// 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 "DB.h"
#include "Types.h"
#include "utils/ThreadPool.h"
#include "src/db/insert/MemManager.h"

#include <mutex>
#include <condition_variable>
#include <memory>
#include <atomic>
#include <thread>
#include <list>
#include <set>


namespace zilliz {
namespace milvus {
namespace engine {

class Env;

namespace meta {
class Meta;
}

class DBImpl : public DB {
 public:
    explicit DBImpl(const DBOptions &options);
    ~DBImpl();

    Status Start() override;
    Status Stop() override;
    Status DropAll() override;

    Status CreateTable(meta::TableSchema &table_schema) override;

    Status DeleteTable(const std::string &table_id, const meta::DatesT &dates) override;

    Status DescribeTable(meta::TableSchema &table_schema) override;

    Status HasTable(const std::string &table_id, bool &has_or_not) override;

    Status AllTables(std::vector<meta::TableSchema> &table_schema_array) override;

    Status PreloadTable(const std::string &table_id) override;

    Status UpdateTableFlag(const std::string &table_id, int64_t flag);

    Status GetTableRowCount(const std::string &table_id, uint64_t &row_count) override;

    Status InsertVectors(const std::string &table_id, uint64_t n, const float *vectors, IDNumbers &vector_ids) override;

    Status CreateIndex(const std::string& table_id, const TableIndex& index) override;

    Status DescribeIndex(const std::string& table_id, TableIndex& index) override;

    Status DropIndex(const std::string& table_id) override;

    Status Query(const std::string &table_id,
                 uint64_t k,
                 uint64_t nq,
                 uint64_t nprobe,
                 const float *vectors,
                 QueryResults &results) override;

    Status Query(const std::string &table_id,
                 uint64_t k,
                 uint64_t nq,
                 uint64_t nprobe,
                 const float *vectors,
                 const meta::DatesT &dates,
                 QueryResults &results) override;

    Status Query(const std::string &table_id,
                 const std::vector<std::string> &file_ids,
                 uint64_t k,
                 uint64_t nq,
                 uint64_t nprobe,
                 const float *vectors,
                 const meta::DatesT &dates,
                 QueryResults &results) override;

    Status Size(uint64_t &result) override;

 private:
    Status QueryAsync(const std::string &table_id,
                      const meta::TableFilesSchema &files,
                      uint64_t k,
                      uint64_t nq,
                      uint64_t nprobe,
                      const float *vectors,
                      const meta::DatesT &dates,
                      QueryResults &results);

    void BackgroundTimerTask();

    void StartMetricTask();

    void StartCompactionTask();
    Status MergeFiles(const std::string &table_id,
                      const meta::DateT &date,
                      const meta::TableFilesSchema &files);
    Status BackgroundMergeFiles(const std::string &table_id);
    void BackgroundCompaction(std::set<std::string> table_ids);

    void StartBuildIndexTask(bool force=false);
    void BackgroundBuildIndex();

    Status BuildIndex(const meta::TableFileSchema &);

    Status MemSerialize();

 private:
    const DBOptions options_;

    std::atomic<bool> shutting_down_;

    std::thread bg_timer_thread_;

    meta::MetaPtr meta_ptr_;
    MemManagerPtr mem_mgr_;
    std::mutex mem_serialize_mutex_;

    ThreadPool compact_thread_pool_;
    std::list<std::future<void>> compact_thread_results_;
    std::set<std::string> compact_table_ids_;

    ThreadPool index_thread_pool_;
    std::list<std::future<void>> index_thread_results_;

    std::mutex build_index_mutex_;

}; // DBImpl


} // namespace engine
} // namespace milvus
} // namespace zilliz