use core::{future::Future, task::Poll};

use hbvm::{
    mem::{softpaging::icache::ICache, Address},
    Vm, VmRunError, VmRunOk,
};

use {
    alloc::boxed::Box,
    hbvm::mem::softpaging::{HandlePageFault, SoftPagedMem},
};

const TIMER_QUOTIENT: usize = 100;

pub struct ExecThread<'p> {
    vm: Vm<SoftPagedMem<'p, PageFaultHandler, true>, TIMER_QUOTIENT>,
}

unsafe impl<'p> Send for ExecThread<'p> {}

impl<'p> ExecThread<'p> {
    pub unsafe fn new(program: &'p [u8], entrypoint: Address) -> Self {
        ExecThread {
            vm: unsafe {
                Vm::new(
                    SoftPagedMem {
                        root_pt: Box::into_raw(Box::default()),
                        pf_handler: PageFaultHandler,
                        program,
                        icache: ICache::default(),
                    },
                    entrypoint,
                )
            },
        }
    }
}

impl<'p> Future for ExecThread<'p> {
    type Output = Result<(), VmRunError>;

    fn poll(
        mut self: core::pin::Pin<&mut Self>,
        cx: &mut core::task::Context<'_>,
    ) -> Poll<Self::Output> {
        match self.vm.run() {
            Err(err) => return Poll::Ready(Err(err)),
            Ok(VmRunOk::End) => return Poll::Ready(Ok(())),
            Ok(VmRunOk::Ecall) => {
                log::info!("Ecall");
                log::info!("{:?}", self.vm.registers);
            }
            Ok(VmRunOk::Timer) => (),
        }

        cx.waker().wake_by_ref();
        Poll::Pending
    }
}

struct PageFaultHandler;
impl HandlePageFault for PageFaultHandler {
    fn page_fault(
        &mut self,
        reason: hbvm::mem::MemoryAccessReason,
        pagetable: &mut hbvm::mem::softpaging::paging::PageTable,
        vaddr: hbvm::mem::Address,
        size: hbvm::mem::softpaging::PageSize,
        dataptr: *mut u8,
    ) -> bool
    where
        Self: Sized,
    {
        log::error!(
            "REASON: {reason} \
             vaddr: {vaddr} \
             size: {size:?} \
             Dataptr {dataptr:p}",
        );

        false
    }
}