// Copyright 2014 The Chromium 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 "services/js/system/waiting_callback.h"

#include "base/bind.h"
#include "base/message_loop/message_loop.h"
#include "gin/per_context_data.h"
#include "mojo/public/cpp/environment/environment.h"

namespace mojo {
namespace js {

namespace {

v8::Handle<v8::String> GetHiddenPropertyName(v8::Isolate* isolate) {
  return gin::StringToSymbol(isolate, "::mojo::js::WaitingCallback");
}

}  // namespace

gin::WrapperInfo WaitingCallback::kWrapperInfo = { gin::kEmbedderNativeGin };

// static
gin::Handle<WaitingCallback> WaitingCallback::Create(
    v8::Isolate* isolate,
    v8::Handle<v8::Function> callback,
    gin::Handle<HandleWrapper> handle_wrapper,
    MojoHandleSignals signals) {
  gin::Handle<WaitingCallback> waiting_callback = gin::CreateHandle(
      isolate, new WaitingCallback(isolate, callback, handle_wrapper));
  waiting_callback->wait_id_ = Environment::GetDefaultAsyncWaiter()->AsyncWait(
      handle_wrapper->get().value(),
      signals,
      MOJO_DEADLINE_INDEFINITE,
      &WaitingCallback::CallOnHandleReady,
      waiting_callback.get());
  return waiting_callback;
}

void WaitingCallback::Cancel() {
  if (!wait_id_)
    return;

  handle_wrapper_->RemoveCloseObserver(this);
  handle_wrapper_ = NULL;
  Environment::GetDefaultAsyncWaiter()->CancelWait(wait_id_);
  wait_id_ = 0;
}

WaitingCallback::WaitingCallback(v8::Isolate* isolate,
                                 v8::Handle<v8::Function> callback,
                                 gin::Handle<HandleWrapper> handle_wrapper)
    : wait_id_(0), handle_wrapper_(handle_wrapper.get()), weak_factory_(this) {
  handle_wrapper_->AddCloseObserver(this);
  v8::Handle<v8::Context> context = isolate->GetCurrentContext();
  runner_ = gin::PerContextData::From(context)->runner()->GetWeakPtr();
  GetWrapper(isolate)->SetHiddenValue(GetHiddenPropertyName(isolate), callback);
}

WaitingCallback::~WaitingCallback() {
  Cancel();
}

// static
void WaitingCallback::CallOnHandleReady(void* closure, MojoResult result) {
  static_cast<WaitingCallback*>(closure)->OnHandleReady(result);
}

void WaitingCallback::ClearWaitId() {
  wait_id_ = 0;
  handle_wrapper_->RemoveCloseObserver(this);
  handle_wrapper_ = nullptr;
}

void WaitingCallback::OnHandleReady(MojoResult result) {
  ClearWaitId();
  CallCallback(result);
}

void WaitingCallback::CallCallback(MojoResult result) {
  // ClearWaitId must already have been called.
  DCHECK(!wait_id_);
  DCHECK(!handle_wrapper_);

  if (!runner_)
    return;

  gin::Runner::Scope scope(runner_.get());
  v8::Isolate* isolate = runner_->GetContextHolder()->isolate();

  v8::Handle<v8::Value> hidden_value =
      GetWrapper(isolate)->GetHiddenValue(GetHiddenPropertyName(isolate));
  v8::Handle<v8::Function> callback;
  CHECK(gin::ConvertFromV8(isolate, hidden_value, &callback));

  v8::Handle<v8::Value> args[] = { gin::ConvertToV8(isolate, result) };
  runner_->Call(callback, runner_->global(), 1, args);
}

void WaitingCallback::OnWillCloseHandle() {
  Environment::GetDefaultAsyncWaiter()->CancelWait(wait_id_);

  // This may be called from GC, so we can't execute Javascript now, call
  // ClearWaitId explicitly, and CallCallback asynchronously.
  ClearWaitId();
  base::MessageLoop::current()->PostTask(
      FROM_HERE,
      base::Bind(&WaitingCallback::CallCallback, weak_factory_.GetWeakPtr(),
                 MOJO_RESULT_INVALID_ARGUMENT));
}

}  // namespace js
}  // namespace mojo