#ifndef SOK_H
#define SOK_H

#ifdef __cplusplus
extern "C" {
#endif /* __cplusplus */

#include <stdint.h> // uint16_t
#include <stddef.h> // size_t

/*********/
/* types */
/*********/

typedef struct {
  uint16_t x, y;
} sok_pos_t;

typedef enum {
  SOK_DIR_RIGHT,
  SOK_DIR_UP,
  SOK_DIR_LEFT,
  SOK_DIR_DOWN,
  SOK_DIR_LAST,
} sok_dir_t;

typedef struct {
  sok_pos_t pos;
  sok_dir_t dir;
  _Bool is_push;
} sok_move_t;

/****************/
/* level parser */
/****************/

typedef struct sok_level_parser_t_ sok_level_parser_t;

typedef _Bool (*sok_level_parser_pos_cb_t)(
  const sok_level_parser_t * const,
  const sok_pos_t
);

typedef _Bool (*sok_level_parser_junk_cb_t)(
  const sok_level_parser_t * const,
  const size_t,
  const char
);

typedef struct {
  sok_level_parser_pos_cb_t on_size,
                            on_home,
                            on_wall,
                            on_goal,
                            on_box;
  sok_level_parser_junk_cb_t on_junk;
} sok_level_parser_cbs_t;

struct sok_level_parser_t_ {
  const sok_level_parser_cbs_t *cbs;
  void *user_data;
};

void sok_level_parser_init(
  sok_level_parser_t * const parser, 
  const sok_level_parser_cbs_t * const cbs,
  void * const user_data
);

_Bool sok_level_parser_parse(
  sok_level_parser_t * const parser,
  const char * const buf,
  const size_t buf_len
);

/*********/
/* level */
/*********/

#define SOK_LEVEL_MAX_WIDTH (1 << 8)
#define SOK_LEVEL_MAX_HEIGHT (1 << 8)
#define SOK_LEVEL_MAX_BOXES 64
#define SOK_LEVEL_MAX_GOALS 64

typedef struct {
  sok_pos_t size;
  _Bool walls[SOK_LEVEL_MAX_WIDTH * SOK_LEVEL_MAX_HEIGHT];

  // player home position
  sok_pos_t home;

  // boxes
  sok_pos_t boxes[SOK_LEVEL_MAX_BOXES];
  size_t num_boxes;

  // goals
  sok_pos_t goals[SOK_LEVEL_MAX_GOALS];
  size_t num_goals;
} sok_level_t;

/***********/
/* context */
/***********/

#define SOK_CTX_MAX_MOVES 1024

typedef struct {
  sok_level_t level;

  // moves
  sok_move_t moves[SOK_CTX_MAX_MOVES];
  size_t num_moves;

  // number of open goals
  size_t num_goals_left;

  // player position
  sok_pos_t home;

  // box positions
  sok_pos_t boxes[SOK_LEVEL_MAX_BOXES];

  // user data
  void *user_data;
} sok_ctx_t;

void sok_ctx_init(sok_ctx_t * const ctx, void *user_data);

_Bool sok_ctx_set_level(sok_ctx_t * const ctx, const char * const level);

_Bool sok_ctx_is_done(sok_ctx_t * const);

_Bool sok_ctx_move(sok_ctx_t * const, const sok_dir_t);
_Bool sok_ctx_undo(sok_ctx_t * const);

/******************/
/* context walker */
/******************/

typedef _Bool (*sok_ctx_walk_pos_cb_t)(
  const sok_ctx_t * const,
  const sok_pos_t,
  void * const
);

typedef _Bool (*sok_ctx_walk_tile_cb_t)(
  const sok_ctx_t * const,
  const sok_pos_t,
  const _Bool,
  void * const
);

typedef _Bool (*sok_ctx_walk_goal_cb_t)(
  const sok_ctx_t * const,
  const sok_pos_t,
  const _Bool has_player,
  const _Bool has_box,
  void * const
);

typedef _Bool (*sok_ctx_walk_move_cb_t)(
  const sok_ctx_t * const,
  const sok_move_t,
  void * const
);

typedef struct {
  sok_ctx_walk_pos_cb_t on_size,
                        on_wall;
  sok_ctx_walk_tile_cb_t on_home,
                         on_box;
  sok_ctx_walk_goal_cb_t on_goal;
  sok_ctx_walk_move_cb_t on_move;
} sok_ctx_walk_cbs_t;

_Bool sok_ctx_walk(
  const sok_ctx_t * const,
  const sok_ctx_walk_cbs_t * const,
  void * const
);

/****************/
/* context hash */
/****************/

uint64_t sok_ctx_hash(const sok_ctx_t * const);

/*********/
/* cache */
/*********/

#define SOK_CACHE_DEFAULT_CAPACITY 1024

typedef struct {
  uint64_t *vals;
  size_t num_vals, capacity;
} sok_cache_t;

_Bool sok_cache_init(sok_cache_t * const, const size_t);
void sok_cache_fini(sok_cache_t * const);

_Bool sok_cache_has(const sok_cache_t * const, const sok_ctx_t * const);
_Bool sok_cache_add(sok_cache_t * const, const sok_ctx_t * const);

/*********/
/* solve */
/*********/

_Bool sok_solve(
  sok_ctx_t * const,
  void (*on_error)(const char * const)
);

#ifdef __cplusplus
};
#endif /* __cplusplus */

#endif /* SOK_H */