from lxml import etree


def prettify(source: str) -> str:
    """Method used to pretty format given XML

    :param source: XML
    :return: prettified XML
    """
    prolog = ""
    prolog_start = source.find("<?")
    
    if prolog_start != -1:
        prolog_end = source.find("?>") + 2
        prolog = source[prolog_start:prolog_end] + "\n"
        source = source[prolog_end: ]
    
    parser = etree.XMLParser(remove_blank_text=True)
    xml = etree.fromstring(source, parser=parser)
    return prolog + etree.tostring(xml, pretty_print=True).decode()

def minimize(source: str) -> str:
    """Method used to minimize XML by deleting not needed whitespaces.

    :param source: XML
    :return: minimized XML
    """
    
    prolog = ""
    prolog_start = source.find("<?")
    
    if prolog_start != -1:
        prolog_end = source.find("?>") + 2
        prolog = source[prolog_start:prolog_end]
        source = source[prolog_end: ]
    
    parser = etree.XMLParser(remove_blank_text=True)
    xml = etree.fromstring(source, parser=parser)
    return prolog + etree.tostring(xml, pretty_print=False).decode()


def xpath(source: str, xpath: str) -> str:
    """
    Method used to get nodes from XML string using XPath

    :param source: XML string used for selection
    :param xpath: XPath query used for selection
    :return: Nodes selected using XPath
    """

    
    root = etree.XML(source)
    nsmap = root.nsmap

    # LXML doesn't accept empty (None) namespace prefix,
    # so it need to be deleted if exists
    if None in nsmap:
        nsmap.pop(None)
    
    result = root.xpath(xpath, namespaces=nsmap)
    
    # root.xpath can return 4 types: float, string, bool and list.
    # List is the only one that can't be simply converted to str
    if result is not list:
        return str(result)
    else:
        result_string = ""
        for e in result:
            result_string += etree.tostring(e, pretty_print=True).decode() + "\n"
        return result_string



def xsd(source: str, xsd: str) -> bool:
    """
    Method used to validate XML string against XSD schema
    :param source: XML string used for validation
    :param xsd: XSD schema to validate XML against
    :return: Message saying, if the validation was successful or not
    """
    xml_schema = etree.XMLSchema(etree.XML(xsd))

    xml = etree.XML(source)
    if xml_schema.validate(xml):
        return "XML is valid."
    else:
        return "XML is NOT valid."
    
    
def xslt(source: str, xslt: str) -> str:
    """
    Method used to transformate XML string using XSLT

    :param source: XML string to transform
    :param xslt: XSLT string used to transformate XML
    :return: Result of transformation
    """
    xslt_transform = etree.XSLT(etree.XML(xslt))

    xml = etree.XML(source)

    transformated = xslt_transform(xml)
    print(transformated)
    return str(transformated)