nephilim/metadata_fetcher.py

   1 #
   2 #    Copyright (C) 2010 Anton Khirnov <anton@khirnov.net>
   3 #
   4 #    Nephilim is free software: you can redistribute it and/or modify
   5 #    it under the terms of the GNU General Public License as published by
   6 #    the Free Software Foundation, either version 3 of the License, or
   7 #    (at your option) any later version.
   8 #
   9 #    Nephilim is distributed in the hope that it will be useful,
  10 #    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 #    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 #    GNU General Public License for more details.
  13 #
  14 #    You should have received a copy of the GNU General Public License
  15 #    along with Nephilim.  If not, see <http://www.gnu.org/licenses/>.
  16 #
  17
  18 from PyQt4 import QtCore, QtNetwork
  19 from PyQt4.QtCore import pyqtSignal as Signal
  20
  21 from song import Song
  22
  23 class MetadataFetcher(QtCore.QObject):
  24     """A basic class for metadata fetchers. Provides a fetch(song) function,
  25        emits a finished(song, metadata) signal when done; lyrics is either a Python
  26        unicode string or None if not found."""
  27     #public, read-only
  28     logger = None
  29     name   = ''
  30
  31     #private
  32     nam  = None  # NetworkAccessManager
  33     rep = None   # current NetworkReply.
  34     song = None  # current song
  35
  36     # SIGNALS
  37     finished = Signal([Song, object])
  38
  39     #### private ####
  40     def __init__(self, plugin):
  41         QtCore.QObject.__init__(self, plugin)
  42
  43         self.nam = QtNetwork.QNetworkAccessManager()
  44         self.logger = plugin.logger
  45
  46     def fetch2(self, song, url):
  47         """A private convenience function to initiate fetch process."""
  48         # abort any existing connections
  49         self.abort()
  50         self.song = song
  51
  52         self.logger.info('Searching %s: %s.'%(self. name, url.toString()))
  53         self.rep = self.nam.get(QtNetwork.QNetworkRequest(url))
  54         self.rep.error.connect(self.handle_error)
  55
  56     def finish(self, metadata = None):
  57         """A private convenience function to clean up and emit finished().
  58            Feel free to reimplement/not use it."""
  59         self.rep = None
  60         self.finished.emit(self.song, metadata)
  61         self.song = None
  62
  63     def handle_error(self):
  64         """Print the error and abort."""
  65         self.logger.error(self.rep.errorString())
  66         self.abort()
  67         self.finish()
  68
  69     #### public ####
  70     def fetch(self, song):
  71         """Reimplement this in subclasses."""
  72         pass
  73
  74     def abort(self):
  75         """Abort all downloads currently in progress."""
  76         if self.rep:
  77             self.rep.blockSignals(True)
  78             self.rep.abort()
  79             self.rep = None