from abc import ABCMeta, abstractmethod

from ..queuethread import QueueThread


@QueueThread.register
class Preprocessor(QueueThread, metaclass=ABCMeta):
    """
    Base class for handlers to be registered with a QueuePickup instance.
    """
    def __init__(self, distributor, daisy, uldir, config):
        super().__init__()
        self.distributor = distributor
        self.daisy = daisy
        self.uploaddir_parent = uldir
        self.config = config

    def _process(self, job):
        """
        Apply preprocessing to job and send the result to the distributor.
        """
        self.distributor.put(self._preprocess(job))

    def _init_jobspec(self, upload_dir=None, created=0, title=''):
        jobspec = {'created': created,
                   'title': {'sv': title,
                             'en': title},
                   'description': '',
                   'presenters': [],
                   'courses': [],
                   'thumb': '',
                   'tags': [],
                   'sources': {}}
        if upload_dir is not None:
            jobspec['upload_dir'] = str(upload_dir)

        return jobspec

    def _fill_jobspec_from_daisy(self, starttime, endtime, room_id, outspec):
        booking = self.daisy.get_booking(starttime, endtime, room_id)
        if booking is not None:
            title = {'sv': booking['displayStringLong']['swedish'],
                     'en': booking['displayStringLong']['english']}
            outspec['title'] = title
            outspec['presenters'] = booking['teachers']
            if booking['description']:
                outspec['description'] = booking['description']
            if not outspec['presenters'] and booking['bookedBy']:
                outspec['presenters'].append(booking['bookedBy'])
            outspec['courses'] = booking['courseSegmentInstances']
            if booking['educationalType']:
                for i in booking['educationalType'].values():
                    # Add both english and swedish name;
                    # sometimes they're identical so don't add twice
                    if i not in outspec['tags']:
                        outspec['tags'].append(i)

        outspec['tags'].append(
            self.daisy.get_room_name(room_id))

    @abstractmethod
    def validate(self, queueitem):
        """
        Validate a jobspec according to this preprocessor's format.
        To be implemented by subclasses.

        Should return True if successful, otherwise throw a KeyError or
        ValueError with a descriptive message.
        """
        raise NotImplementedError('validate must be implemented '
                                  'by Preprocessor subclasses')

    @abstractmethod
    def _preprocess(self, job):
        """
        Abstract method to implement the functionality of this preprocessor.
        To be implemented by subclasses.
        """
        raise NotImplementedError('_preprocess must be implemented '
                                  'by Preprocessor subclasses')