use {
    alloc::boxed::Box,
    core::{default, future::Future, task::Poll},
    hbvm::{
        mem::{
            softpaging::{icache::ICache, HandlePageFault, SoftPagedMem},
            Address,
        },
        Vm, VmRunError, VmRunOk,
    },
};

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) => {
                log::error!(
                    "HBVM Error\r
Register dump: {:?}",
                    self.vm.registers
                );

                return Poll::Ready(Err(err));
            }
            Ok(VmRunOk::End) => return Poll::Ready(Ok(())),
            Ok(VmRunOk::Ecall) => {
                let r255 = self.vm.registers[255];
                let r254 = self.vm.registers[254];
                let r253 = self.vm.registers[253];

                log::debug!("Ecall number {:?}", r255);
                log::trace!("Register dump: {:?}", self.vm.registers);

                match r255.cast::<u64>() {
                    0 => {
                        // TODO: explode computer
                        // hello world ecall
                        for x in 0u64..=255 {
                            self.vm.registers[x as usize] = x.into();
                        }
                    }
                    1 => {
                        // Make buffer
                        log::trace!(
                            "bounded: {}\n\r
length: {:?}",
                            match unsafe { r254.u64 } {
                                0 => {
                                    false
                                }
                                1 => {
                                    true
                                }
                                _ => {
                                    // TODO: throw this back to the runtime
                                    panic!("Bad");
                                }
                            },
                            r253
                        )
                    }
                    2 => {
                        // Delete buffer
                        log::warn!("Syscall 2");
                    }
                    3 => {
                        log::warn!("Syscall 3");
                    }
                    4 => {
                        log::warn!("Syscall 4");
                    }

                    _ => {
                        log::error!("Syscall unknown {:?}", r255)
                    }
                }
            }
            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
    }
}