Update create.sh to quickly check for and update missing submodules

assets/create.sh

@@ -2,10 +2,42 @@
 set -euo pipefail
 
 ASSET_DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
+REPO_DIR="$ASSET_DIR/.."
 
 # Ensure submodules are initialized.
-git submodule init
-git submodule update
+function update_submodules() {
+	local submodule
+	local submodule_prompt=unspecified
+	local submodule_path
+
+	{
+		while { read -r submodule && read -r submodule_path; } <&3; do
+			if ! [[ -d "${REPO_DIR}/.git/modules/${submodule}" ]] && [[ -d "${REPO_DIR}/${submodule_path}" ]]; then
+				if [[ "$submodule_prompt" = "unspecified" ]]; then
+					echo "One or more submodules were found to be uninitialized."
+					printf "Initialize and update them? [Y/n] "
+					read -r submodule_prompt
+				fi
+
+				case "$submodule_prompt" in
+					y|yes|'') {
+						git -C "$REPO_DIR" submodule update --init "$submodule_path"
+					};;
+					n|no) {
+						return
+					};;
+					*) {
+						echo "Unknown answer. Not updating submodules."
+					};;
+				esac
+			fi
+		done
+	} 3< <(git config --file "${REPO_DIR}/.gitmodules" --null --get-regexp path | xargs -0 printf "%s\n" | sed 's/^submodule.//;s/.path$//')
+}
+
+if [ -t 0 ]; then
+	update_submodules
+fi
 
 # Always remove the local cache to avoid any confusion
 bat cache --clear