wc-licensed-product/src/Metrics/PrometheusController.php

<?php
/**
 * Prometheus Metrics Controller
 *
 * @package Jeremias\WcLicensedProduct\Metrics
 */

declare(strict_types=1);

namespace Jeremias\WcLicensedProduct\Metrics;

use Jeremias\WcLicensedProduct\Admin\SettingsController;
use Jeremias\WcLicensedProduct\License\LicenseManager;
use Jeremias\WcLicensedProduct\Product\VersionManager;

/**
 * Exposes license and API metrics for Prometheus monitoring
 */
final class PrometheusController
{
    /**
     * Option name for storing API counters
     */
    private const COUNTERS_OPTION = 'wclp_prometheus_counters';

    private LicenseManager $licenseManager;
    private VersionManager $versionManager;

    public function __construct(LicenseManager $licenseManager, VersionManager $versionManager)
    {
        $this->licenseManager = $licenseManager;
        $this->versionManager = $versionManager;
    }

    /**
     * Register hooks for Prometheus metrics collection
     */
    public function register(): void
    {
        // Only register if metrics are enabled
        if (!SettingsController::isMetricsEnabled()) {
            return;
        }

        add_action('wp_prometheus_collect_metrics', [$this, 'collectMetrics']);
    }

    /**
     * Collect and register all metrics
     *
     * @param object $collector The Prometheus collector object
     */
    public function collectMetrics(object $collector): void
    {
        $this->collectLicenseMetrics($collector);
        $this->collectDownloadMetrics($collector);
        $this->collectApiMetrics($collector);
    }

    /**
     * Collect license-related metrics
     */
    private function collectLicenseMetrics(object $collector): void
    {
        $stats = $this->licenseManager->getStatistics();

        // License count by status (gauge)
        $licensesByStatus = $collector->register_gauge(
            'wclp_licenses_total',
            'Total number of licenses by status',
            ['status']
        );

        foreach ($stats['by_status'] as $status => $count) {
            $licensesByStatus->set($count, [$status]);
        }

        // Lifetime licenses (gauge)
        $lifetimeLicenses = $collector->register_gauge(
            'wclp_licenses_lifetime_total',
            'Total number of lifetime licenses'
        );
        $lifetimeLicenses->set($stats['lifetime']);

        // Expiring licenses (gauge)
        $expiringLicenses = $collector->register_gauge(
            'wclp_licenses_expiring_total',
            'Total number of licenses with expiration date'
        );
        $expiringLicenses->set($stats['expiring']);

        // Licenses expiring soon - next 30 days (gauge)
        $expiringSoon = $collector->register_gauge(
            'wclp_licenses_expiring_soon',
            'Licenses expiring within 30 days'
        );
        $expiringSoon->set($stats['expiring_soon']);
    }

    /**
     * Collect download-related metrics
     */
    private function collectDownloadMetrics(object $collector): void
    {
        $stats = $this->versionManager->getDownloadStatistics();

        // Total downloads (gauge)
        $totalDownloads = $collector->register_gauge(
            'wclp_downloads_total',
            'Total number of file downloads'
        );
        $totalDownloads->set($stats['total']);

        // Active versions count (gauge)
        $activeVersions = $collector->register_gauge(
            'wclp_versions_active_total',
            'Total number of active product versions'
        );
        $activeVersions->set($this->countActiveVersions());
    }

    /**
     * Collect API-related metrics (counters)
     */
    private function collectApiMetrics(object $collector): void
    {
        $counters = $this->getCounters();

        // API requests by endpoint and result (counter)
        $apiRequests = $collector->register_counter(
            'wclp_api_requests_total',
            'Total API requests by endpoint and result',
            ['endpoint', 'result']
        );

        foreach ($counters['api_requests'] ?? [] as $key => $count) {
            [$endpoint, $result] = explode(':', $key);
            $apiRequests->incBy($count, [$endpoint, $result]);
        }

        // Rate limit exceeded events (counter)
        $rateLimitExceeded = $collector->register_counter(
            'wclp_rate_limit_exceeded_total',
            'Total rate limit exceeded events by endpoint',
            ['endpoint']
        );

        foreach ($counters['rate_limit'] ?? [] as $endpoint => $count) {
            $rateLimitExceeded->incBy($count, [$endpoint]);
        }

        // Validation errors by type (counter)
        $validationErrors = $collector->register_counter(
            'wclp_validation_errors_total',
            'Total validation errors by error type',
            ['error_type']
        );

        foreach ($counters['validation_errors'] ?? [] as $errorType => $count) {
            $validationErrors->incBy($count, [$errorType]);
        }
    }

    /**
     * Count active product versions
     */
    private function countActiveVersions(): int
    {
        global $wpdb;

        $tableName = \Jeremias\WcLicensedProduct\Installer::getVersionsTable();

        return (int) $wpdb->get_var(
            "SELECT COUNT(*) FROM {$tableName} WHERE is_active = 1"
        );
    }

    /**
     * Get stored counters
     */
    private function getCounters(): array
    {
        $counters = get_option(self::COUNTERS_OPTION, []);
        return is_array($counters) ? $counters : [];
    }

    /**
     * Increment an API request counter
     *
     * @param string $endpoint The API endpoint (validate, status, activate, update-check)
     * @param string $result The result (success or error)
     */
    public static function incrementApiRequest(string $endpoint, string $result): void
    {
        if (!SettingsController::isMetricsEnabled()) {
            return;
        }

        $counters = get_option(self::COUNTERS_OPTION, []);
        if (!is_array($counters)) {
            $counters = [];
        }

        $key = "{$endpoint}:{$result}";
        $counters['api_requests'][$key] = ($counters['api_requests'][$key] ?? 0) + 1;

        update_option(self::COUNTERS_OPTION, $counters, false);
    }

    /**
     * Increment rate limit exceeded counter
     *
     * @param string $endpoint The API endpoint
     */
    public static function incrementRateLimitExceeded(string $endpoint): void
    {
        if (!SettingsController::isMetricsEnabled()) {
            return;
        }

        $counters = get_option(self::COUNTERS_OPTION, []);
        if (!is_array($counters)) {
            $counters = [];
        }

        $counters['rate_limit'][$endpoint] = ($counters['rate_limit'][$endpoint] ?? 0) + 1;

        update_option(self::COUNTERS_OPTION, $counters, false);
    }

    /**
     * Increment validation error counter
     *
     * @param string $errorType The error type (license_not_found, domain_mismatch, etc.)
     */
    public static function incrementValidationError(string $errorType): void
    {
        if (!SettingsController::isMetricsEnabled()) {
            return;
        }

        $counters = get_option(self::COUNTERS_OPTION, []);
        if (!is_array($counters)) {
            $counters = [];
        }

        $counters['validation_errors'][$errorType] = ($counters['validation_errors'][$errorType] ?? 0) + 1;

        update_option(self::COUNTERS_OPTION, $counters, false);
    }

    /**
     * Reset all counters (useful for testing or maintenance)
     */
    public static function resetCounters(): void
    {
        delete_option(self::COUNTERS_OPTION);
    }
}