function isValidEmail(email) {
    const emailRegex = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;
    return emailRegex.test(email);
}

function isDueDatePassed(dueDate) {
    const now = new Date();
    const dueDateTime = new Date(dueDate);
    return dueDateTime < now;
}

function isDatePassed(dateA, dateB) {
    const dueDateA = new Date(dateA);
    const dueDateB = new Date(dateB);
    return dueDateA < dueDateB;
}

function validateDates(res, startDate, endDate, dueDate) {
    if (isDatePassed(startDate, dueDate)) {
        res.status(400).json({ 'message': 'Due date is after start date' });
        return false;
    }

    if (isDueDatePassed(dueDate)) {
        res.status(400).json({ 'message': 'Due date is in the past' });
        return false;
    }

    if (isDatePassed(endDate, startDate)) {
        res.status(400).json({ 'message': 'End date is before start date' });
        return false;
    }

    return true;
}

export {isValidEmail, isDueDatePassed, isDatePassed, validateDates};