/*
 * Bitarray Hash Table
 *
 * 15-122 Principles of Imperative Computation */

#include <stdlib.h>
#include <stdbool.h>
#include "lib/contracts.h"
#include "lib/ba-ht.h"
#include "lib/hset.h"
#include "lib/xalloc.h"

bitarray to_key(hset_elem x){
  REQUIRES(x!=NULL);
  struct board_data *b = x;
  bitarray k = b->board;
  return k;
}

bool ba_equal (hset_elem x, hset_elem y){
  REQUIRES (x!=NULL && y!=NULL);
  bitarray a = to_key(x);
  bitarray b = to_key(y);
  return a==b;
}

size_t ba_hash (hset_elem x){
  REQUIRES (x!=NULL);
  bitarray a = to_key(x);
  return (size_t) a;
}

void ba_free(hset_elem x){
  free(x);
}

/* Initializes a new hash table with the given capacity
 */
hset ht_new (size_t capacity){
  REQUIRES (capacity > 0);
  return hset_new(capacity,&ba_equal,&ba_hash,&free);
}

/* ht_insert(H,e) has no return value, because it should have as
 * a precondition that no struct currently in the hashtable contains
 * the same board as DAT->board
 */
void ht_insert (hset H, struct board_data *DAT){
  REQUIRES(H!=NULL && DAT!=NULL);
  REQUIRES(ht_lookup(H,DAT->board)==NULL);
  hset_insert(H,DAT);
}

/* ht_lookup(H,B) returns
 * NULL if no struct containing the board B exists in H
 * A struct containing the board B if one exists in H
 */
struct board_data *ht_lookup(hset H, bitarray B){
  REQUIRES(H!=NULL);
  struct board_data *k = xmalloc(sizeof(struct board_data));
  k->last_move = 0;
  k->board = B;
  hset_elem x = hset_lookup(H,k);
  free(k);
  return x;
}

/* ht_lookup(H,B) returns
 * NULL if no struct containing the board B exists in H
 * A struct containing the board B if one exists in H
 */
void ht_free(hset H){
  hset_free(H);
}