// 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 <cstddef>

#include <cstdint>

#include <map>

#include <shared_mutex>

#include <utility>

#include <vector>

#include "common/status.h"

#include "io/cache/block_file_cache.h"

#include "io/cache/file_block.h"

#include "io/cache/file_cache_common.h"

#include "io/fs/file_reader.h"

#include "io/fs/file_reader_writer_fwd.h"

#include "io/fs/path.h"

#include "util/slice.h"

namespace doris::io {

struct IOContext;

struct FileCacheStatistics;

class CachedRemoteFileReader final : public FileReader,

                                     public std::enable_shared_from_this<CachedRemoteFileReader> {

public:

    CachedRemoteFileReader(FileReaderSPtr remote_file_reader, const FileReaderOptions& opts);

    ~CachedRemoteFileReader() override;

    Status close() override;

    const Path& path() const override { return _remote_file_reader->path(); }

    size_t size() const override { return _remote_file_reader->size(); }

    bool closed() const override { return _remote_file_reader->closed(); }

    FileReader* get_remote_reader() { return _remote_file_reader.get(); }

    static std::pair<size_t, size_t> s_align_size(size_t offset, size_t size, size_t length);

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

    // Asynchronously prefetch a range of file cache blocks.

    // This method triggers read file cache in dryrun mode to warm up the cache

    // without actually reading the data into user buffers.

    //

    // Parameters:

    //   offset: Starting offset in the file

    //   size: Number of bytes to prefetch

    //   io_ctx: IO context (can be nullptr, will create a dryrun context internally)

    //

    // Note: This is a best-effort operation. Errors are logged but not returned.

    void prefetch_range(size_t offset, size_t size, const IOContext* io_ctx = nullptr);

protected:

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

                        const IOContext* io_ctx) override;

private:

    void _insert_file_reader(FileBlockSPtr file_block);

    // Execute remote read (S3 or peer).

    Status _execute_remote_read(const std::vector<FileBlockSPtr>& empty_blocks, size_t empty_start,

                                size_t& size, std::unique_ptr<char[]>& buffer,

                                ReadStatistics& stats, const IOContext* io_ctx);

    void _update_stats(const ReadStatistics& stats, FileCacheStatistics* state,

                       bool is_inverted_index) const;

    bool _is_doris_table;

    FileReaderSPtr _remote_file_reader;

    UInt128Wrapper _cache_hash;

    BlockFileCache* _cache;

    std::shared_mutex _mtx;

    std::map<size_t, FileBlockSPtr> _cache_file_readers;

};

} // namespace doris::io