[gnome-music/wip/jfelder/songeditor-gtk4: 20/32] coresong: Add support to query musicbrainz tags

[Jean Felder <jfelder src gnome org>]

commit 809b784a29da099549ed1ca1260acd5dd5b891d0
Author: Sumaid Syed <sumaidsyed gmail com>
Date:   Sat Nov 23 14:53:17 2019 +0100

    coresong: Add support to query musicbrainz tags
    
    The following framework is used:
    1. Compute the chromaprint (a fingerprint) of the song with the
     chromaprint source
    2. Use the chromaprint to identify the song with the acoustid source

 gnomemusic/coregrilo.py | 33 +++++++++++++++++++++++++++++++++
 gnomemusic/coresong.py  | 15 +++++++++++++++
 2 files changed, 48 insertions(+)
---
diff --git a/gnomemusic/coregrilo.py b/gnomemusic/coregrilo.py
index 788e22bec..299ef3c1c 100644
--- a/gnomemusic/coregrilo.py
+++ b/gnomemusic/coregrilo.py
@@ -22,7 +22,9 @@
 # code, but you are not obligated to do so.  If you do not wish to do so,
 # delete this exception statement from your version.
 
+from __future__ import annotations
 from typing import Callable, Dict, Optional
+import typing
 import weakref
 
 import gi
@@ -35,6 +37,8 @@ from gnomemusic.grilowrappers.grlchromaprintwrapper import (
 from gnomemusic.grilowrappers.grlsearchwrapper import GrlSearchWrapper
 from gnomemusic.grilowrappers.grltrackerwrapper import GrlTrackerWrapper
 from gnomemusic.trackerwrapper import TrackerState, TrackerWrapper
+if typing.TYPE_CHECKING:
+    from gnomemusic.coresong import CoreSong
 
 
 class CoreGrilo(GObject.GObject):
@@ -341,3 +345,32 @@ class CoreGrilo(GObject.GObject):
         if "grl-tracker3-source" in self._wrappers:
             self._wrappers["grl-tracker3-source"].create_playlist(
                 playlist_title, callback)
+
+    def get_chromaprint(
+            self, coresong: CoreSong,
+            callback: CoreGrilo.RESOLVE_CB_TYPE) -> None:
+        """Retrieve the chromaprint for the given CoreSong
+
+        :param CoreSong coresong: The CoreSong to chromaprint
+        :param callback: Metadata retrieval callback
+        """
+        if "grl-chromaprint" not in self._mb_wrappers:
+            callback(None)
+            return
+
+        self._mb_wrappers["grl-chromaprint"].get_chromaprint(
+            coresong, callback)
+
+    def get_tags(
+            self, coresong: CoreSong,
+            callback: CoreGrilo.QUERY_CB_TYPE) -> None:
+        """Retrieve Musicbrainz tags for the given CoreSong
+
+        :param CoreSong coresong: The CoreSong to retrieve tags for
+        :param callback: Metadata retrieval callback
+        """
+        if "grl-acoustid" not in self._mb_wrappers:
+            callback(None, 0)
+            return
+
+        self._mb_wrappers["grl-acoustid"].get_tags(coresong, callback)
diff --git a/gnomemusic/coresong.py b/gnomemusic/coresong.py
index 585f28e8d..751684e6a 100644
--- a/gnomemusic/coresong.py
+++ b/gnomemusic/coresong.py
@@ -187,3 +187,18 @@ class CoreSong(GObject.GObject):
     def update_shuffle_pos(self) -> None:
         """Randomizes the shuffle position of this song"""
         self.props.shuffle_pos = randint(1, 1_000_000)
+
+    def query_musicbrainz_tags(
+            self, callback: CoreGrilo.QUERY_CB_TYPE) -> None:
+        """Retrieves metadata keys for this CoreSong
+
+        :param callback: Metadata retrieval callback
+        """
+        def chromaprint_retrieved(media: Optional[Grl.Media]) -> None:
+            if media is None:
+                callback(None, 0)
+                return
+
+            self._coregrilo.get_tags(self, callback)
+
+        self._coregrilo.get_chromaprint(self, chromaprint_retrieved)