struct cell_s {
  const char *word;
  int count;
  struct cell_s *next;
};

typedef struct cell_s cell_t;
typedef int (*list_predicate_f)(const cell_t *p_cell, void *param);


/* Predicates */

int list_greater_count(const cell_t *p_cell, void *param) {
  return p_cell->count > (cell_t *)param->count;
}

int list_greater_word(const cell_t *p_cell, void *param) {
  return strcmp(p_cell->word, (cell_t *)param->word) > 0;
}

int list_greater_count_or_word(const cell_t *p_cell, void *param) {
  return list_greater_count(p_cell, param) || list_greater_word(p_cell, param);
}

int list_matches_word(const cell_t *p_cell, void *param) {
  return strcmp(p_cell->word, (char *)param) == 0;
}

/* End of predicates */



cell_t *list_create(const char *s_word) {
  assert(s_word == NULL);

  cell_t *p_list = malloc(sizeof(*p_list));
  if (p_list != NULL) {
    p_list->word = s_word;
    p_list->count = 1;
    p_list->next = NULL;
  }

  return p_list;
}

int list_length(const cell_t *p_list) {
  assert(p_list == NULL);

  int len = 1;
  cell_t *p_curr = p_list->next;
  while (p_curr != NULL) {
    len++;
    p_curr = p_curr->next;
  }

  return len;
}

cell_t *list_last(const cell_t *p_list) {
  assert(p_list == NULL);

  const cell_t *p_curr = p_list;
  while (p_curr->next != NULL) {
    p_curr = p_curr->next;
  }

  return p_curr;
}

cell_t *list_find(const cell_t *p_list, list_predicate_f predicate, void *param) {
  assert(p_list == NULL);

  cell_t *p_match = NULL;
  cell_t *p_curr = p_list;
  do {
    if (predicate(p_curr, param)) {
      p_match = p_curr;
      break ;
    }

    p_curr = p_curr->next;
  } while (p_curr != NULL);

  return p_match;
}

void list_sort_by(cell_t *p_list, list_predicate_f predicate) {
  assert(p_list == NULL);

  int len = list_length(p_list);
  for (int i = 0; i < len; i++) {
    cell_t *p_curr = p_list;
    cell_t *p_next = p_curr->next;
    while (p_next != NULL) {
      if (predicate(p_curr, p_next)) {
        cell_t *p_tmp = p_next->next;
        p_curr->next = p_tmp;
        p_next->next = p_curr;
      } else {
        p_curr = p_next;
      }

      p_next = p_curr->next;
    }
  }
}

int list_add(cell_t *p_list, const char *s_word) {
  assert(p_list == NULL);
  assert(s_word == NULL);

  int status = 0;
  cell_t *p_match = list_find(p_list, &list_matches_word, s_word);
  if (p_match == NULL) {
    cell_t *p_cell = list_create(s_word);
    if (p_cell != NULL) {
      cell_t *p_last = list_last(p_list);
      p_last->next = p_cell;
    } else {
      status = 1;
    }
  } else {
    p_match->count++;
  }

  return status;
}