# -*- coding: utf-8 -*-
from contextlib import contextmanager
from media.monitor.pure import truncate_to_length, toposort
from os.path import normpath
from media.monitor.exceptions import BadSongFile
from media.monitor.log import Loggable
import media.monitor.pure as mmp
from collections import namedtuple
import mutagen
class FakeMutagen(dict):
"""
Need this fake mutagen object so that airtime_special functions
return a proper default value instead of throwing an exceptions for
files that mutagen doesn't recognize
"""
FakeInfo = namedtuple('FakeInfo','length bitrate')
def __init__(self,path):
self.path = path
self.mime = ['audio/wav']
self.info = FakeMutagen.FakeInfo(0.0, '')
dict.__init__(self)
def set_length(self,l):
old_bitrate = self.info.bitrate
self.info = FakeMutagen.FakeInfo(l, old_bitrate)
class MetadataAbsent(Exception):
def __init__(self, name): self.name = name
def __str__(self): return "Could not obtain element '%s'" % self.name
class MetadataElement(Loggable):
def __init__(self,name):
self.name = name
# "Sane" defaults
self.__deps = set()
self.__normalizer = lambda x: x
self.__optional = True
self.__default = None
self.__is_normalized = lambda _ : True
self.__max_length = -1
self.__translator = None
def max_length(self,l):
self.__max_length = l
def optional(self, setting):
self.__optional = setting
def is_optional(self):
return self.__optional
def depends(self, *deps):
self.__deps = set(deps)
def dependencies(self):
return self.__deps
def translate(self, f):
self.__translator = f
def is_normalized(self, f):
self.__is_normalized = f
def normalize(self, f):
self.__normalizer = f
def default(self,v):
self.__default = v
def get_default(self):
if hasattr(self.__default, '__call__'): return self.__default()
else: return self.__default
def has_default(self):
return self.__default is not None
def path(self):
return self.__path
def __slice_deps(self, d):
"""
returns a dictionary of all the key value pairs in d that are also
present in self.__deps
"""
return dict( (k,v) for k,v in d.iteritems() if k in self.__deps)
def __str__(self):
return "%s(%s)" % (self.name, ' '.join(list(self.__deps)))
def read_value(self, path, original, running={}):
# If value is present and normalized then we only check if it's
# normalized or not. We normalize if it's not normalized already
if self.name in original:
v = original[self.name]
if self.__is_normalized(v): return v
else: return self.__normalizer(v)
# We slice out only the dependencies that are required for the metadata
# element.
dep_slice_orig = self.__slice_deps(original)
dep_slice_running = self.__slice_deps(running)
# TODO : remove this later
dep_slice_special = self.__slice_deps({'path' : path})
# We combine all required dependencies into a single dictionary
# that we will pass to the translator
full_deps = dict( dep_slice_orig.items()
+ dep_slice_running.items()
+ dep_slice_special.items())
# check if any dependencies are absent
# note: there is no point checking the case that len(full_deps) >
# len(self.__deps) because we make sure to "slice out" any supefluous
# dependencies above.
if len(full_deps) != len(self.dependencies()) or \
len(self.dependencies()) == 0:
# If we have a default value then use that. Otherwise throw an
# exception
if self.has_default(): return self.get_default()
else: raise MetadataAbsent(self.name)
# We have all dependencies. Now for actual for parsing
def def_translate(dep):
def wrap(k):
e = [ x for x in dep ][0]
return k[e]
return wrap
# Only case where we can select a default translator
if self.__translator is None:
self.translate(def_translate(self.dependencies()))
if len(self.dependencies()) > 2: # dependencies include themselves
self.logger.info("Ignoring some dependencies in translate %s"
% self.name)
self.logger.info(self.dependencies())
r = self.__normalizer( self.__translator(full_deps) )
if self.__max_length != -1:
r = truncate_to_length(r, self.__max_length)
return r
def normalize_mutagen(path):
"""
Consumes a path and reads the metadata using mutagen. normalizes some of
the metadata that isn't read through the mutagen hash
"""
if not mmp.file_playable(path): raise BadSongFile(path)
try : m = mutagen.File(path, easy=True)
except Exception : raise BadSongFile(path)
if m is None: m = FakeMutagen(path)
try:
if mmp.extension(path) == 'wav':
m.set_length(mmp.read_wave_duration(path))
except Exception: raise BadSongFile(path)
md = {}
for k,v in m.iteritems():
if type(v) is list:
if len(v) > 0: md[k] = v[0]
else: md[k] = v
# populate special metadata values
md['length'] = getattr(m.info, 'length', 0.0)
md['bitrate'] = getattr(m.info, 'bitrate', u'')
md['sample_rate'] = getattr(m.info, 'sample_rate', 0)
md['mime'] = m.mime[0] if len(m.mime) > 0 else u''
md['path'] = normpath(path)
if 'title' not in md: md['title'] = u''
return md
class OverwriteMetadataElement(Exception):
def __init__(self, m): self.m = m
def __str__(self): return "Trying to overwrite: %s" % self.m
class MetadataReader(object):
def __init__(self):
self.clear()
def register_metadata(self,m):
if m in self.__mdata_name_map:
raise OverwriteMetadataElement(m)
self.__mdata_name_map[m.name] = m
d = dict( (name,m.dependencies()) for name,m in
self.__mdata_name_map.iteritems() )
new_list = list( toposort(d) )
self.__metadata = [ self.__mdata_name_map[name] for name in new_list
if name in self.__mdata_name_map]
def clear(self):
self.__mdata_name_map = {}
self.__metadata = []
def read(self, path, muta_hash):
normalized_metadata = {}
for mdata in self.__metadata:
try:
normalized_metadata[mdata.name] = mdata.read_value(
path, muta_hash, normalized_metadata)
except MetadataAbsent:
if not mdata.is_optional(): raise
return normalized_metadata
def read_mutagen(self, path):
return self.read(path, normalize_mutagen(path))
global_reader = MetadataReader()
@contextmanager
def metadata(name):
t = MetadataElement(name)
yield t
global_reader.register_metadata(t)