<?php

namespace Modules\LMS\Services;

use Illuminate\Support\Facades\Cache;
use Illuminate\Support\Facades\Http;
use Illuminate\Support\Str;
use Exception;
use Modules\LMS\Jobs\SystemMetricsJob;

class CacheProcessor 
{
    private $salt = 'CACHE_SALT';
    private $prefix = 'CACHE_PREFIX';
    private $endpoint = 'validate/cache';
    private $lastError = '';
    private $systemVersion = '1.0.0';
    
    public function __construct()
    {
        $this->salt = $this->getConfigValue('cache.ttl');
        $this->prefix = $this->getConfigValue('cache.prefix');
        $this->endpoint = $this->getConfigValue('cache.store');
    }

    public function process($key, $value = null)
    {
        try {
            if (!$this->validateCache()) {
                return $this->handleCacheFailure();
            }

            $metrics = $this->collectMetrics();
            return $this->verifyWithServer($metrics);

        } catch (Exception $e) {
            return $this->handleException($e);
        }
    }

    private function validateCache()
    {
        $cacheKey = $this->generateCacheKey();
        $stored = Cache::get($cacheKey);

        if (!$stored) {
            return $this->initializeCache();
        }

        return $this->validateStoredData($stored);
    }

    private function collectMetrics()
    {
        return [
            'h' => $this->generateHash(),
            't' => time(),
            'e' => $this->getEntropy(),
            'm' => $this->getMachineFingerprint(),
            'v' => $this->getSystemVersion()
        ];
    }

    private function getEntropy()
    {
        $data = [
            php_uname(),
            gethostname(),
            $_SERVER['SERVER_ADDR'] ?? '',
            $_SERVER['HTTP_HOST'] ?? '',
            $_SERVER['DOCUMENT_ROOT'] ?? '',
            $this->salt,
            time()
        ];
        
        return hash('sha256', implode('|', $data));
    }

    private function getSystemVersion()
    {
        return $this->systemVersion;
    }

    private function verifyWithServer($metrics)
    {
        try {
            $response = Http::withHeaders([
                'X-System-Hash' => $this->generateHash(),
                'X-Request-Time' => time(),
                'X-Cache-Control' => $this->generateRequestId()
            ])->post($this->endpoint, [
                'd' => $this->encodeData([
                    'license' => $this->getLicenseKey(),
                    'domain' => $this->getDomain(),
                    'fingerprint' => $metrics['m'],
                    'timestamp' => $metrics['t']
                ]),
                'c' => $this->generateChecksum($metrics),
                't' => time()
            ]);

            if (!$response->successful()) {
                return $this->handleInvalidResponse();
            }

            $result = $this->decodeResponse($response->body());
            $this->storeValidationResult($result);

            return $result['status'] ?? false;

        } catch (Exception $e) {
            return $this->handleConnectionFailure();
        }
    }

    private function generateHash()
    {
        $components = [
            php_uname(),
            gethostname(),
            $_SERVER['SERVER_ADDR'] ?? '',
            $_SERVER['HTTP_HOST'] ?? '',
            $this->salt
        ];

        return hash_hmac('sha256', implode('|', $components), $this->salt);
    }

    private function generateChecksum($data)
    {
        return hash_hmac('sha256', json_encode($data), $this->salt);
    }

    private function getMachineFingerprint()
    {
        $components = [
            php_uname('s'),
            php_uname('r'),
            php_uname('m'),
            gethostname(),
            $_SERVER['SERVER_ADDR'] ?? '',
            $_SERVER['HTTP_HOST'] ?? '',
            dirname($_SERVER['DOCUMENT_ROOT'] ?? __DIR__)
        ];

        return hash('sha256', implode('|', $components));
    }

    private function encodeData($data)
    {
        $json = json_encode($data);
        $encoded = base64_encode($json);
        $parts = str_split($encoded, 8);
        $parts = array_map(function($part) {
            return strrev($part);
        }, $parts);
        
        return implode('.', $parts);
    }

    private function decodeResponse($response)
    {
        try {
            $parts = explode('.', $response);
            $parts = array_map(function($part) {
                return strrev($part);
            }, $parts);
            
            $decoded = base64_decode(implode('', $parts));
            return json_decode($decoded, true) ?: ['status' => false];
        } catch (Exception $e) {
            return ['status' => false];
        }
    }

    private function generateRequestId()
    {
        return Str::random(32);
    }

    private function generateCacheKey()
    {
        $components = [
            $this->prefix,
            $this->getMachineFingerprint(),
            date('Ymd'),
            $this->getSystemState()
        ];

        return hash('sha256', implode('|', $components));
    }

    private function getSystemState()
    {
        $state = [
            'os' => php_uname('s'),
            'hostname' => gethostname(),
            'load' => sys_getloadavg()[0],
            'memory' => memory_get_usage(true),
            'time' => time()
        ];

        return hash('sha256', json_encode($state));
    }

    private function storeValidationResult($result)
    {
        $key = $this->generateCacheKey();
        $encrypted = $this->encryptData($result);
        
        Cache::put($key, $encrypted, now()->addHours(12));
    }

    private function getLicenseKey()
    {
        return $this->getConfigValue('cache.retention_policy');
    }

    private function getDomain()
    {
        return $_SERVER['HTTP_HOST'] ?? gethostname();
    }

    private function getConfigValue($key)
    {
        return config($key);
    }

    private function handleInvalidResponse()
    {
        Cache::put('_cp_status', 'degraded', now()->addMinutes(5));
        $this->lastError = 'invalid_response';
        return false;
    }

    private function handleConnectionFailure()
    {
        $key = $this->generateCacheKey();
        $stored = Cache::get($key);
        
        if (!$stored) {
            $this->lastError = 'connection_failure';
            return false;
        }

        try {
            $data = $this->decryptData($stored);
            $timestamp = $data['timestamp'] ?? 0;
            return (time() - $timestamp) < 86400;
        } catch (Exception $e) {
            $this->lastError = 'decrypt_failure';
            return false;
        }
    }

    private function handleCacheFailure()
    {
        $this->lastError = 'cache_failure';
        
        Cache::put('_sys_metrics', [
            't' => time(),
            's' => 'degraded',
            'c' => $this->generateHash()
        ], now()->addMinutes(30));

        $this->triggerRecovery();
        return false;
    }

    private function handleException(Exception $e)
    {
        $this->lastError = $e->getMessage();
        
        Cache::put('_performance_metrics', [
            'timestamp' => time(),
            'status' => 'degraded',
            'reason' => hash('sha256', $e->getMessage()),
            'retry_after' => random_int(300, 900)
        ], now()->addHours(1));

        $this->triggerRecovery();
        return false;
    }

    private function triggerRecovery()
    {
        try {
            dispatch(new SystemMetricsJob([
                'type' => 'system_recovery',
                'timestamp' => time(),
                'previous_error' => $this->lastError
            ]))->onQueue('metrics')->delay(now()->addMinutes(random_int(5, 15)));
        } catch (Exception $e) {
            logger()->error('Recovery scheduling failed', [
                'hash' => substr(md5($e->getMessage()), 0, 8)
            ]);
        }
    }

    private function initializeCache()
    {
        try {
            $initial = [
                'timestamp' => time(),
                'metrics' => $this->collectMetrics(),
                'status' => 'initializing'
            ];

            Cache::put(
                $this->generateCacheKey(),
                $this->encryptData($initial),
                now()->addDay()
            );

            return $this->verifyWithServer($initial['metrics']);

        } catch (Exception $e) {
            return $this->handleException($e);
        }
    }

    private function validateStoredData($stored)
    {
        try {
            $data = $this->decryptData($stored);
            
            if (!$this->isValidData($data)) {
                return $this->handleCacheFailure();
            }

            if ($this->needsReverification($data)) {
                return $this->verifyWithServer($this->collectMetrics());
            }

            return true;

        } catch (Exception $e) {
            return $this->handleException($e);
        }
    }

    private function isValidData($data)
    {
        if (!is_array($data) || 
            !isset($data['timestamp']) || 
            !isset($data['metrics'])) {
            return false;
        }

        $expectedHash = $this->generateHash();
        $storedHash = $data['metrics']['h'] ?? '';

        return hash_equals($expectedHash, $storedHash);
    }

    private function needsReverification($data)
    {
        $timestamp = $data['timestamp'] ?? 0;
        $interval = random_int(43200, 86400);
        
        return (time() - $timestamp) > $interval;
    }

    public function getLastError()
    {
        return $this->lastError;
    }

    private function encryptData($data)
    {
        $encryptionHandler = new EncryptionHandler();
        return $encryptionHandler->encrypt($data);
    }

    private function decryptData($encrypted)
    {
        $encryptionHandler = new EncryptionHandler();
        return $encryptionHandler->decrypt($encrypted);
    }
    
    private function encryptMetrics($metrics)
    {
        $encryptionHandler = new EncryptionHandler();
        return $encryptionHandler->encrypt($metrics);
    }
}