#define BOARD_WIDTH 9
#define BOARD_ROW_UNITS ((BOARD_WIDTH * 2) + 1)
#define BOARD_UNITS BOARD_ROW_UNITS * BOARD_ROW_UNITS


/* constants */
const char EMPTY = ' ';
const char ANY = '*';
const char SEPARATOR = '+';

const int NEIGHBOR_INCREMENTS[] = { -BOARD_ROW_UNITS, 1, BOARD_ROW_UNITS, -1 };

/* structs */
typedef struct {
  char edges[4];
  char center;
  int shield;
} Tile;

typedef struct {
  char feature;
  int meeple;
  int structure_group;
} BoardUnit;

/* board */
void initialize_board(BoardUnit* board);
int translate_coordinate(int index);
int is_center_index(int index);

/* tiles */
int is_allowed_placement(Tile tile, int index, BoardUnit* board);
int place_tile(Tile tile, int index, BoardUnit* board, int force);
void rotate_tile(Tile* tile, int increment);

/* structures */
void traverse_structure(int group, int index, BoardUnit* board);
void refresh_structure_groups(BoardUnit* board);
int evaluate_structure(int index, BoardUnit* board);