#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include "stack.h"

int main(void)
{
    StackNode *s = NULL;

    // push 3 integers
    int *a = malloc(sizeof(int)); *a = 1; s = push(s, a);
    int *b = malloc(sizeof(int)); *b = 2; s = push(s, b);
    int *c = malloc(sizeof(int)); *c = 3; s = push(s, c);

    // top should be c (3)
    int *topv = (int *)top(s);
    if(topv == NULL || *topv != 3) { fprintf(stderr, "stack top expected 3\n"); return 1; }

    // pop -> now top should be 2
    s = pop(s);
    topv = (int *)top(s);
    if(topv == NULL || *topv != 2) { fprintf(stderr, "stack top expected 2 after pop\n"); return 2; }

    // pop -> now top should be 1
    s = pop(s);
    topv = (int *)top(s);
    if(topv == NULL || *topv != 1) { fprintf(stderr, "stack top expected 1 after pop\n"); return 3; }

    // pop last
    s = pop(s);
    if(s != NULL) { fprintf(stderr, "stack expected empty after popping all\n"); return 4; }

    // free stored data (stack does not free data)
    free(a); free(b); free(c);

    // test clearStack on empty and small stacks
    s = push(s, malloc(sizeof(int)));
    s = push(s, malloc(sizeof(int)));
    clearStack(s); // clearStack must free nodes but not payload; free payloads not necessary because we leaked intentionally for test of API
    // Note: above payloads are not freed (stack API spec); this test ensures clearStack doesn't crash.
    // Success
    printf("test_stack: OK\n");
    return 0;
}