StatsUtils.php

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<?php
declare( strict_types=1 );
 
namespace Wikimedia\Stats;
 
use InvalidArgumentException;
use Wikimedia\Stats\Exceptions\InvalidConfigurationException;
 
class StatsUtils {
 
    public const RE_VALID_NAME_AND_LABEL_NAME = "/^[a-zA-Z_][a-zA-Z0-9_]*$/";
 
    public const DEFAULT_SAMPLE_RATE = 1.0;
 
    public static function validateNewSampleRate( float $newSampleRate ): void {
        if ( $newSampleRate < 0.0 || $newSampleRate > 1.0 ) {
            throw new InvalidArgumentException( "Sample rate can only be between 0.0 and 1.0. Got: " . $newSampleRate );
        }
    }
 
    public static function getFilteredSamples( float $sampleRate, array $samples ): array {
        if ( $sampleRate === 1.0 ) {
            return $samples;
        }
        $output = [];
        $randMax = mt_getrandmax();
        foreach ( $samples as $sample ) {
            if ( mt_rand() / $randMax < $sampleRate ) {
                $output[] = $sample;
            }
        }
        return $output;
    }
 
    public static function validateMetricName( string $name ) {
        if ( $name === "" ) {
            throw new InvalidArgumentException( "Stats: Metric name cannot be empty." );
        }
        if ( !preg_match( self::RE_VALID_NAME_AND_LABEL_NAME, $name ) ) {
            throw new InvalidConfigurationException( "Invalid metric name: '" . $name . "'" );
        }
    }
 
    public static function validateLabelKey( string $key ) {
        if ( $key === "" ) {
            throw new InvalidArgumentException( "Stats: Label key cannot be empty." );
        }
        if ( !preg_match( self::RE_VALID_NAME_AND_LABEL_NAME, $key ) ) {
            throw new InvalidConfigurationException( "Invalid label key: '" . $key . "'" );
        }
    }
 
    public static function validateLabelValue( string $value ) {
        if ( $value === "" ) {
            throw new InvalidArgumentException( "Stats: Label value cannot be empty." );
        }
    }
 
    public static function mergeLabels( array $leftLabels, array $rightLabels ): array {
        $output = [];
        foreach ( $leftLabels as $key => $value ) {
            $output[$key] = $value;
        }
        foreach ( $rightLabels as $key => $value ) {
            if ( array_key_exists( $key, $output ) ) {
                continue;
            }
            $output[$key] = $value;
        }
        return $output;
    }
 
    public static function normalizeArray( array $entities ): array {
        $normalizedEntities = [];
        foreach ( $entities as $entity ) {
            $normalizedEntities[] = self::normalizeString( $entity );
        }
        return $normalizedEntities;
    }
 
    public static function normalizeString( string $entity ): string {
        $entity = preg_replace( "/[^a-z0-9]/i", "_", $entity );
        $entity = preg_replace( "/_+/", "_", $entity );
        return trim( $entity, "_" );
    }
}