// 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 <string>

#include <vector>

#include "common/status.h"

namespace doris {

class RuntimeProfile;

class RuntimeState;

class Block;

class SpillDataDir;

class SpillFileWriter;

class SpillFileReader;

using SpillFileWriterSPtr = std::shared_ptr<SpillFileWriter>;

using SpillFileReaderSPtr = std::shared_ptr<SpillFileReader>;

/// SpillFile represents a logical spill file that may consist of multiple

/// physical "part" files on disk. Parts are managed automatically by

/// SpillFileWriter when a part exceeds the configured size threshold.

///

/// On-disk layout (a directory on a local disk, or a key prefix in object storage;

/// which one is decided by the SpillDataDir the file was created on):

///   spill_dir/         (created lazily by SpillFileWriter on first write)

///   +-- 0              (part 0)

///   +-- 1              (part 1)

///   +-- ...

///

/// Writing workflow:

///   SpillFileWriterSPtr writer;

///   RETURN_IF_ERROR(spill_file->create_writer(state, profile, writer));

///   RETURN_IF_ERROR(writer->write_block(state, block)); // auto-rotates parts

///   RETURN_IF_ERROR(writer->close());                   // finalizes all parts

///

/// Reading workflow:

///   auto reader = spill_file->create_reader(state, profile);

///   RETURN_IF_ERROR(reader->open());

///   while (!eos) { RETURN_IF_ERROR(reader->read(&block, &eos)); }

class SpillFile : public std::enable_shared_from_this<SpillFile> {

public:

    // to avoid too many small file writes

    static constexpr size_t MIN_SPILL_WRITE_BATCH_MEM = 512 * 1024;

    static constexpr size_t MAX_SPILL_WRITE_BATCH_MEM = 32 * 1024 * 1024;

    /// @param data_dir       The spill storage directory (disk) selected by SpillFileManager.

    /// @param relative_path  Relative path under the spill root, formatted by the operator.

    ///                       e.g. "query_id/sort-node_id-task_id-unique_id"

    SpillFile(SpillDataDir* data_dir, std::string relative_path);

    SpillFile() = delete;

    SpillFile(const SpillFile&) = delete;

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

    ~SpillFile();

    void gc();

    /// Returns true after the writer has been closed (all data flushed).

    bool ready_for_reading() const { return _ready_for_reading; }

    /// Create a SpillFileWriter that automatically manages multi-part rotation.

    /// Only one writer should exist per SpillFile at a time.

    /// Part size threshold is read from config::spill_file_part_size_bytes.

    Status create_writer(RuntimeState* state, RuntimeProfile* profile, SpillFileWriterSPtr& writer);

    /// Create a SpillFileReader that reads sequentially across all parts.

    /// The caller should call reader->open() before reading.

    SpillFileReaderSPtr create_reader(RuntimeState* state, RuntimeProfile* profile) const;

private:

    friend class SpillFileWriter;

    friend class SpillFileManager;

    /// Called by SpillFileWriter::close() to mark writing as complete.

    void finish_writing();

    /// Called by SpillFileWriter to incrementally track bytes written to disk.

    /// This ensures SpillFile always knows the correct _total_written_bytes for

    /// gc() accounting, even if the writer's close() is never properly called.

    void update_written_bytes(int64_t delta_bytes);

    /// Called by SpillFileWriter when a part file is completed, in part order.

    /// @param part_bytes  size of the part file including its footer

    void add_part(int64_t part_bytes);

    SpillDataDir* _data_dir = nullptr;

    // Path of this spill file: data_dir->get_spill_data_path() + "/" + relative_path.

    // Absolute for local stores, relative to the vault prefix for remote stores.

    std::string _spill_dir;

    int64_t _total_written_bytes = 0;

    // Size of every completed part, in part order. Passed to readers so that they never

    // have to ask the storage for the file size (one HEAD request per part on S3).

    std::vector<int64_t> _part_sizes;

    // Set by SpillFileWriter once the first part has been created. Files that were never

    // written have nothing to delete.

    bool _dir_created = false;

    bool _ready_for_reading = false;

    // Pointer to the currently-active writer. Mutable to allow checks from const

    // methods like create_reader(). Only one writer may be active at a time. Cleared when

    // the writer finished, was discarded by gc(), or was destroyed.

    mutable SpillFileWriter* _active_writer = nullptr;

};

using SpillFileSPtr = std::shared_ptr<SpillFile>;

} // namespace doris