<?php
/**
 * Metrics collector class.
 *
 * @package WP_Prometheus
 */

namespace Magdev\WpPrometheus\Metrics;

use Prometheus\CollectorRegistry;
use Prometheus\Storage\InMemory;
use Prometheus\RenderTextFormat;

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

/**
 * Collector class.
 *
 * Collects and manages Prometheus metrics.
 */
class Collector {

    /**
     * Prometheus collector registry.
     *
     * @var CollectorRegistry
     */
    private CollectorRegistry $registry;

    /**
     * Metric namespace.
     *
     * @var string
     */
    private string $namespace = 'wordpress';

    /**
     * Constructor.
     */
    public function __construct() {
        $this->registry = new CollectorRegistry( new InMemory() );
    }

    /**
     * Get the collector registry.
     *
     * @return CollectorRegistry
     */
    public function get_registry(): CollectorRegistry {
        return $this->registry;
    }

    /**
     * Get the metric namespace.
     *
     * @return string
     */
    public function get_namespace(): string {
        return $this->namespace;
    }

    /**
     * Collect all enabled metrics.
     *
     * @return void
     */
    public function collect(): void {
        $enabled_metrics = get_option( 'wp_prometheus_enabled_metrics', array() );

        // Always collect WordPress info.
        if ( in_array( 'wordpress_info', $enabled_metrics, true ) ) {
            $this->collect_wordpress_info();
        }

        // Collect user metrics.
        if ( in_array( 'wordpress_users_total', $enabled_metrics, true ) ) {
            $this->collect_users_total();
        }

        // Collect posts metrics.
        if ( in_array( 'wordpress_posts_total', $enabled_metrics, true ) ) {
            $this->collect_posts_total();
        }

        // Collect comments metrics.
        if ( in_array( 'wordpress_comments_total', $enabled_metrics, true ) ) {
            $this->collect_comments_total();
        }

        // Collect plugins metrics.
        if ( in_array( 'wordpress_plugins_total', $enabled_metrics, true ) ) {
            $this->collect_plugins_total();
        }

        /**
         * Fires after default metrics are collected.
         *
         * @param Collector $collector The metrics collector instance.
         */
        do_action( 'wp_prometheus_collect_metrics', $this );
    }

    /**
     * Render metrics in Prometheus text format.
     *
     * @return string
     */
    public function render(): string {
        $this->collect();

        $renderer = new RenderTextFormat();
        return $renderer->render( $this->registry->getMetricFamilySamples() );
    }

    /**
     * Collect WordPress info metric.
     *
     * @return void
     */
    private function collect_wordpress_info(): void {
        $gauge = $this->registry->getOrRegisterGauge(
            $this->namespace,
            'info',
            'WordPress installation information',
            array( 'version', 'php_version', 'multisite' )
        );

        $gauge->set(
            1,
            array(
                get_bloginfo( 'version' ),
                PHP_VERSION,
                is_multisite() ? 'yes' : 'no',
            )
        );
    }

    /**
     * Collect total users metric.
     *
     * @return void
     */
    private function collect_users_total(): void {
        $gauge = $this->registry->getOrRegisterGauge(
            $this->namespace,
            'users_total',
            'Total number of WordPress users',
            array( 'role' )
        );

        $user_count = count_users();
        foreach ( $user_count['avail_roles'] as $role => $count ) {
            $gauge->set( $count, array( $role ) );
        }
    }

    /**
     * Collect total posts metric.
     *
     * @return void
     */
    private function collect_posts_total(): void {
        $gauge = $this->registry->getOrRegisterGauge(
            $this->namespace,
            'posts_total',
            'Total number of posts by type and status',
            array( 'post_type', 'status' )
        );

        $post_types = get_post_types( array( 'public' => true ) );
        foreach ( $post_types as $post_type ) {
            $counts = wp_count_posts( $post_type );
            foreach ( get_object_vars( $counts ) as $status => $count ) {
                if ( $count > 0 ) {
                    $gauge->set( (int) $count, array( $post_type, $status ) );
                }
            }
        }
    }

    /**
     * Collect total comments metric.
     *
     * @return void
     */
    private function collect_comments_total(): void {
        $gauge = $this->registry->getOrRegisterGauge(
            $this->namespace,
            'comments_total',
            'Total number of comments by status',
            array( 'status' )
        );

        $comments = wp_count_comments();
        $statuses = array(
            'approved'       => $comments->approved,
            'moderated'      => $comments->moderated,
            'spam'           => $comments->spam,
            'trash'          => $comments->trash,
            'total_comments' => $comments->total_comments,
        );

        foreach ( $statuses as $status => $count ) {
            $gauge->set( (int) $count, array( $status ) );
        }
    }

    /**
     * Collect total plugins metric.
     *
     * @return void
     */
    private function collect_plugins_total(): void {
        if ( ! function_exists( 'get_plugins' ) ) {
            require_once ABSPATH . 'wp-admin/includes/plugin.php';
        }

        $gauge = $this->registry->getOrRegisterGauge(
            $this->namespace,
            'plugins_total',
            'Total number of plugins by status',
            array( 'status' )
        );

        $all_plugins    = get_plugins();
        $active_plugins = get_option( 'active_plugins', array() );

        $gauge->set( count( $all_plugins ), array( 'installed' ) );
        $gauge->set( count( $active_plugins ), array( 'active' ) );
        $gauge->set( count( $all_plugins ) - count( $active_plugins ), array( 'inactive' ) );
    }

    /**
     * Register a custom gauge metric.
     *
     * @param string $name   Metric name.
     * @param string $help   Metric description.
     * @param array  $labels Label names.
     * @return \Prometheus\Gauge
     */
    public function register_gauge( string $name, string $help, array $labels = array() ): \Prometheus\Gauge {
        return $this->registry->getOrRegisterGauge(
            $this->namespace,
            $name,
            $help,
            $labels
        );
    }

    /**
     * Register a custom counter metric.
     *
     * @param string $name   Metric name.
     * @param string $help   Metric description.
     * @param array  $labels Label names.
     * @return \Prometheus\Counter
     */
    public function register_counter( string $name, string $help, array $labels = array() ): \Prometheus\Counter {
        return $this->registry->getOrRegisterCounter(
            $this->namespace,
            $name,
            $help,
            $labels
        );
    }

    /**
     * Register a custom histogram metric.
     *
     * @param string     $name    Metric name.
     * @param string     $help    Metric description.
     * @param array      $labels  Label names.
     * @param array|null $buckets Histogram buckets.
     * @return \Prometheus\Histogram
     */
    public function register_histogram( string $name, string $help, array $labels = array(), ?array $buckets = null ): \Prometheus\Histogram {
        return $this->registry->getOrRegisterHistogram(
            $this->namespace,
            $name,
            $help,
            $labels,
            $buckets
        );
    }
}