class LastValueAggregation

final class LastValueAggregation implements AggregationInterface {
    public function initialize() : LastValueSummary {
        return new LastValueSummary(null, 0);
    }
    
    /**
     * @param LastValueSummary $summary
     */
    public function record($summary, $value, AttributesInterface $attributes, ContextInterface $context, int $timestamp) : void {
        if ($summary->value === null || $timestamp >= $summary->timestamp) {
            $summary->value = $value;
            $summary->timestamp = $timestamp;
        }
    }
    
    /**
     * @param LastValueSummary $left
     * @param LastValueSummary $right
     */
    public function merge($left, $right) : LastValueSummary {
        return $right->timestamp >= $left->timestamp ? $right : $left;
    }
    
    /**
     * @param LastValueSummary $left
     * @param LastValueSummary $right
     */
    public function diff($left, $right) : LastValueSummary {
        return $right->timestamp >= $left->timestamp ? $right : $left;
    }
    
    /**
     * @param array<LastValueSummary> $summaries
     */
    public function toData(array $attributes, array $summaries, array $exemplars, int $startTimestamp, int $timestamp, $temporality) : Data\Gauge {
        $dataPoints = [];
        foreach ($attributes as $key => $dataPointAttributes) {
            if ($summaries[$key]->value === null) {
                continue;
            }
            $dataPoints[] = new Data\NumberDataPoint($summaries[$key]->value, $dataPointAttributes, $startTimestamp, $timestamp, $exemplars[$key] ?? []);
        }
        return new Data\Gauge($dataPoints);
    }

}