// 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/extensions/webstore_bindings.h"

#include "base/strings/string_util.h"
#include "chrome/common/extensions/extension.h"
#include "chrome/common/extensions/extension_constants.h"
#include "chrome/common/extensions/extension_messages.h"
#include "chrome/renderer/extensions/chrome_v8_context.h"
#include "content/public/renderer/render_view.h"
#include "grit/renderer_resources.h"
#include "third_party/WebKit/public/web/WebDocument.h"
#include "third_party/WebKit/public/web/WebElement.h"
#include "third_party/WebKit/public/web/WebNode.h"
#include "third_party/WebKit/public/web/WebNodeList.h"
#include "third_party/WebKit/public/web/WebUserGestureIndicator.h"
#include "url/gurl.h"
#include "v8/include/v8.h"

using WebKit::WebDocument;
using WebKit::WebElement;
using WebKit::WebFrame;
using WebKit::WebNode;
using WebKit::WebNodeList;
using WebKit::WebUserGestureIndicator;

namespace extensions {

namespace {

const char kWebstoreLinkRelation[] = "chrome-webstore-item";

const char kPreferredStoreLinkUrlNotAString[] =
    "The Chrome Web Store item link URL parameter must be a string.";
const char kSuccessCallbackNotAFunctionError[] =
    "The success callback parameter must be a function.";
const char kFailureCallbackNotAFunctionError[] =
    "The failure callback parameter must be a function.";
const char kNotInTopFrameError[] =
    "Chrome Web Store installations can only be started by the top frame.";
const char kNotUserGestureError[] =
    "Chrome Web Store installations can only be initated by a user gesture.";
const char kNoWebstoreItemLinkFoundError[] =
    "No Chrome Web Store item link found.";
const char kInvalidWebstoreItemUrlError[] =
    "Invalid Chrome Web Store item URL.";

// chrome.webstore.install() calls generate an install ID so that the install's
// callbacks may be fired when the browser notifies us of install completion
// (successful or not) via OnInlineWebstoreInstallResponse.
int g_next_install_id = 0;

} // anonymous namespace

WebstoreBindings::WebstoreBindings(Dispatcher* dispatcher,
                                   ChromeV8Context* context)
    : ChromeV8Extension(dispatcher, context),
      ChromeV8ExtensionHandler(context) {
  RouteFunction("Install",
                base::Bind(&WebstoreBindings::Install, base::Unretained(this)));
}

void WebstoreBindings::Install(
    const v8::FunctionCallbackInfo<v8::Value>& args) {
  WebFrame* frame = WebFrame::frameForContext(context()->v8_context());
  if (!frame || !frame->view())
    return;

  content::RenderView* render_view =
      content::RenderView::FromWebView(frame->view());
  if (!render_view)
    return;

  std::string preferred_store_link_url;
  if (!args[0]->IsUndefined()) {
    if (args[0]->IsString()) {
      preferred_store_link_url = std::string(*v8::String::Utf8Value(args[0]));
    } else {
      v8::ThrowException(v8::String::New(kPreferredStoreLinkUrlNotAString));
      return;
    }
  }

  std::string webstore_item_id;
  std::string error;
  if (!GetWebstoreItemIdFromFrame(
      frame, preferred_store_link_url, &webstore_item_id, &error)) {
    v8::ThrowException(v8::String::New(error.c_str()));
    return;
  }

  int install_id = g_next_install_id++;
  if (!args[1]->IsUndefined() && !args[1]->IsFunction()) {
    v8::ThrowException(v8::String::New(kSuccessCallbackNotAFunctionError));
    return;
  }

  if (!args[2]->IsUndefined() && !args[2]->IsFunction()) {
    v8::ThrowException(v8::String::New(kFailureCallbackNotAFunctionError));
    return;
  }

  Send(new ExtensionHostMsg_InlineWebstoreInstall(
      render_view->GetRoutingID(),
      install_id,
      GetRoutingID(),
      webstore_item_id,
      frame->document().url()));

  args.GetReturnValue().Set(static_cast<int32_t>(install_id));
}

// static
bool WebstoreBindings::GetWebstoreItemIdFromFrame(
      WebFrame* frame, const std::string& preferred_store_link_url,
      std::string* webstore_item_id, std::string* error) {
  if (frame != frame->top()) {
    *error = kNotInTopFrameError;
    return false;
  }

  if (!WebUserGestureIndicator::isProcessingUserGesture()) {
    *error = kNotUserGestureError;
    return false;
  }

  WebDocument document = frame->document();
  if (document.isNull()) {
    *error = kNoWebstoreItemLinkFoundError;
    return false;
  }

  WebElement head = document.head();
  if (head.isNull()) {
    *error = kNoWebstoreItemLinkFoundError;
    return false;
  }

  GURL webstore_base_url =
      GURL(extension_urls::GetWebstoreItemDetailURLPrefix());
  WebNodeList children = head.childNodes();
  for (unsigned i = 0; i < children.length(); ++i) {
    WebNode child = children.item(i);
    if (!child.isElementNode())
      continue;
    WebElement elem = child.to<WebElement>();

    if (!elem.hasTagName("link") || !elem.hasAttribute("rel") ||
        !elem.hasAttribute("href"))
      continue;

    std::string rel = elem.getAttribute("rel").utf8();
    if (!LowerCaseEqualsASCII(rel, kWebstoreLinkRelation))
      continue;

    std::string webstore_url_string(elem.getAttribute("href").utf8());

    if (!preferred_store_link_url.empty() &&
        preferred_store_link_url != webstore_url_string) {
      continue;
    }

    GURL webstore_url = GURL(webstore_url_string);
    if (!webstore_url.is_valid()) {
      *error = kInvalidWebstoreItemUrlError;
      return false;
    }

    if (webstore_url.scheme() != webstore_base_url.scheme() ||
        webstore_url.host() != webstore_base_url.host() ||
        !StartsWithASCII(
            webstore_url.path(), webstore_base_url.path(), true)) {
      *error = kInvalidWebstoreItemUrlError;
      return false;
    }

    std::string candidate_webstore_item_id = webstore_url.path().substr(
        webstore_base_url.path().length());
    if (!extensions::Extension::IdIsValid(candidate_webstore_item_id)) {
      *error = kInvalidWebstoreItemUrlError;
      return false;
    }

    std::string reconstructed_webstore_item_url_string =
        extension_urls::GetWebstoreItemDetailURLPrefix() +
            candidate_webstore_item_id;
    if (reconstructed_webstore_item_url_string != webstore_url_string) {
      *error = kInvalidWebstoreItemUrlError;
      return false;
    }

    *webstore_item_id = candidate_webstore_item_id;
    return true;
  }

  *error = kNoWebstoreItemLinkFoundError;
  return false;
}

bool WebstoreBindings::OnMessageReceived(const IPC::Message& message) {
  IPC_BEGIN_MESSAGE_MAP(WebstoreBindings, message)
    IPC_MESSAGE_HANDLER(ExtensionMsg_InlineWebstoreInstallResponse,
                        OnInlineWebstoreInstallResponse)
    IPC_MESSAGE_UNHANDLED(CHECK(false) << "Unhandled IPC message")
  IPC_END_MESSAGE_MAP()
  return true;
}

void WebstoreBindings::OnInlineWebstoreInstallResponse(
    int install_id,
    bool success,
    const std::string& error) {
  v8::HandleScope handle_scope(context()->isolate());
  v8::Context::Scope context_scope(context()->v8_context());
  v8::Handle<v8::Value> argv[] = {
    v8::Integer::New(install_id),
    v8::Boolean::New(success),
    v8::String::New(error.c_str())
  };
  context()->module_system()->CallModuleMethod(
      "webstore", "onInstallResponse", arraysize(argv), argv);
}

}  // namespace extensions