_callback
      end
    end
  end
end