/* Position history
   Copyright (C) 1992 Joseph H. Allen

This file is part of JOE (Joe's Own Editor)

JOE is free software; you can redistribute it and/or modify it under the 
terms of the GNU General Public License as published by the Free Software 
Foundation; either version 1, or (at your option) any later version.  

JOE is distributed in the hope that it will be useful, but WITHOUT ANY 
WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS 
FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more 
details.  

You should have received a copy of the GNU General Public License along with 
JOE; see the file COPYING.  If not, write to the Free Software Foundation, 
675 Mass Ave, Cambridge, MA 02139, USA.  */ 

#include "poshist.h"
#include "queue.h"
#include "b.h"
#include "w.h"
#include "bw.h"

typedef struct pos POS;

struct pos
 {
 LINK(POS) link;
 P *p;
 W *w;
 };

POS pos={{&pos,&pos}};
POS *curpos=&pos;
int npos=0;

void markpos(w,p)
W *w;
P *p;
{
POS *new=(POS *)malloc(sizeof(POS));
new->p=pdup(p);
new->w=w;
enqueb(POS,link,&pos,new);
if(++npos==20)
 {
 new=pos.link.next;
 if(new->p) prm(new->p);
 free(deque(POS,link,new));
 }
}

void afterpos()
{
if(curpos!=&pos)
 {
 demote(POS,link,&pos,curpos);
 curpos=&pos;
 }
}

void aftermove(w,p)
W *w;
P *p;
{
if(pos.link.prev!=&pos &&
   pos.link.prev->w==w &&
   pos.link.prev->p &&
   Iabs(pos.link.prev->p->line-p->line)<3
  )
 pset(pos.link.prev->p,p);
else markpos(w,p);
}

void windie(w)
W *w;
{
POS *n;
for(n=pos.link.prev;n!=&pos;n=n->link.prev) if(n->w==w) n->w=0;
}

void unextpos(w)
W *w;
{
lp:
if(curpos->link.next!=&pos && curpos!=&pos)
 {
 BW *bw;
 curpos=curpos->link.next;
 if(!curpos->p || !curpos->w) goto lp;
 if(w->t->curwin==curpos->w &&
    curpos->p->byte==((BW *)w->t->curwin->object)->cursor->byte) goto lp;
 if(w->t->curwin!=curpos->w)
  {
  w->t->curwin=curpos->w;
  if(w->t->curwin->y== -1) wfit(w->t);
  }
 w=w->t->curwin;
 bw=(BW *)w->object;
 if(bw->cursor->byte!=curpos->p->byte) pset(bw->cursor,curpos->p);
 }
}

void uprevpos(w)
W *w;
{
lp:
if(curpos->link.prev!=&pos)
 {
 BW *bw;
 curpos=curpos->link.prev;
 if(!curpos->p || !curpos->w) goto lp;
 if(w->t->curwin==curpos->w &&
    curpos->p->byte==((BW *)w->t->curwin->object)->cursor->byte) goto lp;
 if(w->t->curwin!=curpos->w)
  {
  w->t->curwin=curpos->w;
  if(w->t->curwin->y== -1) wfit(w->t);
  }
 w=w->t->curwin;
 bw=(BW *)w->object;
 if(bw->cursor->byte!=curpos->p->byte) pset(bw->cursor,curpos->p);
 }
}