#pragma once
#include "db/dbformat.h"
#include <cstddef>
#include <cstdint>
#include "leveldb/env.h"
#include "leveldb/slice.h"
#include "leveldb/status.h"
#include "leveldb/write_batch.h"
namespace leveldb {

struct FilePointer {
    uint64_t FileNumber;
    uint64_t FileOffset;
    uint64_t Size;
};

void EncodeFP(const struct FilePointer &fp,char *scratch);
void DecodeFp(struct FilePointer &fp, char *src);

class KVLog {
public:
    explicit KVLog(WritableFile *dest,uint64_t file_number);
    KVLog(WritableFile *dest, uint64_t dest_length,uint64_t file_number);
    
    KVLog(const KVLog&) = delete;
    KVLog& operator=(const KVLog&) = delete;

    ~KVLog() = default;

    Status AddRecord(const Slice& slice,FilePointer &fp);
private:
    WritableFile* dest_;
    uint64_t pos_;
    uint64_t file_number;
    char buf[8];
};


class KVLogReader {
public:
    KVLogReader(SequentialFile *file):file(file),rep_(nullptr),rep_size(0),valid(true)
     { Next();};

    ~KVLogReader() {
        delete rep_;
    }

    ValueType Type() {return type;}
    Slice Key() {return key;}
    Slice Value() {return value;}
    SequenceNumber Seq() {return seq;}
    bool Valid() {return valid;}
    void Next();
private:
    void NextWriteBatch();
    void NextKV();

private:
    Slice key;
    Slice value;
    SequenceNumber seq;
    ValueType type;
    bool valid;

    SequentialFile *file;
    Slice input;
    uint64_t rep_size;
    char *rep_;
    char number[8];
};

}