<?php

namespace VendorDuplicator\Aws\Crypto;

use VendorDuplicator\GuzzleHttp\Psr7\StreamDecoratorTrait;
use LogicException;
use VendorDuplicator\Psr\Http\Message\StreamInterface;
use VendorDuplicator\Aws\Crypto\Cipher\CipherMethod;
/**
 * @internal Represents a stream of data to be encrypted with a passed cipher.
 */
class AesEncryptingStream implements AesStreamInterface
{
    const BLOCK_SIZE = 16;
    // 128 bits
    use StreamDecoratorTrait;
    /**
     * @var string
     */
    private $buffer = '';
    /**
     * @var CipherMethod
     */
    private $cipherMethod;
    /**
     * @var string
     */
    private $key;
    /**
     * @var StreamInterface
     */
    private $stream;
    /**
     * @param StreamInterface $plainText
     * @param string $key
     * @param CipherMethod $cipherMethod
     */
    public function __construct(StreamInterface $plainText, $key, CipherMethod $cipherMethod)
    {
        $this->stream = $plainText;
        $this->key = $key;
        $this->cipherMethod = clone $cipherMethod;
    }
    public function getOpenSslName()
    {
        return $this->cipherMethod->getOpenSslName();
    }
    public function getAesName()
    {
        return $this->cipherMethod->getAesName();
    }
    public function getCurrentIv()
    {
        return $this->cipherMethod->getCurrentIv();
    }
    public function getSize(): ?int
    {
        $plainTextSize = $this->stream->getSize();
        if ($this->cipherMethod->requiresPadding() && $plainTextSize !== null) {
            // PKCS7 padding requires that between 1 and self::BLOCK_SIZE be
            // added to the plaintext to make it an even number of blocks.
            $padding = self::BLOCK_SIZE - $plainTextSize % self::BLOCK_SIZE;
            return $plainTextSize + $padding;
        }
        return $plainTextSize;
    }
    public function isWritable(): bool
    {
        return \false;
    }
    public function read($length): string
    {
        if ($length > strlen($this->buffer)) {
            $this->buffer .= $this->encryptBlock((int) self::BLOCK_SIZE * ceil(($length - strlen($this->buffer)) / self::BLOCK_SIZE));
        }
        $data = substr($this->buffer, 0, $length);
        $this->buffer = substr($this->buffer, $length);
        return $data ? $data : '';
    }
    public function seek($offset, $whence = \SEEK_SET): void
    {
        if ($whence === \SEEK_CUR) {
            $offset = $this->tell() + $offset;
            $whence = \SEEK_SET;
        }
        if ($whence === \SEEK_SET) {
            $this->buffer = '';
            $wholeBlockOffset = (int) ($offset / self::BLOCK_SIZE) * self::BLOCK_SIZE;
            $this->stream->seek($wholeBlockOffset);
            $this->cipherMethod->seek($wholeBlockOffset);
            $this->read($offset - $wholeBlockOffset);
        } else {
            throw new LogicException('Unrecognized whence.');
        }
    }
    private function encryptBlock($length)
    {
        if ($this->stream->eof()) {
            return '';
        }
        $plainText = '';
        do {
            $plainText .= $this->stream->read((int) ($length - strlen($plainText)));
        } while (strlen($plainText) < $length && !$this->stream->eof());
        $options = \OPENSSL_RAW_DATA;
        if (!$this->stream->eof() || $this->stream->getSize() !== $this->stream->tell()) {
            $options |= \OPENSSL_ZERO_PADDING;
        }
        $cipherText = openssl_encrypt($plainText, $this->cipherMethod->getOpenSslName(), $this->key, $options, $this->cipherMethod->getCurrentIv());
        $this->cipherMethod->update($cipherText);
        return $cipherText;
    }
}
