#!/bin/sh

set -eu

PLAT=
MAKE_SUBSTVARS=false

substvars=''

info()
{
	local fmt="${1}"
	shift 1

	printf "ppt-mkpkgs: ${fmt}\n" "${@}"
}

make_common_pkg()
{
	# Make "-common" package to provide source package documentation files.
	mkdir -p "config-${PLAT}-common.pkg"
	cat >"config-${PLAT}-common.pkg/control" <<-EOF
		# Generated by ppt-mkpkgs.  Do not edit.
		Architecture: all
		Platform: all
		Section: share
		Description: "${PLAT}" platform configuration - common files
		EOF
	>"config-${PLAT}-common.pkg/docs"
	info 'Metadata for package "%s" generated.' "config-${PLAT}-common"
}

make_base_pkg()
{
	# Make a "config-base" package to depend on packages to be automatically
	# installed.
	mkdir -p "config-base.pkg"
	cat >"config-base.pkg/control" <<-EOF
		# Generated by ppt-mkpkgs.  Do not edit.
		Architecture: all
		Platform: ${PLAT}
		Section: share
		Essential: yes
		Depends: config-${PLAT}-common (= \${Binary-Version}),
		 \${Config-Base-Depends}
		Description: "${PLAT}" platform configuration - base package
		EOF
	if ${MAKE_SUBSTVARS}; then
		printf 'Config-Base-Depends:\n' >>'substvars'
	fi
	info 'Metadata for package "%s" generated.' "config-base"
}

make_build_time_pkgs()
{
	local pkg=
	local var=

	# Make each config-*-* package.
	for pkg in src/build/*; do
		[ -d "${pkg}" ] || continue
		pkg="${pkg#src/build/}"
		var="$(printf '%s' "${pkg}" | tr -C 'A-Za-z0-9-' '-')"
		substvars="${substvars} Config-${var}-Depends"
		mkdir -p "config-${pkg}-${PLAT}.pkg"
		cat >"config-${pkg}-${PLAT}.pkg/control" <<-EOF
			# Generated by ppt-mkpkgs.  Do not edit.
			Architecture: all
			Platform: all
			Section: dev
			Depends: config-${PLAT}-common (= \${Binary-Version}),
			 \${Config-${var}-Depends}
			Description: "${PLAT}" platform configuration for ${pkg}
			EOF
		if ${MAKE_SUBSTVARS}; then
			printf 'Config-%s-Depends:\n' "${var}" >>'substvars'
		fi
		info 'Metadata for package "%s" generated.' \
			"config-${pkg}-${PLAT}"
	done
}

make_run_time_pkgs()
{
	local pkg=
	local var=

	# Make each config-* package.
	for pkg in src/run/*; do
		[ -d "${pkg}" ] || continue
		pkg="${pkg#src/run/}"
		var="$(printf '%s' "${pkg}" | tr -C 'A-Za-z0-9-' '-')"
		substvars="${substvars} Config-${var}-Depends"
		mkdir -p "config-${pkg}.pkg"
		cat >"config-${pkg}.pkg/control" <<-EOF
			# Generated by ppt-mkpkgs.  Do not edit.
			Architecture: all
			Platform: ${PLAT}
			Section: share
			Depends: config-${PLAT}-common (= \${Binary-Version}),
			 \${Config-${var}-Depends}
			Description: "${PLAT}" platform configuration for ${pkg}
			EOF
		if ${MAKE_SUBSTVARS}; then
			printf 'Config-%s-Depends:\n' "${var}" >>'substvars'
		fi
		info 'Metadata for package "%s" generated.' \
			"config-${pkg}"
	done
}

main()
{
	local var=

	PLAT="$(sed '1{s/^config-\([^ ][^ ]*\) (.*$/\1/;};1!q;' changelog)"

	if ! [ -e 'substvars' ]; then
		MAKE_SUBSTVARS=true
		printf '# Generated by ppt-mkpkgs.  DO EDIT.\n' >'substvars'
	fi
	make_common_pkg
	make_base_pkg
	make_build_time_pkgs
	make_run_time_pkgs
	info 'Consider adding "opkbuild (>= 4.2.1-3)" to Build-Depends if '$(: \
		)'not already done'
	if ${MAKE_SUBSTVARS}; then
		info 'Stub "substvars" file generated.  Set variables as '$(: \
			)'needed.'
	else
		info 'Ensure "substvars" contains the following variables:'
		for var in ${substvars}; do
			info '  * %s' "${var}"
		done
	fi
}

main "${@}"