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

// Phase 8: Investigate 4.23 MB mystery overhead
// Try to measure actual memory usage at different stages

void print_smaps_summary(const char* label) {
    printf("\n=== %s ===\n", label);

    FILE* f = fopen("/proc/self/smaps", "r");
    if (!f) {
        printf("Cannot open /proc/self/smaps\n");
        return;
    }

    char line[256];
    unsigned long total_rss = 0;
    unsigned long total_pss = 0;
    unsigned long total_anon = 0;
    unsigned long total_heap = 0;
    int in_heap = 0;

    while (fgets(line, sizeof(line), f)) {
        // Check if this is heap region
        if (strstr(line, "[heap]")) {
            in_heap = 1;
        }

        // Parse RSS/PSS/Anonymous lines
        unsigned long val;
        if (sscanf(line, "Rss: %lu kB", &val) == 1) {
            total_rss += val;
            if (in_heap) total_heap += val;
        }
        if (sscanf(line, "Pss: %lu kB", &val) == 1) {
            total_pss += val;
        }
        if (sscanf(line, "Anonymous: %lu kB", &val) == 1) {
            total_anon += val;
        }

        // Reset heap flag on new mapping
        if (line[0] != ' ' && line[0] != '\t') {
            in_heap = 0;
        }
    }

    fclose(f);

    printf("Total RSS:       %.1f MB\n", total_rss / 1024.0);
    printf("Total PSS:       %.1f MB\n", total_pss / 1024.0);
    printf("Total Anonymous: %.1f MB\n", total_anon / 1024.0);
    printf("Heap RSS:        %.1f MB\n", total_heap / 1024.0);
}

void print_rusage(const char* label) {
    struct rusage usage;
    getrusage(RUSAGE_SELF, &usage);
    printf("%s: RSS = %.1f MB\n", label, usage.ru_maxrss / 1024.0);
}

int main() {
    printf("╔═══════════════════════════════════════════════╗\n");
    printf("║  Phase 8: Mystery 4.23 MB Investigation      ║\n");
    printf("╚═══════════════════════════════════════════════╝\n");

    print_rusage("Baseline (program start)");
    print_smaps_summary("Baseline");

    // Allocate pointer array (same as battle test)
    int n = 1000000;
    void** ptrs = malloc(n * sizeof(void*));
    printf("\nPointer array: %d × 8 = %.1f MB\n", n, (n * 8) / 1024.0 / 1024.0);
    print_rusage("After pointer array malloc");

    // Allocate 1M × 16B (same as battle test)
    for (int i = 0; i < n; i++) {
        ptrs[i] = malloc(16);
    }
    printf("\nData allocation: %d × 16 = %.1f MB\n", n, (n * 16) / 1024.0 / 1024.0);
    print_rusage("After data allocation");
    print_smaps_summary("After allocation");

    // Free all
    for (int i = 0; i < n; i++) {
        free(ptrs[i]);
    }
    print_rusage("After free (before flush)");

    // Flush Magazine (if HAKMEM)
    extern void hak_tiny_magazine_flush_all(void) __attribute__((weak));
    if (hak_tiny_magazine_flush_all) {
        hak_tiny_magazine_flush_all();
        print_rusage("After Magazine flush");
        print_smaps_summary("After flush");
    }

    free(ptrs);

    printf("\n╔═══════════════════════════════════════════════╗\n");
    printf("║  Analysis: Check heap RSS vs total data       ║\n");
    printf("╚═══════════════════════════════════════════════╝\n");
    printf("Expected data: 7.6 MB (ptr array) + 15.3 MB (allocs) = 22.9 MB\n");
    printf("Actual RSS from smaps above\n");
    printf("Overhead = Actual - Expected\n");

    return 0;
}