<?php

/**
 * Raw RSA Key Handler
 *
 * PHP version 5
 *
 * An array containing two \phpseclib3\Math\BigInteger objects.
 *
 * The exponent can be indexed with any of the following:
 *
 * 0, e, exponent, publicExponent
 *
 * The modulus can be indexed with any of the following:
 *
 * 1, n, modulo, modulus
 *
 * @author    Jim Wigginton <terrafrost@php.net>
 * @copyright 2015 Jim Wigginton
 * @license   http://www.opensource.org/licenses/mit-license.html  MIT License
 * @link      http://phpseclib.sourceforge.net
 */

declare(strict_types=1);

namespace phpseclib3\Crypt\RSA\Formats\Keys;

use phpseclib3\Exception\UnexpectedValueException;
use phpseclib3\Exception\UnsupportedFormatException;
use phpseclib3\Math\BigInteger;

/**
 * Raw RSA Key Handler
 *
 * @author  Jim Wigginton <terrafrost@php.net>
 */
abstract class Raw
{
    /**
     * Break a public or private key down into its constituent components
     *
     * @param string|array $key
     */
    public static function load($key, ?string $password = null): array
    {
        if (!is_array($key)) {
            throw new UnexpectedValueException('Key should be a array - not a ' . gettype($key));
        }

        $key = array_change_key_case($key, CASE_LOWER);

        $components = ['isPublicKey' => false];

        foreach (['e', 'exponent', 'publicexponent', 0, 'privateexponent', 'd'] as $index) {
            if (isset($key[$index])) {
                $components['publicExponent'] = $key[$index];
                break;
            }
        }

        foreach (['n', 'modulo', 'modulus', 1] as $index) {
            if (isset($key[$index])) {
                $components['modulus'] = $key[$index];
                break;
            }
        }

        if (!isset($components['publicExponent']) || !isset($components['modulus'])) {
            throw new UnexpectedValueException('Modulus / exponent not present');
        }

        if (isset($key['primes'])) {
            $components['primes'] = $key['primes'];
        } elseif (isset($key['p']) && isset($key['q'])) {
            $indices = [
                ['p', 'q'],
                ['prime1', 'prime2'],
            ];
            foreach ($indices as $index) {
                [$i0, $i1] = $index;
                if (isset($key[$i0]) && isset($key[$i1])) {
                    $components['primes'] = [1 => $key[$i0], $key[$i1]];
                }
            }
        }

        if (isset($key['exponents'])) {
            $components['exponents'] = $key['exponents'];
        } else {
            $indices = [
                ['dp', 'dq'],
                ['exponent1', 'exponent2'],
            ];
            foreach ($indices as $index) {
                [$i0, $i1] = $index;
                if (isset($key[$i0]) && isset($key[$i1])) {
                    $components['exponents'] = [1 => $key[$i0], $key[$i1]];
                }
            }
        }

        if (isset($key['coefficients'])) {
            $components['coefficients'] = $key['coefficients'];
        } else {
            foreach (['inverseq', 'q\'', 'coefficient'] as $index) {
                if (isset($key[$index])) {
                    $components['coefficients'] = [2 => $key[$index]];
                }
            }
        }

        if (!isset($components['primes'])) {
            $components['isPublicKey'] = true;
            return $components;
        }

        if (!isset($components['exponents'])) {
            $one = new BigInteger(1);
            $temp = $components['primes'][1]->subtract($one);
            $exponents = [1 => $components['publicExponent']->modInverse($temp)];
            $temp = $components['primes'][2]->subtract($one);
            $exponents[] = $components['publicExponent']->modInverse($temp);
            $components['exponents'] = $exponents;
        }

        if (!isset($components['coefficients'])) {
            $components['coefficients'] = [2 => $components['primes'][2]->modInverse($components['primes'][1])];
        }

        foreach (['privateexponent', 'd'] as $index) {
            if (isset($key[$index])) {
                $components['privateExponent'] = $key[$index];
                break;
            }
        }

        return $components;
    }

    /**
     * Convert a private key to the appropriate format.
     */
    public static function savePrivateKey(BigInteger $n, BigInteger $e, BigInteger $d, array $primes, array $exponents, array $coefficients, ?string $password = null, array $options = []): string
    {
        if (!empty($password) && is_string($password)) {
            throw new UnsupportedFormatException('Raw private keys do not support encryption');
        }

        return serialize([
            'e' => clone $e,
            'n' => clone $n,
            'd' => clone $d,
            'primes' => array_map(fn ($var) => clone $var, $primes),
            'exponents' => array_map(fn ($var) => clone $var, $exponents),
            'coefficients' => array_map(fn ($var) => clone $var, $coefficients),
        ]);
    }

    /**
     * Convert a public key to the appropriate format
     */
    public static function savePublicKey(BigInteger $n, BigInteger $e): array
    {
        return ['e' => clone $e, 'n' => clone $n];
    }
}