// Copyright (c) 2005-2021 Jay Berkenbilt

// Copyright (c) 2022-2025 Jay Berkenbilt and Manfred Holger

//

// This file is part of qpdf.

//

// Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except

// in compliance with the License. You may obtain a copy of the License at

//

//   http://www.apache.org/licenses/LICENSE-2.0

//

// Unless required by applicable law or agreed to in writing, software distributed under the License

// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express

// or implied. See the License for the specific language governing permissions and limitations under

// the License.

//

// Versions of qpdf prior to version 7 were released under the terms of version 2.0 of the Artistic

// License. At your option, you may continue to consider qpdf to be licensed under those terms.

// Please see the manual for additional information.

#ifndef QPDFCRYPTOPROVIDER_HH

#define QPDFCRYPTOPROVIDER_HH

#include <qpdf/DLL.h>

#include <qpdf/QPDFCryptoImpl.hh>

#include <functional>

#include <map>

#include <memory>

#include <set>

#include <string>

// This class is part of qpdf's pluggable crypto provider support. Most users won't need to know or

// care about this class, but you can use it if you want to supply your own crypto implementation.

// See also comments in QPDFCryptoImpl.hh.

class QPDFCryptoProvider

{

  public:

    // Methods for getting and registering crypto implementations. These methods are not

    // thread-safe.

    // Return an instance of a crypto provider using the default implementation.

    QPDF_DLL

    static std::shared_ptr<QPDFCryptoImpl> getImpl();

    // Return an instance of the crypto provider registered using the given name.

    QPDF_DLL

    static std::shared_ptr<QPDFCryptoImpl> getImpl(std::string const& name);

    typedef std::function<std::shared_ptr<QPDFCryptoImpl>()> provider_fn;

    // Register a crypto implementation with the given name. The provider function must return

    // a shared pointer to an instance of the implementation class, which must be derived from

    // QPDFCryptoImpl.

    QPDF_DLL static void registerImpl(std::string const& name, provider_fn f);

    // Register the given type (T) as a crypto implementation. T must be derived from QPDFCryptoImpl

    // and must have a constructor that takes no arguments.

    template <typename T>

    static void

    registerImpl(std::string const& name)

    {

        registerImpl(name, std::make_shared<T>);

    }

    // Set the crypto provider registered with the given name as the default crypto implementation.

    QPDF_DLL

    static void setDefaultProvider(std::string const& name);

    // Get the names of registered implementations

    QPDF_DLL

    static std::set<std::string> getRegisteredImpls();

    // Get the name of the default crypto provider

    QPDF_DLL

    static std::string getDefaultProvider();

  private:

    QPDFCryptoProvider();

    ~QPDFCryptoProvider() = default;

    QPDFCryptoProvider(QPDFCryptoProvider const&) = delete;

    QPDFCryptoProvider& operator=(QPDFCryptoProvider const&) = delete;

    static QPDFCryptoProvider& getInstance();

    std::shared_ptr<QPDFCryptoImpl> getImpl_internal(std::string const& name) const;

    void registerImpl_internal(std::string const& name, provider_fn f);

    void setDefaultProvider_internal(std::string const& name);

    class Members

    {

        friend class QPDFCryptoProvider;

      public:

        Members() = default;

        ~Members() = default;

      private:

        Members(Members const&) = delete;

        Members& operator=(Members const&) = delete;

        std::string default_provider;

        std::map<std::string, provider_fn> providers;

    };

    std::shared_ptr<Members> m;

};

#endif // QPDFCRYPTOPROVIDER_HH