from django.template import Library

register = Library()

@register.filter
def truncatewords_by_chars(value, arg):
    """Truncate the text when it exceeds a certain number of characters.
    Delete the last word only if partial.
    Adds '...' at the end of the text.
    
    Example:
    
        {{ text|truncatewords_by_chars:25 }}
    """
    try:
        length = int(arg)
    except ValueError:
        return value
    
    if len(value) > length:
        if value[length:length + 1].isspace():
            return value[:length].rstrip() + '...'
        else:
            return value[:length].rsplit(' ', 1)[0].rstrip() + '...'
    else:
        return value