#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include "disjoint.h"

typedef struct {
  int r;
  int c;
  int pixwidth;
  int *hwalls;
  int *vwalls;
} Maze;

void print_maze(Maze *m)
{
  int i, j, k;
  int *pixmap;
  int r1, c1, si, pw;

  r1 = m->r+1;
  c1 = m->c+1;
  pw = m->pixwidth;
  pixmap = (int *) malloc(sizeof(int) * r1 * c1 * m->pixwidth * m->pixwidth);
  if (pixmap == NULL) { perror("malloc"); exit(1); }
  for (i = 0; i < r1 * c1 *m->pixwidth * m->pixwidth; i++) pixmap[i] = 255;
  for (i = 0; i < r1; i++) {
    for (j = 0; j < m->c; j++) {
      if (m->hwalls[i*m->c+j]) { 
         si = (i * c1 * pw * pw) + pw * c1 * (pw/2+1) + j * pw + pw/2+1;
         for (k = 0; k < pw; k++) pixmap[si+k] = 0;
      } 
    }
  }
  for (i = 0; i < m->r; i++) {
    for (j = 0; j < c1; j++) {
      if (m->vwalls[i*c1+j]) { 
        si = (i * c1 * pw * pw) + pw * c1 * (pw/2+1) + j * pw + pw/2+1;
        for (k = 0; k < pw; k++) pixmap[si+k*c1*pw] = 0;
      } 
    }
  }
  printf("P2\n%d %d\n255\n", c1 * m->pixwidth, r1 * m->pixwidth);
  for (i = 0; i < r1 * c1 *m->pixwidth * m->pixwidth; i++) printf("%d\n", pixmap[i]);
  exit(0);
}

main(int argc, char **argv)
{
  Maze *m;
  int i, j;
  DisjointSet *ds;
  int e1, e2, s1, s2;

  if (argc != 4) {
    fprintf(stderr, "usage: maze r c pixwidth\n");
    exit(1);
  }
  m = (Maze *) malloc(sizeof(Maze));
  if (m == NULL) { perror("Malloc"); exit(1); }

  if (sscanf(argv[1], "%d", &(m->r)) != 1 || m->r <= 0) {
    fprintf(stderr, "bad r\n");
    exit(1);
  }
    
  if (sscanf(argv[2], "%d", &(m->c)) != 1 || m->c <= 0) {
    fprintf(stderr, "bad c\n");
    exit(1);
  }
    
  if (sscanf(argv[3], "%d", &(m->pixwidth)) != 1 || m->pixwidth <= 0 || m->pixwidth%2 == 0) {
    fprintf(stderr, "bad pixwidth (has to be odd, sorry)\n");
    exit(1);
  }
    
  m->hwalls = (int *) malloc(sizeof(int) * (m->r+1) * m->c);
  if (m->hwalls == NULL) { perror("Malloc"); exit(1); }
  m->vwalls = (int *) malloc(sizeof(int) * (m->c+1) * m->r);
  if (m->vwalls == NULL) { perror("Malloc"); exit(1); }

  for (i = 0; i < (m->r+1) * m->c; i++) m->hwalls[i] = 1;
  for (i = 0; i < (m->c+1) * m->r; i++) m->vwalls[i] = 1;

  /* Delete the entry and exit walls */
  m->hwalls[0] = 0;
  m->hwalls[m->r*m->c+m->c-1] = 0;
 
  ds = new_disjoint_set(m->r * m->c);
  for (i = 0; i < m->r*m->c; i++) disjoint_makeset(ds, i);

  srand48(time(0));

  while (ds->nsets > 1) {
    if (lrand48()%2) {
      e1 = lrand48()%((m->r-1)*m->c);
      e2 = e1 + m->c;
      s1 = disjoint_find(ds, e1);
      s2 = disjoint_find(ds, e2);
      if (s1 != s2) {
        disjoint_union(ds, s1, s2);
        m->hwalls[e2] = 0;
      }
    } else {
      i = lrand48()%m->r;
      j = lrand48()%(m->c-1);
      e1 = i*m->c+j;
      e2 = e1+1;
      s1 = disjoint_find(ds, e1);
      s2 = disjoint_find(ds, e2);
      if (s1 != s2) {
        disjoint_union(ds, s1, s2);
        m->vwalls[i*(m->c+1)+j+1] = 0;
      }
    }
  }
  print_maze(m);
  
}