electron/atom/browser/net/js_asker.h

// Copyright (c) 2015 GitHub, Inc.
// Use of this source code is governed by the MIT license that can be
// found in the LICENSE file.

#ifndef ATOM_BROWSER_NET_JS_ASKER_H_
#define ATOM_BROWSER_NET_JS_ASKER_H_

#include "base/callback.h"
#include "base/memory/weak_ptr.h"
#include "base/values.h"
#include "content/public/browser/browser_thread.h"
#include "net/base/net_errors.h"
#include "net/url_request/url_request_job.h"
#include "v8/include/v8.h"

namespace atom {

using JavaScriptHandler =
    base::Callback<void(const net::URLRequest*, v8::Local<v8::Value>)>;

namespace internal {

using ResponseCallback =
    base::Callback<void(bool, scoped_ptr<base::Value> options)>;

// Ask handler for options in UI thread.
void AskForOptions(v8::Isolate* isolate,
                   const JavaScriptHandler& handler,
                   net::URLRequest* request,
                   const ResponseCallback& callback);

// Test whether the |options| means an error.
bool IsErrorOptions(base::Value* value, int* error);

}  // namespace internal

template<typename RequestJob>
class JsAsker : public RequestJob {
 public:
  JsAsker(net::URLRequest* request,
          net::NetworkDelegate* network_delegate,
          v8::Isolate* isolate,
          const JavaScriptHandler& handler)
      : RequestJob(request, network_delegate),
        isolate_(isolate),
        handler_(handler),
        weak_factory_(this) {}

  // Subclass should do initailze work here.
  virtual void StartAsync(scoped_ptr<base::Value> options) = 0;

 private:
  // RequestJob:
  void Start() override {
    content::BrowserThread::PostTask(
        content::BrowserThread::UI, FROM_HERE,
        base::Bind(&internal::AskForOptions,
                   isolate_,
                   handler_,
                   RequestJob::request(),
                   base::Bind(&JsAsker::OnResponse,
                              weak_factory_.GetWeakPtr())));
  }

  // Called when the JS handler has sent the response, we need to decide whether
  // to start, or fail the job.
  void OnResponse(bool success, scoped_ptr<base::Value> value) {
    int error = net::ERR_NOT_IMPLEMENTED;
    if (success && value && !internal::IsErrorOptions(value.get(), &error)) {
      StartAsync(value.Pass());
    } else {
      RequestJob::NotifyStartError(
          net::URLRequestStatus(net::URLRequestStatus::FAILED, error));
    }
  }

  v8::Isolate* isolate_;
  JavaScriptHandler handler_;
  base::WeakPtrFactory<JsAsker> weak_factory_;

  DISALLOW_COPY_AND_ASSIGN(JsAsker);
};

}  // namespace atom

#endif  // ATOM_BROWSER_NET_JS_ASKER_H_