#!/bin/sh
#
# Copyright (C) 2012,2014,2016  Etersoft
# Copyright (C) 2012,2014,2016  Vitaly Lipatov <lav@etersoft.ru>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU Affero General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Affero General Public License for more details.
#
# You should have received a copy of the GNU Affero General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
#

load_helper epm-check_updated_repo

__epm_add_alt_apt_downgrade_preferences()
{
	[ -r /etc/apt/preferences ] && fatal "/etc/apt/preferences already exists"
	cat <<EOF | $SUDO tee /etc/apt/preferences
# main repo
Package: *
Pin: release c=classic
Pin-Priority: 1001

# overload with addon repo
Package: *
Pin: release c=addon
Pin-Priority: 1101
EOF
}

# See https://wiki.debian.org/ru/AptPreferences
__epm_add_deb_apt_downgrade_preferences()
{
	[ -r /etc/apt/preferences ] && fatal "/etc/apt/preferences already exists"
	info "Running with /etc/apt/preferences:"
	cat <<EOF | $SUDO tee /etc/apt/preferences
Package: *
Pin: release a=stable
Pin-Priority: 1001

Package: *
Pin: release a=testing
Pin-Priority: 900

Package: *
Pin: release a=unstable
Pin-Priority: 800
EOF
}

__epm_remove_apt_downgrade_preferences()
{
	sudocmd rm -f /etc/apt/preferences
}

epm_downgrade()
{
	local CMD

	# it is useful for first time running
	update_repo_if_needed

	info "Running command for downgrade packages"

	case $PMTYPE in
	apt-rpm)
		__epm_add_alt_apt_downgrade_preferences || return
		if [ -n "$pkg_filenames" ] ; then
			sudocmd apt-get install $pkg_filenames
		else
			sudocmd apt-get dist-upgrade
		fi
		__epm_remove_apt_downgrade_preferences
		;;
	apt-dpkg)
		__epm_add_deb_apt_downgrade_preferences || return
		if [ -n "$pkg_filenames" ] ; then
			sudocmd apt-get install $pkg_filenames
		else
			sudocmd apt-get dist-upgrade
		fi
		__epm_remove_apt_downgrade_preferences
		;;
	yum-rpm)
		# can do update repobase automagically
		if [ -n "$pkg_filenames" ] ; then
			sudocmd yum downgrade $pkg_filenames
		else
			sudocmd yum distro-sync
		fi
		;;
	dnf-rpm)
		if [ -n "$pkg_filenames" ] ; then
			sudocmd dnf downgrade $pkg_filenames
		else
			sudocmd dnf distro-sync
		fi
		;;
	urpm-rpm)
		assure_exists urpm-reposync urpm-tools
		sudocmd urpm-reposync -v
		;;
	*)
		fatal "Have no suitable command for $PMTYPE"
		;;
	esac
}