void UnitConverter::SendCommand()

in src/CalcManager/UnitConverter.cpp [393:532]
120 lines of code
31 McCabe index (conditional complexity)

void UnitConverter::SendCommand(Command command)
{
    if (!CheckLoad())
    {
        return;
    }

    // TODO: Localization of characters
    bool clearFront = false;
    bool clearBack = false;
    if (command != Command::Negate && m_switchedActive)
    {
        ClearValues();
        m_switchedActive = false;
        clearFront = true;
        clearBack = false;
    }
    else
    {
        clearFront = (m_currentDisplay == L"0");
        clearBack =
            ((m_currentHasDecimal && m_currentDisplay.size() - 1 >= MAXIMUMDIGITSALLOWED)
             || (!m_currentHasDecimal && m_currentDisplay.size() >= MAXIMUMDIGITSALLOWED));
    }

    switch (command)
    {
    case Command::Zero:
        m_currentDisplay += L'0';
        break;

    case Command::One:
        m_currentDisplay += L'1';
        break;

    case Command::Two:
        m_currentDisplay += L'2';
        break;

    case Command::Three:
        m_currentDisplay += L'3';
        break;

    case Command::Four:
        m_currentDisplay += L'4';
        break;

    case Command::Five:
        m_currentDisplay += L'5';
        break;

    case Command::Six:
        m_currentDisplay += L'6';
        break;

    case Command::Seven:
        m_currentDisplay += L'7';
        break;

    case Command::Eight:
        m_currentDisplay += L'8';
        break;

    case Command::Nine:
        m_currentDisplay += L'9';
        break;

    case Command::Decimal:
        clearFront = false;
        clearBack = false;
        if (!m_currentHasDecimal)
        {
            m_currentDisplay += L'.';
            m_currentHasDecimal = true;
        }
        break;

    case Command::Backspace:
        clearFront = false;
        clearBack = false;
        if ((m_currentDisplay.front() != L'-' && m_currentDisplay.size() > 1) || m_currentDisplay.size() > 2)
        {
            if (m_currentDisplay.back() == L'.')
            {
                m_currentHasDecimal = false;
            }
            m_currentDisplay.pop_back();
        }
        else
        {
            m_currentDisplay = L"0";
            m_currentHasDecimal = false;
        }
        break;

    case Command::Negate:
        clearFront = false;
        clearBack = false;
        if (m_currentCategory.supportsNegative)
        {
            if (m_currentDisplay.front() == L'-')
            {
                m_currentDisplay.erase(0, 1);
            }
            else
            {
                m_currentDisplay.insert(0, 1, L'-');
            }
        }
        break;

    case Command::Clear:
        clearFront = false;
        clearBack = false;
        ClearValues();
        break;

    case Command::Reset:
        clearFront = false;
        clearBack = false;
        ClearValues();
        ResetCategoriesAndRatios();
        break;

    default:
        break;
    }

    if (clearFront)
    {
        m_currentDisplay.erase(0, 1);
    }
    if (clearBack)
    {
        m_currentDisplay.pop_back();
        m_vmCallback->MaxDigitsReached();
    }

    Calculate();
}