<?php

declare(strict_types=1);

namespace App\Framework\ExceptionHandling\Metrics;

/**
 * Prometheus Exporter
 *
 * Exports exception metrics in Prometheus format.
 */
final readonly class PrometheusExporter
{
    /**
     * Export metrics in Prometheus format
     *
     * @param ExceptionMetrics $metrics Metrics to export
     * @return string Prometheus-formatted metrics
     */
    public function export(ExceptionMetrics $metrics): string
    {
        $lines = [];

        // Total exception count
        $lines[] = sprintf(
            'exception_total %d',
            $metrics->totalCount
        );

        // Exceptions by class
        foreach ($metrics->byClass as $class => $count) {
            $sanitizedClass = $this->sanitizeMetricName($class);
            $lines[] = sprintf(
                'exception_by_class{exception_class="%s"} %d',
                $sanitizedClass,
                $count
            );
        }

        // Exceptions by component
        foreach ($metrics->byComponent as $component => $count) {
            $sanitizedComponent = $this->sanitizeMetricName($component);
            $lines[] = sprintf(
                'exception_by_component{component="%s"} %d',
                $sanitizedComponent,
                $count
            );
        }

        // Average execution time
        $lines[] = sprintf(
            'exception_average_execution_time_ms %.2f',
            $metrics->averageExecutionTimeMs
        );

        return implode("\n", $lines);
    }

    /**
     * Sanitize metric name for Prometheus
     */
    private function sanitizeMetricName(string $name): string
    {
        // Replace invalid characters
        $sanitized = preg_replace('/[^a-zA-Z0-9_:]/', '_', $name);
        return $sanitized;
    }
}