#include "stack.h"


void push(Node **top, int value) {

  Node *new_element = (Node*)malloc(sizeof(Node));
  
  if ( !new_element) {
    fprintf(stderr,"Out of memory\n");
    return;
  }

  new_element->next = *top;
  new_element->value = value;

  *top = new_element;

}

// Return the popped value or -1 if the stack is empty
int pop(Node **top) {

  if ( is_empty(*top) ) {
    return -1;
  }

  Node *temporary_top = *top;

  int value = (*top)->value;

  *top = temporary_top->next;
  //*top = (*temporary_top).next;
  
  free(temporary_top);
  temporary_top = NULL;

  return value;

}


bool is_empty(Node *top) {

  return (top == NULL);

}


void print(Node *top) {

  Node *current = top;
  while ( current != NULL ) {
    printf("%d\n",current->value);
    current = current->next;
  }

}


// We could also print the stack as follows
/*
void print(Node *top) {

  if ( ! top ) {
    return;
  }
  printf("%d\n",top->value);
  print(top->next);
}
*/