ripper: Add support for fetching album art

If the `PIL` module is available, which can be installed by activating
the *art* extra for Rupert, the ripper will now download the album art
for the CD and store it in a file named `folder.jpg`.

.gitignore

@@ -1,2 +1,4 @@
 /.venv
 /dist
+__pycache__/
+*.py[co]

pyproject.toml

@@ -13,6 +13,7 @@ pydantic = "^1.7.3"
 python-libdiscid = "^2.0.1"
 musicbrainzngs = "^0.7.1"
 mutagen = "^1.45.1"
+Pillow = {version = "^8.4.0", optional = true}
 
 [tool.poetry.dev-dependencies]
 pylint = "^2.6.0"
@@ -24,6 +25,7 @@ rope = "^0.18.0"
 ripper = "rupert.main:main"
 
 [tool.poetry.extras]
+art = ["pillow"]
 udev = ["pyudev"]
 
 [tool.black]

src/rupert/musicbrainz.py

@@ -10,6 +10,10 @@ from .disc import Disc
 musicbrainzngs.set_useragent('DCPlayer', '0.0.1', 'https://dcplayer.audio/')
 
 
+class AlbumArtNotFound(Exception):
+    ...
+
+
 class Artist(pydantic.BaseModel):
     id: str
     name: str
@@ -58,6 +62,15 @@ class ReleaseResponse(pydantic.BaseModel):
     release_count: int = pydantic.Field(alias='release-count')
 
 
+def fetch_album_art(release: Release) -> bytes:
+    try:
+        return musicbrainzngs.get_image_front(release.id)
+    except OSError as e:
+        raise AlbumArtNotFound(
+            'No album art found for release %s', release.id
+        ) from e
+
+
 def get_releases_from_disc(disc: Disc) -> ReleaseResponse:
     res = musicbrainzngs.get_releases_by_discid(
         disc.disc_id,

src/rupert/ripper.py

@@ -2,6 +2,7 @@ from __future__ import annotations
 
 import enum
 import glob
+import io
 import logging
 import os
 import queue
@@ -25,7 +26,12 @@ import mutagen
 
 from . import inotify
 from .disc import DiscDrive
-from .musicbrainz import Release
+from .musicbrainz import AlbumArtNotFound, Release, fetch_album_art
+
+try:
+    from PIL import Image
+except ImportError:
+    Image = None  # type: ignore
 
 
 log = logging.getLogger(__name__)
@@ -310,6 +316,8 @@ class Ripper:
         for filename in glob.glob('track*.cdda.wav'):
             os.unlink(filename)
 
+        if Image is not None:
+            threading.Thread(target=self.fetch_album_art).start()
         self._process_thread.start()
         self._encode_thread.start()
         self._rip_thread.start()
@@ -336,6 +344,17 @@ class Ripper:
     def on_complete(self, message: str, is_err: bool) -> None:
         self._status_queue.put((None, (message, is_err)))
 
+    def fetch_album_art(self) -> None:
+        try:
+            data = fetch_album_art(self.release)
+        except AlbumArtNotFound:
+            log.error('No album art found for %s', self.release.title)
+        buf = io.BytesIO(data)
+        img = Image.open(buf)
+        img.thumbnail((1000, 1000))
+        with open('folder.jpg', 'wb') as f:
+            img.save(f)
+
 
 def safe_name(name: str) -> str:
     for k, v in FILENAME_SAFE_MAP.items():