mod capability;
mod fault;
mod ipc;
mod lifecycle;
mod memory;
mod simple;

use domain::{error::KernelError, syscall::Syscall};
use platform::Platform;
use types::{bounded::CapSlot, id::ThreadId, syscall_abi::ErrorCode};

use crate::Kernel;

pub use ipc::{IpcState, ThreadRef};
pub use types::syscall_abi::{Delivery, DeliveryKind};

pub enum SyscallOutcome {
    Complete(SyscallResult),
    BlockCaller(domain::thread::BlockReason),
    /// The caller blocked and `ThreadId` should run next.
    SwitchTo(ThreadId),
    TerminateCaller,
}

#[derive(Debug)]
pub enum SyscallResult {
    Ok,
    Value(usize),
    Slot(CapSlot),
    Received(Delivery),
    Error(KernelError),
}

/// The status code userspace sees for a kernel error.
pub fn error_code(error: &KernelError) -> ErrorCode {
    use KernelError::*;
    match error {
        InvalidSlot(_) | RevokedCapability(_) | NoSuchObject | InvalidEndpoint(_) => {
            ErrorCode::InvalidCap
        }
        PermissionDenied { .. } | ProcessCreateDenied | WritableAndExecutable => {
            ErrorCode::PermissionDenied
        }
        WrongObject => ErrorCode::WrongObject,
        NoFreeSlot => ErrorCode::NoFreeSlot,
        OutOfMemory => ErrorCode::OutOfMemory,
        InvalidAddress => ErrorCode::InvalidAddress,
        AddressInUse => ErrorCode::AddressInUse,
        NoReply => ErrorCode::NoReply,
        TooManyThreadsInProcess | TooManyProcesses | TooManyThreads | EndpointFull => {
            ErrorCode::LimitReached
        }
        InvalidProcess(_)
        | InvalidThread(_)
        | InvalidStateTransition(_)
        | InvalidIrq(_)
        | InvalidRegion
        | IrqAlreadyOwned(_)
        | WouldBlock
        | InvalidArgument => ErrorCode::InvalidArgument,
    }
}

fn complete(result: Result<SyscallResult, KernelError>) -> SyscallOutcome {
    SyscallOutcome::Complete(result.unwrap_or_else(SyscallResult::Error))
}

impl<P: Platform> Kernel<P> {
    pub fn handle_syscall(&mut self, syscall: Syscall) -> SyscallOutcome {
        let (tid, pid) = match self.caller() {
            Ok(caller) => caller,
            Err(e) => return SyscallOutcome::Complete(SyscallResult::Error(e)),
        };

        match syscall {
            Syscall::GetTime => self.handle_get_time(),
            Syscall::GetProcessId => self.handle_get_process_id(pid),
            Syscall::Yield => self.handle_yield(tid),
            Syscall::Exit => self.handle_exit(tid, pid),
            Syscall::ExitThread => self.handle_exit_thread(tid, pid),
            Syscall::RequestPages { count } => self.handle_request_pages(pid, count),
            Syscall::ReleasePages { addr, count } => self.handle_release_pages(pid, addr, count),
            Syscall::SpawnThread { entry, stack, arg } => {
                self.handle_spawn_thread(pid, entry, stack, arg)
            }
            Syscall::CreateProcess {
                create_cap,
                image,
                limits,
            } => self.handle_create_process(pid, create_cap, image, limits),
            Syscall::Kill { process } => self.handle_kill(pid, process),
            Syscall::Revoke { slot } => self.handle_revoke(pid, slot),
            Syscall::DropCap { slot } => self.handle_drop_cap(pid, slot),
            Syscall::CreateRegion { pages } => {
                complete(self.create_region_cap(pid, pages).map(SyscallResult::Slot))
            }
            Syscall::MapRegion { region, va, perms } => complete(
                self.map_region_cap(pid, region, va, perms)
                    .map(|pages| SyscallResult::Value(pages.value() as usize)),
            ),
            Syscall::RegionAddress { region } => complete(
                self.region_address_cap(pid, region)
                    .map(|pa| SyscallResult::Value(pa.raw())),
            ),
            Syscall::WatchDeath {
                process,
                notification,
            } => complete(
                self.watch_death(pid, process, notification)
                    .map(|()| SyscallResult::Ok),
            ),
            Syscall::SetTimer {
                notification,
                deadline,
            } => complete(
                self.set_timer(pid, notification, deadline)
                    .map(|()| SyscallResult::Ok),
            ),
            Syscall::Delegate {
                slot,
                to_endpoint,
                permissions,
            } => self.handle_delegate(pid, slot, to_endpoint, permissions),
            Syscall::Mint {
                slot,
                badge,
                permissions,
            } => complete(
                self.mint(pid, slot, badge, permissions)
                    .map(SyscallResult::Slot),
            ),
            Syscall::Send { endpoint, message } => self.send(tid, pid, endpoint, message, false),
            Syscall::Call { endpoint, message } => self.send(tid, pid, endpoint, message, true),
            Syscall::Receive { endpoint } => self.receive(tid, pid, endpoint, true),
            Syscall::Reply { message } => {
                complete(self.reply(tid, pid, message).map(|()| SyscallResult::Ok))
            }
            Syscall::ReplyRecv { endpoint, message } => {
                self.reply_recv(tid, pid, endpoint, message)
            }
            Syscall::SaveReply => complete(
                self.save_reply(tid)
                    .map(|r| SyscallResult::Value(usize::from(r.value()))),
            ),
            Syscall::ReplySaved { reply, message } => complete(
                self.reply_saved(tid, pid, reply, message)
                    .map(|()| SyscallResult::Ok),
            ),
            Syscall::CreateNotification => {
                complete(self.create_notification_cap(pid).map(SyscallResult::Slot))
            }
            Syscall::Signal { notification } => {
                complete(self.signal(pid, notification).map(|()| SyscallResult::Ok))
            }
            Syscall::Wait { notification } => self.wait(tid, pid, notification),
            Syscall::Poll { notification } => complete(
                self.poll(pid, notification)
                    .map(|bits| SyscallResult::Received(Delivery::signal(bits))),
            ),
            Syscall::BindNotification { notification } => complete(
                self.bind_notification(tid, pid, notification)
                    .map(|()| SyscallResult::Ok),
            ),
            Syscall::SetIrqNotification { irq, notification } => complete(
                self.set_irq_notification(pid, irq, notification)
                    .map(|()| SyscallResult::Ok),
            ),
            Syscall::AcknowledgeInterrupt { irq } => {
                complete(self.ack_interrupt(pid, irq).map(|()| SyscallResult::Ok))
            }
            Syscall::Halt { control } => self.handle_halt(pid, control),
            Syscall::CreateEndpoint => self.handle_create_endpoint(pid),
            Syscall::DebugPutchar { console, byte } => complete(
                self.debug_putchar(pid, console, byte)
                    .map(|()| SyscallResult::Ok),
            ),
            Syscall::MapPage {
                process,
                src_va,
                dst_va,
                executable,
            } => self.handle_map_page(pid, process, src_va, dst_va, executable),
            Syscall::SpawnThreadIn {
                process,
                entry,
                stack,
                arg,
            } => self.handle_spawn_thread_in(pid, process, entry, stack, arg),
        }
    }
}