/* generate a rogue/nethack-like layout */
#include <global.h>
#include <random_map.h>
#include <math.h>

typedef struct
{
  int x;
  int y;                        /* coordinates of room centers */

  int sx;
  int sy;                       /* sizes */
  int ax, ay, zx, zy;           /* coordinates of extrema of the rectangle */

  int rtype;                    /* circle or rectangular */
} Room;

static int roguelike_place_room  (Room *rooms, int xsize, int ysize, int nrooms);
static void roguelike_make_rooms (Room *rooms, char **maze, int options);
static void roguelike_link_rooms (Room *rooms, char **maze, int xsize, int ysize);

int
surround_check (char **layout, int i, int j, int Xsize, int Ysize)
{
  /* 1 = wall to left,
     2 = wall to right,
     4 = wall above
     8 = wall below */
  int surround_index = 0;

  if ((i > 0) && (layout[i - 1][j] != 0 && layout[i - 1][j] != '.'))
    surround_index += 1;
  if ((i < Xsize - 1) && (layout[i + 1][j] != 0 && layout[i + 1][j] != '.'))
    surround_index += 2;
  if ((j > 0) && (layout[i][j - 1] != 0 && layout[i][j - 1] != '.'))
    surround_index += 4;
  if ((j < Ysize - 1) && (layout[i][j + 1] != 0 && layout[i][j + 1] != '.'))
    surround_index += 8;
  return surround_index;
}

/* actually make the layout:  we work by a reduction process:
 * first we make everything a wall, then we remove areas to make rooms 
 */
Maze
roguelike_layout_gen (int xsize, int ysize, int options)
{
  int i, j;
  Room *walk;
  int nrooms = 0;
  int tries = 0;

  Maze maze (xsize, ysize);

  for (i = 0; i < xsize; i++)
    for (j = 0; j < ysize; j++)
      maze[i][j] = '#';

  /* minimum room size is basically 5x5:  if xsize/ysize is
     less than 3x that then hollow things out, stick in
     a stairsup and stairs down, and exit */

  if (xsize < 11 || ysize < 11)
    {
      for (i = 1; i < xsize - 1; i++)
        for (j = 1; j < ysize - 1; j++)
          maze[i][j] = 0;

      maze[(xsize - 1) / 2][(ysize - 1) / 2    ] = '>';
      maze[(xsize - 1) / 2][(ysize - 1) / 2 + 1] = '<';

      return maze;
    }

  /* decide on the number of rooms */
  nrooms = rndm (10) + 6;
  Room *rooms = salloc0<Room> (nrooms + 1);

  /* actually place the rooms */
  i = 0;
  while (tries < 450 && i < nrooms)
    {
      /* try to place the room */
      if (!roguelike_place_room (rooms, xsize, ysize, nrooms))
        tries++;
      else
        i++;
    }

  if (i == 0)
    {                           /* no can do! */
      for (i = 1; i < xsize - 1; i++)
        for (j = 1; j < ysize - 1; j++)
          maze[i][j] = 0;

      maze [(xsize - 1) / 2][(ysize - 1) / 2    ] = '>';
      maze [(xsize - 1) / 2][(ysize - 1) / 2 + 1] = '<';

      sfree (rooms, nrooms + 1);
      return maze;
    }


  /* erase the areas occupied by the rooms */
  roguelike_make_rooms (rooms, maze, options);

  roguelike_link_rooms (rooms, maze, xsize, ysize);

  /* put in the stairs */

  maze[rooms->x][rooms->y] = '<';

  /* get the last one */
  for (walk = rooms; walk->x != 0; walk++)
    ;

  /* back up one */
  walk--;

  if (walk == rooms)
    {
      /* In this case, there is only a single room.  We don't want to
       * clobber are up exit (above) with a down exit, so put the
       * other exit one space up/down, depending which is a space
       * and not a wall.
       */
      if (maze[walk->x][walk->y + 1] == '.')
        maze[walk->x][walk->y + 1] = '>';
      else
        maze[walk->x][walk->y - 1] = '>';
    }
  else
    maze[walk->x][walk->y] = '>';

  /* convert all the '.' to 0, we're through with the '.' */
  for (i = 0; i < xsize; i++)
    for (j = 0; j < ysize; j++)
      {
        if (maze[i][j] == '.')
          maze[i][j] = 0;

        if (maze[i][j] == 'D')
          {                     /* remove bad door. */
            int si = surround_check (maze, i, j, xsize, ysize);

            if (si != 3 && si != 12)
              {
                maze[i][j] = 0;
                /* back up and recheck any nearby doors */
                i = 0;
                j = 0;
              }
          }
      }

  sfree (rooms, nrooms + 1);
  return maze;
}

static int
roguelike_place_room (Room *rooms, int xsize, int ysize, int nrooms)
{
  int tx, ty;                   /* trial center locations */
  int sx, sy;                   /* trial sizes */
  int ax, ay;                   /* min coords of rect */
  int zx, zy;                   /* max coords of rect */
  int x_basesize;
  int y_basesize;
  Room *walk;

  /* decide on the base x and y sizes */
  x_basesize = xsize / isqrt (nrooms);
  y_basesize = ysize / isqrt (nrooms);

  tx = rndm (xsize);
  ty = rndm (ysize);

  /* generate a distribution of sizes centered about basesize */
  sx = rndm (x_basesize) + rndm (x_basesize) + rndm (x_basesize);
  sy = rndm (y_basesize) + rndm (y_basesize) + rndm (y_basesize);
  sy = (int) (sy * .5);         /* renormalize */

  /* find the corners */
  ax = tx - sx / 2;
  zx = tx + sx / 2 + sx % 2;

  ay = ty - sy / 2;
  zy = ty + sy / 2 + sy % 2;

  /* check to see if it's in the map */
  if (zx > xsize - 1 || ax < 1) return 0;
  if (zy > ysize - 1 || ay < 1) return 0;

  /* no small fish */
  if (sx < 3 || sy < 3)
    return 0;

  /* check overlap with existing rooms */
  for (walk = rooms; walk->x != 0; walk++)
    {
      int dx = abs (tx - walk->x);
      int dy = abs (ty - walk->y);

      if ((dx < (walk->sx + sx) / 2 + 2) && (dy < (walk->sy + sy) / 2 + 2))
        return 0;
    }

  /* if we've got here, presumably the room is OK. */

  /* get a pointer to the first free room */
  for (walk = rooms; walk->x != 0; walk++)
    ;

  walk->x = tx;
  walk->y = ty;
  walk->sx = sx;
  walk->sy = sy;
  walk->ax = ax;
  walk->ay = ay;
  walk->zx = zx;
  walk->zy = zy;

  return 1;                     /* success */
}

/* write all the rooms into the maze */
static void
roguelike_make_rooms (Room *rooms, char **maze, int options)
{
  int making_circle = 0;
  int i, j;
  int R;
  Room *walk;

  for (walk = rooms; walk->x != 0; walk++)
    {
      /* first decide what shape to make */
      switch (options)
        {
          case 1:
            making_circle = 0;
            break;
          case 2:
            making_circle = 1;
            break;
          default:
            making_circle = ((rndm (3) == 0) ? 1 : 0);
            break;
        }

      if (walk->sx < walk->sy)
        R = walk->sx / 2;
      else
        R = walk->sy / 2;

      /* enscribe a rectangle */
      for (i = walk->ax; i < walk->zx; i++)
        for (j = walk->ay; j < walk->zy; j++)
          if (!making_circle || ((int) (0.5 + hypot (walk->x - i, walk->y - j))) <= R)
            maze[i][j] = '.';
    }
}

static void
roguelike_link_rooms (Room *rooms, char **maze, int xsize, int ysize)
{
  Room *walk;
  int i, j;

  /* link each room to the previous room */
  if (rooms[1].x == 0)
    return;                     /* only 1 room */

  for (walk = rooms + 1; walk->x != 0; walk++)
    {
      int x1 = walk->x;
      int y1 = walk->y;
      int x2 = (walk - 1)->x;
      int y2 = (walk - 1)->y;
      int in_wall = 0;

      if (rndm (2))
        {                       /* connect in x direction first */
          /* horizontal connect */
          /* swap (x1,y1) (x2,y2) if necessary */

          if (x2 < x1)
            {
              int tx = x2, ty = y2;

              x2 = x1;
              y2 = y1;
              x1 = tx;
              y1 = ty;
            }


          j = y1;
          for (i = x1; i < x2; i++)
            {
              if (in_wall == 0 && maze[i][j] == '#')
                {
                  in_wall = 1;
                  maze[i][j] = 'D';
                }
              else if (in_wall && maze[i][j] == '.')
                {
                  in_wall = 0;
                  maze[i - 1][j] = 'D';
                }
              else if (maze[i][j] != 'D' && maze[i][j] != '.')
                maze[i][j] = 0;
            }
          j = MIN (y1, y2);
          if (maze[i][j] == '.')
            in_wall = 0;
          if (maze[i][j] == 0 || maze[i][j] == '#')
            in_wall = 1;
          for ( /* j set already */ ; j < MAX (y1, y2); j++)
            {
              if (in_wall == 0 && maze[i][j] == '#')
                {
                  in_wall = 1;
                  maze[i][j] = 'D';
                }
              else if (in_wall && maze[i][j] == '.')
                {
                  in_wall = 0;
                  maze[i][j - 1] = 'D';
                }
              else if (maze[i][j] != 'D' && maze[i][j] != '.')
                maze[i][j] = 0;
            }

        }
      else
        {                       /* connect in y direction first */
          in_wall = 0;
          /* swap if necessary */
          if (y2 < y1)
            {
              int tx = x2, ty = y2;

              x2 = x1;
              y2 = y1;
              x1 = tx;
              y1 = ty;
            }
          i = x1;
          /* vertical connect */
          for (j = y1; j < y2; j++)
            {
              if (in_wall == 0 && maze[i][j] == '#')
                {
                  in_wall = 1;
                  maze[i][j] = 'D';
                }
              else if (in_wall && maze[i][j] == '.')
                {
                  in_wall = 0;
                  maze[i][j - 1] = 'D';
                }
              else if (maze[i][j] != 'D' && maze[i][j] != '.')
                maze[i][j] = 0;
            }

          i = MIN (x1, x2);
          if (maze[i][j] == '.')
            in_wall = 0;
          if (maze[i][j] == 0 || maze[i][j] == '#')
            in_wall = 1;
          for ( /* i set already */ ; i < MAX (x1, x2); i++)
            {
              if (in_wall == 0 && maze[i][j] == '#')
                {
                  in_wall = 1;
                  maze[i][j] = 'D';
                }
              else if (in_wall && maze[i][j] == '.')
                {
                  in_wall = 0;
                  maze[i - 1][j] = 'D';
                }
              else if (maze[i][j] != 'D' && maze[i][j] != '.')
                maze[i][j] = 0;

            }

        }

    }
}