<?php

namespace App\Services;

use Exception;

class LegacyEncryption
{
    private $key;
    private $iv;

    public function __construct()
    {
        $keyPath = config('intaleq.legacy_enc_key_path', '/home/intaleq-api/.enckey');
        
        if (file_exists($keyPath)) {
            $this->key = trim(file_get_contents($keyPath));
        } else {
            $this->key = env('LEGACY_ENC_KEY', '');
        }

        $this->iv = config('intaleq.legacy_iv', env('initializationVector', ''));

        if (strlen($this->key) !== 32) {
            // Log warning or throw error in production
        }
        if (strlen($this->iv) !== 16) {
            // Log warning
        }
    }

    /**
     * Encrypt data using AES-256-CBC (Legacy V1 compatibility)
     */
    public function encrypt($plainText)
    {
        if (empty($plainText)) return $plainText;
        
        try {
            $plainText = (string) $plainText;
            $paddedText = $this->addPadding($plainText);
            $encrypted = openssl_encrypt($paddedText, 'AES-256-CBC', $this->key, OPENSSL_RAW_DATA, $this->iv);
            return base64_encode($encrypted);
        } catch (Exception $e) {
            return $plainText;
        }
    }

    /**
     * Decrypt data using AES-256-CBC (Legacy V1 compatibility)
     */
    public function decrypt($encryptedText)
    {
        if (empty($encryptedText)) return $encryptedText;

        try {
            $decoded = base64_decode($encryptedText, true);
            if ($decoded === false) return $encryptedText;

            $decrypted = openssl_decrypt($decoded, 'AES-256-CBC', $this->key, OPENSSL_RAW_DATA, $this->iv);
            if ($decrypted === false) return $encryptedText;

            return $this->removePadding($decrypted);
        } catch (Exception $e) {
            return $encryptedText;
        }
    }

    private function addPadding($data, $blockSize = 16)
    {
        $pad = $blockSize - (strlen($data) % $blockSize);
        return $data . str_repeat(chr($pad), $pad);
    }

    private function removePadding($data)
    {
        $pad = ord($data[strlen($data) - 1]);
        if ($pad < 1 || $pad > 16) return $data;
        return substr($data, 0, -$pad);
    }
}