#![no_std]
#![allow(dead_code)]

use core::panic::PanicInfo;
use core::sync::atomic::{AtomicU32, AtomicU8, Ordering};

/* ══════════════════════════════════════════════════════════════
   CYBERARMOR SECURITY ENGINE v2.0 - NASA GRADE
   Hybrid 32/64-bit | Hardware-Assisted | Zero-Tolerance
   ══════════════════════════════════════════════════════════════ */

/* ── Hybrid type ────────────────────────────────────────────── */
#[cfg(target_arch = "x86_64")]
type AddrT = u64;
#[cfg(not(target_arch = "x86_64"))]
type AddrT = u32;

/* ── Security constants ─────────────────────────────────────── */
const CANARY_MAGIC:       u32 = 0xDEADC0DE;
const STACK_GUARD:        u32 = 0xCAFEBABE;
const KERNEL_GUARD:       u32 = 0xBEEFCAFE;
const DRIVER_GUARD:       u32 = 0xFEEDFACE;
const MAX_FAULTS:         u32 = 3;
const MAX_VIRUS_SIGS:     usize = 16;
const MEMORY_POISON:      u8  = 0xAA;
const HW_WIPE_CHUNK:      usize = 4096;

/* ── Atomic state ───────────────────────────────────────────── */
static FAULT_COUNT:       AtomicU32 = AtomicU32::new(0);
static THREAT_LEVEL:      AtomicU32 = AtomicU32::new(0);
static CANARY:            AtomicU32 = AtomicU32::new(0xDEADC0DE);
static PANIC_ACTIVE:      AtomicU32 = AtomicU32::new(0);
static LOCKDOWN:          AtomicU32 = AtomicU32::new(0);
static SCAN_GENERATION:   AtomicU32 = AtomicU32::new(0);
static HW_CHIP_STATUS:    AtomicU8  = AtomicU8::new(0);

/* ── Threat levels ──────────────────────────────────────────── */
#[repr(u32)]
#[derive(Copy, Clone)]
pub enum ThreatLevel {
    Safe     = 0,
    Low      = 1,
    Medium   = 2,
    High     = 3,
    Critical = 4,
    Omega    = 5,
}

/* ── Security events ────────────────────────────────────────── */
#[repr(u32)]
#[derive(Copy, Clone)]
pub enum SecurityEvent {
    MemoryOverflow      = 1,
    StackCorruption     = 2,
    UnauthorizedWrite   = 3,
    VirusDetected       = 4,
    DriverTamper        = 5,
    KernelCorruption    = 6,
    PanicDetected       = 7,
    BufferOverflow      = 8,
    RootkitPattern      = 9,
    HardwareAnomaly     = 10,
    SelfRepairSuccess   = 11,
    SystemLockdown      = 12,
}

/* ── Hardware interface ─────────────────────────────────────── */
extern "C" {
    fn hw_security_chip_alert(event: u32, addr: AddrT, level: u32) -> i32;
    fn hw_chip_virus_destroy(addr: AddrT, size: usize) -> i32;
    fn hw_memory_lock(addr: AddrT, size: usize) -> i32;
    fn hw_memory_wipe(addr: AddrT, size: usize) -> i32;
    fn hw_memory_restore(addr: AddrT, size: usize) -> i32;
    fn hw_driver_verify(addr: AddrT, checksum: u32) -> i32;
    fn hw_driver_restore(addr: AddrT) -> i32;
    fn hw_kernel_snapshot_verify() -> i32;
    fn hw_kernel_restore() -> i32;
    fn hw_panic_keepalive() -> i32;
    fn hw_full_system_scan(report: *mut u32) -> i32;
    fn hw_emergency_halt() -> !;
    fn hw_chip_status() -> u8;
    fn kprint(msg: *const u8);
}

macro_rules! sec_print {
    ($msg:expr) => {
        unsafe { kprint(concat!("[SECURITY] ", $msg, "\0").as_ptr()); }
    };
}

/* ══════════════════════════════════════════════════════════════
   VIRUS SIGNATURES DATABASE
   ══════════════════════════════════════════════════════════════ */
const VIRUS_SIGNATURES: &[[u8; 8]] = &[
    [0x4D, 0x5A, 0x90, 0x00, 0x03, 0x00, 0x00, 0x00], /* PE/MZ executable   */
    [0xEB, 0xFE, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00], /* Infinite loop trap  */
    [0xCC, 0xCC, 0xCC, 0xCC, 0xCC, 0xCC, 0xCC, 0xCC], /* INT3 sled          */
    [0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90, 0x90], /* NOP sled           */
    [0x6A, 0x00, 0x68, 0x00, 0x00, 0x00, 0x00, 0xFF], /* Shellcode pattern  */
    [0xFF, 0xD0, 0x83, 0xC4, 0x04, 0x85, 0xC0, 0x74], /* Call chain exploit */
    [0x31, 0xC0, 0x50, 0x68, 0x2F, 0x2F, 0x73, 0x68], /* /bin/sh shellcode  */
    [0xB8, 0x01, 0x00, 0x00, 0x00, 0xBB, 0x00, 0x00], /* Syscall hijack     */
];

/* ══════════════════════════════════════════════════════════════
   MEMORY SECURITY
   ══════════════════════════════════════════════════════════════ */

#[no_mangle]
pub extern "C" fn security_check_memory(addr: AddrT, size: usize) -> i32 {
    if size == 0 || size > 0x40000000 {
        sec_print!("ALERT: Invalid memory size detected!");
        register_threat(SecurityEvent::MemoryOverflow, addr, ThreatLevel::High);
        attempt_self_repair(SecurityEvent::MemoryOverflow, addr);
        return -1;
    }
    if addr == 0 {
        sec_print!("ALERT: NULL pointer access blocked!");
        register_threat(SecurityEvent::MemoryOverflow, addr, ThreatLevel::High);
        return -1;
    }

    #[cfg(target_arch = "x86_64")]
    {
        if addr < 0x1000 {
            sec_print!("ALERT: Zero page access blocked!");
            register_threat(SecurityEvent::UnauthorizedWrite, addr, ThreatLevel::Critical);
            trigger_hardware_response(SecurityEvent::UnauthorizedWrite, addr);
            return -1;
        }
        if addr >= 0xFFFF800000000000 && addr < 0xFFFFFFFF80000000 {
            sec_print!("ALERT: Kernel space violation!");
            register_threat(SecurityEvent::UnauthorizedWrite, addr, ThreatLevel::Omega);
            trigger_hardware_response(SecurityEvent::UnauthorizedWrite, addr);
            return -1;
        }
        if addr.wrapping_add(size as u64) < addr {
            sec_print!("ALERT: Integer overflow in memory range!");
            register_threat(SecurityEvent::BufferOverflow, addr, ThreatLevel::Critical);
            return -1;
        }
    }

    #[cfg(not(target_arch = "x86_64"))]
    {
        if addr < 0x1000 {
            sec_print!("ALERT: Zero page access blocked!");
            register_threat(SecurityEvent::UnauthorizedWrite, addr, ThreatLevel::Critical);
            trigger_hardware_response(SecurityEvent::UnauthorizedWrite, addr);
            return -1;
        }
        if addr > 0xC0000000 {
            sec_print!("ALERT: Kernel space violation!");
            register_threat(SecurityEvent::UnauthorizedWrite, addr, ThreatLevel::Omega);
            trigger_hardware_response(SecurityEvent::UnauthorizedWrite, addr);
            return -1;
        }
    }
    0
}

/* ══════════════════════════════════════════════════════════════
   STACK PROTECTION
   ══════════════════════════════════════════════════════════════ */

#[no_mangle]
pub extern "C" fn security_check_stack(canary: u32) -> i32 {
    if canary != STACK_GUARD {
        sec_print!("CRITICAL: Stack corruption! Hardware chip engaged!");
        register_threat(SecurityEvent::StackCorruption, 0, ThreatLevel::Omega);
        trigger_hardware_response(SecurityEvent::StackCorruption, 0);
        attempt_self_repair(SecurityEvent::StackCorruption, 0);
        return -1;
    }
    0
}

/* ══════════════════════════════════════════════════════════════
   KERNEL INTEGRITY
   ══════════════════════════════════════════════════════════════ */

#[no_mangle]
pub extern "C" fn monitor_system_integrity() -> i32 {
    let canary = CANARY.load(Ordering::SeqCst);
    if canary != CANARY_MAGIC {
        sec_print!("CRITICAL: Kernel integrity compromised! Restoring...");
        register_threat(SecurityEvent::KernelCorruption, 0, ThreatLevel::Omega);

        let restore = unsafe { hw_kernel_restore() };
        if restore == 0 {
            sec_print!("INFO: Kernel successfully restored by hardware!");
            CANARY.store(CANARY_MAGIC, Ordering::SeqCst);
            register_threat(SecurityEvent::SelfRepairSuccess, 0, ThreatLevel::Safe);
        } else {
            sec_print!("CRITICAL: Kernel restore failed! Emergency halt!");
            trigger_hardware_response(SecurityEvent::KernelCorruption, 0);
        }
        return -1;
    }

    let hw_check = unsafe { hw_kernel_snapshot_verify() };
    if hw_check != 0 {
        sec_print!("ALERT: Hardware kernel snapshot mismatch!");
        register_threat(SecurityEvent::KernelCorruption, 0, ThreatLevel::Critical);
        unsafe { hw_kernel_restore(); }
        return -1;
    }
    0
}

/* ══════════════════════════════════════════════════════════════
   VIRUS DETECTION & HARDWARE DESTRUCTION
   ══════════════════════════════════════════════════════════════ */

#[no_mangle]
pub extern "C" fn security_scan_buffer(buf: *const u8, len: usize) -> i32 {
    if buf.is_null() || len == 0 { return -1; }

    let slice = unsafe { core::slice::from_raw_parts(buf, len) };
    SCAN_GENERATION.fetch_add(1, Ordering::Relaxed);

    for sig in VIRUS_SIGNATURES {
        for window in slice.windows(8) {
            if window == sig.as_ref() {
                sec_print!("VIRUS DETECTED! Engaging hardware chip for destruction!");
                register_threat(SecurityEvent::VirusDetected, buf as AddrT, ThreatLevel::Omega);

                let destroy = unsafe {
                    hw_chip_virus_destroy(buf as AddrT, len)
                };

                if destroy == 0 {
                    sec_print!("INFO: Virus destroyed by hardware chip!");
                    unsafe { hw_memory_wipe(buf as AddrT, len); }
                } else {
                    sec_print!("CRITICAL: Hardware destruction failed! Lockdown!");
                    initiate_lockdown();
                }
                return -1;
            }
        }
    }

    /* Rootkit pattern check */
    if len >= 3 {
        for i in 0..len - 2 {
            if slice[i] == 0xFF && slice[i+1] == 0x25 {
                sec_print!("ALERT: Rootkit JMP pattern detected!");
                register_threat(SecurityEvent::RootkitPattern, buf as AddrT, ThreatLevel::Critical);
                trigger_hardware_response(SecurityEvent::RootkitPattern, buf as AddrT);
                return -1;
            }
        }
    }
    0
}

/* ══════════════════════════════════════════════════════════════
   DRIVER PROTECTION
   ══════════════════════════════════════════════════════════════ */

#[no_mangle]
pub extern "C" fn security_verify_driver(driver_addr: AddrT, checksum: u32) -> i32 {
    if driver_addr == 0 {
        sec_print!("ALERT: Null driver address rejected!");
        return -1;
    }

    let result = unsafe { hw_driver_verify(driver_addr, checksum) };
    if result != 0 {
        sec_print!("ALERT: Driver tampering detected! Hardware restoring driver...");
        register_threat(SecurityEvent::DriverTamper, driver_addr, ThreatLevel::Critical);

        let restore = unsafe { hw_driver_restore(driver_addr) };
        if restore == 0 {
            sec_print!("INFO: Driver restored by hardware chip!");
            register_threat(SecurityEvent::SelfRepairSuccess, driver_addr, ThreatLevel::Safe);
        } else {
            sec_print!("CRITICAL: Driver restore failed! Locking region...");
            unsafe { hw_memory_lock(driver_addr, 0x10000); }
        }
        return -1;
    }
    0
}

/* ══════════════════════════════════════════════════════════════
   FULL SYSTEM SCAN
   ══════════════════════════════════════════════════════════════ */

#[no_mangle]
pub extern "C" fn security_full_scan() -> i32 {
    sec_print!("INFO: Full system scan initiated with hardware assist...");
    let mut report: u32 = 0;
    let result = unsafe { hw_full_system_scan(&mut report as *mut u32) };

    if result != 0 || report != 0 {
        sec_print!("ALERT: System scan found anomalies! Engaging repair...");
        register_threat(SecurityEvent::HardwareAnomaly, 0, ThreatLevel::High);
        attempt_self_repair(SecurityEvent::HardwareAnomaly, 0);
        return -1;
    }

    sec_print!("INFO: Full system scan complete. System clean.");
    0
}

/* ══════════════════════════════════════════════════════════════
   SELF REPAIR ENGINE
   ══════════════════════════════════════════════════════════════ */

fn attempt_self_repair(event: SecurityEvent, addr: AddrT) {
    sec_print!("INFO: Self-repair engine activated...");
    match event {
        SecurityEvent::MemoryOverflow |
        SecurityEvent::BufferOverflow => {
            unsafe { hw_memory_restore(addr, HW_WIPE_CHUNK); }
            sec_print!("INFO: Memory region restored.");
        }
        SecurityEvent::DriverTamper => {
            unsafe { hw_driver_restore(addr); }
            sec_print!("INFO: Driver restored.");
        }
        SecurityEvent::KernelCorruption => {
            unsafe { hw_kernel_restore(); }
            sec_print!("INFO: Kernel snapshot restored.");
        }
        SecurityEvent::HardwareAnomaly => {
            unsafe { hw_full_system_scan(core::ptr::null_mut()); }
        }
        _ => {
            unsafe { hw_security_chip_alert(event as u32, addr, ThreatLevel::Medium as u32); }
        }
    }
}

/* ══════════════════════════════════════════════════════════════
   HARDWARE RESPONSE ENGINE
   ══════════════════════════════════════════════════════════════ */

fn trigger_hardware_response(event: SecurityEvent, addr: AddrT) {
    HW_CHIP_STATUS.store(unsafe { hw_chip_status() }, Ordering::SeqCst);

    match event {
        SecurityEvent::VirusDetected |
        SecurityEvent::RootkitPattern => {
            sec_print!("HW: Chip engaging virus destruction protocol!");
            unsafe {
                hw_chip_virus_destroy(addr, HW_WIPE_CHUNK);
                hw_memory_wipe(addr, HW_WIPE_CHUNK);
            }
        }
        SecurityEvent::StackCorruption |
        SecurityEvent::KernelCorruption => {
            sec_print!("HW: Chip engaging kernel restore protocol!");
            unsafe { hw_kernel_restore(); }
        }
        SecurityEvent::UnauthorizedWrite => {
            sec_print!("HW: Locking memory region!");
            unsafe { hw_memory_lock(addr, HW_WIPE_CHUNK); }
        }
        SecurityEvent::DriverTamper => {
            sec_print!("HW: Restoring tampered driver!");
            unsafe { hw_driver_restore(addr); }
        }
        _ => {
            unsafe { hw_security_chip_alert(event as u32, addr, ThreatLevel::High as u32); }
        }
    }
}

/* ══════════════════════════════════════════════════════════════
   LOCKDOWN & THREAT MANAGEMENT
   ══════════════════════════════════════════════════════════════ */

fn initiate_lockdown() {
    LOCKDOWN.store(1, Ordering::SeqCst);
    sec_print!("CRITICAL: SYSTEM LOCKDOWN INITIATED!");
    register_threat(SecurityEvent::SystemLockdown, 0, ThreatLevel::Omega);
    unsafe { hw_security_chip_alert(SecurityEvent::SystemLockdown as u32, 0, ThreatLevel::Omega as u32); }
}

fn register_threat(event: SecurityEvent, addr: AddrT, level: ThreatLevel) {
    let count = FAULT_COUNT.fetch_add(1, Ordering::SeqCst) + 1;
    THREAT_LEVEL.fetch_max(level as u32, Ordering::SeqCst);
    unsafe { hw_security_chip_alert(event as u32, addr, level as u32); }

    if count >= MAX_FAULTS {
        sec_print!("CRITICAL: MAX FAULT THRESHOLD REACHED! HALTING!");
        unsafe { hw_emergency_halt(); }
    }
}

/* ══════════════════════════════════════════════════════════════
   PANIC HANDLER - HARDWARE ASSISTED
   ══════════════════════════════════════════════════════════════ */

#[no_mangle]
pub extern "C" fn security_panic_keepalive() -> i32 {
    PANIC_ACTIVE.store(1, Ordering::SeqCst);
    sec_print!("PANIC: Kernel panic detected! Hardware keepalive active!");
    sec_print!("PANIC: Scanning system state...");

    let mut report: u32 = 0;
    unsafe {
        hw_security_chip_alert(SecurityEvent::PanicDetected as u32, 0, ThreatLevel::Omega as u32);
        hw_full_system_scan(&mut report as *mut u32);
        hw_panic_keepalive()
    }
}

#[no_mangle]
pub extern "C" fn security_get_threat_level() -> u32 {
    THREAT_LEVEL.load(Ordering::SeqCst)
}

#[no_mangle]
pub extern "C" fn security_is_panic_active() -> u32 {
    PANIC_ACTIVE.load(Ordering::SeqCst)
}

#[no_mangle]
pub extern "C" fn security_is_lockdown() -> u32 {
    LOCKDOWN.load(Ordering::SeqCst)
}

#[no_mangle]
pub extern "C" fn security_reset() {
    FAULT_COUNT.store(0, Ordering::SeqCst);
    THREAT_LEVEL.store(0, Ordering::SeqCst);
    CANARY.store(CANARY_MAGIC, Ordering::SeqCst);
    PANIC_ACTIVE.store(0, Ordering::SeqCst);
    LOCKDOWN.store(0, Ordering::SeqCst);
    sec_print!("INFO: Security engine reset complete.");
}

#[panic_handler]
fn panic_handler(_info: &PanicInfo) -> ! {
    PANIC_ACTIVE.store(1, Ordering::SeqCst);
    unsafe {
        hw_security_chip_alert(SecurityEvent::PanicDetected as u32, 0, ThreatLevel::Omega as u32);
        hw_full_system_scan(core::ptr::null_mut());
        hw_panic_keepalive();
        hw_emergency_halt();
    }
}
