# -*- coding: utf-8 -*-
import os
import mutagen
import abc
from media.monitor.exceptions import BadSongFile

class PathChannel(object):
    """a dumb struct; python has no record types"""
    def __init__(self, signal, path):
        self.signal = signal
        self.path = path

# It would be good if we could parameterize this class by the attribute
# that would contain the path to obtain the meta data. But it would be too much
# work for little reward
class HasMetaData(object):
    # TODO : add documentation for HasMetaData
    __metaclass__ = abc.ABCMeta
    # doing weird bullshit here because python constructors only
    # call the constructor of the leftmost superclass.
    @property
    def metadata(self):
        # Normally this would go in init but we don't like
        # relying on consumers of this behaviour to have to call
        # the constructor
        if not hasattr(self,"_loaded"): self._loaded = False
        if self._loaded: return self._metadata
        else:
            f = None
            try: f  = mutagen.File(self.path, easy=True)
            except Exception: raise BadSongFile(self.path)
            # value returned by mutagen only acts like a dictionary.
            # in fact it comes with a nice surprise for you if you try
            # to add elements to it
            self._metadata = {}
            for k,v in f:
                if isinstance(v, list):
                    if len(v) == 1:
                        self._metadata[k] = v[0]
                    else:
                        raise Exception("Weird mutagen %s:%s" % (k,str(v)))
                else:
                    self._metadata[k] = v
            self._loaded = True
            return self.metadata


class BaseEvent(object):
    __metaclass__ = abc.ABCMeta
    def __init__(self, raw_event):
        # TODO : clean up this idiotic hack
        # we should use keyword constructors instead of this behaviour checking
        # bs to initialize BaseEvent
        if getattr(raw_event,"pathname"):
            self.__raw_event = raw_event
            self.path = os.path.normpath(raw_event.pathname)
        else: self.path = raw_event
    def exists(self): return os.path.exists(self.path)
    def __str__(self):
        return "Event. Path: %s" % self.__raw_event.pathname

class OrganizeFile(BaseEvent, HasMetaData):
    def __init__(self, *args, **kwargs): super(OrganizeFile, self).__init__(*args, **kwargs)
class NewFile(BaseEvent, HasMetaData):
    def __init__(self, *args, **kwargs): super(NewFile, self).__init__(*args, **kwargs)
class DeleteFile(BaseEvent):
    def __init__(self, *args, **kwargs): super(DeleteFile, self).__init__(*args, **kwargs)