michaelschiemer/src/Framework/ExceptionHandling/Health/ExceptionHealthChecker.php

<?php

declare(strict_types=1);

namespace App\Framework\ExceptionHandling\Health;

use App\Framework\ExceptionHandling\Metrics\ExceptionMetrics;
use App\Framework\ExceptionHandling\Metrics\ExceptionMetricsCollector;
use App\Framework\Health\HealthCheckInterface;
use App\Framework\Health\HealthCheckResult;

/**
 * Exception Health Checker
 *
 * Provides health checks based on exception rate.
 */
final readonly class ExceptionHealthChecker implements HealthCheckInterface
{
    public readonly string $name;
    public readonly int $timeout;

    /**
     * @param ExceptionMetricsCollector $metricsCollector Metrics collector
     * @param string $name Health check name
     * @param int $timeout Timeout in milliseconds
     * @param float $errorRateThreshold Error rate threshold (0.0 to 1.0, e.g., 0.1 = 10%)
     * @param int $timeWindowSeconds Time window in seconds for error rate calculation
     */
    public function __construct(
        private ExceptionMetricsCollector $metricsCollector,
        string $name = 'Exception Rate',
        int $timeout = 2000,
        private float $errorRateThreshold = 0.1, // 10% default
        private int $timeWindowSeconds = 60
    ) {
        $this->name = $name;
        $this->timeout = $timeout;

        if ($errorRateThreshold < 0.0 || $errorRateThreshold > 1.0) {
            throw new \InvalidArgumentException('errorRateThreshold must be between 0.0 and 1.0');
        }
    }

    /**
     * Perform health check
     */
    public function check(): HealthCheckResult
    {
        $metrics = $this->metricsCollector->getMetrics();
        $errorRate = $this->calculateErrorRate($metrics);

        if ($errorRate >= $this->errorRateThreshold) {
            return HealthCheckResult::unhealthy(
                "Exception error rate too high: " . number_format($errorRate * 100, 2) . "%",
                [
                    'error_rate' => $errorRate,
                    'threshold' => $this->errorRateThreshold,
                    'total_exceptions' => $metrics->totalCount,
                ]
            );
        }

        if ($errorRate >= $this->errorRateThreshold * 0.5) {
            return HealthCheckResult::warning(
                "Exception error rate elevated: " . number_format($errorRate * 100, 2) . "%",
                [
                    'error_rate' => $errorRate,
                    'threshold' => $this->errorRateThreshold,
                    'total_exceptions' => $metrics->totalCount,
                ]
            );
        }

        return HealthCheckResult::healthy(
            "Exception error rate normal: " . number_format($errorRate * 100, 2) . "%",
            [
                'error_rate' => $errorRate,
                'total_exceptions' => $metrics->totalCount,
            ]
        );
    }

    /**
     * Calculate error rate
     *
     * Simplified implementation - in production, would calculate based on request count.
     */
    private function calculateErrorRate(ExceptionMetrics $metrics): float
    {
        // Simplified: use total count as proxy for error rate
        // In production, would compare against total request count
        if ($metrics->totalCount === 0) {
            return 0.0;
        }

        // Normalize to 0-1 range (simplified)
        return min(1.0, $metrics->totalCount / 1000.0);
    }

    /**
     * Get health check category
     */
    public function getCategory(): \App\Framework\Health\HealthCheckCategory
    {
        return \App\Framework\Health\HealthCheckCategory::APPLICATION;
    }
}