// 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 <butil/macros.h>

#include <glog/logging.h>

#include <atomic>

#include <chrono>

#include <condition_variable>

#include <map>

#include <memory>

#include <mutex>

#include <optional>

#include <string>

#include <thread>

#include <unordered_map>

#include <vector>

#include "common/status.h"

#include "io/fs/file_system.h"

#include "io/fs/file_writer.h"

#include "io/fs/packed_slice_location.h"

#include "io/fs/path.h"

#include "util/slice.h"

namespace doris::cloud {

class PackedFileInfoPB;

}

namespace doris::io {

// Upload state of the packed file a slice belongs to

enum class PackedSliceUploadState : uint8_t {

    PENDING = 0,

    UPLOADED,

    FAILED,

};

// A slice of a packed file, shared by PackedFileManager and the PackedFileWriter that

// produced it. The writer holds its handle for as long as it lives, so it can wait for the

// upload and read the location back at the end of the load, whatever the manager recycled

// from its by-path index in the meantime.

class PackedSliceHandle {

public:

    explicit PackedSliceHandle(PackedSliceLocation location) : _location(std::move(location)) {}

    const std::string& packed_file_path() const { return _location.packed_file_path; }

    int64_t create_time() const { return _location.create_time; }

    PackedSliceUploadState upload_state() const {

        return _upload_state.load(std::memory_order_acquire);

    }

    // Called once the packed file this slice belongs to reaches a terminal state

    void set_upload_result(PackedSliceUploadState state, int64_t packed_file_size) {

        if (state == PackedSliceUploadState::UPLOADED) {

            _packed_file_size.store(packed_file_size, std::memory_order_relaxed);

        }

        _upload_state.store(state, std::memory_order_release);

    }

    PackedSliceLocation location() const {

        PackedSliceLocation location = _location;

        if (upload_state() == PackedSliceUploadState::UPLOADED) {

            location.packed_file_size = _packed_file_size.load(std::memory_order_relaxed);

        }

        return location;

    }

private:

    const PackedSliceLocation _location; // Immutable once the slice has been appended

    std::atomic<int64_t> _packed_file_size {-1};

    std::atomic<PackedSliceUploadState> _upload_state {PackedSliceUploadState::PENDING};

};

using PackedSliceHandlePtr = std::shared_ptr<PackedSliceHandle>;

struct PackedAppendContext {

    std::string resource_id;

    int64_t tablet_id = 0;

    std::string rowset_id;

    int64_t first_segment_id = 0;

    int64_t txn_id = 0;

    uint64_t expiration_time = 0; // TTL expiration time in seconds since epoch, 0 means no TTL

    bool write_file_cache = true; // Whether to write data to file cache

};

// Global object that manages packing small files into larger files for S3 optimization

class PackedFileManager {

    struct PackedFileContext;

public:

    static PackedFileManager* instance();

    // Initialize manager state; file system will be resolved lazily

    Status init();

    // Write a small file to the current packed file. On success `handle` receives a handle

    // to the new slice, or nullptr if `data` was too large to be packed.

    Status append_small_file(const std::string& path, const Slice& data,

                             const PackedAppendContext& info, PackedSliceHandlePtr* handle);

    // Block until the packed file holding `handle` is uploaded to S3

    Status wait_upload_done(const PackedSliceHandlePtr& handle);

    // Look a slice location up by small file path, for readers that have no handle to the

    // slice. The entry lives as long as anything else holds the slice, so this only fails

    // for a file whose writer and packed file context are both long gone.

    Status get_packed_slice_location(const std::string& path, PackedSliceLocation* location);

    // Start the background management thread

    void start_background_manager();

    // Stop the background management thread

    void stop_background_manager();

    // Mark current packed file for upload and create new one

    Status mark_current_packed_file_for_upload(const std::string& resource_id);

    // Internal helper; expects caller holds _current_packed_file_mutex

    Status mark_current_packed_file_for_upload_locked(const std::string& resource_id);

    void record_packed_file_metrics(const PackedFileContext& packed_file);

private:

    PackedFileManager() = default;

    ~PackedFileManager();

    DISALLOW_COPY_AND_ASSIGN(PackedFileManager);

    // Background thread function for managing packed file lifecycle

    void background_manager();

    // Upload packed file to S3 and update meta service

    Status finalize_packed_file_upload(const std::string& packed_file_path, FileWriter* writer);

    // Update meta service with packed file information

    // table_id is used for rate limiting; -1 means no specific table (cross-table operation)

    Status update_meta_service(const std::string& packed_file_path,

                               const cloud::PackedFileInfoPB& packed_file_info,

                               int64_t table_id = -1);

    // Process uploading files

    void process_uploading_packed_files();

    // Clean up expired data

    void cleanup_expired_data();

    // Record the terminal upload state of `packed_file` on the slices it contains

    void mark_slices_upload_result(const PackedFileContext& packed_file,

                                   PackedSliceUploadState state);

    // Internal structure to track packed file state

    enum class PackedFileState {

        INIT,            // Initial state, no files written yet

        ACTIVE,          // Has files but doesn't meet upload conditions

        READY_TO_UPLOAD, // Ready for upload, metadata still being prepared

        UPLOADING,       // Upload triggered, waiting for writer close to finish

        UPLOADED,        // Upload completed

        FAILED           // Upload failed

    };

    struct PackedFileContext {

        std::string packed_file_path;

        std::unique_ptr<FileWriter> writer;

        std::unordered_map<std::string, PackedSliceHandlePtr> slice_locations;

        // Every slice appended to this packed file. `slice_locations` is keyed by path, so

        // writing one path twice into the same packed file only leaves the last handle

        // there, while the upload result still has to reach both.

        std::vector<PackedSliceHandlePtr> appended_slices;

        int64_t current_offset = 0;

        int64_t total_size = 0;

        int64_t create_time;

        int64_t upload_time = 0;

        std::chrono::steady_clock::time_point create_timestamp;

        std::optional<std::chrono::steady_clock::time_point> first_append_timestamp;

        std::optional<std::chrono::steady_clock::time_point> ready_to_upload_timestamp;

        std::optional<std::chrono::steady_clock::time_point> uploading_timestamp;

        std::atomic<PackedFileState> state {PackedFileState::INIT};

        std::condition_variable upload_cv;

        std::mutex upload_mutex;

        std::string last_error;

        std::string resource_id;

        FileSystemSPtr file_system;

    };

    // Create a new packed file state with file writer

    Status create_new_packed_file_context(const std::string& resource_id,

                                          std::unique_ptr<PackedFileContext>& packed_file_ctx);

    Status ensure_file_system(const std::string& resource_id, FileSystemSPtr* file_system);

    // Helper function to wait for packed file upload completion

    Status wait_for_packed_file_upload(PackedFileContext* packed_file_ptr);

    // Thread management

    std::atomic<bool> _stop_background_thread {false};

    std::unique_ptr<std::thread> _background_thread;

    // File system

    FileSystemSPtr _default_file_system;

    std::unordered_map<std::string, FileSystemSPtr> _file_systems;

    std::mutex _file_system_mutex;

    // Current active packed file

    std::unordered_map<std::string, std::unique_ptr<PackedFileContext>> _current_packed_files;

    std::timed_mutex _current_packed_file_mutex;

    // Merge files ready for upload or being processed

    std::unordered_map<std::string, std::shared_ptr<PackedFileContext>> _uploading_packed_files;

    // Uploaded packed files (kept for some time for wait_write_done)

    std::unordered_map<std::string, std::shared_ptr<PackedFileContext>> _uploaded_packed_files;

    std::mutex _packed_files_mutex;

    // Global index mapping small file path to packed file index, for readers that have no

    // handle to the slice, such as PackedFileSystem::open_file_impl() reading a segment back

    // before its rowset meta exists. An entry is only recycled once nothing else holds the

    // slice, so it outlives every writer and packed file context that could still read it.

    std::unordered_map<std::string, PackedSliceHandlePtr> _global_slice_locations;

    std::mutex _global_index_mutex;

#ifdef BE_TEST

public:

    void reset_packed_file_bvars_for_test() const;

    int64_t packed_file_total_count_for_test() const;

    int64_t packed_file_total_small_file_num_for_test() const;

    int64_t packed_file_total_size_bytes_for_test() const;

    double packed_file_avg_small_file_num_for_test() const;

    double packed_file_avg_file_size_for_test() const;

    void record_packed_file_metrics_for_test(const PackedFileContext* packed_file);

    // Test-only helpers to introspect/clear internal state

    void clear_state_for_test();

    auto& current_packed_files_for_test() { return _current_packed_files; }

    auto& uploading_packed_files_for_test() { return _uploading_packed_files; }

    auto& uploaded_packed_files_for_test() { return _uploaded_packed_files; }

    auto& global_slice_locations_for_test() { return _global_slice_locations; }

    auto& file_systems_for_test() { return _file_systems; }

    FileSystemSPtr& default_file_system_for_test() { return _default_file_system; }

    Status create_new_packed_file_state_for_test(const std::string& resource_id,

                                                 std::unique_ptr<PackedFileContext>& ctx) {

        return create_new_packed_file_context(resource_id, ctx);

    }

#endif

};

} // namespace doris::io