/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "xpcprivate.h"
#include "XPCJSWeakReference.h"

#include "nsContentUtils.h"

using namespace JS;

xpcJSWeakReference::xpcJSWeakReference() = default;

NS_IMPL_ISUPPORTS(xpcJSWeakReference, xpcIJSWeakReference)

nsresult xpcJSWeakReference::Init(JSContext* cx, const JS::Value& object) {
  if (!object.isObject()) {
    return NS_OK;
  }

  JS::RootedObject obj(cx, &object.toObject());

  XPCCallContext ccx(cx);

  // See if the object is a wrapped native that supports weak references.
  nsCOMPtr<nsISupports> supports = xpc::ReflectorToISupportsDynamic(obj, cx);
  nsCOMPtr<nsISupportsWeakReference> supportsWeakRef =
      do_QueryInterface(supports);
  if (supportsWeakRef) {
    supportsWeakRef->GetWeakReference(getter_AddRefs(mReferent));
    if (mReferent) {
      return NS_OK;
    }
  }
  // If it's not a wrapped native, or it is a wrapped native that does not
  // support weak references, fall back to getting a weak ref to the object.

  // See if object is a wrapped JSObject.
  RefPtr<nsXPCWrappedJS> wrapped;
  nsresult rv = nsXPCWrappedJS::GetNewOrUsed(cx, obj, NS_GET_IID(nsISupports),
                                             getter_AddRefs(wrapped));
  if (!wrapped) {
    NS_ERROR("can't get nsISupportsWeakReference wrapper for obj");
    return rv;
  }

  return wrapped->GetWeakReference(getter_AddRefs(mReferent));
}

NS_IMETHODIMP
xpcJSWeakReference::Get(JSContext* aCx, MutableHandleValue aRetval) {
  aRetval.setNull();

  if (!mReferent) {
    return NS_OK;
  }

  nsCOMPtr<nsISupports> supports = do_QueryReferent(mReferent);
  if (!supports) {
    return NS_OK;
  }

  nsCOMPtr<nsIXPConnectWrappedJS> wrappedObj = do_QueryInterface(supports);
  if (!wrappedObj) {
    // We have a generic XPCOM object that supports weak references here.
    // Wrap it and pass it out.
    return nsContentUtils::WrapNative(aCx, supports, &NS_GET_IID(nsISupports),
                                      aRetval);
  }

  JS::RootedObject obj(aCx, wrappedObj->GetJSObject());
  if (!obj) {
    return NS_OK;
  }

  // Most users of XPCWrappedJS don't need to worry about
  // re-wrapping because things are implicitly rewrapped by
  // xpcconvert. However, because we're doing this directly
  // through the native call context, we need to call
  // JS_WrapObject().
  if (!JS_WrapObject(aCx, &obj)) {
    return NS_ERROR_FAILURE;
  }

  aRetval.setObject(*obj);
  return NS_OK;
}