config: List which Endless Key collections to preload

Instead of loading every channel from every collection JSON from the
Endless Key app, allow the image configuration to list which collections
to include.

#117

config/defaults.ini

@@ -304,6 +304,12 @@ regular_users_can_manage_content = false
 #   # Kolibri 0.12.2 User Guide for Admins [document]
 #   5bb37c1832c8489ab2940f31588305f6
 
+[endlesskey]
+# Which Endless Key collections to preload in the image.
+# Must match the name of one of the collections shipped with the Endless Key
+# (ex. artist, explorer, spanish etc).
+collections =
+
 [usb]
 size = 16000000000
 free_space = 1000

hooks/image/51-ek-content-list

@@ -1,5 +1,9 @@
 # Populate the Endless Key home directory
 
+if [ -z "${EIB_ENDLESSKEY_COLLECTIONS}" ]; then
+  exit 0
+fi
+
 if [[ ! "${EIB_FLATPAK_REMOTE_FLATHUB_APPS}" =~ .*"org.endlessos.Key".* ]]; then
   exit 0
 fi
@@ -11,5 +15,10 @@ EK_CHANNELS_FILE="${EIB_TMPDIR}"/ek-channels
 rm -f "${EK_CHANNELS_FILE}"
 collections="${OSTREE_VAR}"/lib/flatpak/app/org.endlessos.Key/current/active/files/share/endless-key/collections/*.json
 for collection in ${collections}; do
-  jq -r '.channels[].id' "${collection}" >> "${EK_CHANNELS_FILE}"
+  # Check if the file basename stripped off of -0001.json is part of the list
+  # of collections to be installed.
+  bn=$(basename ${collection})
+  if [[ "${EIB_ENDLESSKEY_COLLECTIONS}" =~ .*"${bn%-????.json}".* ]] ; then
+    jq -r '.channels[].id' "${collection}" >> "${EK_CHANNELS_FILE}"
+  fi
 done