Snap packaging improvements (#207)

* fixup! snap: Support official config paths via *-files confinement interfaces (#197)

* FIXME no longer applied
* Obsoleted HOME environment variable assignment

Signed-off-by: 林博仁(Buo-ren Lin) <Buo.Ren.Lin@gmail.com>

* snap: Migrate to selective-checkout

The selective-pull stage snap is superseded by selective-checkout, prefer the new one.

Refer-to: Selective-checkout: Check out the tagged release revision if it isn't promoted to the stable channel <https://forum.snapcraft.io/t/the-selective-pull-scriptlet-stage-snap-workaround/10389>
Signed-off-by: 林博仁(Buo-ren Lin) <Buo.Ren.Lin@gmail.com>

* snap: Support bash completion

Refer-to: Scriptlets <https://docs.snapcraft.io/scriptlets/4892>
Refer-to: Tab completion for snaps <https://docs.snapcraft.io/tab-completion-for-snaps/2261>
Signed-off-by: 林博仁(Buo-ren Lin) <Buo.Ren.Lin@gmail.com>

* snap: Implement interface connection warning in the launcher

This patch ensures that the user will be acknowledge the missing
connection to the `removable-media` interface.

Signed-off-by: 林博仁(Buo-ren Lin) <Buo.Ren.Lin@gmail.com>

snap/local/launchers/gallery-dl-launch

@@ -8,12 +8,25 @@ set \
 	-o pipefail
 
 # Use user's real home directory for canonical configuration path access
-# FIXME: Waiting for Snap Store assertion
 declare REALHOME="$(
 	getent passwd "${USER}" \
 		| cut --delimiter=: --fields=6
 )"
 HOME="${REALHOME}"
 
+if ! test -f "${SNAP_USER_COMMON}"/marker_disable_interface_warning; then
+	# Warn if the `removable-media` interface isn't connected
+	if ! ls /media &>/dev/null; then
+		printf -- \
+			"It seems that this snap isn't connected to the \`removable-media\` security confinement interface.  If you want to save the files under \`/media\`, \`/run/media\`, or \`/mnt\` directories you need to connect this snap to the \`removable-media\` interface by running the following command in a terminal:\\n\\n    sudo snap connect %s:removable-media\\n\\n" \
+			"${SNAP_NAME}" \
+			>&2
+		printf -- \
+			"To disable this warning create an empty file at the following path:\\n\\n    %s/marker_disable_interface_warning\\n\\n" \
+			"${SNAP_USER_COMMON}" \
+			>&2
+	fi
+fi
+
 # Finally run the next part of the command chain
 exec "${@}"

snap/snapcraft.yaml

@@ -55,22 +55,34 @@ parts:
     organize:
       '*': bin/
 
-  selective-pull:
+  # Check out the tagged release revision if it isn’t promoted to the stable channel
+  # https://forum.snapcraft.io/t/selective-checkout-check-out-the-tagged-release-revision-if-it-isnt-promoted-to-the-stable-channel/10617
+  selective-checkout:
     plugin: nil
     build-packages:
     - git
     stage-snaps:
-    - selective-pull
+    - selective-checkout
 
   gallery-dl:
     after:
-    - selective-pull
+    - selective-checkout
 
     source: .
-    override-pull: $SNAPCRAFT_STAGE/scriptlets/selective-pull
+    override-pull: |
+      snapcraftctl pull
+      $SNAPCRAFT_STAGE/scriptlets/selective-checkout
+
     plugin: python
+    build-packages:
+    - make
     python-packages:
     - youtube_dl
+    override-build: |
+      # build manpages and bash completion
+      make
+
+      snapcraftctl build
 
   ffmpeg:
     plugin: nil
@@ -94,11 +106,10 @@ apps:
     command-chain:
     - bin/gallery-dl-launch
     command: bin/gallery-dl
+    completer: etc/bash_completion.d/gallery-dl.bash_completion
     environment:
       LANG: C.UTF-8
       LC_ALL: C.UTF-8
 
       # Satisfy FFmpeg's libpulsecommon dependency
       LD_LIBRARY_PATH: $LD_LIBRARY_PATH:$SNAP/usr/lib/$SNAPCRAFT_ARCH_TRIPLET/pulseaudio
-
-      HOME: $SNAP_USER_COMMON