#include <stdint.h>
#include "unity.h"
#include "stack.h"

void setUp(void)  {}
void tearDown(void) {}

static void push_n(StackNode **ps, int n) {
    for (int i = 1; i <= n; ++i)
        *ps = push(*ps, (void*)(intptr_t)i);
}

void test_empty_stack(void) {
    StackNode *s = NULL;
    TEST_ASSERT_NULL(top(s));
    s = pop(s);
    TEST_ASSERT_NULL(s);
    clearStack(s);  // kein Crash
}

void test_push_top_pop_order(void) {
    StackNode *s = NULL;
    push_n(&s, 3); // 1,2,3 -> Top = 3
    TEST_ASSERT_EQUAL_INT(3, (int)(intptr_t)top(s));
    s = pop(s);    // 2
    TEST_ASSERT_EQUAL_INT(2, (int)(intptr_t)top(s));
    s = pop(s);    // 1
    TEST_ASSERT_EQUAL_INT(1, (int)(intptr_t)top(s));
    s = pop(s);    // NULL
    TEST_ASSERT_NULL(s);
}

void test_clearStack_then_safe_ops(void) {
    StackNode *s = NULL;
    push_n(&s, 50);
    clearStack(s);
    s = NULL; // WICHTIG: externen Zeiger selbst nullen
    TEST_ASSERT_NULL(top(s));
    s = pop(s);
    TEST_ASSERT_NULL(s);
}

int main(void) {
    UNITY_BEGIN();
    RUN_TEST(test_empty_stack);
    RUN_TEST(test_push_top_pop_order);
    RUN_TEST(test_clearStack_then_safe_ops);
    return UNITY_END();
}