// Copyright 2013 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 "chrome/browser/prerender/prerender_resource_throttle.h"

#include "build/build_config.h"
#include "chrome/browser/prerender/prerender_final_status.h"
#include "chrome/browser/prerender/prerender_manager.h"
#include "chrome/browser/prerender/prerender_util.h"
#include "content/public/browser/browser_thread.h"
#include "content/public/browser/render_frame_host.h"
#include "content/public/browser/resource_controller.h"
#include "content/public/browser/resource_request_info.h"
#include "content/public/browser/web_contents.h"
#include "net/url_request/redirect_info.h"
#include "net/url_request/url_request.h"

using content::ResourceType;

namespace prerender {

namespace {
static const char kFollowOnlyWhenPrerenderShown[] =
    "follow-only-when-prerender-shown";

PrerenderContents* g_prerender_contents_for_testing;
}

void PrerenderResourceThrottle::OverridePrerenderContentsForTesting(
    PrerenderContents* contents) {
  g_prerender_contents_for_testing = contents;
}

PrerenderResourceThrottle::PrerenderResourceThrottle(net::URLRequest* request)
    : request_(request) {
}

void PrerenderResourceThrottle::WillStartRequest(bool* defer) {
  const content::ResourceRequestInfo* info =
      content::ResourceRequestInfo::ForRequest(request_);
  *defer = true;
  content::BrowserThread::PostTask(
      content::BrowserThread::UI,
      FROM_HERE,
      base::Bind(&PrerenderResourceThrottle::WillStartRequestOnUI,
                 AsWeakPtr(), request_->method(), info->GetResourceType(),
                 info->GetChildID(), info->GetRenderFrameID(),
                 request_->url()));
}

void PrerenderResourceThrottle::WillRedirectRequest(
    const net::RedirectInfo& redirect_info,
    bool* defer) {
  const content::ResourceRequestInfo* info =
      content::ResourceRequestInfo::ForRequest(request_);
  *defer = true;
  std::string header;
  request_->GetResponseHeaderByName(kFollowOnlyWhenPrerenderShown, &header);

  content::BrowserThread::PostTask(
      content::BrowserThread::UI,
      FROM_HERE,
      base::Bind(&PrerenderResourceThrottle::WillRedirectRequestOnUI,
                 AsWeakPtr(), header, info->GetResourceType(), info->IsAsync(),
                 info->GetChildID(), info->GetRenderFrameID(),
                 redirect_info.new_url));
}

const char* PrerenderResourceThrottle::GetNameForLogging() const {
  return "PrerenderResourceThrottle";
}

void PrerenderResourceThrottle::Resume() {
  controller()->Resume();
}

void PrerenderResourceThrottle::Cancel() {
  controller()->Cancel();
}

void PrerenderResourceThrottle::WillStartRequestOnUI(
    const base::WeakPtr<PrerenderResourceThrottle>& throttle,
    const std::string& method,
    ResourceType resource_type,
    int render_process_id,
    int render_frame_id,
    const GURL& url) {
  bool cancel = false;
  PrerenderContents* prerender_contents =
      PrerenderContentsFromRenderFrame(render_process_id, render_frame_id);
  if (prerender_contents) {
    // Abort any prerenders that spawn requests that use unsupported HTTP
    // methods or schemes.
    if (!PrerenderManager::IsValidHttpMethod(method)) {
      prerender_contents->Destroy(FINAL_STATUS_INVALID_HTTP_METHOD);
      cancel = true;
    } else if (!PrerenderManager::DoesSubresourceURLHaveValidScheme(url)) {
      prerender_contents->Destroy(FINAL_STATUS_UNSUPPORTED_SCHEME);
      ReportUnsupportedPrerenderScheme(url);
      cancel = true;
#if defined(OS_ANDROID)
    } else if (resource_type == content::RESOURCE_TYPE_FAVICON) {
      // Delay icon fetching until the contents are getting swapped in
      // to conserve network usage in mobile devices.
      prerender_contents->AddResourceThrottle(throttle);
      return;
#endif
    }
  }

  content::BrowserThread::PostTask(
      content::BrowserThread::IO,
      FROM_HERE,
      base::Bind(cancel ? &PrerenderResourceThrottle::Cancel :
                 &PrerenderResourceThrottle::Resume, throttle));
}

void PrerenderResourceThrottle::WillRedirectRequestOnUI(
    const base::WeakPtr<PrerenderResourceThrottle>& throttle,
    const std::string& follow_only_when_prerender_shown_header,
    ResourceType resource_type,
    bool async,
    int render_process_id,
    int render_frame_id,
    const GURL& new_url) {
  bool cancel = false;
  PrerenderContents* prerender_contents =
      PrerenderContentsFromRenderFrame(render_process_id, render_frame_id);
  if (prerender_contents) {
    // Abort any prerenders with requests which redirect to invalid schemes.
    if (!PrerenderManager::DoesURLHaveValidScheme(new_url)) {
      prerender_contents->Destroy(FINAL_STATUS_UNSUPPORTED_SCHEME);
      ReportUnsupportedPrerenderScheme(new_url);
      cancel = true;
    } else if (follow_only_when_prerender_shown_header == "1" &&
               resource_type != content::RESOURCE_TYPE_MAIN_FRAME) {
      // Only defer redirects with the Follow-Only-When-Prerender-Shown
      // header. Do not defer redirects on main frame loads.
      if (!async) {
        // Cancel on deferred synchronous requests. Those will
        // indefinitely hang up a renderer process.
        prerender_contents->Destroy(FINAL_STATUS_BAD_DEFERRED_REDIRECT);
        cancel = true;
      } else {
        // Defer the redirect until the prerender is used or canceled.
        prerender_contents->AddResourceThrottle(throttle);
        return;
      }
    }
  }

  content::BrowserThread::PostTask(
      content::BrowserThread::IO,
      FROM_HERE,
      base::Bind(cancel ? &PrerenderResourceThrottle::Cancel :
                 &PrerenderResourceThrottle::Resume, throttle));
}

PrerenderContents* PrerenderResourceThrottle::PrerenderContentsFromRenderFrame(
    int render_process_id, int render_frame_id) {
  if (g_prerender_contents_for_testing)
    return g_prerender_contents_for_testing;
  content::RenderFrameHost* rfh = content::RenderFrameHost::FromID(
      render_process_id, render_frame_id);
  content::WebContents* web_contents =
      content::WebContents::FromRenderFrameHost(rfh);
  return PrerenderContents::FromWebContents(web_contents);
}

}  // namespace prerender