// Copyright (c) 2012 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.

#ifndef CONTENT_BROWSER_LOADER_CROSS_SITE_RESOURCE_HANDLER_H_
#define CONTENT_BROWSER_LOADER_CROSS_SITE_RESOURCE_HANDLER_H_

#include "base/memory/ref_counted.h"
#include "base/memory/weak_ptr.h"
#include "content/browser/loader/layered_resource_handler.h"
#include "content/common/content_export.h"
#include "net/url_request/url_request_status.h"

namespace net {
class URLRequest;
}

namespace content {

// Ensures that cross-site responses are delayed until the onunload handler of
// the previous page is allowed to run.  This handler wraps an
// AsyncEventHandler, and it sits inside SafeBrowsing and Buffered event
// handlers.  This is important, so that it can intercept OnResponseStarted
// after we determine that a response is safe and not a download.
class CrossSiteResourceHandler : public LayeredResourceHandler {
 public:
  CrossSiteResourceHandler(scoped_ptr<ResourceHandler> next_handler,
                           net::URLRequest* request);
  virtual ~CrossSiteResourceHandler();

  // ResourceHandler implementation:
  virtual bool OnRequestRedirected(const GURL& new_url,
                                   ResourceResponse* response,
                                   bool* defer) OVERRIDE;
  virtual bool OnResponseStarted(ResourceResponse* response,
                                 bool* defer) OVERRIDE;
  virtual bool OnReadCompleted(int bytes_read,
                               bool* defer) OVERRIDE;
  virtual void OnResponseCompleted(const net::URLRequestStatus& status,
                                   const std::string& security_info,
                                   bool* defer) OVERRIDE;

  // We can now send the response to the new renderer, which will cause
  // WebContentsImpl to swap in the new renderer and destroy the old one.
  void ResumeResponse();

  // When set to true, requests are leaked when they can't be passed to a
  // RenderViewHost, for unit tests.
  CONTENT_EXPORT static void SetLeakRequestsForTesting(
      bool leak_requests_for_testing);

  // Navigations are deferred at OnResponseStarted to parse out any navigation
  // transition link headers, and give the navigation transition (if it exists)
  // a chance to run.
  void ResumeResponseDeferredAtStart(int request_id);

  // Returns whether the handler is deferred.
  bool did_defer_for_testing() const { return did_defer_; }

 private:
  // Prepare to render the cross-site response in a new RenderViewHost, by
  // telling the old RenderViewHost to run its onunload handler.
  void StartCrossSiteTransition(ResourceResponse* response,
                                bool should_transfer);

  // Defer the navigation to the UI thread to check whether transfer is required
  // or not. Currently only used in --site-per-process.
  bool DeferForNavigationPolicyCheck(ResourceRequestInfoImpl* info,
                                     ResourceResponse* response,
                                     bool* defer);

  bool OnNavigationTransitionResponseStarted(ResourceResponse* response,
                                             bool* defer);

  bool OnNormalResponseStarted(ResourceResponse* response,
                               bool* defer);

  void ResumeOrTransfer(bool is_transfer);
  void ResumeIfDeferred();

  // Called when about to defer a request.  Sets |did_defer_| and logs the
  // defferral
  void OnDidDefer();

  bool has_started_response_;
  bool in_cross_site_transition_;
  bool completed_during_transition_;
  bool did_defer_;
  net::URLRequestStatus completed_status_;
  std::string completed_security_info_;
  scoped_refptr<ResourceResponse> response_;

  // TODO(nasko): WeakPtr is needed in --site-per-process, since all navigations
  // are deferred to the UI thread and come back to IO thread via
  // PostTaskAndReplyWithResult. If a transfer is needed, it goes back to the UI
  // thread. This can be removed once the code is changed to only do one hop.
  base::WeakPtrFactory<CrossSiteResourceHandler> weak_ptr_factory_;

  DISALLOW_COPY_AND_ASSIGN(CrossSiteResourceHandler);
};

}  // namespace content

#endif  // CONTENT_BROWSER_LOADER_CROSS_SITE_RESOURCE_HANDLER_H_