#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <sys/resource.h>

typedef struct {
    char* arr;
    size_t size;
    size_t capacity;
} Vec8_t;

Vec8_t create(const Vec8_t* input) {
    Vec8_t vec = { .arr = NULL, .size = 0, .capacity = 4 };
    if (input == NULL) {
        vec.arr = calloc(vec.capacity, sizeof(char));
        return vec;
    }
    if (input->size > 0) {
        vec.size = input->size + 1;
    }
    if (input->capacity >= vec.capacity) {
        vec.capacity = 2 * input->capacity;
    }
    vec.arr = calloc(vec.capacity, sizeof(char));
    return vec;
}

void delete(Vec8_t* vec) {
    if (vec->arr != NULL) {
        free(vec->arr);
    }
    vec->arr = NULL;
}

Vec8_t add_back(Vec8_t* vec, const char val) {
    if (vec->size < vec->capacity) {
        vec->arr[vec->size] = val;
        vec->size++;
        return *vec;
    }
    if (vec->size >= vec->capacity) {
        Vec8_t nvec = create(vec);
        if (nvec.arr == NULL) {
            return *vec;
        }
        memcpy(&nvec.arr[0], &vec->arr[0], vec->size * sizeof(char));
        if (nvec.arr && (nvec.size > 0 || nvec.size > vec->size)) {
            nvec.arr[vec->size] = val;
        }
        free(vec->arr);
        return nvec;
    }
    Vec8_t ret = { .arr = NULL, .capacity = 0, .size = 0 };
    return ret;
}

void print_rusage(const char* label) {
    struct rusage ru;
    getrusage(RUSAGE_SELF, &ru);
    printf("%s: %.2f MB maxRSS\n", label, ru.ru_maxrss / 1024.0);
}

void force_rusage_reset() {
    struct rusage start;
    getrusage(RUSAGE_SELF, &start);
}

int main() {
    printf("=== MEMORY CRASH + LEAK TEST ===\n\n");
    
    printf("Initial memory:\n");
    print_rusage("before");
    
    printf("\n=== TEST 1: PUSH UNTIL CRASH ===\n\n");
    
    Vec8_t vec = create(NULL);
    size_t crashed_at = 0;
    
    for (size_t i = 0; ; i++) {
        vec = add_back(&vec, (char)(i % 256));
        
        if (vec.arr == NULL) {
            crashed_at = i;
            break;
        }
        
        if (i % 50000000 == 0 && i > 0) {
            struct rusage ru;
            getrusage(RUSAGE_SELF, &ru);
            printf("  %zu elements: %.2f MB used\n", i, ru.ru_maxrss / 1024.0);
        }
        
        if (i >= 4000000000UL) {
            crashed_at = i;
            printf("  STOPPED at 4 billion\n");
            break;
        }
    }
    
    struct rusage ru;
    getrusage(RUSAGE_SELF, &ru);
    
    if (crashed_at > 0) {
        printf("\nCRASHED at %zu elements\n", crashed_at);
    } else {
        printf("\nStopped at %zu elements\n", vec.size);
        printf("capacity: %zu\n", vec.capacity);
    }
    
    printf("memory used: %.2f MB\n", ru.ru_maxrss / 1024.0);
    
    delete(&vec);
    
    printf("\nAfter delete:\n");
    print_rusage("after delete");
    
    printf("\n=== TEST 2: MULTIPLE VECTORS (LEAK CHECK) ===\n\n");
    
    size_t num_vectors = 10000;
    Vec8_t* vectors = calloc(num_vectors, sizeof(Vec8_t));
    
    printf("Creating %zu vectors...\n", num_vectors);
    print_rusage("before vectors");
    
    for (size_t i = 0; i < num_vectors; i++) {
        vectors[i] = create(NULL);
        for (size_t j = 0; j < 10000; j++) {
            vectors[i] = add_back(&vectors[i], (char)(j % 256));
        }
    }
    
    print_rusage("with vectors");
    printf("Each vector has %zu elements\n", vectors[0].size);
    
    printf("\nFreeing vectors...\n");
    for (size_t i = 0; i < num_vectors; i++) {
        delete(&vectors[i]);
    }
    free(vectors);
    
    print_rusage("after free");
    
    printf("\n=== TEST 3: CREATE/DELETE CYCLES ===\n\n");
    
    size_t cycles = 100000;
    printf("Running %zu create/delete cycles...\n", cycles);
    print_rusage("before cycles");
    
    for (size_t c = 0; c < cycles; c++) {
        Vec8_t v = create(NULL);
        for (size_t i = 0; i < 1000; i++) {
            v = add_back(&v, 'x');
        }
        delete(&v);
        
        if (c % 10000 == 0) {
            struct rusage ru;
            getrusage(RUSAGE_SELF, &ru);
            printf("  cycle %zu: %.2f MB\n", c, ru.ru_maxrss / 1024.0);
        }
    }
    
    print_rusage("after cycles");
    
    printf("\n=== TEST 4: REALLOC STRESS ===\n\n");
    
    Vec8_t big = create(NULL);
    printf("Single vec realloc stress...\n");
    
    size_t prev_cap = 0;
    for (size_t i = 0; i < 100000000; i++) {
        big = add_back(&big, 'x');
        
        if (big.capacity != prev_cap) {
            struct rusage ru;
            getrusage(RUSAGE_SELF, &ru);
            printf("  cap %zu -> %.2f MB\n", big.capacity, ru.ru_maxrss / 1024.0);
            prev_cap = big.capacity;
        }
    }
    
    print_rusage("final big vec");
    printf("size: %zu, capacity: %zu\n", big.size, big.capacity);
    
    delete(&big);
    
    printf("\nAfter cleanup:\n");
    print_rusage("cleanup done");
    
    printf("\n=== RESULT ===\n");
    
    struct rusage final;
    getrusage(RUSAGE_SELF, &final);
    printf("Peak memory: %.2f MB\n", final.ru_maxrss / 1024.0);
    
    return 0;
}