/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */

/*

 * This file is part of the LibreOffice project.

 *

 * This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, You can obtain one at http://mozilla.org/MPL/2.0/.

 */

#pragma once

#include <sal/types.h>

#include <utility>

#include <vector>

#include <rtl/strbuf.hxx>

#include <rtl/ustring.hxx>

#include <com/sun/star/uno/Reference.hxx>

#include <svl/svldllapi.h>

// Is this length truly the maximum possible, or just a number that

// seemed large enough when the author tested this (with some type of

// certificates)? I suspect the latter.

// Used to be 0x4000 = 16384, but a sample signed PDF (produced by

// some other software) provided by the customer has a signature

// content that is 30000 bytes. The SampleSignedPDFDocument.pdf from

// Adobe has one that is 21942 bytes. So let's be careful. Pity this

// can't be dynamic, at least not without restructuring the code. Also

// note that the checks in the code for this being too small

// apparently are broken, if this overflows you end up with an invalid

// PDF. Need to fix that.

#define MAX_SIGNATURE_CONTENT_LENGTH 50000

namespace com::sun::star::security { class XCertificate; }

class SvStream;

struct SignatureInformation;

namespace svl::crypto {

class SigningContext;

/// Converts a hex-encoded string into a byte array.

SVL_DLLPUBLIC std::vector<unsigned char> DecodeHexString(std::string_view rHex);

/// Helper to cryptographically sign and verify

/// arbitrary data blocks.

class SVL_DLLPUBLIC Signing

{

public:

    Signing(svl::crypto::SigningContext& rSigningContext) :

        m_rSigningContext(rSigningContext)

    {

    }

    /// Add a range to sign.

    /// Note: for efficiency this takes a naked pointer, which must remain valid

    /// until this object is discarded.

    void AddDataRange(const void* pData, sal_Int32 size)

    {

        m_dataBlocks.emplace_back(pData, size);

    }

    void SetSignTSA(const OUString& tsa) { m_aSignTSA = tsa; }

    void SetSignPassword(const OUString& password) { m_aSignPassword = password; }

    /// Signs one or more data blocks (as a single, contiguous, array).

    /// Returns the signature (in PKCS#7 format) as string (hex).

    bool Sign(OStringBuffer& rCMSHexBuffer);

    /// Verify and get Signature Information given a byte array.

    static bool Verify(const std::vector<unsigned char>& aData,

                       const bool bNonDetached,

                       const std::vector<unsigned char>& aSignature,

                       SignatureInformation& rInformation);

    /// Verify and get Signature Information given a signature and stream.

    static bool Verify(SvStream& rStream,

                       const std::vector<std::pair<size_t, size_t>>& aByteRanges,

                       const bool bNonDetached,

                       const std::vector<unsigned char>& aSignature,

                       SignatureInformation& rInformation);

    static void appendHex(sal_Int8 nInt, OStringBuffer& rBuffer);

private:

    /// The certificate to use for signing.

    [[maybe_unused]] svl::crypto::SigningContext& m_rSigningContext;

    /// Data blocks (pointer-size pairs).

    std::vector<std::pair<const void*, sal_Int32>> m_dataBlocks;

    OUString m_aSignTSA;

    OUString m_aSignPassword;

};

/// Wrapper around a certificate: allows either an actual signing or extracting enough info, so a

/// 3rd-party can sign our document.

///

/// The following states are supported:

/// - actual signing: set m_xCertificate

/// - hash extract before external signing: don't set anything, m_nSignatureTime and m_aDigest will

///   be set

/// - signature serialization after external signing: set m_nSignatureTime and m_aSignatureValue

class SVL_DLLPUBLIC SigningContext

{

public:

    /// If set, the certificate used for signing.

    css::uno::Reference<css::security::XCertificate> m_xCertificate;

    /// If m_xCertificate is not set, the time that would be used, in milliseconds since the epoch

    /// (1970-01-01 UTC).

    sal_Int64 m_nSignatureTime = 0;

    /// SHA-256 digest of the to-be signed document.

    std::vector<unsigned char> m_aDigest;

    /// PKCS#7 data, produced externally.

    std::vector<unsigned char> m_aSignatureValue;

};

/// Used for visual signing: an XCertificate or a signer name.

class SVL_DLLPUBLIC CertificateOrName

{

public:

    /// If set, the certificate used for signing.

    css::uno::Reference<css::security::XCertificate> m_xCertificate;

    /// Otherwise we don't have a certificate but have a name to be featured on the visual

    /// signature.

    OUString m_aName;

    /// Returns if a certificate or a name is set.

    bool Is() const;

};

}

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