// 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.

#include "chrome/renderer/safe_browsing/threat_dom_details.h"

#include "base/compiler_specific.h"
#include "chrome/common/chrome_constants.h"
#include "chrome/common/safe_browsing/safebrowsing_messages.h"
#include "content/public/renderer/render_view.h"
#include "third_party/WebKit/public/platform/WebString.h"
#include "third_party/WebKit/public/web/WebDocument.h"
#include "third_party/WebKit/public/web/WebElement.h"
#include "third_party/WebKit/public/web/WebElementCollection.h"
#include "third_party/WebKit/public/web/WebFrame.h"
#include "third_party/WebKit/public/web/WebView.h"

namespace safe_browsing {

namespace {

// Handler for the various HTML elements that we extract URLs from.
void HandleElement(
    const blink::WebElement& element,
    SafeBrowsingHostMsg_ThreatDOMDetails_Node* parent_node,
    std::vector<SafeBrowsingHostMsg_ThreatDOMDetails_Node>* resources) {
  if (!element.hasAttribute("src"))
    return;

  // Retrieve the link and resolve the link in case it's relative.
  blink::WebURL full_url =
      element.document().completeURL(element.getAttribute("src"));

  const GURL& child_url = GURL(full_url);

  // Add to the parent node.
  parent_node->children.push_back(child_url);

  // Create the child node.
  SafeBrowsingHostMsg_ThreatDOMDetails_Node child_node;
  child_node.url = child_url;
  child_node.tag_name = element.tagName().utf8();
  child_node.parent = parent_node->url;
  resources->push_back(child_node);
}

}  // namespace

// An upper limit on the number of nodes we collect.
uint32 ThreatDOMDetails::kMaxNodes = 500;

// static
ThreatDOMDetails* ThreatDOMDetails::Create(content::RenderView* render_view) {
  // Private constructor and public static Create() method to facilitate
  // stubbing out this class for binary-size reduction purposes.
  return new ThreatDOMDetails(render_view);
}

ThreatDOMDetails::ThreatDOMDetails(content::RenderView* render_view)
    : content::RenderViewObserver(render_view) {}

ThreatDOMDetails::~ThreatDOMDetails() {}

bool ThreatDOMDetails::OnMessageReceived(const IPC::Message& message) {
  bool handled = true;
  IPC_BEGIN_MESSAGE_MAP(ThreatDOMDetails, message)
    IPC_MESSAGE_HANDLER(SafeBrowsingMsg_GetThreatDOMDetails,
                        OnGetThreatDOMDetails)
    IPC_MESSAGE_UNHANDLED(handled = false)
  IPC_END_MESSAGE_MAP()
  return handled;
}

void ThreatDOMDetails::OnGetThreatDOMDetails() {
  std::vector<SafeBrowsingHostMsg_ThreatDOMDetails_Node> resources;
  ExtractResources(&resources);
  // Notify the browser.
  render_view()->Send(new SafeBrowsingHostMsg_ThreatDOMDetails(
      render_view()->GetRoutingID(), resources));
}

void ThreatDOMDetails::ExtractResources(
    std::vector<SafeBrowsingHostMsg_ThreatDOMDetails_Node>* resources) {
  blink::WebView* web_view = render_view()->GetWebView();
  if (!web_view) {
    NOTREACHED();
    return;
  }
  blink::WebFrame* frame = web_view->mainFrame();
  for (; frame; frame = frame->traverseNext(false /* don't wrap */)) {
    DCHECK(frame);
    SafeBrowsingHostMsg_ThreatDOMDetails_Node details_node;
    blink::WebDocument document = frame->document();
    details_node.url = GURL(document.url());
    if (document.isNull()) {
      // Nothing in this frame, move on to the next one.
      resources->push_back(details_node);
      continue;
    }

    blink::WebElementCollection elements = document.all();
    blink::WebElement element = elements.firstItem();
    for (; !element.isNull(); element = elements.nextItem()) {
      if (element.hasHTMLTagName("iframe") || element.hasHTMLTagName("frame") ||
          element.hasHTMLTagName("embed") || element.hasHTMLTagName("script")) {
        HandleElement(element, &details_node, resources);
        if (resources->size() >= kMaxNodes) {
          // We have reached kMaxNodes, exit early.
          resources->push_back(details_node);
          return;
        }
      }
    }

    resources->push_back(details_node);
  }
}

}  // namespace safe_browsing