<?php

namespace TablePress\PhpOffice\PhpSpreadsheet\Shared;

use TablePress\PhpOffice\PhpSpreadsheet\Exception as SpException;
use TablePress\PhpOffice\PhpSpreadsheet\Worksheet\Protection;

class PasswordHasher
{
	const MAX_PASSWORD_LENGTH = 255;

	/**
	 * Get algorithm name for PHP.
	 */
	private static function getAlgorithm(string $algorithmName): string
	{
		if (!$algorithmName) {
			return '';
		}

		// Mapping between algorithm name in Excel and algorithm name in PHP
		$mapping = [
			Protection::ALGORITHM_MD2 => 'md2',
			Protection::ALGORITHM_MD4 => 'md4',
			Protection::ALGORITHM_MD5 => 'md5',
			Protection::ALGORITHM_SHA_1 => 'sha1',
			Protection::ALGORITHM_SHA_256 => 'sha256',
			Protection::ALGORITHM_SHA_384 => 'sha384',
			Protection::ALGORITHM_SHA_512 => 'sha512',
			Protection::ALGORITHM_RIPEMD_128 => 'ripemd128',
			Protection::ALGORITHM_RIPEMD_160 => 'ripemd160',
			Protection::ALGORITHM_WHIRLPOOL => 'whirlpool',
		];

		if (array_key_exists($algorithmName, $mapping)) {
			return $mapping[$algorithmName];
		}

		throw new SpException('Unsupported password algorithm: ' . $algorithmName);
	}

	/**
	 * Create a password hash from a given string.
	 *
	 * This method is based on the spec at:
	 * https://interoperability.blob.core.windows.net/files/MS-OFFCRYPTO/[MS-OFFCRYPTO].pdf
	 * 2.3.7.1 Binary Document Password Verifier Derivation Method 1
	 *
	 * It replaces a method based on the algorithm provided by
	 * Daniel Rentz of OpenOffice and the PEAR package
	 * Spreadsheet_Excel_Writer by Xavier Noguer <xnoguer@rezebra.com>.
	 *
	 * @param string $password Password to hash
	 */
	private static function defaultHashPassword(string $password): string
	{
		$verifier = 0;
		$pwlen = strlen($password);
		$passwordArray = pack('c', $pwlen) . $password;
		for ($i = $pwlen; $i >= 0; --$i) {
			$intermediate1 = (($verifier & 0x4000) === 0) ? 0 : 1;
			$intermediate2 = 2 * $verifier;
			$intermediate2 = $intermediate2 & 0x7FFF;
			$intermediate3 = $intermediate1 | $intermediate2;
			$verifier = $intermediate3 ^ ord($passwordArray[$i]);
		}
		$verifier ^= 0xCE4B;

		return strtoupper(dechex($verifier));
	}

	/**
	 * Create a password hash from a given string by a specific algorithm.
	 *
	 * 2.4.2.4 ISO Write Protection Method
	 *
	 * @see https://docs.microsoft.com/en-us/openspecs/office_file_formats/ms-offcrypto/1357ea58-646e-4483-92ef-95d718079d6f
	 *
	 * @param string $password Password to hash
	 * @param string $algorithm Hash algorithm used to compute the password hash value
	 * @param string $salt Pseudorandom string
	 * @param int $spinCount Number of times to iterate on a hash of a password
	 *
	 * @return string Hashed password
	 */
	public static function hashPassword(string $password, string $algorithm = '', string $salt = '', int $spinCount = 10000): string
	{
		if (strlen($password) > self::MAX_PASSWORD_LENGTH) {
			throw new SpException('Password exceeds ' . self::MAX_PASSWORD_LENGTH . ' characters');
		}
		$phpAlgorithm = self::getAlgorithm($algorithm);
		if (!$phpAlgorithm) {
			return self::defaultHashPassword($password);
		}

		$saltValue = base64_decode($salt);
		$encodedPassword = mb_convert_encoding($password, 'UCS-2LE', 'UTF-8');

		$hashValue = hash($phpAlgorithm, $saltValue . $encodedPassword, true);
		for ($i = 0; $i < $spinCount; ++$i) {
			$hashValue = hash($phpAlgorithm, $hashValue . pack('L', $i), true);
		}

		return base64_encode($hashValue);
	}
}
