/*--------------------------------------------------------
  public interface of the log, lsn and logrecord classes
---------------------------------------------------------*/

class log {
    
public:
    log(const char *dbname, Status &error_status);
    log(const char *dbname, unsigned int maxlogsize,
        unsigned int logtailsize, Status &error_status);
    ~log();

    Status read(const lsn_t &lsn, logrecord &logrec);
    Status write(logrecord &logrec, bool is_rollback, lsn_t &assigned_lsn);
    Status read_next_logrec(const lsn_t &currentlsn, logrecord &logrec);
    Status read_next_logrec(const logrecord &curr_logrec,
                            logrecord &next_logrec);
    
    Status get_next_lsn(lsn_t &nextlsn);

    Status get_lastckpt_lsn(lsn_t &lastckpt_lsn);
    Status set_newckpt_lsn(const lsn_t &newckpt);

    Status flush();
    Status bufmgr_flush(lsn_t &flushed_lsn);
};

class lsn_t {

public:
    lsn_t();
    lsn_t(unsigned int wrap, PageId page, unsigned int off);
    ~lsn_t() {}
    
    bool operator==(const lsn_t &rhs) const;
    bool operator!=(const lsn_t &rhs) const;
    bool operator< (const lsn_t &rhs) const;
    bool operator> (const lsn_t &rhs) const;
    bool operator<=(const lsn_t &rhs) const;
    bool operator>=(const lsn_t &rhs) const;

    lsn_t &operator=(const lsn_t &rhs);

    bool   is_invalid() const;
    
    friend ostream &operator<<(ostream &out, const lsn_t &lsn);
    
    friend class log;
};

class logrecord {

public:
    logrecord();
    logrecord(const logrecord &rhs);
    ~logrecord() {}

    const unsigned int LOG_MAXRECSIZ = PAGESIZE * 3;
    
    void set_datalength(unsigned int logrecdatalen) {
        logrechead_ptr->lh_length = logrecdatalen + sizeof(logrecheader);
    }

    lsn_t          get_lsn() const        { return logrechead_ptr->lh_lsn; }
    unsigned int   get_datalength() const { return logrechead_ptr->lh_length - 
                                                   sizeof(logrecheader); }
    unsigned char *get_data_ptr() const   { return data_ptr; }

    logrecord     &operator=(const logrecord &rhs);

    friend ostream &operator<<(ostream &out, const logrecord &logrec);
    
    friend class log;
    
};

/*-------------------------------------------------------------------------*/