// Copyright (c) 2014-2017 Thomas Fussell
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, WRISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE
//
// @license: http://www.opensource.org/licenses/mit-license.php
// @author: see AUTHORS file

#include <detail/constants.hpp>
#include <detail/unicode.hpp>
#include <detail/cryptography/base64.hpp>
#include <detail/cryptography/encryption_info.hpp>
#include <detail/cryptography/value_traits.hpp>
#include <detail/external/include_libstudxml.hpp>
#include <detail/serialization/vector_streambuf.hpp>
#include <detail/serialization/xlsx_producer.hpp>
#include <xlnt/utils/exceptions.hpp>

namespace {

using xlnt::detail::encryption_info;

encryption_info generate_encryption_info(const std::u16string &password)
{
    encryption_info result;

    result.agile.key_data.salt_value.assign(
        reinterpret_cast<const std::uint8_t *>(password.data()),
        reinterpret_cast<const std::uint8_t *>(password.data() + password.size()));

    return result;
}

std::vector<std::uint8_t> write_agile_encryption_info(
    const encryption_info::agile_encryption_info &info)
{
    static const auto &xmlns = xlnt::constants::ns("encryption");
    static const auto &xmlns_p = xlnt::constants::ns("encryption-password");

    std::vector<std::uint8_t> encryption_info;
    xlnt::detail::vector_ostreambuf encryption_info_buffer(encryption_info);
    std::ostream encryption_info_stream(&encryption_info_buffer);
    xml::serializer serializer(encryption_info_stream, "EncryptionInfo");

    serializer.start_element(xmlns, "encryption");

    serializer.start_element(xmlns, "keyData");
    serializer.attribute("saltSize", info.key_data.salt_size);
    serializer.attribute("blockSize", info.key_data.block_size);
    serializer.attribute("keyBits", info.key_data.key_bits);
    serializer.attribute("hashSize", info.key_data.hash_size);
    serializer.attribute("cipherAlgorithm", info.key_data.cipher_algorithm);
    serializer.attribute("cipherChaining", info.key_data.cipher_chaining);
    serializer.attribute("hashAlgorithm", info.key_data.hash_algorithm);
    serializer.attribute("saltValue", xlnt::detail::encode_base64(info.key_data.salt_value));
    serializer.end_element(xmlns, "keyData");

    serializer.start_element(xmlns, "dataIntegrity");
    serializer.attribute("encryptedHmacKey", xlnt::detail::encode_base64(info.data_integrity.hmac_key));
    serializer.attribute("encryptedHmacValue", xlnt::detail::encode_base64(info.data_integrity.hmac_value));
    serializer.end_element(xmlns, "dataIntegrity");

    serializer.start_element(xmlns, "keyEncryptors");
    serializer.start_element(xmlns, "keyEncryptor");
    serializer.attribute("uri", "");
    serializer.start_element(xmlns_p, "encryptedKey");
    serializer.attribute("spinCount", info.key_encryptor.spin_count);
    serializer.attribute("saltSize", info.key_encryptor.salt_size);
    serializer.attribute("blockSize", info.key_encryptor.block_size);
    serializer.attribute("keyBits", info.key_encryptor.key_bits);
    serializer.attribute("hashSize", info.key_encryptor.hash_size);
    serializer.attribute("cipherAlgorithm", info.key_encryptor.cipher_algorithm);
    serializer.attribute("cipherChaining", info.key_encryptor.cipher_chaining);
    serializer.attribute("hashAlgorithm", info.key_encryptor.hash);
    serializer.attribute("saltValue", xlnt::detail::encode_base64(info.key_encryptor.salt_value));
    serializer.attribute("encryptedVerifierHashInput", xlnt::detail::encode_base64(info.key_encryptor.verifier_hash_input));
    serializer.attribute("encryptedVerifierHashValue", xlnt::detail::encode_base64(info.key_encryptor.verifier_hash_value));
    serializer.attribute("encryptedKeyValue", xlnt::detail::encode_base64(info.key_encryptor.encrypted_key_value));
    serializer.end_element(xmlns_p, "encryptedKey");
    serializer.end_element(xmlns, "keyEncryptor");
    serializer.end_element(xmlns, "keyEncryptors");

    serializer.end_element(xmlns, "encryption");

    return encryption_info;
}

std::vector<std::uint8_t> write_standard_encryption_info(
    const encryption_info::standard_encryption_info &/*info*/)
{
    return {};
}

std::vector<std::uint8_t> write_encryption_info(const encryption_info &info)
{
    return (info.is_agile)
        ? write_agile_encryption_info(info.agile)
        : write_standard_encryption_info(info.standard);
}

std::vector<std::uint8_t> write_encryption_info(const std::u16string &password)
{
    return write_encryption_info(generate_encryption_info(password));
}

std::vector<std::uint8_t> encrypt_xlsx(
    const std::vector<std::uint8_t> &bytes,
    const std::u16string &password)
{
    if (bytes.empty())
    {
        throw xlnt::exception("empty file");
    }

    write_encryption_info(password);

    return {};
}

} // namespace

namespace xlnt {
namespace detail {

std::vector<std::uint8_t> XLNT_API encrypt_xlsx(
    const std::vector<std::uint8_t> &data,
    const std::string &password)
{
    return ::encrypt_xlsx(data, utf8_to_utf16(password));
}

void xlsx_producer::write(std::ostream &destination, const std::string &password)
{
    std::vector<std::uint8_t> decrypted;

    {
        vector_ostreambuf decrypted_buffer(decrypted);
        std::ostream decrypted_stream(&decrypted_buffer);
        write(decrypted_stream);
    }

    const auto encrypted = ::encrypt_xlsx(decrypted, utf8_to_utf16(password));
    vector_istreambuf encrypted_buffer(encrypted);

    destination << &encrypted_buffer;
}

} // namespace detail
} // namespace xlnt