// 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 PL_FUNCTION_HH
#define PL_FUNCTION_HH

#include <qpdf/Pipeline.hh>

#include <functional>

// This pipeline calls an arbitrary function with whatever data is passed to it. This pipeline can
// be reused.
//
// For this pipeline, "next" may be null. If a next pointer is provided, this pipeline will also
// pass the data through to it and will forward finish() to it.
//
// It is okay to not call finish() on this pipeline if it has no "next".
//
// It is okay to keep calling write() after a previous write throws an exception as long as the
// delegated function allows it.
class QPDF_DLL_CLASS Pl_Function: public Pipeline
{
  public:
    typedef std::function<void(unsigned char const*, size_t)> writer_t;

    // The supplied function is called every time write is called.
    QPDF_DLL
    Pl_Function(char const* identifier, Pipeline* next, writer_t fn);

    // The supplied C-style function is called every time write is called. The udata option is
    // passed into the function with each call. If the function returns a non-zero value, a runtime
    // error is thrown.
    typedef int (*writer_c_t)(unsigned char const*, size_t, void*);
    QPDF_DLL
    Pl_Function(char const* identifier, Pipeline* next, writer_c_t fn, void* udata);
    typedef int (*writer_c_char_t)(char const*, size_t, void*);
    QPDF_DLL
    Pl_Function(char const* identifier, Pipeline* next, writer_c_char_t fn, void* udata);

    QPDF_DLL
    ~Pl_Function() override;

    QPDF_DLL
    void write(unsigned char const* buf, size_t len) override;
    QPDF_DLL
    void finish() override;

  private:
    class QPDF_DLL_PRIVATE Members
    {
        friend class Pl_Function;

      public:
        QPDF_DLL
        ~Members() = default;

      private:
        Members(writer_t);
        Members(Members const&) = delete;

        writer_t fn;
    };

    std::shared_ptr<Members> m;
};

#endif // PL_FUNCTION_HH