// Copyright 2014 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "extensions/renderer/object_backed_native_handler.h"

#include <stddef.h>

#include <utility>

#include "base/logging.h"
#include "content/public/renderer/worker_thread.h"
#include "extensions/common/extension_api.h"
#include "extensions/renderer/console.h"
#include "extensions/renderer/module_system.h"
#include "extensions/renderer/script_context.h"
#include "extensions/renderer/script_context_set.h"
#include "extensions/renderer/v8_helpers.h"
#include "gin/public/gin_embedders.h"
#include "third_party/blink/public/web/web_local_frame.h"
#include "v8/include/v8-context.h"
#include "v8/include/v8-external.h"
#include "v8/include/v8-function-callback.h"
#include "v8/include/v8-isolate.h"
#include "v8/include/v8-object.h"
#include "v8/include/v8-primitive.h"
#include "v8/include/v8-template.h"
#include "v8/include/v8-value.h"

namespace extensions {

namespace {
// Key for the base::Bound routed function.
const char kHandlerFunction[] = "handler_function";
const char kFeatureName[] = "feature_name";
}  // namespace

ObjectBackedNativeHandler::ObjectBackedNativeHandler(ScriptContext* context)
    : context_(context),
      object_template_(context->isolate(),
                       v8::ObjectTemplate::New(context->isolate())) {}

ObjectBackedNativeHandler::~ObjectBackedNativeHandler() {
}

void ObjectBackedNativeHandler::Initialize() {
  DCHECK_EQ(kUninitialized, init_state_)
      << "Initialize() can only be called once!";
  init_state_ = kInitializingRoutes;
  AddRoutes();
  init_state_ = kInitialized;
}

bool ObjectBackedNativeHandler::IsInitialized() {
  return init_state_ == kInitialized;
}

v8::Local<v8::Object> ObjectBackedNativeHandler::NewInstance() {
  DCHECK_EQ(kInitialized, init_state_)
      << "Initialize() must be called before a new instance is created!";
  return v8::Local<v8::ObjectTemplate>::New(GetIsolate(), object_template_)
      ->NewInstance(GetIsolate()->GetCurrentContext())
      .ToLocalChecked();
}

// static
void ObjectBackedNativeHandler::Router(
    const v8::FunctionCallbackInfo<v8::Value>& args) {
  v8::Isolate* isolate = args.GetIsolate();
  v8::HandleScope handle_scope(isolate);
  v8::Local<v8::Object> data = args.Data().As<v8::Object>();
  v8::Local<v8::Context> context = isolate->GetCurrentContext();

  v8::Local<v8::Value> handler_function_value;
  v8::Local<v8::Value> feature_name_value;

  // If the execution is terminating, it's unsafe to access any privates on the
  // object. Bail.
  if (isolate->IsExecutionTerminating())
    return;

  // Check with cbruni@ if we can turn on the following CHECK:
  // // We should never enter a v8::Function callback if execution is
  // // terminating.
  // CHECK(!isolate->IsExecutionTerminating());

  // See comment in header file for why we do this.
  if (!GetPrivate(context, data, kHandlerFunction, &handler_function_value) ||
      handler_function_value->IsUndefined() ||
      !GetPrivate(context, data, kFeatureName, &feature_name_value) ||
      !feature_name_value->IsString()) {
    ScriptContext* script_context =
        ScriptContextSet::GetContextByV8Context(context);
    console::AddMessage(script_context,
                        blink::mojom::ConsoleMessageLevel::kError,
                        "Extension view no longer exists");
    return;
  }

  // We can't access the ScriptContextSet on a worker thread. Luckily, we also
  // don't inject many bindings into worker threads.
  // TODO(devlin): Figure out a way around this.
  if (content::WorkerThread::GetCurrentId() == 0) {
    ScriptContext* script_context =
        ScriptContextSet::GetContextByV8Context(context);
    v8::Local<v8::String> feature_name_string =
        feature_name_value->ToString(context).ToLocalChecked();
    std::string feature_name =
        *v8::String::Utf8Value(isolate, feature_name_string);
    // TODO(devlin): Eventually, we should fail if either script_context is null
    // or feature_name is empty.
    if (script_context && !feature_name.empty()) {
      Feature::Availability availability =
          script_context->GetAvailability(feature_name);
      if (!availability.is_available()) {
        DVLOG(1) << feature_name
                 << " is not available: " << availability.message();
        return;
      }
    }
  }
  // This CHECK is *important*. Otherwise, we'll go around happily executing
  // something random.  See crbug.com/548273.
  CHECK(handler_function_value->IsExternal());
  static_cast<HandlerFunction*>(
      handler_function_value.As<v8::External>()->Value(
          gin::kObjectBackedNativeHandlerHandlerFunctionTag))
      ->Run(args);

  // Verify that the return value, if any, is accessible by the context.
  v8::ReturnValue<v8::Value> ret = args.GetReturnValue();
  v8::Local<v8::Value> ret_value = ret.Get();
  if (ret_value->IsObject() && !ret_value->IsNull() &&
      !ContextCanAccessObject(isolate, context,
                              v8::Local<v8::Object>::Cast(ret_value), true)) {
    NOTREACHED() << "Insecure return value";
  }
}

void ObjectBackedNativeHandler::RouteHandlerFunction(
    const std::string& name,
    HandlerFunction handler_function) {
  RouteHandlerFunction(name, "", std::move(handler_function));
}

void ObjectBackedNativeHandler::RouteHandlerFunction(
    const std::string& name,
    const std::string& feature_name,
    HandlerFunction handler_function) {
  DCHECK_EQ(init_state_, kInitializingRoutes)
      << "RouteHandlerFunction() can only be called from AddRoutes()!";

  v8::Isolate* isolate = GetIsolate();
  v8::HandleScope handle_scope(isolate);
  v8::Context::Scope context_scope(context_->v8_context());

  v8::Local<v8::Object> data = v8::Object::New(isolate);
  // Create and store a new HandlerFunction, and add a weak reference to it
  // in a v8 object so that we can retrieve it from the constructed v8
  // function.
  handler_functions_.push_back(
      std::make_unique<HandlerFunction>(std::move(handler_function)));
  SetPrivate(
      data, kHandlerFunction,
      v8::External::New(isolate, handler_functions_.back().get(),
                        gin::kObjectBackedNativeHandlerHandlerFunctionTag));
  DCHECK(feature_name.empty() ||
         ExtensionAPI::GetSharedInstance()->GetFeatureDependency(feature_name))
      << feature_name;
  SetPrivate(data, kFeatureName,
             v8_helpers::ToV8StringUnsafe(isolate, feature_name));
  v8::Local<v8::FunctionTemplate> function_template = v8::FunctionTemplate::New(
      isolate, Router, data, v8::Local<v8::Signature>(), 0,
      v8::ConstructorBehavior::kThrow);
  v8::Local<v8::ObjectTemplate>::New(isolate, object_template_)
      ->Set(isolate, name.c_str(), function_template);
  router_data_.emplace_back(isolate, data);
}

v8::Isolate* ObjectBackedNativeHandler::GetIsolate() const {
  return context_->isolate();
}

void ObjectBackedNativeHandler::Invalidate() {
  v8::Isolate* isolate = GetIsolate();
  v8::HandleScope handle_scope(isolate);
  v8::Context::Scope context_scope(context_->v8_context());

  // Note: It isn't safe to access v8::Private if IsExecutionTerminating returns
  // true. It crashes if we do so: http://crbug.com/1276144.
  if (!isolate->IsExecutionTerminating()) {
    for (auto& data : router_data_) {
      v8::Local<v8::Object> local_data = data.Get(isolate);
      v8::Local<v8::Value> handler_function_value;
      CHECK(GetPrivate(local_data, kHandlerFunction, &handler_function_value));
      DeletePrivate(local_data, kHandlerFunction);
    }
  }

  router_data_.clear();
  handler_functions_.clear();
  object_template_.Reset();

  NativeHandler::Invalidate();
}

// static
bool ObjectBackedNativeHandler::ContextCanAccessObject(
    v8::Isolate* isolate,
    const v8::Local<v8::Context>& context,
    const v8::Local<v8::Object>& object,
    bool allow_null_context) {
  if (object->IsNull())
    return true;
  if (context == object->GetCreationContextChecked())
    return true;
  // TODO(lazyboy): ScriptContextSet isn't available on worker threads. We
  // should probably use WorkerScriptContextSet somehow.
  ScriptContext* other_script_context =
      content::WorkerThread::GetCurrentId() == 0
          ? ScriptContextSet::GetContextByObject(object)
          : nullptr;
  if (!other_script_context || !other_script_context->web_frame())
    return allow_null_context;

  return blink::WebFrame::ScriptCanAccess(other_script_context->isolate(),
                                          other_script_context->web_frame());
}

bool ObjectBackedNativeHandler::SetPrivate(v8::Local<v8::Object> obj,
                                           const char* key,
                                           v8::Local<v8::Value> value) {
  return SetPrivate(context_->v8_context(), obj, key, value);
}

// static
bool ObjectBackedNativeHandler::SetPrivate(v8::Local<v8::Context> context,
                                           v8::Local<v8::Object> obj,
                                           const char* key,
                                           v8::Local<v8::Value> value) {
  v8::Isolate* isolate = v8::Isolate::GetCurrent();
  return obj
      ->SetPrivate(context,
                   v8::Private::ForApi(
                       isolate, v8::String::NewFromUtf8(
                                    isolate, key, v8::NewStringType::kNormal)
                                    .ToLocalChecked()),
                   value)
      .FromJust();
}

bool ObjectBackedNativeHandler::GetPrivate(v8::Local<v8::Object> obj,
                                           const char* key,
                                           v8::Local<v8::Value>* result) {
  return GetPrivate(context_->v8_context(), obj, key, result);
}

// static
bool ObjectBackedNativeHandler::GetPrivate(v8::Local<v8::Context> context,
                                           v8::Local<v8::Object> obj,
                                           const char* key,
                                           v8::Local<v8::Value>* result) {
  v8::Isolate* isolate = v8::Isolate::GetCurrent();
  return obj
      ->GetPrivate(context,
                   v8::Private::ForApi(
                       isolate, v8::String::NewFromUtf8(
                                    isolate, key, v8::NewStringType::kNormal)
                                    .ToLocalChecked()))
      .ToLocal(result);
}

void ObjectBackedNativeHandler::DeletePrivate(v8::Local<v8::Object> obj,
                                              const char* key) {
  DeletePrivate(context_->v8_context(), obj, key);
}

// static
void ObjectBackedNativeHandler::DeletePrivate(v8::Local<v8::Context> context,
                                              v8::Local<v8::Object> obj,
                                              const char* key) {
  v8::Isolate* isolate = v8::Isolate::GetCurrent();
  obj->DeletePrivate(context,
                     v8::Private::ForApi(
                         isolate, v8::String::NewFromUtf8(
                                      isolate, key, v8::NewStringType::kNormal)
                                      .ToLocalChecked()))
      .FromJust();
}

}  // namespace extensions