// Copyright 2018 the V8 project authors.  All rights reserved. 
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. 

#include "src/builtins/builtins-utils-inl.h"
#include "src/counters.h"
#include "src/objects/js-weak-refs-inl.h"

namespace v8 {
namespace internal {

BUILTIN(FinalizationGroupConstructor) {
  HandleScope scope(isolate);
  Handle<JSFunction> target = args.target();
  if (args.new_target()->IsUndefined(isolate)) {  // [[Call]]
    THROW_NEW_ERROR_RETURN_FAILURE(
        isolate, NewTypeError(MessageTemplate::kConstructorNotFunction,
                              handle(target->shared()->Name(), isolate)));
  }
  // [[Construct]]
  Handle<JSReceiver> new_target = Handle<JSReceiver>::cast(args.new_target());
  Handle<Object> cleanup = args.atOrUndefined(isolate, 1);

  if (! cleanup->IsCallable()) {
    THROW_NEW_ERROR_RETURN_FAILURE(
        isolate, NewTypeError(MessageTemplate::kWeakRefsCleanupMustBeCallable));
  }

  Handle<JSObject> result;
  ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
      isolate, result,
      JSObject::New(target, new_target, Handle<AllocationSite>::null()));

  Handle<JSFinalizationGroup> finalization_group =
      Handle<JSFinalizationGroup>::cast(result);
  finalization_group->set_native_context(*isolate->native_context());
  finalization_group->set_cleanup(*cleanup);
  finalization_group->set_flags(
      JSFinalizationGroup::ScheduledForCleanupField::encode(false));

  DCHECK(finalization_group->active_cells()->IsUndefined(isolate));
  DCHECK(finalization_group->cleared_cells()->IsUndefined(isolate));
  DCHECK(finalization_group->key_map()->IsUndefined(isolate));
  return *finalization_group;
}

BUILTIN(FinalizationGroupRegister) {
  HandleScope scope(isolate);
  const char* method_name = "FinalizationGroup.prototype.register";

  CHECK_RECEIVER(JSFinalizationGroup, finalization_group, method_name);

  Handle<Object> target = args.atOrUndefined(isolate, 1);
  if (! target->IsJSReceiver()) {
    THROW_NEW_ERROR_RETURN_FAILURE(
        isolate,
        NewTypeError(MessageTemplate::kWeakRefsRegisterTargetMustBeObject));
  }
  Handle<Object> holdings = args.atOrUndefined(isolate, 2);
  if (target->SameValue(*holdings)) {
    THROW_NEW_ERROR_RETURN_FAILURE(
        isolate,
        NewTypeError(
            MessageTemplate::kWeakRefsRegisterTargetAndHoldingsMustNotBeSame));
  }

  Handle<Object> key = args.atOrUndefined(isolate, 3);
  // TODO(marja, gsathya): Restrictions on "key" (e.g., does it need to be an
  // object). 

  // TODO(marja): Realms. 

  JSFinalizationGroup::Register(finalization_group,
                                Handle<JSReceiver>::cast(target), holdings, key,
                                isolate);
  return ReadOnlyRoots(isolate).undefined_value();
}

BUILTIN(FinalizationGroupUnregister) {
  HandleScope scope(isolate);
  const char* method_name = "FinalizationGroup.prototype.unregister";

  CHECK_RECEIVER(JSFinalizationGroup, finalization_group, method_name);

  Handle<Object> key = args.atOrUndefined(isolate, 1);
  JSFinalizationGroup::Unregister(finalization_group, key, isolate);
  return ReadOnlyRoots(isolate).undefined_value();
}

BUILTIN(FinalizationGroupCleanupSome) {
  HandleScope scope(isolate);
  const char* method_name = "FinalizationGroup.prototype.cleanupSome";

  CHECK_RECEIVER(JSFinalizationGroup, finalization_group, method_name);

  // TODO(marja, gsathya): Add missing "cleanup" callback. 

  // Don't do set_scheduled_for_cleanup(false); we still have the microtask
  // scheduled and don't want to schedule another one in case the user never
  // executes microtasks. 
  JSFinalizationGroup::Cleanup(finalization_group, isolate);
  return ReadOnlyRoots(isolate).undefined_value();
}

BUILTIN(FinalizationGroupCleanupIteratorNext) {
  HandleScope scope(isolate);
  CHECK_RECEIVER(JSFinalizationGroupCleanupIterator, iterator, "next");

  Handle<JSFinalizationGroup> finalization_group(iterator->finalization_group(),
                                                 isolate);
  if (! finalization_group->NeedsCleanup()) {
    return *isolate->factory()->NewJSIteratorResult(
        handle(ReadOnlyRoots(isolate).undefined_value(), isolate), true);
  }
  Handle<Object> holdings = handle(
      JSFinalizationGroup::PopClearedCellHoldings(finalization_group, isolate),
      isolate);

  return *isolate->factory()->NewJSIteratorResult(holdings, false);
}

BUILTIN(WeakRefConstructor) {
  HandleScope scope(isolate);
  Handle<JSFunction> target = args.target();
  if (args.new_target()->IsUndefined(isolate)) {  // [[Call]]
    THROW_NEW_ERROR_RETURN_FAILURE(
        isolate, NewTypeError(MessageTemplate::kConstructorNotFunction,
                              handle(target->shared()->Name(), isolate)));
  }
  // [[Construct]]
  Handle<JSReceiver> new_target = Handle<JSReceiver>::cast(args.new_target());
  Handle<Object> target_object = args.atOrUndefined(isolate, 1);
  if (! target_object->IsJSReceiver()) {
    THROW_NEW_ERROR_RETURN_FAILURE(
        isolate,
        NewTypeError(
            MessageTemplate::kWeakRefsWeakRefConstructorTargetMustBeObject));
  }
  Handle<JSReceiver> target_receiver =
      handle(JSReceiver::cast(*target_object), isolate);
  isolate->heap()->AddKeepDuringJobTarget(target_receiver);

  // TODO(marja): Realms. 

  Handle<JSObject> result;
  ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
      isolate, result,
      JSObject::New(target, new_target, Handle<AllocationSite>::null()));

  Handle<JSWeakRef> weak_ref = Handle<JSWeakRef>::cast(result);
  weak_ref->set_target(*target_receiver);
  return *weak_ref;
}

BUILTIN(WeakRefDeref) {
  HandleScope scope(isolate);
  CHECK_RECEIVER(JSWeakRef, weak_ref, "WeakRef.prototype.deref");
  if (weak_ref->target()->IsJSReceiver()) {
    Handle<JSReceiver> target =
        handle(JSReceiver::cast(weak_ref->target()), isolate);
    // AddKeepDuringJobTarget might allocate and cause a GC, but it won't clear
    // weak_ref since we hold a Handle to its target. 
    isolate->heap()->AddKeepDuringJobTarget(target);
  } else {
    DCHECK(weak_ref->target()->IsUndefined(isolate));
  }
  return weak_ref->target();
}

}  // namespace internal
}  // namespace v8
