[WIP] Album Art and Binary Responses

mopidy_mpd/dispatcher.py

@@ -155,7 +155,11 @@ def _add_ok_filter(self, request, response, filter_chain):
         return response
 
     def _has_error(self, response):
-        return response and response[-1].startswith("ACK")
+        return (
+            response
+            and isinstance(response[-1], str)
+            and response[-1].startswith("ACK")
+        )
 
     # Filter: call handler
 
@@ -239,6 +243,12 @@ class MpdContext:
     #: The subsytems that we want to be notified about in idle mode.
     subscriptions = None
 
+    #: The maximum binary chunk size
+    binary_limit = 1024 * 1024
+
+    #: A cache of the most recently sent artwork
+    art_cache = ("", bytes())
+
     _uri_map = None
 
     def __init__(

mopidy_mpd/network.py

@@ -494,8 +494,7 @@ def decode(self, line):
     def join_lines(self, lines):
         if not lines:
             return ""
-        line_terminator = self.decode(self.terminator)
-        return line_terminator.join(lines) + line_terminator
+        return self.terminator.join(lines) + self.terminator
 
     def send_lines(self, lines):
         """
@@ -507,5 +506,11 @@ def send_lines(self, lines):
         if not lines:
             return
 
-        data = self.join_lines(lines)
-        self.connection.queue_send(self.encode(data))
+        encoded_lines = []
+        for line in lines:
+            if not isinstance(line, bytes):
+                encoded_lines.append(self.encode(line))
+            else:
+                encoded_lines.append(line)
+
+        self.connection.queue_send(self.join_lines(encoded_lines))

mopidy_mpd/protocol/connection.py

@@ -51,3 +51,12 @@ def ping(context):
         Does nothing but return ``OK``.
     """
     pass
+
+
+@protocol.commands.add("binarylimit")
+def binarylimit(context, size):
+    """
+    Set the maximum binary response size for the current connection to the
+    specified number of bytes.
+    """
+    context.binary_limit = size

mopidy_mpd/protocol/music_db.py

@@ -1,5 +1,8 @@
 import functools
 import itertools
+import os.path
+from urllib.request import Request, urlopen
+import urllib.error
 
 from mopidy.models import Track
 from mopidy_mpd import exceptions, protocol, translator
@@ -84,6 +87,65 @@ def _artist_as_track(artist):
     )
 
 
+def _get_art(context, uri=None, offset=0):
+    # TODO work out how validators work and move these there
+    if uri is None:
+        raise exceptions.MpdArgError("Need to specify uri")
+    offset = protocol.INT(offset)
+
+    images = context.core.library.get_images([uri]).get()[uri]
+
+    if len(images) == 0:
+        raise exceptions.MpdNoExistError("No file exists")
+
+    image_uri = images[0].uri
+
+    if image_uri == context.art_cache[0]:
+        bytes = context.art_cache[1]
+    else:
+        if image_uri.startswith("/"):
+            data_path = context.config["core"]["config_dir"]
+            _, extension, file = image_uri.split("/")
+            with open(
+                os.path.join(data_path, extension, "images", file), "rb"
+            ) as image_file:
+                bytes = image_file.read()
+        elif image_uri.startswith("https://") or image_uri.startswith("http://"):
+            try:
+                with urlopen(Request(image_uri)) as r:
+                    bytes = r.read()
+            except urllib.error.URLError as e:
+                raise exceptions.MpdArgError(f"There was an error with getting the uri, reason: {e.reason}")
+        else:
+            raise exceptions.MpdNotImplemented(
+                f"Cannot make sense of the uri {image_uri}"
+            )
+
+        context.art_cache = (image_uri, bytes)
+
+    if offset > len(bytes):
+        raise exceptions.MpdArgError("Offset too large")
+
+    return [
+        ("size", len(bytes)),
+        ("binary", len(bytes[offset : offset + context.binary_limit])),
+        bytes[offset : offset + context.binary_limit],
+    ]
+    pass
+
+
+@protocol.commands.add("albumart")
+def albumart(context, uri=None, offset=0):
+    """
+    `albumart {URI} {OFFSET}`
+
+    Locate album art for the given song and return a chunk of an album art
+    image file at offset OFFSET.
+    """
+    track = context.core.library.lookup([uri]).get()[uri]
+    return _get_art(context, track[0].album.uri, offset)
+
+
 @protocol.commands.add("count")
 def count(context, *args):
     """
@@ -548,3 +610,14 @@ def readcomments(context, uri):
         support it. For example, on Ogg files, this lists the Vorbis comments.
     """
     pass
+
+
+@protocol.commands.add("readpicture")
+def readpicture(context, uri=None, offset=0):
+    """
+    `readpicture {URI} {OFFSET}`
+
+    Locate a picture for the given song and return a chunk of the image file at
+    offset OFFSET.
+    """
+    return _get_art(context, uri, offset)

mopidy_mpd/session.py

@@ -36,7 +36,11 @@ def on_line_received(self, line):
         logger.debug(
             "Response to %s: %s",
             self.connection,
-            formatting.indent(self.decode(self.terminator).join(response)),
+            formatting.indent(
+                self.decode(self.terminator).join(
+                    [r for r in response if not isinstance(r, bytes)]
+                )
+            ),
         )
 
         self.send_lines(response)