#include <stdio.h>
#include <stdlib.h>

#define DO_TEST_PLAY

typedef unsigned char byte;

typedef unsigned char bool;
#define TRUE 1
#define FALSE 0

#define MAX_X  10
#define MAX_Y  10
#define BOARD_T(B) byte B[MAX_X][MAX_Y]
#define BOARD_T_P(B) byte B[MAX_X][MAX_Y]
BOARD_T(board);
byte max_x;
byte max_y;
byte nr_colors;

#define FOR_ALL_X(X) for (X = 0; X < max_x; X++)
#define FOR_ALL_Y(Y) for (Y = 0; Y < max_y; Y++)
#define FOR_ALL_XY(X,Y) FOR_ALL_X(X) FOR_ALL_Y(Y)

void print_board()
{
  int x,y;
  
  for (y = max_y-1; y >= 0; y--)
  {
    FOR_ALL_X(x)
      printf("%c", "_123456789"[board[x][y]]);
    printf("\n");
  }
  printf("\n");
}      

void fill_board_str_value(BOARD_T_P(board), char *value)
 {
  int x, y;

  FOR_ALL_XY(x,y)
    board[x][y] = (*value++) - '0';
}

bool board_eq_str_value(BOARD_T_P(board), char *value)
{
  int x, y;
  
  FOR_ALL_XY(x,y)
    if (board[x][y] != (*value++) - '0')
      return FALSE;
      
  return TRUE;
}

void fill_board_value(BOARD_T_P(board), long value)
{
  int x, y;

  FOR_ALL_XY(x,y)
  { board[x][y] = (value % nr_colors) + 1;
    value = value / nr_colors;
  }
}       

void fill_board_random(BOARD_T_P(board), int seed)
{
  int x, y;

  srand(seed);

  FOR_ALL_XY(x,y)
    board[x][y] = (rand() % nr_colors) + 1;
}

int debug_play = 0;

void play(BOARD_T_P(board), int at_x, int at_y)
{
  int x,y;	
  BOARD_T(m);
  bool more;
  int size;
  int max_x_m1 = max_x - 1;
  int max_y_m1 = max_y - 1;

  FOR_ALL_XY(x,y)
    m[x][y] = 0;

  m[at_x][at_y] = 1;

  size = 1;
  do
  {
    more = FALSE;

    FOR_ALL_XY(x,y)
      if (m[x][y])
      {
        int color = board[x][y]; 	    

#define TRY(C,X,Y) if ((C) && board[x X][y Y] == color && m[x X][y Y] == 0) \
                      { m[x X][y Y] = 1; size++; more = TRUE;}

        TRY(x > 0, -1,+0 )
        TRY(y > 0, +0, -1)
        TRY(x < max_x_m1, +1, +0)
        TRY(y < max_y_m1, +0, +1)
      } 
  } while (more);

  if (size > 1)
  {   
    int nx = 0;
    
    FOR_ALL_X(x)
    {
      int ny = 0;

      FOR_ALL_Y(y)
        if (m[x][y] == 0)
        { board[nx][ny] = board[x][y];
          ny++;
        }
      if (ny > 0 && board[nx][0] > 0)
      {  
        for (; ny < max_y; ny++)
          board[nx][ny] = 0;
        nx++;
      }    
    }
    for (; nx < max_x; nx++)
      FOR_ALL_Y(y)
        board[nx][y] = 0;
  }    
}


#ifdef DO_TEST_PLAY

void test_play(int gmax_x, int gmax_y,
               char *before, int px, int py, char *result)
{
  max_x = gmax_x;
  max_y = gmax_y;
  nr_colors = 10;

  fill_board_str_value(board, before);
  play(board,px,py);

  if (!board_eq_str_value(board, result))
  {
    printf("test play %d,%d %s play %d,%d to %s failed\n",
           gmax_x, gmax_y, before, px,py, result);

    fill_board_str_value(board, before);
    print_board();
    play(board,px,py);
    print_board();
    fill_board_str_value(board, result);
    print_board();
    exit(0);
  }  
}
  
	
void do_test_play()
{
  char *before, *after1, *after2, *after3, *after4;

  test_play(1,1, "1", 0,0, "1");
  test_play(1,2, "12", 0,0, "12");
  test_play(1,2, "11", 0,0, "00");
  test_play(2,1, "12", 0,0, "12");
  test_play(2,1, "11", 0,0, "00");
  
  /* testing:
      4444
      2243
      2133
      1123
  */    
  before = "1224112423443334";
  after1 = "2240240023443334";
  after2 = "1400114023443334";
  after3 = "1224112424404000";
  after4 = "1220112023003330";

#define TEST_PLAY_Y(Y,I,A,B,C,D) \
        test_play(4,4, I, 0,Y, A);\
        test_play(4,4, I, 1,Y, B);\
        test_play(4,4, I, 2,Y, C);\
        test_play(4,4, I, 3,Y, D);
  TEST_PLAY_Y(3, before, after4, after4, after4, after4)
  TEST_PLAY_Y(2, before, after2, after2, after4, after3)
  TEST_PLAY_Y(1, before, after2, after1, after3, after3)
  TEST_PLAY_Y(0, before, after1, after1, before, after3)

                                           
  test_play(4,4, "1000110014000000", 0,0, "4000000000000000");
  test_play(4,4, "1000222020002000", 1,0, "1000000000000000");
  test_play(4,4, "1000100040004400", 3,0, "1000100000000000");
  
  printf("test play -- passed!\n");
}
#else 
void do_test_play()
{
  printf("test play -- skipped!\n");
}
#endif   

main()
{
  do_test_play();
}