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#include "win32/base/win32_window_util.h"

#include <windows.h>

#include <cstddef>
#include <string>

#include "base/vlog.h"

namespace mozc {
namespace win32 {
namespace {

std::wstring SafeGetWindowText(HWND window_handle) {
  if (!::IsWindow(window_handle)) {
    return std::wstring();
  }

  const int text_len_without_null = GetWindowTextLength(window_handle);
  if (text_len_without_null <= 0) {
    return std::wstring();
  }

  std::wstring buffer(text_len_without_null, 0);

  const int copied_len_without_null =
      GetWindowText(window_handle, buffer.data(), buffer.size() + 1);

  if (copied_len_without_null <= 0) {
    return std::wstring();
  }

  return buffer;
}

}  // namespace

std::wstring WindowUtil::GetWindowClassName(HWND window_handle) {
  // Maximum length of WindowClass is assumed to be 256.
  // http://msdn.microsoft.com/en-us/library/ms633576.aspx
  wchar_t buffer[256 + 1] = {};
  const size_t num_copied_without_null =
      ::GetClassNameW(window_handle, buffer, std::size(buffer));
  if (num_copied_without_null + 1 >= std::size(buffer)) {
    return L"";
  }
  return std::wstring(buffer, num_copied_without_null);
}

// static
bool WindowUtil::ChangeMessageFilter(HWND window_handle, UINT message) {
  // http://msdn.microsoft.com/en-us/library/dd388202.aspx
  if (!ChangeWindowMessageFilterEx(window_handle, message, MSGFLT_ALLOW,
                                   nullptr)) {
    // Note: this actually fails in Internet Explorer 10 on Windows 8
    // with ERROR_ACCESS_DENIED (0x5).
    const int error = ::GetLastError();
    MOZC_VLOG(1) << "ChangeWindowMessageFilterEx failed. error = " << error;
    return false;
  }
  return true;
}

}  // namespace win32
}  // namespace mozc
