""" Mini-Challenge"""

from os.path import join
from xml.etree import ElementTree as ET
from twisted.internet import defer


class Adapter:
    """Adapter class

    Aufgabe: Asynchron XML-Daten lesen, konvertieren und zurückliefern.
    """

    def __init__(self, path):
        self.path = path

    def _read(self, name):
        with open(join(self.path, name + ".xml")) as f:
            return f.read()

    def _parse(self, xml_data):
        root = ET.fromstring(xml_data)
        token = root.find("{*}Token").text
        return token

    def _convert(self, token):
        return '{"token": %s}' % token

    def retrieve_token(self, name):
        """
        Retrieve the content from file name.xml in adapters path directory
        in a synchronous way, extract the DataReceived/Token and return it
        as a JSON-Object (stringified) '{"token": value}'.
        """
        try:
            xml_data = self._read(name)
            token = self._parse(xml_data)
            return self._convert(token)
        except Exception as e:
            raise ValueError("Could not retrieve token: %s" % e)

    def retrieve_token_async(self, name):
        """
        Retrieve the content from file name.xml in adapters path directory
        in an asynchronous way, extract the DataReceived/Token and return it
        as a Deferred which ends up in a JSON-Object (as above).

        see: https://twistedmatrix.com/documents/8.0.0/api/twisted.internet.defer.Deferred.html

        Hint: The simple way is to use defer.succeed(), bonus points for doing
              it with a callback chain read->parse->convert.
        """
        d = defer.Deferred()

        def on_success(xml_data):
            try:
                token = self._parse(xml_data)
                converted = self._convert(token)
                d.callback(converted)
            except Exception as e:
                d.errback(e)

        def on_error(error):
            d.errback(error)

        deferred = defer.maybeDeferred(self._read, name)
        deferred.addCallbacks(on_success, on_error)

        return d