<?php
/**
 * 2007-2021 patworx.de
 *
 * DISCLAIMER
 *
 * Do not edit or add to this file if you wish to upgrade AmazonPay to newer
 * versions in the future. If you wish to customize PrestaShop for your
 * needs please refer to http://www.prestashop.com for more information.
 *
 *  @author    patworx multimedia GmbH <service@patworx.de>
 *  @copyright 2007-2021 patworx multimedia GmbH
 *  @license   http://opensource.org/licenses/afl-3.0.php  Academic Free License (AFL 3.0)
 */

use phpseclib\Crypt\AES;

class AmazonPayKeyShareHandler
{
    private $jsonData;
    private $encrypted_data;
    private $is_valid = false;
    private $data;
    private $amazon_public_key;

    /**
     * AmazonPayKeyShareHandler constructor.
     */
    public function __construct()
    {
        AmazonPayLogger::getInstance()->addLog(Tools::file_get_contents('php://input'), 1);
        try {
            $this->jsonData = Tools::file_get_contents('php://input');
            $this->encrypted_data = Tools::jsonDecode($this->jsonData, true);
            if (isset($this->encrypted_data['encryptedKey']) &&
                isset($this->encrypted_data['encryptedPayload']) &&
                isset($this->encrypted_data['iv']) &&
                isset($this->encrypted_data['sigKeyID']) &&
                isset($this->encrypted_data['signature'])
            ) {
                if ($this->hasKeyPair()) {
                    $this->is_valid = true;
                }
            }
        } catch (\Exception $e) {
            return;
        }
    }

    /**
     * decrypt payload
     */
    public function decrypt()
    {
        $this->setAmazonPublicKey();
        $decoded_signature = AmazonPayVendorEncodeDecode::base64_decode($this->encrypted_data['signature']);
        $payloadVerify = $this->encrypted_data;
        unset($payloadVerify['signature']);
        $payloadVerifyJson = Tools::jsonEncode($payloadVerify);
        if (openssl_verify($payloadVerifyJson, AmazonPayVendorEncodeDecode::base64_decode($this->encrypted_data['signature']), $this->key2pem($this->amazon_public_key), 'SHA256')) {
            $decryptedKey = null;
            openssl_private_decrypt(
                AmazonPayVendorEncodeDecode::base64_decode($this->encrypted_data['encryptedKey']),
                $decryptedKey,
                $this->getPrivateKey(),
                OPENSSL_PKCS1_OAEP_PADDING
            );

            $aes = new AES();
            $aes->setKey($decryptedKey);
            $aes->setIV(AmazonPayVendorEncodeDecode::base64_decode($this->encrypted_data['iv']));
            $aes->setKeyLength(256);
            $finalPayload = $aes->decrypt(AmazonPayVendorEncodeDecode::base64_decode($this->encrypted_data['encryptedPayload']));

            // Remove binary characters
            $finalPayload = preg_replace('/[\x00-\x1F\x80-\xFF]/', '', $finalPayload);

            if ($this->data = Tools::jsonDecode($finalPayload)) {
                return true;
            }
        }
        return false;
    }

    /*
     * store into database
     */
    public function store()
    {
        foreach (AmazonPayDefinitions::$keyShareJson as $jsonKey => $value) {
            if (isset($this->data[$jsonKey])) {
                Configuration::updateValue($value, $this->data[$jsonKey]);
            }
        }
        return $this->data;
    }

    /**
     * @return false|string
     */
    public function setAmazonPublicKey()
    {
        $url = AmazonPayHelper::getPublicKeyURL();
        $this->amazon_public_key = Tools::file_get_contents($url . '?sigkey_id=' . $this->encrypted_data['sigKeyID']);
        return $this->amazon_public_key;
    }

    protected function getPrivateKey()
    {
        return Configuration::get('AMAZONPAY_KEYEXCHANGE_PRIVATE_KEY');
    }

    /**
     * @param $key
     * @return string
     */
    protected function key2pem($key)
    {
        return "-----BEGIN PUBLIC KEY-----\n" .
            chunk_split($key, 64, "\n") .
            "-----END PUBLIC KEY-----\n";
    }

    /**
     * @return bool
     */
    public static function createKeyPair()
    {
        try {
            $config = array(
                "digest_alg" => "sha512",
                "private_key_bits" => 4096,
                "private_key_type" => OPENSSL_KEYTYPE_RSA,
            );

            $res = openssl_pkey_new($config);

            openssl_pkey_export($res, $privKey);
            $pubKey = openssl_pkey_get_details($res);
            $pubKey = $pubKey["key"];

            if ($pubKey != '' && $privKey != '') {
                Configuration::updateValue('AMAZONPAY_KEYEXCHANGE_PUBLIC_KEY', $pubKey);
                Configuration::updateValue('AMAZONPAY_KEYEXCHANGE_PRIVATE_KEY', $privKey);
                return true;
            }
        } catch (Exception $e) {
            return false;
        }
        return false;
    }

    /**
     * @return bool
     */
    protected function hasKeyPair()
    {
        return Configuration::get('AMAZONPAY_KEYEXCHANGE_PUBLIC_KEY') != '' &&
               Configuration::get('AMAZONPAY_KEYEXCHANGE_PRIVATE_KEY') != '';
    }

    /**
     * @return bool
     */
    public function isValid()
    {
        return $this->is_valid;
    }
}