update.sh

#!/bin/bash
set -eo pipefail

cd "$(dirname "$(readlink -f "$BASH_SOURCE")")"

versions=( "$@" )
if [ ${#versions[@]} -eq 0 ]; then
	versions=( */ )
fi
versions=( "${versions[@]%/}" )
releasePage="$(curl -fsSL 'https://www.ruby-lang.org/en/downloads/releases/')"

latest_gem_version() {
	curl -fsSL "https://rubygems.org/api/v1/gems/$1.json" | sed -r 's/^.*"version":"([^"]+)".*$/\1/'
}

rubygems="$(latest_gem_version rubygems-update)"
bundler="$(latest_gem_version bundler)"

travisEnv=
for version in "${versions[@]}"; do
	rcGrepV='-v'
	rcVersion="${version%-rc}"
	if [ "$rcVersion" != "$version" ]; then
		rcGrepV=
	fi
	
	IFS=$'\n'; allVersions=(
		$(curl -fsSL --compressed "https://cache.ruby-lang.org/pub/ruby/$rcVersion/" \
			| grep -E '<a href="ruby-'"$rcVersion"'.[^"]+\.tar\.xz' \
			| grep $rcGrepV -E 'preview|rc' \
			| sed -r 's!.*<a href="ruby-([^"]+)\.tar\.xz.*!\1!' \
			| sort -rV)
	); unset IFS

	fullVersion=
	for tryVersion in "${allVersions[@]}"; do
		if echo "$releasePage" | grep -q "Ruby ${tryVersion}<"; then
			fullVersion="$tryVersion"
			break
		fi
	done

	if [ -z "$fullVersion" ]; then
		echo >&2 "warning: cannot determine sha for $version (tried all of ${allVersions[*]}); skipping"
		continue
	fi
	versionReleasePage="$(echo "$releasePage" | grep "<td>Ruby $fullVersion</td>" -A 2 | awk -F '"' '$1 == "<td><a href=" { print $2; exit }')"
	shaVal="$(curl -fsSL "https://www.ruby-lang.org/$versionReleasePage" |tac|tac| grep "ruby-$fullVersion.tar.xz" -A 5 | awk '/^SHA256:/ { print $2; exit }')"

	sedStr="
		s!%%VERSION%%!$version!g;
		s!%%FULL_VERSION%%!$fullVersion!g;
		s!%%SHA256%%!$shaVal!g;
		s!%%RUBYGEMS%%!$rubygems!g;
		s!%%BUNDLER%%!$bundler!g;
	"
	echo "$version: $fullVersion; rubygems $rubygems, bundler $bundler; $shaVal"
	for variant in alpine slim onbuild ''; do
		[ -d "$version/$variant" ] || continue
		sed -r "$sedStr" "Dockerfile${variant:+-$variant}.template" > "$version/$variant/Dockerfile"
		if [ "$variant" != 'onbuild' ]; then
			travisEnv='\n  - VERSION='"$version VARIANT=$variant$travisEnv"
		fi
	done
done

travis="$(awk -v 'RS=\n\n' '$1 == "env:" { $0 = "env:'"$travisEnv"'" } { printf "%s%s", $0, RS }' .travis.yml)"
echo "$travis" > .travis.yml