use crate::plan::{ObjectQueue, VectorObjectQueue};
use crate::policy::copy_context::PolicyCopyContext;
use crate::policy::gc_work::TRACE_KIND_TRANSITIVE_PIN;
use crate::policy::sft::GCWorkerMutRef;
use crate::policy::sft::SFT;
use crate::policy::space::{CommonSpace, Space};
use crate::scheduler::GCWorker;
use crate::util::alloc::allocator::AllocatorContext;
use crate::util::heap::{MonotonePageResource, PageResource};
use crate::util::metadata::{extract_side_metadata, MetadataSpec};
use crate::util::object_enum::ObjectEnumerator;
use crate::util::object_forwarding;
use crate::util::{copy::*, object_enum};
use crate::util::{Address, ObjectReference};
use crate::vm::*;
use libc::{mprotect, PROT_EXEC, PROT_NONE, PROT_READ, PROT_WRITE};
use std::sync::atomic::{AtomicBool, Ordering};
use std::sync::Arc;

/// This type implements a simple copying space.
pub struct CopySpace<VM: VMBinding> {
    common: CommonSpace<VM>,
    pr: MonotonePageResource<VM>,
    from_space: AtomicBool,
}

impl<VM: VMBinding> SFT for CopySpace<VM> {
    fn name(&self) -> &str {
        self.get_name()
    }

    fn is_live(&self, object: ObjectReference) -> bool {
        !self.is_from_space() || object_forwarding::is_forwarded::<VM>(object)
    }

    #[cfg(feature = "object_pinning")]
    fn pin_object(&self, _object: ObjectReference) -> bool {
        panic!("Cannot pin/unpin objects of CopySpace.")
    }

    #[cfg(feature = "object_pinning")]
    fn unpin_object(&self, _object: ObjectReference) -> bool {
        panic!("Cannot pin/unpin objects of CopySpace.")
    }

    #[cfg(feature = "object_pinning")]
    fn is_object_pinned(&self, _object: ObjectReference) -> bool {
        false
    }

    fn is_movable(&self) -> bool {
        true
    }

    #[cfg(feature = "sanity")]
    fn is_sane(&self) -> bool {
        !self.is_from_space()
    }

    fn initialize_object_metadata(&self, _object: ObjectReference, _alloc: bool) {
        #[cfg(feature = "vo_bit")]
        crate::util::metadata::vo_bit::set_vo_bit(_object);
    }

    fn get_forwarded_object(&self, object: ObjectReference) -> Option<ObjectReference> {
        if !self.is_from_space() {
            return None;
        }

        if object_forwarding::is_forwarded::<VM>(object) {
            Some(object_forwarding::read_forwarding_pointer::<VM>(object))
        } else {
            None
        }
    }

    #[cfg(feature = "is_mmtk_object")]
    fn is_mmtk_object(&self, addr: Address) -> Option<ObjectReference> {
        crate::util::metadata::vo_bit::is_vo_bit_set_for_addr(addr)
    }

    #[cfg(feature = "is_mmtk_object")]
    fn find_object_from_internal_pointer(
        &self,
        ptr: Address,
        max_search_bytes: usize,
    ) -> Option<ObjectReference> {
        crate::util::metadata::vo_bit::find_object_from_internal_pointer::<VM>(
            ptr,
            max_search_bytes,
        )
    }

    fn sft_trace_object(
        &self,
        queue: &mut VectorObjectQueue,
        object: ObjectReference,
        worker: GCWorkerMutRef,
    ) -> ObjectReference {
        let worker = worker.into_mut::<VM>();
        self.trace_object(queue, object, self.common.copy, worker)
    }
}

impl<VM: VMBinding> Space<VM> for CopySpace<VM> {
    fn as_space(&self) -> &dyn Space<VM> {
        self
    }

    fn as_sft(&self) -> &(dyn SFT + Sync + 'static) {
        self
    }

    fn get_page_resource(&self) -> &dyn PageResource<VM> {
        &self.pr
    }

    fn maybe_get_page_resource_mut(&mut self) -> Option<&mut dyn PageResource<VM>> {
        Some(&mut self.pr)
    }

    fn common(&self) -> &CommonSpace<VM> {
        &self.common
    }

    fn initialize_sft(&self, sft_map: &mut dyn crate::policy::sft_map::SFTMap) {
        self.common().initialize_sft(self.as_sft(), sft_map)
    }

    fn release_multiple_pages(&mut self, _start: Address) {
        panic!("copyspace only releases pages enmasse")
    }

    fn set_copy_for_sft_trace(&mut self, semantics: Option<CopySemantics>) {
        self.common.copy = semantics;
    }

    fn enumerate_objects(&self, enumerator: &mut dyn ObjectEnumerator) {
        object_enum::enumerate_blocks_from_monotonic_page_resource(enumerator, &self.pr);
    }
}

impl<VM: VMBinding> crate::policy::gc_work::PolicyTraceObject<VM> for CopySpace<VM> {
    fn trace_object<Q: ObjectQueue, const KIND: crate::policy::gc_work::TraceKind>(
        &self,
        queue: &mut Q,
        object: ObjectReference,
        copy: Option<CopySemantics>,
        worker: &mut GCWorker<VM>,
    ) -> ObjectReference {
        debug_assert!(
            KIND != TRACE_KIND_TRANSITIVE_PIN,
            "Copyspace does not support transitive pin trace."
        );
        self.trace_object(queue, object, copy, worker)
    }

    fn may_move_objects<const KIND: crate::policy::gc_work::TraceKind>() -> bool {
        true
    }
}

impl<VM: VMBinding> CopySpace<VM> {
    pub fn new(args: crate::policy::space::PlanCreateSpaceArgs<VM>, from_space: bool) -> Self {
        let vm_map = args.vm_map;
        let is_discontiguous = args.vmrequest.is_discontiguous();
        let common = CommonSpace::new(args.into_policy_args(
            true,
            false,
            extract_side_metadata(&[
                *VM::VMObjectModel::LOCAL_FORWARDING_BITS_SPEC,
                *VM::VMObjectModel::LOCAL_FORWARDING_POINTER_SPEC,
            ]),
        ));
        CopySpace {
            pr: if is_discontiguous {
                MonotonePageResource::new_discontiguous(vm_map)
            } else {
                MonotonePageResource::new_contiguous(common.start, common.extent, vm_map)
            },
            common,
            from_space: AtomicBool::new(from_space),
        }
    }

    pub fn prepare(&self, from_space: bool) {
        self.from_space.store(from_space, Ordering::SeqCst);
    }

    pub fn release(&self) {
        for (start, size) in self.pr.iterate_allocated_regions() {
            // Clear the forwarding bits if it is on the side.
            if let MetadataSpec::OnSide(side_forwarding_status_table) =
                *<VM::VMObjectModel as ObjectModel<VM>>::LOCAL_FORWARDING_BITS_SPEC
            {
                side_forwarding_status_table.bzero_metadata(start, size);
            }

            // Clear VO bits because all objects in the space are dead.
            #[cfg(feature = "vo_bit")]
            crate::util::metadata::vo_bit::bzero_vo_bit(start, size);
        }

        unsafe {
            self.pr.reset();
        }
        self.from_space.store(false, Ordering::SeqCst);
    }

    fn is_from_space(&self) -> bool {
        self.from_space.load(Ordering::SeqCst)
    }

    pub fn trace_object<Q: ObjectQueue>(
        &self,
        queue: &mut Q,
        object: ObjectReference,
        semantics: Option<CopySemantics>,
        worker: &mut GCWorker<VM>,
    ) -> ObjectReference {
        trace!("copyspace.trace_object(, {:?}, {:?})", object, semantics,);

        // If this is not from space, we do not need to trace it (the object has been copied to the tosapce)
        if !self.is_from_space() {
            // The copy semantics for tospace should be none.
            return object;
        }

        // This object is in from space, we will copy. Make sure we have a valid copy semantic.
        debug_assert!(semantics.is_some());

        #[cfg(feature = "vo_bit")]
        debug_assert!(
            crate::util::metadata::vo_bit::is_vo_bit_set(object),
            "{:x}: VO bit not set",
            object
        );

        trace!("attempting to forward");
        let forwarding_status = object_forwarding::attempt_to_forward::<VM>(object);

        trace!("checking if object is being forwarded");
        if object_forwarding::state_is_forwarded_or_being_forwarded(forwarding_status) {
            trace!("... yes it is");
            let new_object =
                object_forwarding::spin_and_get_forwarded_object::<VM>(object, forwarding_status);
            trace!("Returning");
            new_object
        } else {
            trace!("... no it isn't. Copying");
            let new_object = object_forwarding::forward_object::<VM>(
                object,
                semantics.unwrap(),
                worker.get_copy_context_mut(),
                |_new_object| {
                    #[cfg(feature = "vo_bit")]
                    crate::util::metadata::vo_bit::set_vo_bit(_new_object);
                },
            );

            trace!("Forwarding pointer");
            queue.enqueue(new_object);
            trace!("Copied [{:?} -> {:?}]", object, new_object);
            new_object
        }
    }

    #[allow(dead_code)] // Only used with certain features (such as sanity)
    pub fn protect(&self) {
        if !self.common().contiguous {
            panic!(
                "Implement Options.protectOnRelease for MonotonePageResource.release_pages_extent"
            )
        }
        let start = self.common().start;
        let extent = self.common().extent;
        unsafe {
            mprotect(start.to_mut_ptr(), extent, PROT_NONE);
        }
        trace!("Protect {:x} {:x}", start, start + extent);
    }

    #[allow(dead_code)] // Only used with certain features (such as sanity)
    pub fn unprotect(&self) {
        if !self.common().contiguous {
            panic!(
                "Implement Options.protectOnRelease for MonotonePageResource.release_pages_extent"
            )
        }
        let start = self.common().start;
        let extent = self.common().extent;
        unsafe {
            mprotect(
                start.to_mut_ptr(),
                extent,
                PROT_READ | PROT_WRITE | PROT_EXEC,
            );
        }
        trace!("Unprotect {:x} {:x}", start, start + extent);
    }
}

use crate::util::alloc::Allocator;
use crate::util::alloc::BumpAllocator;
use crate::util::opaque_pointer::VMWorkerThread;

/// Copy allocator for CopySpace
pub struct CopySpaceCopyContext<VM: VMBinding> {
    copy_allocator: BumpAllocator<VM>,
}

impl<VM: VMBinding> PolicyCopyContext for CopySpaceCopyContext<VM> {
    type VM = VM;

    fn prepare(&mut self) {}

    fn release(&mut self) {}

    fn alloc_copy(
        &mut self,
        _original: ObjectReference,
        bytes: usize,
        align: usize,
        offset: usize,
    ) -> Address {
        self.copy_allocator.alloc(bytes, align, offset)
    }
}

impl<VM: VMBinding> CopySpaceCopyContext<VM> {
    pub(crate) fn new(
        tls: VMWorkerThread,
        context: Arc<AllocatorContext<VM>>,
        tospace: &'static CopySpace<VM>,
    ) -> Self {
        CopySpaceCopyContext {
            copy_allocator: BumpAllocator::new(tls.0, tospace, context),
        }
    }
}

impl<VM: VMBinding> CopySpaceCopyContext<VM> {
    pub fn rebind(&mut self, space: &CopySpace<VM>) {
        self.copy_allocator
            .rebind(unsafe { &*{ space as *const _ } });
    }
}