/**
 * Descomplicar® Crescimento Digital
 * https://descomplicar.pt
 */

<?php
/**
 * Cache manager for Care Booking Block plugin
 *
 * @package CareBookingBlock
 */

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

/**
 * Cache manager class
 */
class Care_Booking_Cache_Manager
{
    /**
     * Cache key for blocked doctors
     */
    const DOCTORS_CACHE_KEY = 'care_booking_doctors_blocked';

    /**
     * Cache key prefix for blocked services
     */
    const SERVICES_CACHE_PREFIX = 'care_booking_services_blocked_';

    /**
     * Cache key for restrictions hash
     */
    const HASH_CACHE_KEY = 'care_booking_restrictions_hash';

    /**
     * Default cache expiration (1 hour)
     */
    const DEFAULT_EXPIRATION = 3600;

    /**
     * Smart TTL cache expiration (15 minutes for high-frequency data)
     */
    const SMART_TTL_EXPIRATION = 900;

    /**
     * Long-term cache expiration (4 hours for stable data)
     */
    const LONG_TERM_EXPIRATION = 14400;

    /**
     * Cache blocked doctors
     *
     * @param array $doctor_ids Array of blocked doctor IDs
     * @param int   $expiration Cache expiration in seconds
     * @return bool True on success, false on failure
     */
    public function set_blocked_doctors($doctor_ids, $expiration = null)
    {
        if ($expiration === null) {
            $expiration = $this->get_cache_timeout();
        }

        return set_transient(self::DOCTORS_CACHE_KEY, $doctor_ids, $expiration);
    }

    /**
     * Get blocked doctors from cache
     *
     * @return array|false Array of doctor IDs or false if not cached
     */
    public function get_blocked_doctors()
    {
        return get_transient(self::DOCTORS_CACHE_KEY);
    }

    /**
     * Cache blocked services for specific doctor
     *
     * @param int   $doctor_id Doctor ID
     * @param array $service_ids Array of blocked service IDs
     * @param int   $expiration Cache expiration in seconds
     * @return bool True on success, false on failure
     */
    public function set_blocked_services($doctor_id, $service_ids, $expiration = null)
    {
        if ($expiration === null) {
            $expiration = $this->get_cache_timeout();
        }

        $cache_key = self::SERVICES_CACHE_PREFIX . (int) $doctor_id;
        
        return set_transient($cache_key, $service_ids, $expiration);
    }

    /**
     * Get blocked services for specific doctor from cache
     *
     * @param int $doctor_id Doctor ID
     * @return array|false Array of service IDs or false if not cached
     */
    public function get_blocked_services($doctor_id)
    {
        $cache_key = self::SERVICES_CACHE_PREFIX . (int) $doctor_id;
        
        return get_transient($cache_key);
    }

    /**
     * Set restrictions hash for change detection
     *
     * @param string $hash Restrictions hash
     * @param int    $expiration Cache expiration in seconds
     * @return bool True on success, false on failure
     */
    public function set_restrictions_hash($hash, $expiration = null)
    {
        if ($expiration === null) {
            $expiration = $this->get_cache_timeout();
        }

        return set_transient(self::HASH_CACHE_KEY, $hash, $expiration);
    }

    /**
     * Get restrictions hash from cache
     *
     * @return string|false Hash string or false if not cached
     */
    public function get_restrictions_hash()
    {
        return get_transient(self::HASH_CACHE_KEY);
    }

    /**
     * Invalidate all plugin caches with smart recovery
     *
     * @param bool $smart_recovery Whether to enable smart cache recovery
     * @return bool True on success
     */
    public function invalidate_all($smart_recovery = true)
    {
        $start_time = microtime(true);
        
        // Delete main cache keys
        delete_transient(self::DOCTORS_CACHE_KEY);
        delete_transient(self::HASH_CACHE_KEY);

        // Delete all service caches (optimized pattern-based deletion)
        global $wpdb;
        
        $service_prefix = '_transient_' . self::SERVICES_CACHE_PREFIX;
        $timeout_prefix = '_transient_timeout_' . self::SERVICES_CACHE_PREFIX;
        
        // Use optimized queries with LIMIT for large datasets
        $wpdb->query($wpdb->prepare("DELETE FROM {$wpdb->options} WHERE option_name LIKE %s LIMIT 1000", $service_prefix . '%'));
        $wpdb->query($wpdb->prepare("DELETE FROM {$wpdb->options} WHERE option_name LIKE %s LIMIT 1000", $timeout_prefix . '%'));

        // Clear smart cache stats
        delete_transient('care_booking_cache_stats');

        // Smart recovery - preload critical caches
        if ($smart_recovery && class_exists('Care_Booking_Database_Handler')) {
            wp_schedule_single_event(time() + 30, 'care_booking_smart_cache_recovery');
        }

        // Performance tracking
        $execution_time = (microtime(true) - $start_time) * 1000;
        if (defined('WP_DEBUG') && WP_DEBUG) {
            error_log(sprintf('Care Booking Block: Cache invalidation completed in %.2fms', $execution_time));
        }

        // Trigger WordPress action for other plugins/themes
        do_action('care_booking_cache_cleared', $execution_time);

        return true;
    }

    /**
     * Invalidate doctor-specific caches
     *
     * @param int $doctor_id Doctor ID
     * @return bool True on success
     */
    public function invalidate_doctor_cache($doctor_id)
    {
        // Invalidate blocked doctors cache (affects all doctors)
        delete_transient(self::DOCTORS_CACHE_KEY);

        // Invalidate blocked services cache for this doctor
        $cache_key = self::SERVICES_CACHE_PREFIX . (int) $doctor_id;
        delete_transient($cache_key);

        // Invalidate hash cache
        delete_transient(self::HASH_CACHE_KEY);

        return true;
    }

    /**
     * Invalidate service-specific caches
     *
     * @param int $service_id Service ID
     * @param int $doctor_id Doctor ID
     * @return bool True on success
     */
    public function invalidate_service_cache($service_id, $doctor_id)
    {
        // Invalidate blocked services cache for this doctor
        $cache_key = self::SERVICES_CACHE_PREFIX . (int) $doctor_id;
        delete_transient($cache_key);

        // Invalidate hash cache
        delete_transient(self::HASH_CACHE_KEY);

        return true;
    }

    /**
     * Warm up caches with fresh data
     *
     * @param Care_Booking_Database_Handler $db_handler Database handler instance
     * @return bool True on success
     */
    public function warm_up_cache($db_handler)
    {
        try {
            // Warm up blocked doctors cache
            $blocked_doctors = $db_handler->get_blocked_doctors();
            $this->set_blocked_doctors($blocked_doctors);

            // Generate and cache restrictions hash
            $hash = $this->generate_restrictions_hash($db_handler);
            $this->set_restrictions_hash($hash);

            return true;
        } catch (Exception $e) {
            // Log error if logging is available
            if (function_exists('error_log')) {
                error_log('Care Booking Block: Cache warm-up failed - ' . $e->getMessage());
            }
            
            return false;
        }
    }

    /**
     * Check if cache needs refresh based on restrictions hash
     *
     * @param Care_Booking_Database_Handler $db_handler Database handler instance
     * @return bool True if cache needs refresh, false otherwise
     */
    public function needs_refresh($db_handler)
    {
        $current_hash = $this->get_restrictions_hash();
        
        if ($current_hash === false) {
            // No cached hash - needs refresh
            return true;
        }

        $actual_hash = $this->generate_restrictions_hash($db_handler);
        
        return $current_hash !== $actual_hash;
    }

    /**
     * Generate hash of current restrictions for change detection
     *
     * @param Care_Booking_Database_Handler $db_handler Database handler instance
     * @return string Hash of current restrictions
     */
    public function generate_restrictions_hash($db_handler)
    {
        $restrictions = $db_handler->get_all();
        
        // Create a deterministic hash from restrictions data
        $hash_data = [];
        foreach ($restrictions as $restriction) {
            $hash_data[] = sprintf(
                '%s-%d-%d-%d',
                $restriction->restriction_type,
                $restriction->target_id,
                $restriction->doctor_id ?? 0,
                $restriction->is_blocked ? 1 : 0
            );
        }
        
        sort($hash_data); // Ensure consistent ordering
        
        return md5(implode('|', $hash_data));
    }

    /**
     * Get cache timeout from WordPress options
     *
     * @return int Cache timeout in seconds
     */
    public function get_cache_timeout()
    {
        $timeout = get_option('care_booking_cache_timeout', self::DEFAULT_EXPIRATION);
        
        // Ensure timeout is within reasonable bounds
        $timeout = max(300, min(86400, (int) $timeout)); // Between 5 minutes and 24 hours
        
        return $timeout;
    }

    /**
     * Set cache timeout in WordPress options
     *
     * @param int $timeout Timeout in seconds
     * @return bool True on success, false on failure
     */
    public function set_cache_timeout($timeout)
    {
        $timeout = max(300, min(86400, (int) $timeout));
        
        return update_option('care_booking_cache_timeout', $timeout);
    }

    /**
     * Get cache statistics
     *
     * @return array Array of cache statistics
     */
    public function get_cache_stats()
    {
        global $wpdb;

        // Count service cache entries
        $service_count = $wpdb->get_var($wpdb->prepare(
            "SELECT COUNT(*) FROM {$wpdb->options} WHERE option_name LIKE %s",
            '_transient_' . self::SERVICES_CACHE_PREFIX . '%'
        ));

        return [
            'doctors_cached' => get_transient(self::DOCTORS_CACHE_KEY) !== false,
            'service_caches' => (int) $service_count,
            'hash_cached' => get_transient(self::HASH_CACHE_KEY) !== false,
            'cache_timeout' => $this->get_cache_timeout()
        ];
    }

    /**
     * Preload service caches for multiple doctors
     *
     * @param array                         $doctor_ids Array of doctor IDs
     * @param Care_Booking_Database_Handler $db_handler Database handler instance
     * @return int Number of caches preloaded
     */
    public function preload_service_caches($doctor_ids, $db_handler)
    {
        if (!is_array($doctor_ids) || empty($doctor_ids)) {
            return 0;
        }

        $preloaded = 0;

        foreach ($doctor_ids as $doctor_id) {
            // Check if cache already exists
            if ($this->get_blocked_services($doctor_id) === false) {
                // Cache miss - preload from database
                $blocked_services = $db_handler->get_blocked_services($doctor_id);
                
                if ($this->set_blocked_services($doctor_id, $blocked_services)) {
                    $preloaded++;
                }
            }
        }

        return $preloaded;
    }

    /**
     * Clean up expired caches
     *
     * @return int Number of expired caches cleaned
     */
    public function cleanup_expired_caches()
    {
        global $wpdb;

        // WordPress automatically handles transient cleanup, but we can force it
        $cleaned = 0;

        // Delete expired transients
        $expired_transients = $wpdb->get_col(
            "SELECT option_name FROM {$wpdb->options} 
             WHERE option_name LIKE '_transient_timeout_care_booking_%' 
             AND option_value < UNIX_TIMESTAMP()"
        );

        foreach ($expired_transients as $timeout_option) {
            $transient_name = str_replace('_transient_timeout_', '_transient_', $timeout_option);
            
            delete_option($timeout_option);
            delete_option($transient_name);
            
            $cleaned++;
        }

        return $cleaned;
    }

    /**
     * Hook into WordPress action for automatic cache invalidation
     */
    public static function init_cache_hooks()
    {
        // Invalidate cache when restrictions are modified
        add_action('care_booking_restriction_updated', [__CLASS__, 'handle_restriction_change'], 10, 3);
        add_action('care_booking_restriction_created', [__CLASS__, 'handle_restriction_change'], 10, 3);
        add_action('care_booking_restriction_deleted', [__CLASS__, 'handle_restriction_change'], 10, 3);
    }

    /**
     * Handle restriction changes for cache invalidation
     *
     * @param string $type Restriction type
     * @param int    $target_id Target ID
     * @param int    $doctor_id Doctor ID (optional)
     */
    public static function handle_restriction_change($type, $target_id, $doctor_id = null)
    {
        $cache_manager = new self();
        
        if ($type === 'doctor') {
            $cache_manager->invalidate_doctor_cache($target_id);
        } elseif ($type === 'service' && $doctor_id) {
            $cache_manager->invalidate_service_cache($target_id, $doctor_id);
        }
    }

    /**
     * Smart cache with intelligent TTL based on access patterns
     *
     * @param string $key Cache key
     * @param mixed  $data Data to cache
     * @param string $type Cache type ('frequent', 'stable', 'default')
     * @return bool True on success
     */
    public function smart_cache($key, $data, $type = 'default')
    {
        $ttl = $this->get_smart_ttl($type);
        
        // Add access tracking for performance analytics
        $this->track_cache_access($key, 'set');
        
        return set_transient($key, $data, $ttl);
    }

    /**
     * Get smart TTL based on cache type and usage patterns
     *
     * @param string $type Cache type
     * @return int TTL in seconds
     */
    private function get_smart_ttl($type)
    {
        switch ($type) {
            case 'frequent':
                return self::SMART_TTL_EXPIRATION;
            case 'stable':
                return self::LONG_TERM_EXPIRATION;
            default:
                return self::DEFAULT_EXPIRATION;
        }
    }

    /**
     * Track cache access patterns for optimization
     *
     * @param string $key Cache key
     * @param string $action Action type (get/set/hit/miss)
     * @return void
     */
    private function track_cache_access($key, $action)
    {
        if (!defined('WP_DEBUG') || !WP_DEBUG) {
            return; // Only track in debug mode
        }

        $stats_key = 'care_booking_cache_stats';
        $stats = get_transient($stats_key) ?: [];
        
        $stats[$key][$action] = ($stats[$key][$action] ?? 0) + 1;
        $stats[$key]['last_accessed'] = time();
        
        set_transient($stats_key, $stats, DAY_IN_SECONDS);
    }

    /**
     * Bulk cache operations for maximum efficiency
     *
     * @param array $cache_data Array of [key => data] pairs
     * @param string $type Cache type
     * @return array Results of cache operations
     */
    public function bulk_cache($cache_data, $type = 'default')
    {
        $results = [];
        $ttl = $this->get_smart_ttl($type);
        
        foreach ($cache_data as $key => $data) {
            $results[$key] = set_transient($key, $data, $ttl);
        }
        
        return $results;
    }
}

// Initialize cache hooks
Care_Booking_Cache_Manager::init_cache_hooks();