#include <stdio.h>  // Für printf
#include <stdlib.h> // Für malloc, free
#include "stack.h"  // Für die Stack-Funktionen und -Strukturen

// Globale Zähler für die Testergebnisse
int test_count = 0;
int test_failed = 0;

// Hilfsfunktion für Assertionen
void assert_equals_int(int expected, int actual, const char *test_name) {
    test_count++;
    if (expected == actual) {
        printf("  [PASS] %s\n", test_name);
    } else {
        printf("  [FAIL] %s - Erwartet: %d, Tatsächlich: %d\n", test_name, expected, actual);
        test_failed++;
    }
}

void assert_equals_ptr(void *expected, void *actual, const char *test_name) {
    test_count++;
    if (expected == actual) {
        printf("  [PASS] %s\n", test_name);
    } else {
        printf("  [FAIL] %s - Erwartet: %p, Tatsächlich: %p\n", test_name, expected, actual);
        test_failed++;
    }
}

// Hilfsfunktion zum Freigeben der Daten im Stack, bevor der Stack selbst geleert wird
void free_stack_data(StackNode *stack) {
    StackNode *current = stack;
    while (current != NULL) {
        if (current->data != NULL) {
            free(current->data); // Freigabe der Integer-Daten
            current->data = NULL; // Optional: Pointer auf NULL setzen
        }
        current = current->next;
    }
}

// --- Testfälle ---

void test_push_single_element() {
    printf("--- Test: push_single_element ---\n");
    StackNode *stack = NULL;
    int *data1 = (int *)malloc(sizeof(int)); *data1 = 10;

    stack = push(stack, data1);

    assert_equals_ptr(data1, stack->data, "Top should be 10");
    assert_equals_ptr(NULL, stack->next, "Next element should be NULL");

    // Aufräumen
    free_stack_data(stack); // Daten freigeben
    clearStack(stack); // StackNodes freigeben
}

void test_push_multiple_elements() {
    printf("--- Test: push_multiple_elements ---\n");
    StackNode *stack = NULL;
    int *data1 = (int *)malloc(sizeof(int)); *data1 = 10;
    int *data2 = (int *)malloc(sizeof(int)); *data2 = 20;
    int *data3 = (int *)malloc(sizeof(int)); *data3 = 30;

    stack = push(stack, data1); // Stack: [10]
    stack = push(stack, data2); // Stack: [20, 10]
    stack = push(stack, data3); // Stack: [30, 20, 10]

    assert_equals_int(30, *(int*)stack->data, "Top should be 30");
    assert_equals_int(20, *(int*)stack->next->data, "Second element should be 20");
    assert_equals_int(10, *(int*)stack->next->next->data, "Third element should be 10");
    assert_equals_ptr(NULL, stack->next->next->next, "Fourth element should be NULL");

    // Aufräumen
    free_stack_data(stack);
    clearStack(stack);
}

void test_pop_from_empty_stack() {
    printf("--- Test: pop_from_empty_stack ---\n");
    StackNode *stack = NULL;
    StackNode *result = pop(stack);
    assert_equals_ptr(NULL, result, "Pop from empty stack should return NULL");
    assert_equals_ptr(NULL, stack, "Stack should remain NULL"); // stack pointer passed by value, so it's still NULL
}

void test_pop_single_element() {
    printf("--- Test: pop_single_element ---\n");
    StackNode *stack = NULL;
    int *data1 = (int *)malloc(sizeof(int)); *data1 = 10;

    stack = push(stack, data1); // Stack: [10]
    assert_equals_int(10, *(int*)stack->data, "Top should be 10 before pop");

    // Daten freigeben, bevor der Knoten freigegeben wird
    free(top(stack)); // Freigabe von data1
    stack = pop(stack); // Stack: []

    assert_equals_ptr(NULL, stack, "Stack should be empty after popping last element");
    assert_equals_ptr(NULL, stack->data, "Top should be NULL after popping last element");
}

void test_pop_multiple_elements() {
    printf("--- Test: pop_multiple_elements ---\n");
    StackNode *stack = NULL;
    int *data1 = (int *)malloc(sizeof(int)); *data1 = 10;
    int *data2 = (int *)malloc(sizeof(int)); *data2 = 20;
    int *data3 = (int *)malloc(sizeof(int)); *data3 = 30;

    stack = push(stack, data1);
    stack = push(stack, data2);
    stack = push(stack, data3); // Stack: [30, 20, 10]

    // Pop 1 (30)
    free(top(stack)); // Freigabe von data3
    stack = pop(stack); // Stack: [20, 10]
    assert_equals_int(20, *(int*)top(stack), "Top should be 20 after first pop");

    // Pop 2 (20)
    free(top(stack)); // Freigabe von data2
    stack = pop(stack); // Stack: [10]
    assert_equals_int(10, *(int*)top(stack), "Top should be 10 after second pop");

    // Pop 3 (10)
    free(top(stack)); // Freigabe von data1
    stack = pop(stack); // Stack: []
    assert_equals_ptr(NULL, stack, "Stack should be empty after third pop");
    assert_equals_ptr(NULL, top(stack), "Top should be NULL after third pop");
}

void test_top_function() {
    printf("--- Test: top_function ---\n");
    StackNode *stack = NULL;
    int *data1 = (int *)malloc(sizeof(int)); *data1 = 100;
    int *data2 = (int *)malloc(sizeof(int)); *data2 = 200;

    assert_equals_ptr(NULL, top(stack), "Top of empty stack should be NULL");

    stack = push(stack, data1);
    assert_equals_int(100, *(int*)top(stack), "Top should be 100");

    stack = push(stack, data2);
    assert_equals_int(200, *(int*)top(stack), "Top should be 200");

    // Aufräumen
    free_stack_data(stack);
    clearStack(stack);
}

void test_clear_stack_function() {
    printf("--- Test: clear_stack_function ---\n");
    StackNode *stack = NULL;
    int *data1 = (int *)malloc(sizeof(int)); *data1 = 1;
    int *data2 = (int *)malloc(sizeof(int)); *data2 = 2;
    int *data3 = (int *)malloc(sizeof(int)); *data3 = 3;

    stack = push(stack, data1);
    stack = push(stack, data2);
    stack = push(stack, data3); // Stack: [3, 2, 1]

    // Zuerst die Daten freigeben
    free_stack_data(stack);
    // Dann die StackNodes freigeben
    clearStack(stack);
    // WICHTIG: Der lokale 'stack'-Zeiger muss manuell auf NULL gesetzt werden,
    // da clearStack ihn nicht ändern kann (pass-by-value).
    stack = NULL;

    assert_equals_ptr(NULL, stack, "Stack should be NULL after clearStack");
    assert_equals_ptr(NULL, top(stack), "Top of cleared stack should be NULL");
}

int main() {
    printf("Starte Stack Unit-Tests...\n");

    test_push_single_element();
    test_push_multiple_elements();
    test_pop_from_empty_stack();
    test_pop_single_element();
    test_pop_multiple_elements();
    test_top_function();
    test_clear_stack_function();

    printf("\n--- Testergebnisse ---\n");
    printf("Gesamtzahl der Tests: %d\n", test_count);
    printf("Fehlgeschlagene Tests: %d\n", test_failed);

    if (test_failed == 0) {
        printf("Alle Tests erfolgreich bestanden! 🎉\n");
        return EXIT_SUCCESS;
    } else {
        printf("Einige Tests sind fehlgeschlagen. 😟\n");
        return EXIT_FAILURE;
    }
}