<?php
/**
 * Nonce Manager - WordPress Nonce Validation Layer
 * 
 * Implements bulletproof nonce generation and validation with auto-refresh
 * 
 * @package CareBook\Ultimate\Security
 * @since 1.0.0
 */

declare(strict_types=1);

namespace CareBook\Ultimate\Security;

/**
 * Nonce Manager
 * 
 * Handles WordPress nonce generation, validation and auto-refresh
 * 
 * @since 1.0.0
 */
final class NonceManager
{
    /** @var string Nonce field name prefix */
    private const NONCE_FIELD_PREFIX = 'care_book_nonce_';
    
    /** @var int Nonce lifetime in seconds */
    private const NONCE_LIFETIME = 3600; // 1 hour
    
    /** @var array<string, string> Generated nonces cache */
    private array $nonceCache = [];
    
    /**
     * Generate nonce for specific action
     * 
     * @param string $action Action name
     * @param int|null $userId User ID (defaults to current user)
     * @return string Generated nonce
     * @since 1.0.0
     */
    public function generateNonce(string $action, ?int $userId = null): string
    {
        $userId = $userId ?? get_current_user_id();
        $nonceAction = $this->getNonceAction($action, $userId);
        
        // Check cache first
        $cacheKey = $this->getCacheKey($nonceAction);
        if (isset($this->nonceCache[$cacheKey])) {
            return $this->nonceCache[$cacheKey];
        }
        
        $nonce = wp_create_nonce($nonceAction);
        $this->nonceCache[$cacheKey] = $nonce;
        
        return $nonce;
    }
    
    /**
     * Validate nonce from request
     * 
     * @param array<string, mixed> $request Request data
     * @param string $action Action name
     * @param int|null $userId User ID (defaults to current user)
     * @return ValidationLayerResult
     * @since 1.0.0
     */
    public function validateNonce(array $request, string $action, ?int $userId = null): ValidationLayerResult
    {
        $result = new ValidationLayerResult();
        $userId = $userId ?? get_current_user_id();
        
        // Check if nonce field exists
        $nonceField = $this->getNonceFieldName($action);
        if (!isset($request[$nonceField])) {
            $result->setValid(false);
            $result->setError("Missing nonce field: {$nonceField}");
            return $result;
        }
        
        $nonce = $request[$nonceField];
        if (!is_string($nonce)) {
            $result->setValid(false);
            $result->setError('Invalid nonce format');
            return $result;
        }
        
        // Validate nonce
        $nonceAction = $this->getNonceAction($action, $userId);
        $isValid = wp_verify_nonce($nonce, $nonceAction);
        
        if ($isValid === false) {
            $result->setValid(false);
            $result->setError('Nonce validation failed');
            return $result;
        }
        
        // Check if nonce is about to expire (and needs refresh)
        if ($isValid === 1) {
            // Nonce is valid but in second half of its lifetime
            $result->setWarning('Nonce approaching expiration');
            $result->setMetadata(['refresh_recommended' => true]);
        }
        
        $result->setValid(true);
        $result->setMetadata([
            'nonce_age' => $isValid,
            'action' => $action,
            'user_id' => $userId
        ]);
        
        return $result;
    }
    
    /**
     * Generate nonce field HTML
     * 
     * @param string $action Action name
     * @param bool $referer Include referer field
     * @return string HTML nonce field
     * @since 1.0.0
     */
    public function generateNonceField(string $action, bool $referer = true): string
    {
        $nonce = $this->generateNonce($action);
        $fieldName = $this->getNonceFieldName($action);
        
        $html = sprintf(
            '<input type="hidden" name="%s" value="%s" />',
            esc_attr($fieldName),
            esc_attr($nonce)
        );
        
        if ($referer) {
            $html .= wp_referer_field(false);
        }
        
        return $html;
    }
    
    /**
     * Generate nonce URL parameter
     * 
     * @param string $url Base URL
     * @param string $action Action name
     * @return string URL with nonce parameter
     * @since 1.0.0
     */
    public function generateNonceUrl(string $url, string $action): string
    {
        $nonce = $this->generateNonce($action);
        $fieldName = $this->getNonceFieldName($action);
        
        return add_query_arg($fieldName, $nonce, $url);
    }
    
    /**
     * Validate nonce from URL
     * 
     * @param string $action Action name
     * @param int|null $userId User ID (defaults to current user)
     * @return ValidationLayerResult
     * @since 1.0.0
     */
    public function validateNonceUrl(string $action, ?int $userId = null): ValidationLayerResult
    {
        $fieldName = $this->getNonceFieldName($action);
        $nonce = $_GET[$fieldName] ?? '';
        
        return $this->validateNonce([$fieldName => $nonce], $action, $userId);
    }
    
    /**
     * Check if nonce needs refresh
     * 
     * @param array<string, mixed> $request Request data
     * @param string $action Action name
     * @return bool
     * @since 1.0.0
     */
    public function needsRefresh(array $request, string $action): bool
    {
        $result = $this->validateNonce($request, $action);
        
        if (!$result->isValid()) {
            return false;
        }
        
        $metadata = $result->getMetadata();
        return isset($metadata['refresh_recommended']) && $metadata['refresh_recommended'];
    }
    
    /**
     * Generate AJAX nonce for JavaScript
     * 
     * @param string $action Action name
     * @return array<string, string> Nonce data for AJAX
     * @since 1.0.0
     */
    public function generateAjaxNonce(string $action): array
    {
        return [
            'nonce' => $this->generateNonce($action),
            'field_name' => $this->getNonceFieldName($action),
            'action' => $action,
            'expires_in' => self::NONCE_LIFETIME
        ];
    }
    
    /**
     * Validate AJAX nonce
     * 
     * @param string $action Action name
     * @return ValidationLayerResult
     * @since 1.0.0
     */
    public function validateAjaxNonce(string $action): ValidationLayerResult
    {
        $nonce = $_POST['security'] ?? $_POST[$this->getNonceFieldName($action)] ?? '';
        
        if (empty($nonce)) {
            $result = new ValidationLayerResult();
            $result->setValid(false);
            $result->setError('Missing AJAX nonce');
            return $result;
        }
        
        return $this->validateNonce([$this->getNonceFieldName($action) => $nonce], $action);
    }
    
    /**
     * Get nonce action name
     * 
     * @param string $action Base action
     * @param int $userId User ID
     * @return string Full nonce action
     * @since 1.0.0
     */
    private function getNonceAction(string $action, int $userId): string
    {
        return "care_book_ultimate_{$action}_{$userId}";
    }
    
    /**
     * Get nonce field name
     * 
     * @param string $action Action name
     * @return string Field name
     * @since 1.0.0
     */
    private function getNonceFieldName(string $action): string
    {
        return self::NONCE_FIELD_PREFIX . $action;
    }
    
    /**
     * Get cache key for nonce
     * 
     * @param string $nonceAction Nonce action
     * @return string Cache key
     * @since 1.0.0
     */
    private function getCacheKey(string $nonceAction): string
    {
        return md5($nonceAction . floor(time() / 300)); // 5-minute buckets
    }
    
    /**
     * Clear nonce cache
     * 
     * @return void
     * @since 1.0.0
     */
    public function clearCache(): void
    {
        $this->nonceCache = [];
    }
    
    /**
     * Get nonce statistics
     * 
     * @return array<string, mixed>
     * @since 1.0.0
     */
    public function getStats(): array
    {
        return [
            'cache_size' => count($this->nonceCache),
            'lifetime' => self::NONCE_LIFETIME,
            'prefix' => self::NONCE_FIELD_PREFIX
        ];
    }
    
    /**
     * Batch validate multiple nonces
     * 
     * @param array<string, mixed> $request Request data
     * @param array<string> $actions Actions to validate
     * @return array<string, ValidationLayerResult>
     * @since 1.0.0
     */
    public function validateMultipleNonces(array $request, array $actions): array
    {
        $results = [];
        
        foreach ($actions as $action) {
            $results[$action] = $this->validateNonce($request, $action);
        }
        
        return $results;
    }
}