wp-prometheus/src/Plugin.php

<?php
/**
 * Main plugin class.
 *
 * @package WP_Prometheus
 */

namespace Magdev\WpPrometheus;

use Magdev\WpPrometheus\Admin\Settings;
use Magdev\WpPrometheus\Endpoint\MetricsEndpoint;
use Magdev\WpPrometheus\License\Manager as LicenseManager;
use Magdev\WpPrometheus\Metrics\Collector;
use Magdev\WpPrometheus\Metrics\RuntimeCollector;

// Prevent direct file access.
if ( ! defined( 'ABSPATH' ) ) {
    exit;
}

/**
 * Plugin singleton class.
 *
 * Initializes and manages all plugin components.
 */
final class Plugin {

    /**
     * Singleton instance.
     *
     * @var Plugin|null
     */
    private static ?Plugin $instance = null;

    /**
     * Metrics collector instance.
     *
     * @var Collector|null
     */
    private ?Collector $collector = null;

    /**
     * Get singleton instance.
     *
     * @return Plugin
     */
    public static function get_instance(): Plugin {
        if ( null === self::$instance ) {
            self::$instance = new self();
        }
        return self::$instance;
    }

    /**
     * Private constructor to enforce singleton pattern.
     */
    private function __construct() {
        $this->init_components();
        $this->init_hooks();
        $this->load_textdomain();
    }

    /**
     * Prevent cloning.
     *
     * @return void
     */
    private function __clone() {}

    /**
     * Prevent unserialization.
     *
     * @throws \Exception Always throws to prevent unserialization.
     * @return void
     */
    public function __wakeup(): void {
        throw new \Exception( 'Cannot unserialize singleton' );
    }

    /**
     * Initialize plugin components.
     *
     * @return void
     */
    private function init_components(): void {
        // Initialize license manager.
        LicenseManager::get_instance();

        // Initialize admin settings (always needed).
        if ( is_admin() ) {
            new Settings();
        }

        // Initialize runtime collector for request metrics (always runs to collect data).
        // Only collect if at least one runtime metric is enabled.
        $enabled_metrics  = get_option( 'wp_prometheus_enabled_metrics', array() );
        $runtime_metrics  = array(
            'wordpress_http_requests_total',
            'wordpress_http_request_duration_seconds',
            'wordpress_db_queries_total',
        );
        $has_runtime_metrics = ! empty( array_intersect( $runtime_metrics, $enabled_metrics ) );

        if ( $has_runtime_metrics && LicenseManager::is_license_valid() ) {
            RuntimeCollector::get_instance();
        }

        // Initialize metrics endpoint (only if licensed).
        if ( LicenseManager::is_license_valid() ) {
            $this->collector = new Collector();
            new MetricsEndpoint( $this->collector );
        }
    }

    /**
     * Initialize WordPress hooks.
     *
     * @return void
     */
    private function init_hooks(): void {
        // Add settings link to plugins page.
        add_filter( 'plugin_action_links_' . WP_PROMETHEUS_BASENAME, array( $this, 'add_plugin_action_links' ) );
    }

    /**
     * Add action links to the plugins page.
     *
     * @param array $links Existing action links.
     * @return array Modified action links.
     */
    public function add_plugin_action_links( array $links ): array {
        $settings_link = sprintf(
            '<a href="%s">%s</a>',
            esc_url( admin_url( 'options-general.php?page=wp-prometheus' ) ),
            esc_html__( 'Settings', 'wp-prometheus' )
        );

        // Add our link at the beginning.
        array_unshift( $links, $settings_link );

        return $links;
    }

    /**
     * Load plugin textdomain.
     *
     * @return void
     */
    private function load_textdomain(): void {
        load_plugin_textdomain(
            'wp-prometheus',
            false,
            dirname( WP_PROMETHEUS_BASENAME ) . '/languages'
        );
    }

    /**
     * Get the metrics collector.
     *
     * @return Collector|null
     */
    public function get_collector(): ?Collector {
        return $this->collector;
    }
}