// Copyright (c) 2005-2020 Jay Berkenbilt
//
// 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 QPDF_CLOSEDFILEINPUTSOURCE_HH
#define QPDF_CLOSEDFILEINPUTSOURCE_HH

// This is an input source that reads from files, like
// FileInputSource, except that it opens and close the file
// surrounding every operation. This decreases efficiency, but it allows
// many more of these to exist at once than the maximum number of open
// file descriptors. This is used for merging large numbers of files.

#include <qpdf/InputSource.hh>
#include <qpdf/PointerHolder.hh>

class FileInputSource;

class ClosedFileInputSource: public InputSource
{
  public:
    QPDF_DLL
    ClosedFileInputSource(char const* filename);
    QPDF_DLL
    virtual ~ClosedFileInputSource();
    QPDF_DLL
    virtual qpdf_offset_t findAndSkipNextEOL();
    QPDF_DLL
    virtual std::string const& getName() const;
    QPDF_DLL
    virtual qpdf_offset_t tell();
    QPDF_DLL
    virtual void seek(qpdf_offset_t offset, int whence);
    QPDF_DLL
    virtual void rewind();
    QPDF_DLL
    virtual size_t read(char* buffer, size_t length);
    QPDF_DLL
    virtual void unreadCh(char ch);

    // The file stays open between calls to stayOpen(true) and
    // stayOpen(false). You can use this to surround multiple
    // operations on a single ClosedFileInputSource to reduce the
    // overhead of a separate open/close on each call.
    QPDF_DLL
    void stayOpen(bool);

  private:
    ClosedFileInputSource(ClosedFileInputSource const&) = delete;
    ClosedFileInputSource& operator=(ClosedFileInputSource const&) = delete;

    void before();
    void after();

    class Members
    {
        friend class ClosedFileInputSource;

      public:
        QPDF_DLL
        ~Members();

      private:
        Members(char const* filename);

        std::string filename;
        qpdf_offset_t offset;
        PointerHolder<FileInputSource> fis;
        bool stay_open;
    };
    PointerHolder<Members> m;
};

#endif // QPDF_CLOSEDFILEINPUTSOURCE_HH
