use super::Interrupts;
use crate::io::qemu;
use x86_64::structures::idt::{InterruptStackFrame, PageFaultErrorCode};

macro_rules! exception_default {
    ($stack_frame: expr) => {
        format_args!(
            "instruction addr: 0x{:08x}\nstack addr: 0x{:08x}\nflags: 0x{:x}",
            $stack_frame.instruction_pointer.as_u64(),
            $stack_frame.stack_pointer.as_u64(),
            $stack_frame.cpu_flags,
        )
    };
}

static mut expected_fault: Interrupts = Interrupts::None;

pub unsafe fn expect_fault(int: Interrupts) {
    if expected_fault == Interrupts::None {
        expected_fault = int;
    }
}

fn get_expected_fault() -> Interrupts {
    unsafe { expected_fault }
}

pub extern "x86-interrupt" fn breakpoint_handler(stack_frame: &mut InterruptStackFrame) {
    match get_expected_fault() {
        Interrupts::Breakpoint => qemu::exit_qemu(qemu::QemuExitCode::Success),
        _ => panic!(
            "BREAKPOINT exception thrown\n\n{}",
            exception_default!(stack_frame)
        ),
    }
}

pub extern "x86-interrupt" fn general_protection_fault_handler(
    stack_frame: &mut InterruptStackFrame,
    error_code: u64,
) {
    match get_expected_fault() {
        Interrupts::GeneralProtectionFault => qemu::exit_qemu(qemu::QemuExitCode::Success),
        _ => panic!(
            "GENERAL PROTECTION exception thrown\nerror code: {:x}\n{}",
            error_code,
            exception_default!(stack_frame)
        ),
    }
}

pub extern "x86-interrupt" fn page_fault_handler(
    stack_frame: &mut InterruptStackFrame,
    error_code: PageFaultErrorCode,
) {
    use x86_64::registers::control::Cr2;

    match get_expected_fault() {
        Interrupts::PageFault => qemu::exit_qemu(qemu::QemuExitCode::Success),
        _ => panic!(
            "PAGE FAULT while accessing address: 0x{:08x}\nerror code: {:?}(0x{:x})\n{}",
            Cr2::read().as_u64(),
            error_code,
            error_code.bits(),
            exception_default!(stack_frame)
        ),
    }
}

pub extern "x86-interrupt" fn segment_not_present_handler(
    stack_frame: &mut InterruptStackFrame,
    error_code: u64,
) {
    match get_expected_fault() {
        Interrupts::NotPresent => qemu::exit_qemu(qemu::QemuExitCode::Success),
        _ => panic!(
            "SEGMENT NOT PRESENT exception\nerror code: 0x{:x}\n{}",
            error_code,
            exception_default!(stack_frame)
        ),
    }
}

pub extern "x86-interrupt" fn double_fault_handler(
    stack_frame: &mut InterruptStackFrame,
    _error_code: u64, // code is always zero
) {
    match get_expected_fault() {
        Interrupts::DoubleFault => qemu::exit_qemu(qemu::QemuExitCode::Success),
        _ => panic!(
            "DOUBLE FAULT\nthis is a fatal exception\n{}",
            exception_default!(stack_frame)
        ),
    }
}