cpp/IEDriver/CommandHandlers/ExecuteAsyncScriptCommandHandler.h

// Copyright 2011 Software Freedom Conservancy
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#ifndef WEBDRIVER_IE_EXECUTEASYNCSCRIPTCOMMANDHANDLER_H_
#define WEBDRIVER_IE_EXECUTEASYNCSCRIPTCOMMANDHANDLER_H_

#include "../Browser.h"
#include "../IECommandHandler.h"
#include "../IECommandExecutor.h"
#include "ExecuteScriptCommandHandler.h"

#define GUID_STRING_LEN 40

namespace webdriver {

class ExecuteAsyncScriptCommandHandler : public ExecuteScriptCommandHandler {
 public:
  ExecuteAsyncScriptCommandHandler(void) {
  }

  virtual ~ExecuteAsyncScriptCommandHandler(void) {
  }

 protected:
  void ExecuteInternal(const IECommandExecutor& executor,
                       const LocatorMap& locator_parameters,
                       const ParametersMap& command_parameters,
                       Response* response) {
    ParametersMap::const_iterator script_parameter_iterator = command_parameters.find("script");
    ParametersMap::const_iterator args_parameter_iterator = command_parameters.find("args");
    if (script_parameter_iterator == command_parameters.end()) {
      response->SetErrorResponse(400, "Missing parameter: script");
      return;
    } else if (args_parameter_iterator == command_parameters.end()) {
      response->SetErrorResponse(400, "Missing parameter: args");
      return;
    } else {
      wchar_t page_id_buffer[GUID_STRING_LEN] = {0};
      GUID page_id_guid;
      ::CoCreateGuid(&page_id_guid);
      ::StringFromGUID2(page_id_guid, page_id_buffer, GUID_STRING_LEN);
      std::wstring page_id = &page_id_buffer[0];

      wchar_t pending_id_buffer[GUID_STRING_LEN] = {0};
      GUID pending_id_guid;
      ::CoCreateGuid(&pending_id_guid);
      ::StringFromGUID2(pending_id_guid, pending_id_buffer, GUID_STRING_LEN);
      std::wstring pending_id = &pending_id_buffer[0];

      Json::Value json_args = args_parameter_iterator->second;

      int timeout_value = executor.async_script_timeout();
      wchar_t timeout_buffer[12] = {0};
      _itow_s(timeout_value, &timeout_buffer[0], 12, 10);
      std::wstring timeout = &timeout_buffer[0];

      std::wstring script_body = CA2W(script_parameter_iterator->second.asCString(), CP_UTF8);

      std::wstring async_script = L"(function() { return function(){\n";
      async_script += L"document.__$webdriverAsyncExecutor = {\n";
      async_script += L"  pageId: '" + page_id + L"',\n";
      async_script += L"  asyncTimeout: 0\n";
      async_script += L"};\n";
      async_script += L"var timeoutId = window.setTimeout(function() {\n";
      async_script += L"  window.setTimeout(function() {\n";
      async_script += L"    document.__$webdriverAsyncExecutor.asyncTimeout = 1;\n";
      async_script += L"  }, 0);\n";
      async_script += L"}," + timeout + L");\n";
      async_script += L"var callback = function(value) {\n";
      async_script += L"  document.__$webdriverAsyncExecutor.asyncTimeout = 0;\n";
      async_script += L"  document.__$webdriverAsyncExecutor.asyncScriptResult = value;\n";
      async_script += L"  window.clearTimeout(timeoutId);\n";
      async_script += L"};\n";
      async_script += L"var argsArray = Array.prototype.slice.call(arguments);\n";
      async_script += L"argsArray.push(callback);\n";
      async_script += L"if (document.__$webdriverAsyncExecutor.asyncScriptResult !== undefined) {\n";
      async_script += L"  delete document.__$webdriverAsyncExecutor.asyncScriptResult;\n";
      async_script += L"}\n";
      async_script += L"(function() {" + script_body + L"}).apply(null, argsArray);\n";
      async_script += L"};})();";

      std::wstring polling_script = L"(function() { return function(){\n";
      polling_script += L"var pendingId = '" + pending_id + L"';\n";
      polling_script += L"if ('__$webdriverAsyncExecutor' in document) {\n";
      polling_script += L"  if (document.__$webdriverAsyncExecutor.pageId != '" + page_id + L"') {\n";
      polling_script += L"    return [pendingId, -1];\n";
      polling_script += L"  } else if ('asyncScriptResult' in document.__$webdriverAsyncExecutor) {\n";
      polling_script += L"    var value = document.__$webdriverAsyncExecutor.asyncScriptResult;\n";
      polling_script += L"    delete document.__$webdriverAsyncExecutor.asyncScriptResult;\n";
      polling_script += L"    return value;\n";
      polling_script += L"  } else {\n";
      polling_script += L"    return [pendingId, document.__$webdriverAsyncExecutor.asyncTimeout];\n";
      polling_script += L"  }\n";
      polling_script += L"} else {\n";
      polling_script += L"  return [pendingId, -1];\n";
      polling_script += L"}\n";
      polling_script += L"};})();";

      BrowserHandle browser_wrapper;
      int status_code = executor.GetCurrentBrowser(&browser_wrapper);
      if (status_code != SUCCESS) {
        response->SetErrorResponse(status_code, "Unable to get browser");
        return;
      }

      CComPtr<IHTMLDocument2> doc;
      browser_wrapper->GetDocument(&doc);
      Script async_script_wrapper(doc, async_script, json_args.size());
      status_code = this->PopulateArgumentArray(executor,
                                                async_script_wrapper,
                                                json_args);
      if (status_code != SUCCESS) {
        response->SetErrorResponse(status_code,
                                   "Error setting arguments for script");
        return;
      }

      status_code = async_script_wrapper.Execute();

      if (status_code != SUCCESS) {
        response->SetErrorResponse(status_code,
                                   "JavaScript error in async script.");
        return;
      } else {
        Script polling_script_wrapper(doc, polling_script, 0);
        while (true) {
          Json::Value polling_result;
          status_code = polling_script_wrapper.Execute();
          if (status_code != SUCCESS) {
            // Assume that if the polling script errors, it's because
            // of a page reload. Note that experience shows this to
            // happen most frequently when a refresh occurs, since
            // the document object is not yet ready for accessing.
            // However, this is still a big assumption,and could be faulty.
            response->SetErrorResponse(EUNEXPECTEDJSERROR,
                                       "Page reload detected during async script");
            break;
          }

          polling_script_wrapper.ConvertResultToJsonValue(executor, &polling_result);
          
          Json::UInt index = 0;
          std::string narrow_pending_id(CW2A(pending_id.c_str(), CP_UTF8));
          if (polling_result.isArray() &&
              polling_result.size() == 2 && 
              polling_result[index].isString() && 
              polling_result[index].asString() == narrow_pending_id) {
            int timeout_flag = polling_result[1].asInt();
            if (timeout_flag < 0) {
              response->SetErrorResponse(EUNEXPECTEDJSERROR,
                                         "Page reload detected during async script");
              break;
            }
            if (timeout_flag > 0) {
              response->SetErrorResponse(ESCRIPTTIMEOUT,
                                         "Timeout expired waiting for async script");
              break;
            }
          } else {
            response->SetSuccessResponse(polling_result);
            break;
          }
        }

        return;
      }
    }
  }
};

} // namespace webdriver

#endif // WEBDRIVER_IE_EXECUTEASYNCSCRIPTCOMMANDHANDLER_H_