assign uuid via ID3 UFID tag to single track

symuid

@@ -0,0 +1,58 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+
+import mutagen
+import mutagen.id3
+import os
+import subprocess
+
+# http://id3.org/id3v2.4.0-frames#4.1.
+TRACK_UUID_ID3_OWNER_ID = 'symuid'
+
+# TODO http://mutagen.readthedocs.io/en/latest/api/mp4.html
+
+def generate_uuid():
+    return subprocess.check_output(['uuid', '-v', '4', '-F', 'BIN']).strip()
+
+def get_uuid(id3_tags):
+    assert isinstance(id3_tags, mutagen.id3.ID3)
+    ufids = id3_tags.getall('UFID')
+    for ufid in ufids:
+        if ufid.owner == TRACK_UUID_ID3_OWNER_ID:
+            return ufid.data
+    return None
+
+def get_or_assign_uuid(id3_tags):
+    uuid = get_uuid(id3_tags)
+    if uuid is None:
+        # mutagen.id3._specs.EncodedTextSpec.write encodes 'owner'
+        id3_tags.add(mutagen.id3.UFID(
+            owner=TRACK_UUID_ID3_OWNER_ID,
+            data=generate_uuid(),
+        ))
+        id3_tags.save()
+        id3_tags.load(filename=id3_tags.filename)
+        uuid = get_uuid(id3_tags)
+        print("{!r}: assigned uuid {!r}".format(id3_tags.filename, uuid))
+        assert uuid is not None
+    return uuid
+
+def symuid(track_path):
+    f = mutagen.File(filename=track_path)
+    print(get_or_assign_uuid(f.tags))
+
+def _init_argparser():
+    import argparse
+    argparser = argparse.ArgumentParser(description=None)
+    argparser.add_argument('track_path')
+    return argparser
+
+def main(argv):
+    argparser = _init_argparser()
+    args = argparser.parse_args(argv[1:])
+    symuid(**vars(args))
+    return 0
+
+if __name__ == "__main__":
+    import sys
+    sys.exit(main(sys.argv))