sintonia/python_apps/media-monitor2/media/monitor/events.py

# -*- coding: utf-8 -*-
import os
import abc
from media.monitor.pure import LazyProperty
import media.monitor.pure as mmp
from media.monitor.metadata import Metadata
from media.monitor.log import Loggable
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

class EventRegistry(object):
    registry = {}
    @staticmethod
    def register(evt):
        EventRegistry.registry[evt.cookie] = evt
    @staticmethod
    def unregister(evt):
        del EventRegistry.registry[evt.cookie]
    @staticmethod
    def registered(evt):
        return evt.cookie in EventRegistry.registry
    @staticmethod
    def matching(evt):
        event = EventRegistry.registry[evt.cookie]
        # Want to disallow accessing the same event twice
        EventRegistry.unregister(event)
        return event


# 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
class HasMetaData(object):
    __metaclass__ = abc.ABCMeta
    @LazyProperty
    def metadata(self):
        return Metadata(self.path)

class BaseEvent(Loggable):
    __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 hasattr(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)
    @LazyProperty
    def cookie(self):
        return getattr( self._raw_event, 'cookie', None )
    def __str__(self):
        return "Event. Path: %s" % self.__raw_event.pathname

    def is_dir_event(self):
        return self._raw_event.dir

    # As opposed to unsafe_pack...
    def safe_pack(self):
        """
        returns exceptions instead of throwing them to be consistent with
        events that must catch their own BadSongFile exceptions since generate
        a set of exceptions instead of a single one
        """
        # pack will only throw an exception if it processes one file but this
        # is a little bit hacky
        try: return self.pack()
        except BadSongFile as e: return [e]

    # nothing to see here, please move along
    def morph_into(self, evt):
        """
        'Morphing' should preserve the self.cookie invariant. I.e. either
        None -> None or int -> int
        """
        self.logger.info("Morphing '%s' into '%s'" % (self.__class__.__name__,
            evt.__class__.__name__))
        self._raw_event = evt
        self.path = evt.path
        self.__class__ = evt.__class__
        return self

class FakePyinotify(object):
    def __init__(self, path):
        self.pathname = path


class OrganizeFile(BaseEvent, HasMetaData):
    def __init__(self, *args, **kwargs): super(OrganizeFile, self).__init__(*args, **kwargs)
    def pack(self):
        raise AttributeError("What the hell are you doing? You can't send organize events to airtime!!!")

class NewFile(BaseEvent, HasMetaData):
    def __init__(self, *args, **kwargs): super(NewFile, self).__init__(*args, **kwargs)
    def pack(self):
        """
        packs turns an event into a media monitor request
        """
        req_dict = self.metadata.extract()
        req_dict['mode'] = u'create'
        req_dict['MDATA_KEY_FILEPATH'] = unicode( self.path )
        return [req_dict]

class DeleteFile(BaseEvent):
    def __init__(self, *args, **kwargs): super(DeleteFile, self).__init__(*args, **kwargs)
    def pack(self):
        req_dict = {}
        req_dict['mode'] = u'delete'
        req_dict['MDATA_KEY_FILEPATH'] = unicode( self.path )
        return [req_dict]

class MoveFile(BaseEvent, HasMetaData):
    """Path argument should be the new path of the file that was moved"""
    def __init__(self, *args, **kwargs): super(MoveFile, self).__init__(*args, **kwargs)
    def pack(self):
        req_dict = {}
        req_dict['mode'] = u'moved'
        req_dict['MDATA_KEY_MD5'] = self.metadata.extract()['MDATA_KEY_MD5']
        req_dict['MDATA_KEY_FILEPATH'] = unicode( self.path )
        return [req_dict]

def map_events(directory, constructor):
    for f in mmp.walk_supported(directory.replace("-unknown-path",""),
            clean_empties=True):
        try:
            for e in constructor( FakePyinotify(f) ).pack(): yield e
        except BadSongFile as e: yield e

class DeleteDir(BaseEvent):
    def __init__(self, *args, **kwargs): super(DeleteDir, self).__init__(*args, **kwargs)
    def pack(self):
        return map_events( self.path, DeleteFile )

class MoveDir(BaseEvent):
    def __init__(self, *args, **kwargs): super(MoveDir, self).__init__(*args, **kwargs)
    def pack(self):
        return map_events( self.path, MoveFile )

class DeleteDirWatch(BaseEvent):
    def __init__(self, *args, **kwargs): super(DeleteDirWatch, self).__init__(*args, **kwargs)
    def pack(self):
        req_dict = {}
        req_dict['mode'] = u'delete_dir'
        req_dict['MDATA_KEY_FILEPATH'] = unicode( self.path )
        return [req_dict]

class ModifyFile(BaseEvent, HasMetaData):
    def __init__(self, *args, **kwargs): super(ModifyFile, self).__init__(*args, **kwargs)
    def pack(self):
        req_dict = self.metadata.extract()
        req_dict['mode'] = u'modify'
        # path to directory that is to be removed
        req_dict['MDATA_KEY_FILEPATH'] = unicode( self.path )
        return [req_dict]