<?php
/**
 * Ticket Tailor Health Check
 *
 * Enterprise-grade health check endpoint for monitoring
 * ENTERPRISE: Provides comprehensive health status for monitoring systems
 */

// Exit if accessed directly
if (!defined('ABSPATH')) {
    exit;
}

class Ticket_Tailor_Health_Check {

    /**
     * API Client
     */
    private $api;

    /**
     * Event Manager
     */
    private $events;

    /**
     * Order Manager
     */
    private $orders;

    /**
     * Constructor
     */
    public function __construct($api, $events, $orders) {
        $this->api = $api;
        $this->events = $events;
        $this->orders = $orders;

        // Register health check endpoint
        add_action('rest_api_init', array($this, 'register_health_endpoint'));
    }

    /**
     * Register health check REST endpoint
     */
    public function register_health_endpoint() {
        register_rest_route('ticket-tailor/v1', '/health', array(
            'methods' => 'GET',
            'callback' => array($this, 'get_health_status'),
            'permission_callback' => array($this, 'health_check_permission'),
        ));

        register_rest_route('ticket-tailor/v1', '/health/detailed', array(
            'methods' => 'GET',
            'callback' => array($this, 'get_detailed_health_status'),
            'permission_callback' => array($this, 'detailed_health_check_permission'),
        ));
    }

    /**
     * Permission callback for basic health check
     * ENTERPRISE: Can be accessed without authentication for monitoring
     */
    public function health_check_permission() {
        // Allow unauthenticated access for monitoring tools
        return true;
    }

    /**
     * Permission callback for detailed health check
     * ENTERPRISE: Requires authentication
     */
    public function detailed_health_check_permission() {
        return current_user_can('manage_options');
    }

    /**
     * Get basic health status
     * ENTERPRISE: Fast check for monitoring systems
     */
    public function get_health_status() {
        $status = 'healthy';
        $checks = array();

        // Check API configuration
        $checks['api_configured'] = $this->api->is_configured();
        if (!$checks['api_configured']) {
            $status = 'degraded';
        }

        // Check database connectivity
        global $wpdb;
        $checks['database'] = $wpdb->check_connection();
        if (!$checks['database']) {
            $status = 'unhealthy';
        }

        // Check if syncs are running (not stuck)
        $event_sync = get_transient('ticket_tailor_sync_events_lock');
        $order_sync = get_transient('ticket_tailor_sync_orders_lock');

        $checks['sync_status'] = array(
            'events_syncing' => !empty($event_sync),
            'orders_syncing' => !empty($order_sync),
        );

        // Check if locks are stale (stuck for > 10 minutes)
        if ($event_sync && (time() - $event_sync) > 600) {
            $status = 'degraded';
            $checks['sync_status']['events_stuck'] = true;
        }

        if ($order_sync && (time() - $order_sync) > 600) {
            $status = 'degraded';
            $checks['sync_status']['orders_stuck'] = true;
        }

        $response = array(
            'status' => $status,
            'timestamp' => current_time('mysql'),
            'checks' => $checks,
        );

        $http_status = ($status === 'healthy') ? 200 : (($status === 'degraded') ? 200 : 503);

        return new WP_REST_Response($response, $http_status);
    }

    /**
     * Get detailed health status
     * ENTERPRISE: Comprehensive diagnostics for administrators
     */
    public function get_detailed_health_status() {
        $status = 'healthy';
        $diagnostics = array();

        // 1. API Configuration
        $diagnostics['api'] = array(
            'configured' => $this->api->is_configured(),
            'rate_limit' => $this->api->get_rate_limit_info(),
        );

        // Test API connectivity
        $api_test = $this->api->test_connection();
        $diagnostics['api']['connectivity'] = !is_wp_error($api_test);
        if (is_wp_error($api_test)) {
            $diagnostics['api']['error'] = $api_test->get_error_message();
            $status = 'unhealthy';
        }

        // 2. Database Health
        global $wpdb;
        $diagnostics['database'] = array(
            'connected' => $wpdb->check_connection(),
            'events_table_exists' => $this->check_table_exists($wpdb->prefix . 'ticket_tailor_events'),
            'orders_table_exists' => $this->check_table_exists($wpdb->prefix . 'ticket_tailor_orders'),
            'security_log_table_exists' => $this->check_table_exists($wpdb->prefix . 'ticket_tailor_security_log'),
            'rate_limit_table_exists' => $this->check_table_exists($wpdb->prefix . 'ticket_tailor_rate_limits'),
        );

        // 3. Cache Statistics
        $diagnostics['cache'] = array(
            'events' => $this->events->get_cache_stats(),
            'orders' => $this->orders->get_cache_stats(),
        );

        // 4. Sync Status
        $last_event_sync = get_option('ticket_tailor_last_event_sync', 0);
        $last_order_sync = get_option('ticket_tailor_last_order_sync', 0);

        $diagnostics['sync'] = array(
            'last_event_sync' => $last_event_sync ? gmdate('Y-m-d H:i:s', $last_event_sync) : 'never',
            'last_order_sync' => $last_order_sync ? gmdate('Y-m-d H:i:s', $last_order_sync) : 'never',
            'event_sync_age_hours' => $last_event_sync ? round((time() - $last_event_sync) / 3600, 1) : null,
            'order_sync_age_hours' => $last_order_sync ? round((time() - $last_order_sync) / 3600, 1) : null,
            'events_lock' => get_transient('ticket_tailor_sync_events_lock'),
            'orders_lock' => get_transient('ticket_tailor_sync_orders_lock'),
        );

        // Check for stale syncs
        if ($last_event_sync && (time() - $last_event_sync) > 86400) {
            $diagnostics['sync']['event_sync_stale'] = true;
            $status = 'degraded';
        }

        if ($last_order_sync && (time() - $last_order_sync) > 86400) {
            $diagnostics['sync']['order_sync_stale'] = true;
            $status = 'degraded';
        }

        // 5. Cron Jobs
        $diagnostics['cron'] = array(
            'event_sync_scheduled' => wp_next_scheduled('ticket_tailor_sync_events') ? true : false,
            'order_sync_scheduled' => wp_next_scheduled('ticket_tailor_sync_orders') ? true : false,
            'security_cleanup_scheduled' => wp_next_scheduled('ticket_tailor_cleanup_security_logs') ? true : false,
            'rate_limit_cleanup_scheduled' => wp_next_scheduled('ticket_tailor_cleanup_rate_limits') ? true : false,
        );

        // 6. PHP Environment
        $diagnostics['environment'] = array(
            'php_version' => PHP_VERSION,
            'wordpress_version' => get_bloginfo('version'),
            'plugin_version' => TICKET_TAILOR_VERSION,
            'openssl_enabled' => function_exists('openssl_encrypt'),
            'curl_enabled' => function_exists('curl_init'),
            'memory_limit' => ini_get('memory_limit'),
            'max_execution_time' => ini_get('max_execution_time'),
        );

        // 7. Security Configuration
        $diagnostics['security'] = array(
            'api_key_encrypted' => !empty(get_option('ticket_tailor_api_key_encrypted')),
            'webhook_secret_configured' => !empty(get_option('ticket_tailor_webhook_secret')),
            'security_alerts_enabled' => get_option('ticket_tailor_security_alerts', true),
        );

        $response = array(
            'status' => $status,
            'timestamp' => current_time('mysql'),
            'diagnostics' => $diagnostics,
        );

        $http_status = ($status === 'healthy') ? 200 : (($status === 'degraded') ? 200 : 503);

        return new WP_REST_Response($response, $http_status);
    }

    /**
     * Check if table exists
     */
    private function check_table_exists($table_name) {
        global $wpdb;
        $result = $wpdb->get_var($wpdb->prepare(
            "SHOW TABLES LIKE %s",
            $wpdb->esc_like($table_name)
        ));
        return !empty($result);
    }

    /**
     * Get health check URL
     */
    public function get_health_check_url() {
        return rest_url('ticket-tailor/v1/health');
    }

    /**
     * Get detailed health check URL
     */
    public function get_detailed_health_check_url() {
        return rest_url('ticket-tailor/v1/health/detailed');
    }
}