/*
 * Expands a layout by 2x in each dimension.
 * H. S. Teoh
 * --------------------------------------------------------------------------
 * $Id: expand2x.C,v 1.4 2006/09/14 22:34:02 root Exp $
 *
 * ALGORITHM
 *
 * ... (TBW)
 */

#include <stdlib.h>             /* just in case */
#include <expand2x.h>           /* use compiler to do sanity check */


/* PROTOTYPES */

static void expand_misc (char **newlayout, int i, int j, char **layout, int xsize, int ysize);
static void expand_wall (char **newlayout, int i, int j, char **layout, int xsize, int ysize);
static void expand_door (char **newlayout, int i, int j, char **layout, int xsize, int ysize);


/* FUNCTIONS */

char **
expand2x (char **layout, int xsize, int ysize)
{
  int i, j;
  int nxsize = xsize * 2 - 1;
  int nysize = ysize * 2 - 1;

  /* Allocate new layout */
  char **newlayout = (char **) calloc (sizeof (char *), nxsize);

  for (i = 0; i < nxsize; i++)
    {
      newlayout[i] = (char *) calloc (sizeof (char), nysize);
    }

  for (i = 0; i < xsize; i++)
    {
      for (j = 0; j < ysize; j++)
        {
          switch (layout[i][j])
            {
                case '#':
                  expand_wall (newlayout, i, j, layout, xsize, ysize);
                  break;
                case 'D':
                  expand_door (newlayout, i, j, layout, xsize, ysize);
                  break;
                default:
                  expand_misc (newlayout, i, j, layout, xsize, ysize);
            }
        }
    }

  /* Dump old layout */
  for (i = 0; i < xsize; i++)
    {
      free (layout[i]);
    }
  free (layout);

  return newlayout;
}

/* Copy the old tile X into the new one at location (i*2, j*2) and
 * fill up the rest of the 2x2 result with \0:
 *	X  --->	X  \0
 *		\0 \0
 */
static void
expand_misc (char **newlayout, int i, int j, char **layout, int xsize, int ysize)
{
  newlayout[i * 2][j * 2] = layout[i][j];
  /* (Note: no need to reset rest of 2x2 area to \0 because calloc does that
   * for us.) */
}

/* Returns a bitmap that represents which squares on the right and bottom
 * edges of a square (i,j) match the given character:
 *	1	match on (i+1, j)
 *	2	match on (i, j+1)
 *	4	match on (i+1, j+1)
 * and the possible combinations thereof.
 */
static int
calc_pattern (char ch, char **layout, int i, int j, int xsize, int ysize)
{
  int pattern = 0;

  if (i + 1 < xsize && layout[i + 1][j] == ch)
    pattern |= 1;

  if (j + 1 < ysize)
    {
      if (layout[i][j + 1] == ch)
        pattern |= 2;
      if (i + 1 < xsize && layout[i + 1][j + 1] == ch)
        pattern |= 4;
    }

  return pattern;
}

/* Expand a wall. This function will try to sensibly connect the resulting
 * wall to adjacent wall squares, so that the result won't have disconnected
 * walls.
 */
static void
expand_wall (char **newlayout, int i, int j, char **layout, int xsize, int ysize)
{
  int wall_pattern = calc_pattern ('#', layout, i, j, xsize, ysize);
  int door_pattern = calc_pattern ('D', layout, i, j, xsize, ysize);
  int both_pattern = wall_pattern | door_pattern;

  newlayout[i * 2][j * 2] = '#';
  if (i + 1 < xsize)
    {
      if (both_pattern & 1)
        {                       /* join walls/doors to the right */

/*      newlayout[i*2+1][j*2] = '#'; */
          newlayout[i * 2 + 1][j * 2] = layout[i + 1][j];
        }
    }

  if (j + 1 < ysize)
    {
      if (both_pattern & 2)
        {                       /* join walls/doors to the bottom */

/*      newlayout[i*2][j*2+1] = '#'; */
          newlayout[i * 2][j * 2 + 1] = layout[i][j + 1];
        }

      if (wall_pattern == 7)
        {                       /* if orig layout is a 2x2 wall block,
                                 * we fill the result with walls. */
          newlayout[i * 2 + 1][j * 2 + 1] = '#';
        }
    }
}

/* This function will try to sensibly connect doors so that they meet up with
 * adjacent walls. Note that it will also presumptuously delete (ignore) doors
 * that it doesn't know how to correctly expand.
 */
static void
expand_door (char **newlayout, int i, int j, char **layout, int xsize, int ysize)
{
  int wall_pattern = calc_pattern ('#', layout, i, j, xsize, ysize);
  int door_pattern = calc_pattern ('D', layout, i, j, xsize, ysize);
  int join_pattern;

  /* Doors "like" to connect to walls more than other doors. If there is
   * a wall and another door, this door will connect to the wall and
   * disconnect from the other door. */
  if (wall_pattern & 3)
    {
      join_pattern = wall_pattern;
    }
  else
    {
      join_pattern = door_pattern;
    }

  newlayout[i * 2][j * 2] = 'D';
  if (i + 1 < xsize)
    {
      if (join_pattern & 1)
        {                       /* there is a door/wall to the right */
          newlayout[i * 2 + 1][j * 2] = 'D';
        }
    }

  if (j + 1 < ysize)
    {
      if (join_pattern & 2)
        {                       /* there is a door/wall below */
          newlayout[i * 2][j * 2 + 1] = 'D';
        }
    }
}