upstream_version = $$(printf '%s\n' '$(OPK_SOURCE_VERSION_UPSTREAM)' | \
	sed 's/+/-/')
upstream_archive = $(OPK_SOURCE)-$(upstream_version).tgz
upstream_url_base = https://invisible-mirror.net/archives/dialog
upstream_url = $(upstream_url_base)/$(upstream_archive)
source_archive = ../$(OPK_SOURCE)-$(OPK_SOURCE_VERSION_UPSTREAM).orig.tar.gz

gpg = GNUPGHOME=gnupghome/ gpg --no-default-keyring --keyring ../keyring.gpg
keys = \
	'C520 48C0 C074 8FEE 227D  47A2 7023 53E0 F7E4 8EDB'

$(source_archive):
	wget -c "$(upstream_url)" "$(upstream_url).asc"
	install -m 0700 -d gnupghome/
	[ -e ../keyring.gpg ] || \
		$(gpg) --keyserver hkp://pool.sks-keyservers.net \
			--recv-keys $(keys); \
	rm -f ../keyring.gpg~; \
	if ! $(gpg) --verify "$(upstream_archive).asc"; then \
		rm -Rf gnupghome/; \
		exit 1; \
	fi
	rm -Rf gnupghome/
	mv "$(upstream_archive)" '$(source_archive)'

source: $(source_archive)