// 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 <condition_variable>

#include <memory>

#include <mutex>

#include <string>

#include <vector>

#include "common/status.h"

#include "olap/rowset/pending_rowset_helper.h"

#include "olap/rowset/rowset_fwd.h"

#include "olap/tablet_fwd.h"

namespace doris {

class RowsetMetaPB;

class TabletSchemaPB;

class TSnapshotRequest;

struct RowsetId;

class StorageEngine;

class MemTrackerLimiter;

class LocalSnapshotLockGuard;

// A simple lock to protect the local snapshot path.

class LocalSnapshotLock {

    friend class LocalSnapshotLockGuard;

public:

    LocalSnapshotLock() = default;

    ~LocalSnapshotLock() = default;

    LocalSnapshotLock(const LocalSnapshotLock&) = delete;

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

    static LocalSnapshotLock& instance() {

        static LocalSnapshotLock instance;

        return instance;

    }

    // Acquire the lock for the specified path. It will block if the lock is already held by another.

    LocalSnapshotLockGuard acquire(const std::string& path);

private:

    void release(const std::string& path);

    class LocalSnapshotContext {

    public:

        bool _is_locked = false;

        size_t _waiting_count = 0;

        std::condition_variable _cv;

        LocalSnapshotContext() = default;

        LocalSnapshotContext(const LocalSnapshotContext&) = delete;

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

    };

    std::mutex _lock;

    std::unordered_map<std::string, LocalSnapshotContext> _local_snapshot_contexts;

};

class LocalSnapshotLockGuard {

public:

    LocalSnapshotLockGuard(std::string path) : _snapshot_path(std::move(path)) {}

    LocalSnapshotLockGuard(const LocalSnapshotLockGuard&) = delete;

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

    ~LocalSnapshotLockGuard() { LocalSnapshotLock::instance().release(_snapshot_path); }

private:

    std::string _snapshot_path;

};

class SnapshotManager {

public:

    SnapshotManager(StorageEngine& engine);

    ~SnapshotManager();

    /// Create a snapshot

    /// snapshot_path: out param, the dir of snapshot

    /// allow_incremental_clone: out param, true if it is an incremental clone

    Status make_snapshot(const TSnapshotRequest& request, std::string* snapshot_path,

                         bool* allow_incremental_clone);

    std::string static get_schema_hash_full_path(const TabletSharedPtr& ref_tablet,

                                                 const std::string& prefix);

    // @brief 释放snapshot

    // @param snapshot_path [in] 要被释放的snapshot的路径，只包含到ID

    Status release_snapshot(const std::string& snapshot_path);

    Result<std::vector<PendingRowsetGuard>> convert_rowset_ids(const std::string& clone_dir,

                                                               int64_t tablet_id,

                                                               int64_t replica_id, int64_t table_id,

                                                               int64_t partition_id,

                                                               int32_t schema_hash);

private:

    Status _calc_snapshot_id_path(const TabletSharedPtr& tablet, int64_t timeout_s,

                                  std::string* out_path);

    std::string _get_header_full_path(const TabletSharedPtr& ref_tablet,

                                      const std::string& schema_hash_path) const;

    std::string _get_json_header_full_path(const TabletSharedPtr& ref_tablet,

                                           const std::string& schema_hash_path) const;

    Status _link_index_and_data_files(const std::string& header_path,

                                      const TabletSharedPtr& ref_tablet,

                                      const std::vector<RowsetSharedPtr>& consistent_rowsets);

    Status _create_snapshot_files(const TabletSharedPtr& ref_tablet,

                                  const TabletSharedPtr& target_tablet,

                                  const TSnapshotRequest& request, std::string* snapshot_path,

                                  bool* allow_incremental_clone);

    Status _prepare_snapshot_dir(const TabletSharedPtr& ref_tablet, std::string* snapshot_id_path);

    Status _rename_rowset_id(const RowsetMetaPB& rs_meta_pb, const std::string& new_tablet_path,

                             TabletSchemaSPtr tablet_schema, const RowsetId& next_id,

                             RowsetMetaPB* new_rs_meta_pb);

    Status _rename_index_ids(TabletSchemaPB& schema_pb,

                             const TabletSchemaSPtr& tablet_schema) const;

    StorageEngine& _engine;

    std::atomic<uint64_t> _snapshot_base_id {0};

    std::shared_ptr<MemTrackerLimiter> _mem_tracker;

}; // SnapshotManager

} // namespace doris