#include <curses.h>

#include "vars.h"
#include "math.h"
#include "structs.h"
#include "display.h"

#include "see.h"

/*
 * See a cell.  The observer's location for wall display purposes is
 *  taken from seecell_loc.
 */
void seecell(LOC *lc)
{
 if ((lc->type == LOC_WALL) || (lc->type == LOC_SDOOR))
  { checkwall_from(lc,seecell_loc);
  }
 upddisp(lc);
}

/*
 * Return true if we have line-of-sight from lc to offset (dx,dy).
 */
static int los(LOC *lc, int dx, int dy)
{
 int px;
 int py;
 LEVEL *lv;
 LOC *lc2;
 int i;
 int df;

 lv = lc->on;
 df = isqrt((dx*dx)+(dy*dy));
 for (i=0;i<df;i++)
  { px = lc->x + ((dx * i) / df);
    py = lc->y + ((dy * i) / df);
    if (lv->flags & LVF_WRAPAROUND)
     { if (px < 0) px += LEV_X; else if (px >= LEV_X) px -= LEV_X;
       if (py < 0) py += LEV_Y; else if (py >= LEV_Y) py -= LEV_Y;
     }
    else if ((px < 0) || (py < 0) || (px >= LEV_X) || (py >= LEV_Y))
     { return(0);
     }
    lc2 = &lv->cells[px][py];
    if ( (lc2->type != LOC_CAVE) &&
	 ( (lc2->type != LOC_DOOR) ||
	   !(lc2->walldoor & LOC_DOOR_OPEN) ) )
     { return(0);
     }
  }
 return(1);
}

/*
 * See level cells. lc is the observer's location.  rad is the vision
 *  radius.  Each seen LOC has flg set in its flags and has (*fxn)()
 *  called on it.  perc indicates that potion-of-perception style sight
 *  should be done (see through walls).
 */
void see(LOC *lc, int rad, int flg, void (*fxn)(LOC *), int perc)
{
 int atx;
 int aty;
 int x1;
 int y1;
 int x2;
 int y2;
 int x;
 int y;
 int dx;
 int dy;
 int px;
 int py;
 int sd2;
 int d2;
 int r2;
 LOC *lc2;
 LEVEL *lv;

 atx = lc->x;
 aty = lc->y;
 lv = lc->on;
 x1 = atx - rad;
 x2 = atx + rad;
 y1 = aty - rad;
 y2 = aty + rad;
 if (! lv->flags & LVF_WRAPAROUND)
  { if (x1 < 0) x1 = 0;
    if (x2 >= LEV_X) x2 = LEV_X - 1;
    if (y1 < 0) y1 = 0;
    if (y2 >= LEV_Y) y2 = LEV_Y - 1;
  }
 r2 = rad * rad;
 sd2 = ((x1-atx)*(x1-atx)) + ((y1-aty)*(y1-aty));
 for (x=x1,dx=x1-atx;x<=x2;x++,dx++)
  { px = (x < 0) ? x+LEV_X : (x >= LEV_X) ? x-LEV_X : x;
    d2 = sd2;
    for (y=y1,dy=y1-aty;y<=y2;y++,dy++)
     { if (d2 <= r2)
	{ py = (y < 0) ? y+LEV_Y : (y >= LEV_Y) ? y-LEV_Y : y;
	  if (perc || los(lc,dx,dy))
	   { lc2 = &lv->cells[px][py];
	     lc2->flags |= flg;
	     (*fxn)(lc2);
	   }
	}
       d2 += (2 * (y-aty)) + 1;
     }
    sd2 += (2 * (x-atx)) + 1;
  }
}