#include "port/port_stdcxx.h"
#include "db/db_impl.h"
#include <deque>
#include <map>
#include <set>
#include <string>
#include "leveldb/db.h"
#include "leveldb/env.h"
#include "leveldb/options.h"
#include "leveldb/slice.h"
#include "leveldb/status.h"
#include "fielddb/request.h"
#include <shared_mutex>
# ifndef FIELD_DB_H
# define FIELD_DB_H
namespace fielddb {
using namespace leveldb;

enum IndexStatus{
        Creating,
        Deleting,
        Exist,
        NotExist
    };

class FieldDB : DB {
public:
    friend class Request;
    friend class FieldsReq;
    friend class iCreateReq;
    friend class iDeleteReq;
    friend class DeleteReq;

    //用的时候必须FieldDB *db = new FieldDB()再open，不能像之前一样DB *db
    FieldDB() : indexDB_(nullptr), kvDB_(nullptr), metaDB_(nullptr) {};
    ~FieldDB();
/*lab1的要求，作为db派生类要实现的虚函数*/
    Status Put(const WriteOptions &options, const Slice &key, const Slice &value) override;
    Status PutFields(const WriteOptions &, const Slice &key, const FieldArray &fields) override;
    Status Delete(const WriteOptions &options, const Slice &key) override;
    Status Write(const WriteOptions &options, WriteBatch *updates) override;
    Status Get(const ReadOptions &options, const Slice &key, std::string *value) override;
    Status GetFields(const ReadOptions &options, const Slice &key, FieldArray *fields) override;
    std::vector<std::string> FindKeysByField(Field &field) override;
    Iterator * NewIterator(const ReadOptions &options) override;
    const Snapshot * GetSnapshot() override;
    void ReleaseSnapshot(const Snapshot *snapshot) override;
    bool GetProperty(const Slice &property, std::string *value) override;
    void GetApproximateSizes(const Range *range, int n, uint64_t *sizes) override;
    void CompactRange(const Slice *begin, const Slice *end) override;
/*与索引相关*/
    Status CreateIndexOnField(const std::string& field_name);
    Status DeleteIndex(const std::string &field_name);
    std::vector<std::string> QueryByIndex(const Field &field, Status *s);
    //返回当前数据库中索引状态，用来测试，不过也可以作为一个功能？
    IndexStatus GetIndexStatus(const std::string &fieldName);

    static Status OpenFieldDB(const Options& options,const std::string& name,FieldDB** dbptr);

private:
    //根据metaDB的内容进行恢复
    Status Recover(); 

private:
    std::string dbname_;
    const Options *options_;
    Env *env_;

    leveldb::DB *metaDB_;
    leveldb::DB *indexDB_;
    leveldb::DB *kvDB_;

    using FieldName = std::string;
    // 标记index的状态,如果是creating/deleting，则会附带相应的请求
    std::map<FieldName, std::pair<IndexStatus,Request*>> index_; 
    port::Mutex index_mu;

    leveldb::port::Mutex mutex_; // mutex for taskqueue
    std::deque<Request *> taskqueue_;

    std::vector<std::pair<std::string, std::string>> FindKeysAndValByFieldName (
                                                    const std::string &fieldName);

    /*For request handling*/
    Status HandleRequest(Request &req); //每个请求自行构造请求后交由这个函数处理
    Request *GetHandleInterval(); //获得任务队列中的待处理区间，区间划分规则和原因见文档

};

Status DestroyDB(const std::string& name,
                                const Options& options);
} // end of namespace
# endif