Made mutagen import optional

ipod-shuffle-4g.py

@@ -1,11 +1,11 @@
 #!/usr/bin/env python3
+
+# Builtin libraries
 import sys
 import struct
 import urllib.request, urllib.parse, urllib.error
 import os
 import hashlib
-import mutagen
-import binascii
 import subprocess
 import collections
 import errno
@@ -15,6 +15,12 @@ import re
 import tempfile
 import signal
 
+# External libraries
+try:
+    import mutagen
+except ImportError:
+    mutagen = None
+
 audio_ext = (".mp3", ".m4a", ".m4b", ".m4p", ".aa", ".wav")
 list_ext = (".pls", ".m3u")
 def make_dir_if_absent(path):
@@ -359,6 +365,9 @@ class Track(Record):
             self["filetype"] = 2
 
         text = os.path.splitext(os.path.basename(filename))[0]
+
+        # Try to get album and artist information with mutagen
+        if mutagen:
             audio = None
             try:
                 audio = mutagen.File(filename, easy = True)
@@ -622,10 +631,15 @@ class Shuffler(object):
                     self.lists.append(os.path.abspath(dirpath))
 
         if self.auto_id3_playlists != None:
+            if mutagen:
                 for grouped_list in group_tracks_by_id3_template(self.tracks, self.auto_id3_playlists):
                     self.lists.append(grouped_list)
+            else:
+                print("Error: No mutagen found. Cannot generate auto-id3-playlists.")
+                sys.exit(1)
 
     def write_database(self):
+        print("Writing database. This may take a while...")
         with open(os.path.join(self.path, "iPod_Control", "iTunes", "iTunesSD"), "wb") as f:
             try:
                 f.write(self.tunessd.construct())
@@ -633,6 +647,7 @@ class Shuffler(object):
                 print("I/O error({0}): {1}".format(e.errno, e.strerror))
                 print("Error: Writing iPod database failed.")
                 sys.exit(1)
+
         print("Database written successfully:")
         print("Tracks", len(self.tracks))
         print("Albums", len(self.albums))
@@ -740,6 +755,9 @@ if __name__ == '__main__':
     if result.rename_unicode:
         check_unicode(result.path)
 
+    if not mutagen:
+        print("Warning: No mutagen found. Database will not contain any album nor artist information.")
+
     verboseprint("Playlist voiceover requested:", result.playlist_voiceover)
     verboseprint("Track voiceover requested:", result.track_voiceover)
     if (result.track_voiceover or result.playlist_voiceover):