#!/usr/bin/env bash
name="Libredbdiff"

# Copyright (C) 2014 Esteban Carnevale <alfplayer@mailoo.org>
# Copyright (C) 2014 Luke Shumaker <lukeshu@sbcglobal.net>
#
# License: GNU GPLv3+
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU 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 General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

baseconfpath="/etc/libredbdiff"
basedbpath="/var/lib/libredbdiff"

conffile="$baseconfpath/pacman.conf.parabola"
conffilearch="$baseconfpath/pacman.conf.archlinux"

dbpath="$basedbpath/pacman.parabola"
dbpatharch="$basedbpath/pacman.archlinux"

mirrorlist="$baseconfpath/mirrorlist.parabola"
mirrorlistarch="$baseconfpath/mirrorlist.archlinux"

mirror='http://repo.parabola.nu/$repo/os/$arch'
mirrorarch='http://mirrors.kernel.org/archlinux/$repo/os/$arch'

. libremessages

cmd="${0##*/}"

downloadfile() {
	local outfile=$1
	local url=$2
	local mesg=("${@:3}")
	if [[ ! -e $outfile ]] ; then
		msg "${mesg[@]}"
		if wget -q "$url" -O "$outfile"; then
			return 255
		else
			die "Failed to download %q. Exiting." "$outfile"
		fi
	elif [[ $init ]]; then
		warning "%q already exists. Skipping." "$outfile"
	fi
}

createdir() {
	local dir=$1
	if [[ ! -e $dir ]] ; then
		msg "Creating directory %q" "$dir"
		mkdir -- "$1" || die "Failed to create directory %q. Exiting." "$dir"
	elif [[ $init ]]; then
		warning "%q already exists. Skipping." "$dir"
	fi
}

setmirror() {
	local distro="$1"
	local mirror="$2"
	local mirrorlist="$3"
	if [[ $init ]] && [[ $mirror ]]; then
		mirrorescaped="${mirror//./\\.}"
		mirrorescaped="${mirrorescaped//\$/\\$}"
		msg "Setting %q as the only enabled %s mirror." "${mirror}" "${distro}"
		sed -i 's|^#\(Server = '"${mirrorescaped}"'\)$|\1|' "${mirrorlist}"
	fi
}

filenotfound() {
	local file=$1
	if [[ ! -r $1 ]]; then
		die "Could not read %q. Nothing done." "$file"
		plain "It may be necessary to run %q without arguments as root to initialize %s." "$cmd" "$name"
	fi
}

comparepkgs() {
	if [[ ${verarch[$pkgname]} ]] ; then
		cmp=$(vercmp "${ver[$pkgname]}" "${verarch[$pkgname]}")
		if [[ $cmp -lt 0 ]]; then
			msg "%s needs update from the Arch package of the same name. Versions: %s - %s" "${pkgname}" "${ver[$pkgname]}" "${verarch[$pkgname]}"
		fi
	elif [[ ${provides[$pkgname]} ]]; then
		for provide in "${provides[$pkgname]}"; do
			if [[ ${verarch["$provide"]} ]]; then
				cmp=$(vercmp "${ver[$pkgname]}" "${verarch[$provide]}")
				if [[ $cmp -lt 0 ]]; then
					msg "%s may need update from provide candidate %s. Versions: %s - %s" "${pkgname}" "${provide}" "${ver[$pkgname]}" "${verarch[$provide]}"
				fi
			fi
		done
	else
		msg "Could not find candidate to compare %s" "${pkgname}"
	fi
}

usage() {
	print "Usage: %q [-n|-h]" "$cmd"
	print 'Show [libre] packages that need to be updated from Arch repositories.'
	echo
	prose "The default mode of operation is to download/update all necessary
	       files for comparison, but not compare them.  Specify the \`-n\`
	       flag to not download anything, but to compare already downloaded
	       files."
	echo
	print 'Options:'
	flag '-n' "Don't update anything, just compare already downloaded files."
	flag '-h' 'Show this message'
}

main() {
	local UPDATE=1
	local arg
	for arg in "$@"; do
		case "$arg" in
			-n) UPDATE=0;;
			-h) usage; return 0;;
			*)
				error "Bad arguments. Nothing done."
				usage >&2
				return 1
				;;
		esac
	done

	if (( $UPDATE )) ; then
		if [[ $EUID != 0 ]]; then
			die "To initialize $name or update %s pacman databases, the script must be run as root. Nothing done." "$name"
		fi

		if ! [[ -d "$baseconfpath" && -d "$basedbpath" && -d "$dbpath" && -d "$dbpatharch" && -e "${conffile}" && -e "${conffilearch}" && -e "${mirrorlist}" && -e  "${mirrorlist}" ]]; then
			msg "%s files are missing. Initializing." "${name}"
			init=1
		fi

		createdir "$baseconfpath"
		createdir "$basedbpath"
		createdir "$dbpath"
		createdir "$dbpatharch"

		downloadfile "${conffile}" "https://projects.parabola.nu/abslibre.git/plain/libre/pacman/pacman.conf.x86_64" \
			"Downloading Parabola %q" pacman.conf

		downloadfile "${conffilearch}" "https://projects.archlinux.org/svntogit/packages.git/plain/pacman/trunk/pacman.conf.x86_64" \
			"Downloading Arch %q" pacman.conf
		if [[ $? == 255 ]] ; then
			msg "Setting Arch mirrorlist file in %q" "${conffilearch}"
			sed -i "s|/etc/pacman\.d/mirrorlist$|$baseconfpath/mirrorlist.archlinux|" "${conffilearch}"
		fi

		downloadfile "${mirrorlist}" "https://repo.parabola.nu/mirrorlist.txt" \
			"Downloading Parabola %q" mirrorlist
		if [[ $? == 255 ]] ; then
			sed -i 's|^Server|#Server|' "${mirrorlist}"
			setmirror "Parabola" "$mirror" "$mirrorlist"
		fi

		downloadfile "${mirrorlistarch}" "https://projects.archlinux.org/svntogit/packages.git/plain/pacman-mirrorlist/trunk/mirrorlist" \
			"Downloading Arch %q" mirrorlist
		if [[ $? == 255 ]] ; then
			setmirror "Arch" "$mirrorarch" "$mirrorlistarch"
		fi

		msg "Synchronizing %s pacman databases for Parabola" "$name"
		pacman --config "${conffile}" -b "${dbpath}" -Sy || die "Failed to synchronize pacman database for Parabola. Exiting."

		msg "Synchronizing %s pacman databases for Arch" "$name"
		pacman --config "${conffilearch}" -b "${dbpatharch}" -Sy || die "Failed to synchronize pacman database for Arch. Exiting."

		msg "%s pacman databases are updated. %s is ready. Run %q -n to print results." "$name" "$name" "$cmd"
		return 0
	else
		filenotfound "${dbpath}"
		filenotfound "${dbpatharch}"
		filenotfound "${conffile}"
		filenotfound "${conffilearch}"
		filenotfound "${mirrorlist}"
		filenotfound "${mirrorlistarch}"
	fi

	unset provides ver verarch
	declare -gA provides ver verarch

	while read -a line; do
		verarch["${line[0]}"]="${line[1]}"
	done < <(pacman --dbpath "${dbpatharch}" --config "${conffilearch}" -Ss | grep -v '^ ' | awk -F/ '{print $2}')

	while read -a line; do
		ver[${line[0]}]="${line[1]}"
		provides[${line[0]}]="${line[@]:2}"
		pkgname=${line[0]}
		comparepkgs
	done < <(expac -b "${dbpath}" -c "${conffile}" -Ss '%r/%n %v %S' | awk -F/ '$1 == "libre" {print $2}')
}

main "$@"