// Licensed to the Apache Software Foundation (ASF) under one

// or more contributor license agreements.  See the NOTICE file

// distributed with this work for additional information

// regarding copyright ownership.  The ASF licenses this file

// to you 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 <memory>

#include "butil/macros.h"

#include "common/status.h"

#include "io/fs/file_reader.h"

#include "io/fs/file_reader_writer_fwd.h"

#include "io/fs/path.h"

namespace doris::io {

struct IOContext;

// FileReader wrapper that reads data from packed file using offset and size

// It wraps an inner reader that points to the packed file,

// and adjusts read offsets based on the slice's position in the packed file

class PackedFileReader final : public FileReader {

public:

    PackedFileReader(FileReaderSPtr inner_reader, Path path, int64_t offset, int64_t size);

    ~PackedFileReader() override;

    PackedFileReader(const PackedFileReader&) = delete;

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

    Status close() override;

    const Path& path() const override { return _path; }

    size_t size() const override { return _file_size; }

    bool closed() const override { return _closed; }

    int64_t mtime() const override { return _inner_reader->mtime(); }

protected:

    Status read_at_impl(size_t offset, Slice result, size_t* bytes_read,

                        const IOContext* io_ctx) override;

private:

    FileReaderSPtr _inner_reader;

    Path _path;

    int64_t _packed_file_offset; // Offset in packed file where this slice starts

    int64_t _file_size;          // Size of the slice

    bool _closed = false;

};

} // namespace doris::io