apply-templates.sh

#!/usr/bin/env bash
set -Eeuo pipefail

[ -f versions.json ] # run "versions.sh" first

jqt='.jq-template.awk'
if [ -n "${BASHBREW_SCRIPTS:-}" ]; then
	jqt="$BASHBREW_SCRIPTS/jq-template.awk"
elif [ "$BASH_SOURCE" -nt "$jqt" ]; then
	# https://github.com/docker-library/bashbrew/blob/master/scripts/jq-template.awk
	wget -qO "$jqt" 'https://github.com/docker-library/bashbrew/raw/9f6a35772ac863a0241f147c820354e4008edf38/scripts/jq-template.awk'
fi

if [ "$#" -eq 0 ]; then
	versions="$(jq -r 'keys | map(@sh) | join(" ")' versions.json)"
	eval "set -- $versions"
fi

generated_warning() {
	cat <<-EOH
		#
		# NOTE: THIS DOCKERFILE IS GENERATED VIA "apply-templates.sh"
		#
		# PLEASE DO NOT EDIT IT DIRECTLY.
		#

	EOH
}

for version; do
	export version

	rm -rf "$version/"

	variants="$(jq -r '.[env.version].variants | map(@sh) | join(" ")' versions.json)"
	eval "variants=( $variants )"

	for variant in "${variants[@]}"; do
		export variant

		dir="$version/$variant"
		mkdir -p "$dir"

		case "$variant" in
			windows/*)
				# TODO someday? :)
				variant="$(basename "$dir")" # "buster", "windowsservercore-1809", etc
				windowsVariant="${variant%%-*}" # "windowsservercore", "nanoserver"
				windowsRelease="${variant#$windowsVariant-}" # "ltsc2022", "1809", etc
				windowsVariant="${windowsVariant#windows}" # "servercore", "nanoserver"
				export windowsVariant windowsRelease
				template="Dockerfile-windows-$windowsVariant.template"
				;;

			*)
				template='Dockerfile-linux.template'
				;;
		esac

		echo "processing $dir ..."

		{
			generated_warning
			gawk -f "$jqt" "$template"
		} > "$dir/Dockerfile"
	done
done