// Copyright (c) 2013 GitHub, Inc. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "atom/common/node_bindings.h"

#include <string>
#include <vector>

#include "atom/common/browser_v8_locker.h"
#include "base/command_line.h"
#include "base/base_paths.h"
#include "base/files/file_path.h"
#include "base/message_loop/message_loop.h"
#include "base/path_service.h"
#include "content/public/browser/browser_thread.h"

#if defined(OS_WIN)
#include "base/strings/utf_string_conversions.h"
#endif

#include "atom/common/node_includes.h"

using content::BrowserThread;

// Forward declaration of internal node functions.
namespace node {
void Init(int*, const char**, int*, const char***);
void Load(Environment* env);
void SetupProcessObject(Environment*, int, const char* const*, int,
                        const char* const*);
}

namespace atom {

namespace {

// Empty callback for async handle.
void UvNoOp(uv_async_t* handle, int status) {
}

// Convert the given vector to an array of C-strings. The strings in the
// returned vector are only guaranteed valid so long as the vector of strings
// is not modified.
scoped_ptr<const char*[]> StringVectorToArgArray(
    const std::vector<std::string>& vector) {
  scoped_ptr<const char*[]> array(new const char*[vector.size()]);
  for (size_t i = 0; i < vector.size(); ++i)
    array[i] = vector[i].c_str();
  return array.Pass();
}

#if defined(OS_WIN)
std::vector<std::string> String16VectorToStringVector(
    const std::vector<string16>& vector) {
  std::vector<std::string> utf8_vector;
  utf8_vector.reserve(vector.size());
  for (size_t i = 0; i < vector.size(); ++i)
    utf8_vector.push_back(UTF16ToUTF8(vector[i]));
  return utf8_vector;
}
#endif

}  // namespace

node::Environment* global_env = NULL;

NodeBindings::NodeBindings(bool is_browser)
    : is_browser_(is_browser),
      message_loop_(NULL),
      uv_loop_(uv_default_loop()),
      embed_closed_(false),
      uv_env_(NULL),
      weak_factory_(this) {
}

NodeBindings::~NodeBindings() {
  // Quit the embed thread.
  embed_closed_ = true;
  uv_sem_post(&embed_sem_);
  WakeupEmbedThread();

  // Wait for everything to be done.
  uv_thread_join(&embed_thread_);

  // Clear uv.
  uv_sem_destroy(&embed_sem_);
  uv_timer_stop(&idle_timer_);
}

void NodeBindings::Initialize() {
  // Init idle GC for browser.
  if (is_browser_) {
    uv_timer_init(uv_default_loop(), &idle_timer_);
    uv_timer_start(&idle_timer_, IdleCallback, 5000, 5000);
  }

  // Open node's error reporting system for browser process.
  node::g_standalone_mode = is_browser_;
  node::g_upstream_node_mode = false;

  // Init node.
  // (we assume it would not node::Init would not modify the parameters under
  // embedded mode).
  node::Init(NULL, NULL, NULL, NULL);
}

node::Environment* NodeBindings::CreateEnvironment(
    v8::Handle<v8::Context> context) {
  std::vector<std::string> args =
#if defined(OS_WIN)
      String16VectorToStringVector(CommandLine::ForCurrentProcess()->argv());
#else
      CommandLine::ForCurrentProcess()->argv();
#endif

  // Feed node the path to initialization script.
  base::FilePath exec_path(CommandLine::ForCurrentProcess()->argv()[0]);
  PathService::Get(base::FILE_EXE, &exec_path);
  base::FilePath resources_path =
#if defined(OS_MACOSX)
      is_browser_ ? exec_path.DirName().DirName().Append("Resources") :
                    exec_path.DirName().DirName().DirName().DirName().DirName()
                             .Append("Resources");
#else
      exec_path.DirName().AppendASCII("resources");
#endif
  base::FilePath script_path =
      resources_path.AppendASCII("atom")
                    .AppendASCII(is_browser_ ? "browser" : "renderer")
                    .AppendASCII("lib")
                    .AppendASCII("init.js");
  std::string script_path_str = script_path.AsUTF8Unsafe();
  args.insert(args.begin() + 1, script_path_str.c_str());

  // Convert string vector to const char* array.
  scoped_ptr<const char*[]> c_argv = StringVectorToArgArray(args);

  // Construct the parameters that passed to node::CreateEnvironment:
  v8::Isolate* isolate = context->GetIsolate();
  int argc = args.size();
  const char** argv = c_argv.get();
  int exec_argc = 0;
  const char** exec_argv = NULL;

  using namespace v8;  // NOLINT
  using namespace node;  // NOLINT

  // Following code are stripped from node::CreateEnvironment in node.cc:
  HandleScope handle_scope(isolate);
  Context::Scope context_scope(context);

  Environment* env = Environment::New(context);

  uv_check_init(env->event_loop(), env->immediate_check_handle());
  uv_unref(
      reinterpret_cast<uv_handle_t*>(env->immediate_check_handle()));
  uv_idle_init(env->event_loop(), env->immediate_idle_handle());

  uv_prepare_init(env->event_loop(), env->idle_prepare_handle());
  uv_check_init(env->event_loop(), env->idle_check_handle());
  uv_unref(reinterpret_cast<uv_handle_t*>(env->idle_prepare_handle()));
  uv_unref(reinterpret_cast<uv_handle_t*>(env->idle_check_handle()));

  Local<FunctionTemplate> process_template = FunctionTemplate::New();
  process_template->SetClassName(FIXED_ONE_BYTE_STRING(isolate, "process"));

  Local<Object> process_object = process_template->GetFunction()->NewInstance();
  env->set_process_object(process_object);

  SetupProcessObject(env, argc, argv, exec_argc, exec_argv);
  Load(env);

  return env;
}

void NodeBindings::PrepareMessageLoop() {
  DCHECK(!is_browser_ || BrowserThread::CurrentlyOn(BrowserThread::UI));

  // Add dummy handle for libuv, otherwise libuv would quit when there is
  // nothing to do.
  uv_async_init(uv_loop_, &dummy_uv_handle_, UvNoOp);

  // Start worker that will interrupt main loop when having uv events.
  uv_sem_init(&embed_sem_, 0);
  uv_thread_create(&embed_thread_, EmbedThreadRunner, this);
}

void NodeBindings::RunMessageLoop() {
  DCHECK(!is_browser_ || BrowserThread::CurrentlyOn(BrowserThread::UI));

  // The MessageLoop should have been created, remember the one in main thread.
  message_loop_ = base::MessageLoop::current();

  // Run uv loop for once to give the uv__io_poll a chance to add all events.
  UvRunOnce();
}

void NodeBindings::UvRunOnce() {
  DCHECK(!is_browser_ || BrowserThread::CurrentlyOn(BrowserThread::UI));

  // Use Locker in browser process.
  BrowserV8Locker locker(node_isolate);

  v8::HandleScope handle_scope(node_isolate);

  // Enter node context while dealing with uv events, by default the global
  // env would be used unless user specified another one (this happens for
  // renderer process, which wraps the uv loop with web page context).
  node::Environment* env = uv_env() ? uv_env() : global_env;
  v8::Context::Scope context_scope(env->context());

  // Deal with uv events.
  int r = uv_run(uv_loop_, (uv_run_mode)(UV_RUN_ONCE | UV_RUN_NOWAIT));
  if (r == 0 || uv_loop_->stop_flag != 0)
    message_loop_->QuitWhenIdle();  // Quit from uv.

  // Tell the worker thread to continue polling.
  uv_sem_post(&embed_sem_);
}

void NodeBindings::WakeupMainThread() {
  DCHECK(message_loop_);
  message_loop_->PostTask(FROM_HERE, base::Bind(&NodeBindings::UvRunOnce,
                                                weak_factory_.GetWeakPtr()));
}

void NodeBindings::WakeupEmbedThread() {
  uv_async_send(&dummy_uv_handle_);
}

// static
void NodeBindings::EmbedThreadRunner(void *arg) {
  NodeBindings* self = static_cast<NodeBindings*>(arg);

  while (true) {
    // Wait for the main loop to deal with events.
    uv_sem_wait(&self->embed_sem_);
    if (self->embed_closed_)
      break;

    // Wait for something to happen in uv loop.
    // Note that the PollEvents() is implemented by derived classes, so when
    // this class is being destructed the PollEvents() would not be available
    // anymore. Because of it we must make sure we only invoke PollEvents()
    // when this class is alive.
    self->PollEvents();
    if (self->embed_closed_)
      break;

    // Deal with event in main thread.
    self->WakeupMainThread();
  }
}

// static
void NodeBindings::IdleCallback(uv_timer_t*, int) {
  v8::V8::IdleNotification();
}

}  // namespace atom