/*      $Id: relation.h,v 1.2 1994-08-26 14:06:07 alex Exp $      */
// join.h
// fv 12/8/93
// join class for isam files

#ifndef __RELATION_H
#define __RELATION_H

#ifndef __ISAM_H
#include <isam.h>
#endif

#ifndef __ARRAY_H
#include <array.h>
#endif


// @C

class TRelation : public TObject
{
  friend class TRelationdef;

  // class TRelation : public TLocalisamfile
  // @END

  // @DPRIV
  TToken_string   _status;  // stato della relazione
  TArray _files;            // file descriptors
  TArray _reldefs;          // TRelationdef array
  int _errors;
  // @END

  // @FPROT
protected:
  virtual void print_on(ostream& out) const;

  int log2ind(int logicnum) const;
  int alias2ind(byte alias) const;
  int name2ind(const char* name) const;

  TRelationdef* reldef(int i) const { return (TRelationdef*)&_reldefs[i]; }
  TLocalisamfile* file(int i = 0) const { return (TLocalisamfile*)&_files[i]; }

  // @LONGDES
  // position_rels fa tutto il lavoro: se non trova un record
  // adatto su un file, svuota il record corrente e non ritorna errore.
  // write etc. poi procedono normalmente
  // @END
  int position_rels(TIsamop op = _isequal, TReclock lockop = _nolock, TDate& atdate = botime, int first = 0);

  friend class TCursor;

public:
  // @FPUB
  int update() { return position_rels(_isequal, _nolock);}
  void zero();
  virtual int next(TReclock lockop = _nolock) { return file()->next(lockop) == NOERR ? position_rels(_isequal, lockop) : file()->status(); }
  virtual int prev(TReclock lockop = _nolock) { return file()->prev(lockop) == NOERR ? position_rels(_isequal, lockop) : file()->status(); }
  virtual int next(TDate& atdate) { return file()->next(atdate) == NOERR ? position_rels(_isequal, _nolock, atdate) : file()->status(); }
  virtual int prev(TDate& atdate) { return file()->prev(atdate) == NOERR ? position_rels(_isequal, _nolock, atdate) : file()->status(); }
  virtual int first(TReclock lockop = _nolock) { return file()->first(lockop) == NOERR ? position_rels(_isequal, lockop) : file()->status(); }
  virtual int last(TReclock lockop = _nolock) { return file()->last(lockop) == NOERR ? position_rels(_isequal, lockop) : file()->status(); }
  virtual int skip(TRecnotype nrec, TReclock lockop = _nolock) { return file()->skip(nrec, lockop) == NOERR ? position_rels(_isequal, lockop) : file()->status(); }
  virtual int read(TIsamop op = _isgteq, TReclock lockop = _nolock, TDate& atdate = botime) { return file()->read(op, lockop, atdate) == NOERR ? position_rels(_isequal, lockop, atdate) : file()->status();}

  TLocalisamfile* lfile(int logicnum = 0) const;
  TLocalisamfile* lfile(const char* name) const;
  void write_enable(int logicnum = -1, const bool on = TRUE) ;
  void write_enable(const char* name, const bool on = TRUE) ;
  void write_disable(int logicnum = -1) { write_enable(logicnum, FALSE); }
  void write_disable(const char* name) { write_enable(name, FALSE); }

  TRectype& curr(int logicnum = 0) const { return lfile(logicnum)->curr(); }
  // next_match for 0ne-to-many relations; positions logicnum (!= main)
  // on next matching record; returns TRUE or FALSE if no more matches; in
  // any case relation is kept consistent except when inconsistent in
  // first place
  bool next_match(int logicnum,  const char* fieldlist = NULL, int nkey = 0);

  // @DES add relation
  // @FPUB
  bool add(int logicnum, const char* relexprs, int key = 1,
           int linkto = 0, byte alias = 0, bool allow_lock = FALSE);
  bool add(const char* tabname, const char* relexprs, int key = 1,
           int linkto = 0, byte alias = 0, bool allow_lock = FALSE);


  // @DES write methods
  // @FPUB
  virtual int write  (bool force = TRUE, TDate& atdate = botime);
  virtual int rewrite(bool force = TRUE, TDate& atdate = botime);
  virtual int remove (TDate& atdate = botime);

  // @DES checking methods
  // @FPUB
  bool eof( int logicnum = 0) { return lfile(logicnum)->eof(); }
  bool bof( int logicnum = 0) { return lfile(logicnum)->bof(); }

  // @N
  // status(), good() and bad() return the status of the relation when called
  // with no args, or the status of the file when called with
  // a logical number
  // @END

  bool status(int logicnum = 0) { return lfile(logicnum)->status(); }
  bool good( int logicnum = 0) { return lfile(logicnum)->good(); }
  bool bad( int logicnum = 0) { return lfile(logicnum)->bad(); }
  bool empty( int logicnum = 0) { return lfile(logicnum)->empty(); }
  // @END

  // @LONGDES
  // isconsistent() returns TRUE if every file in the relation is
  // OK, current record is non-empty, and relation is consistent.
  // If it's not and reset is TRUE, it tries to reset the relation
  // to a consistent state (based on main record) -- no further check
  // is done.
  // Also called internally by update and remove.
  // @END
  bool isconsistent(bool reset = FALSE);

  // TRUE se c'e' un record ed e' il primo match (non si e' mai fatta
  // position_rels)
  bool is_first_match(int logicnum);

  void   save_status    () ;
  void   restore_status () ;

  // @DES positioning operators. return status
  // @FPUB

  TRecnotype operator +=(const TRecnotype npos) { return skip(npos);  }
  TRecnotype operator -=(const TRecnotype npos) { return skip(-npos); }
  TRecnotype operator ++() { return next(); }
  TRecnotype operator --() { return prev(); }

  TRelation(int logicnum, bool linkrecinst = TRUE);
  TRelation(const char* tabname, bool linkrecinst = TRUE);
  virtual ~TRelation();
};

// @C
// Classe TCursor : public TObject
//
// @END

class TExpression;

typedef bool (*FILTERFUNCTION)(const TRelation* r);

class TCursor : public TObject
{
  // @DPRIV
  TRelation*            _if;
  int                   _nkey;
  TRecnotype            _pos; // Posizione corrente
  TRecnotype            _totrec;
  TRecnotype            _lastrec;
  TRecnotype            _lastkrec;
  TFilename                                                     _filename;
  TString               _filter; // Filtro
  TString               _keyfrom; // chiave iniziale
  TString               _keyto; // chiave finale
  TExpression*                                  _fexpr; // Espressione relativo filtro
  bool                                                                  _frozen;
  FILTERFUNCTION                                _filterfunction;
  TFilename                                             _indexname;
  // @END

  // @FPRIV
  virtual TRecnotype buildcursor(TRecnotype rp);
  int filtercursor(int pagecnt, TRecnotype* page);
  bool changed();

  FILE* open_index(bool create = FALSE) const;
  TRecnotype update();


protected:
  TRecnotype readrec();
  void filter(const char* filter, const TRectype* from = NULL,
              const TRectype* to = NULL);

public:
  // @FPUB
  TRecnotype operator =(const TRecnotype nr);   // Assegnazione
  TCursor& operator +=(const TRecnotype nr); // Scorri avanti
  TCursor& operator -=(const TRecnotype nr); // Scorri indietro
  TCursor& operator ++();       // Avanti di un record
  TCursor& operator --();       // Indietro di un record
  TRecnotype pos() const { return _pos; }
  TRecnotype items();
  TRecnotype size() const { return file()->eod(); }
  const TString& from() const { return _keyfrom; }
  const TString& to() const { return _keyto; }

  TRectype& curr(int log = 0) const { return _if->curr(log); }
  TRectype& curr(const char * tab) const
  { return _if->lfile(tab)->curr(); }
  TRecnotype read(TIsamop op = _isgteq, TReclock lockop = _nolock, TDate& atdate = botime);
  virtual bool ok() const;

  const char* filter() const { return _filter; }
  void freeze(bool on = TRUE) { _frozen = on; }
  bool frozen() const { return _frozen; }
  void setfilter(const char* filter_expr) { filter(filter_expr); }
  void setregion(const TRectype& from, const TRectype& to)
  { filter(NULL,&from, &to); }

  TRelation* relation() const { return _if; }
  TLocalisamfile* file(int lnum = 0)    const { return _if->lfile(lnum); }
  TLocalisamfile* file(const char* name) const { return _if->lfile(name); }
  int repos() { return _if->position_rels(); }

  void setkey() { file()->setkey(_nkey); }
  void setkey(int nkey);
  int key() const { return _nkey; }

  bool next_match(int lognum, const char* fl = NULL, int nk = 0);
  bool is_first_match(int ln);
  
  void set_filterfunction(FILTERFUNCTION ff) { _filterfunction = ff; _lastrec = 0L;}
  bool has_filter() const { return _filter.not_empty() || _filterfunction; }

  void save_status    () { _if->save_status(); }
  void restore_status () { _if->restore_status(); }

  TCursor(TRelation* f, const char* filter = "", int key = 1, TRectype* from = NULL, TRectype* to = NULL);
  virtual ~TCursor();
};


// @C
// Classe TFieldref : public TObject
// @END

class TFieldref : public TObject
{
  // @DPRIV
  short _fileid;        // Numero del file
  TString16 _id;        // Nome tabella o stringa col numero del file
  TString16 _name;      // Nome del campo
  int _from, _to;       // Substring

protected:
  virtual void print_on(ostream& out) const;

public:
  // @FPUB
  TFieldref();
  TFieldref(const TString&, short defid);

  TFieldref& operator =(const TString& s);   // Operatore di assegnazione

  virtual bool ok() const { return _name.not_empty(); }    // Vero se il numero del file e' valido

  int file() const { return _fileid; }       // ritorna il file
  const char* name() const { return (const char*) _name; } // ritorna il nome del campo
  int from() const { return _from; }
  int to() const { return _to; }
  int len(TRectype &rec) const;
  const char* read(const TRelation* = NULL) const;
  const char* read(const TRectype&) const;
  void write(const char* val, TRelation* = NULL) const;
  void write(const char* val, TRectype& rec) const;
};
// Converte una stringa in numero logico o numero tabella
int name2log(const char* name);
#endif
// ** EOF relation.h