feat: add snapcraft source

docs/usage.rst

@@ -1080,6 +1080,20 @@ repo
 
 This source supports :ref:`list options`.
 
+Check Snapcraft
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+::
+
+  source = "snapcraft"
+
+This source allows you to check the latest package versions in the `Snapcraft <https://snapcraft.io>`_.
+
+snap
+  Name of the snap package.
+
+channel
+  Name of the channel.
+
 Combine others' results
 ~~~~~~~~~~~~~~~~~~~~~~~
 ::

nvchecker_source/snapcraft.py

@@ -0,0 +1,32 @@
+# MIT licensed
+# Copyright (c) 2025 Maxim Slipenko <maxim@slipenko.com>, et al.
+
+from nvchecker.api import (
+  GetVersionError
+)
+
+URL="https://api.snapcraft.io/v2/snaps/info/%(snap)s"
+
+async def get_version(
+  name: str, conf, *,
+  cache, keymanager,
+  **kwargs,
+):
+  try:
+    snap = conf.get("snap")
+    channel = conf.get("channel")
+
+    result = await cache.get_json(
+      URL % { "snap": snap },
+      headers={
+        "Snap-Device-Series": "16",
+      },
+    )
+  except:
+    raise GetVersionError(f"Failed to request snap info for {snap}")
+  
+  for c in result['channel-map']:
+    if c['channel']['name'] == channel:
+      return c['version']
+  
+  raise GetVersionError(f"Failed to find version for {snap}")