public function parseHeadersImpl()

in agent/php/ElasticApm/Impl/HttpDistributedTracing.php [122:174]
42 lines of code
7 McCabe index (conditional complexity)

    public function parseHeadersImpl(
        array $traceParentHeaderValues,
        array $traceStateHeaderValues,
        bool &$isTraceParentValid,
        ?bool &$isTraceStateValid
    ): ?DistributedTracingDataInternal {
        $localLogger = $this->logger->inherit()->addAllContext(
            [
                'traceParentHeaderValues' => $traceParentHeaderValues,
                'traceStateHeaderValues' => $traceStateHeaderValues
            ]
        );
        if (count($traceParentHeaderValues) === 0) {
            ($loggerProxy = $localLogger->ifDebugLevelEnabled(__LINE__, __FUNCTION__))
            && $loggerProxy->log(
                'Found no ' . self::TRACE_PARENT_HEADER_NAME . ' HTTP header so there is nothing to parse'
            );
            $isTraceParentValid = false;
            $isTraceStateValid = null;
            return null;
        }

        if (count($traceParentHeaderValues) > 1) {
            ($loggerProxy = $this->logger->ifDebugLevelEnabled(__LINE__, __FUNCTION__))
            && $loggerProxy->log(
                'Found more than one ' . self::TRACE_PARENT_HEADER_NAME . ' HTTP header which is invalid'
            );
            $isTraceParentValid = false;
            $isTraceStateValid = null;
            return null;
        }

        /**
         * @link https://www.w3.org/TR/trace-context/#tracestate-header
         *
         * If the vendor failed to parse traceparent, it MUST NOT attempt to parse tracestate.
         * Note that the opposite is not true: failure to parse tracestate MUST NOT affect the parsing of traceparent.
         */

        $isTraceParentValid = ($result = $this->parseTraceParentHeader($traceParentHeaderValues[0])) !== null;
        if (!$isTraceParentValid) {
            $isTraceStateValid = null;
            return null;
        }
        /** @var DistributedTracingDataInternal $result */

        if (ArrayUtil::isEmpty($traceStateHeaderValues)) {
            $isTraceStateValid = null;
        } else {
            $isTraceStateValid = $this->parseTraceStateHeaders($traceStateHeaderValues, $result);
        }
        return $result;
    }