downloader.hpp

// Copyright 2017 MongoDB Inc.
//
// 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.

#pragma once

#include <cstddef>
#include <cstdint>
#include <memory>

#include <bsoncxx/document/value.hpp>
#include <bsoncxx/document/view.hpp>
#include <bsoncxx/stdx/optional.hpp>
#include <bsoncxx/types/value.hpp>
#include <mongocxx/cursor.hpp>
#include <mongocxx/stdx.hpp>

#include <mongocxx/config/prelude.hpp>

namespace mongocxx {
MONGOCXX_INLINE_NAMESPACE_BEGIN
namespace gridfs {

class MONGOCXX_API downloader {
   public:
    downloader() noexcept;

    downloader(downloader&&) noexcept;

    downloader& operator=(downloader&&) noexcept;

    downloader(const downloader&) = delete;

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

    ~downloader();

    explicit operator bool() const noexcept;

    std::size_t read(std::uint8_t* buffer, std::size_t length);

    void close();

    std::int32_t chunk_size() const;

    std::int64_t file_length() const;

    bsoncxx::document::view files_document() const;

   private:
    friend class bucket;

    //
    // Constructs a new downloader stream.
    //
    // @param chunks
    //   The cursor to read the chunks of the file from. It must have a value if the length of the
    //   file is non-zero.
    //
    // @param files_doc
    //   The files collection document of the file being downloaded.
    //
    MONGOCXX_PRIVATE downloader(stdx::optional<cursor> chunks, bsoncxx::document::value files_doc);

    MONGOCXX_PRIVATE void fetch_chunk();

    class MONGOCXX_PRIVATE impl;

    MONGOCXX_PRIVATE impl& _get_impl();
    MONGOCXX_PRIVATE const impl& _get_impl() const;

    std::unique_ptr<impl> _impl;
};

}  // namespace gridfs
MONGOCXX_INLINE_NAMESPACE_END
}  // namespace mongocxx