#!/usr/bin/env bash
# libredbdiff
#
# Copyright (C) 2014 Esteban Carnevale <alfplayer@mailoo.org>
# Copyright (C) 2014, 2017 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/>.

. "$(librelib messages)"
. "$(librelib conf)"
load_files libredbdiff || exit 1

conffile_prbl="$statedir/pacman.conf.parabola"
conffile_arch="$statedir/pacman.conf.archlinux"

dbpath_prbl="$statedir/pacman.parabola"
dbpath_arch="$statedir/pacman.archlinux"

mirrorlist_prbl="$statedir/mirrorlist.parabola"
mirrorlist_arch="$statedir/mirrorlist.archlinux"

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

field_pkgname_prbl=30
field_pkgname_arch=30
field_pkgname_total="$((field_pkgname_prbl + field_pkgname_arch))"

printf_format="%s  %-${field_pkgname_prbl}s%-${field_pkgname_arch}s   %s | %s\n"
printf_format_noarch="%s  %-${field_pkgname_total}s   %s\n"

enablerepo() {
	local repo="$1"
	local conffile_arg="$2"

	msg2 "Enabling repo %q in %q" "$repo" "$conffile_arg"
	sed -i "s/\#\[$repo\]/[$repo]/" "$conffile_arg"
	sed -i "\/\[$repo\]/,+1 s/#Include/Include/" "$conffile_arg"
}

createdir() {
	local dir=$1

	if ! [[ -d "$dir" ]] ; then
		msg "Creating directory %q" "$dir"
		mkdir -- "$dir" || die "Failed to create directory %q.  Exiting." "$dir"
	fi
}

# {{ A -lt B }} is like [ A -lt B ], but for pacman version numbers
{{() {
	  [[ $# = 4 ]] || panic
	  [[ $4 = '}}' ]] || panic
	  local a=$1
	  local op=$2
	  local b=$3

	  local cmp
	  cmp="$(vercmp "$a" "$b")" || die "vercmp failed"
	  [ "$cmp" "$op" 0 ]
}

# Globals:
#  - pkgname  : the Parabola pkgname
#  - ver_prbl : a map of pkgname->arch_pkgver
#  - ver_arch : a map of pkgname->prbl_pkgver
#  - provides : a map of pkgname->provides
compare_pkgs() {
	if [[ -n "${ver_arch[$pkgname]}" ]] ; then
		if {{ "${ver_prbl[$pkgname]}" -lt "${ver_arch[$pkgname]}" }}; then
			printf "$printf_format" \
				'=' \
				"$pkgname" \
				"" \
				"${ver_prbl[$pkgname]}" \
				"${ver_arch[$pkgname]}"
		fi
	elif [[ -n "${provides[$pkgname]}" ]]; then
		local _provides provide
		read -r -a _provides <<<"${provides[$pkgname]}"
		for provide in "${_provides[@]}"; do
			if [[ -n "${ver_arch[$provide]}" ]]; then
				if {{ "${ver_prbl[$pkgname]}" -lt "${ver_arch[$provide]}" }}; then
					printf "$printf_format" \
						'p' \
						"$pkgname" \
						"$provide" \
						"${ver_prbl[$pkgname]}" \
						"${ver_arch[$provide]}"
				fi
			fi
		done
	else
		printf "$printf_format_noarch" \
			'o' \
			"$pkgname" \
			"${ver_prbl[$pkgname]}"
	fi
}

# Globals:
#  - prbl_packages_tmp
#  - ver_prbl
#  - ver_arch (transitively through compare_pkgs)
#  - provides
print_cmp() {
	local repo="$1"

	< "$prbl_packages_tmp" \
		awk -F/ -v repo="$repo" '$1 == repo {print $2}' |
		while read -a line ; do
			ver_prbl["${line[0]}"]="${line[1]}"
			provides["${line[0]}"]="${line[*]:2}"
			pkgname="${line[0]}"
			compare_pkgs
		done
}

usage() {
	print "Usage: sudo %q" "$cmd"
	print "   or: %q -n [REPO]" "$cmd"
	print "   or: %q -h" "$cmd"
	print 'Show packages that need to be updated from Arch repositories.'
	echo
	prose "Compares packages in Parabola repositories.  Packages from
	       all configured Parabola repositories are compared.  A Parabola
	       repository name can be specified as argument to compare only
	       packages in that repository."
	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
	prose "In the compare mode (if the \`-n\` flag is given), by default it
	       will iterate over each of the configured repositories, prefixing
	       each section with a line in the format \`[REPO]\`.  However, if a
	       REPO is specified on the command line, it scan for packages only
	       in that repository, and no \`[REPO]\` line will be printed."
	echo
	print 'Options:'
	flag '-n' "Don't update anything, just compare already downloaded files."
	flag '-h' 'Show this message'
	echo
	print "Output format:"
	print "type_character  parabola_pkgname  (arch_pkgname)   parabola_pkgver - (arch_pkgver)"
	echo
	print "Type characters:"
	flag '=' "Arch package with the same pkgname and greater pkgver was found"
	flag 'p' "Arch package with pkgname equal to a provide and greater
	          pkgver was found In this case arch_pkgname is a provide of
	          parabola_pkgname"
	flag 'o' "No Arch package with the same pkgname or with pkgname equal to
	          a provide was found"
}

main() {
	local args arg mode=update badargs=false
	args="$(getopt -n "$cmd" -o nh -l noupdate,help -- "$@")" || badargs=true
	eval "set -- $args"
	while [[ $# -gt 0 ]]; do
		arg=$1
		shift
		case "$arg" in
			-n|--noupdate)
				mode=compare
				;;
			-h|--help)
				usage
				return 0
				;;
			--)
				break
				;;
		esac
	done
	if $badargs; then
		usage >&2
		return 2
	fi

	case $mode in
		update)
			if [[ $# -gt 0 ]]; then
				print "%s: found non-flag arguments; a repo list may only be specified with the -n flag: %s" "$cmd" "$*" >&2
				usage >&2
				return 2
			fi
			main_update
			;;
		compare)
			if [[ $# -gt 1 ]]; then
				print "%s: found too many non-flag arguments; only one repo may be specified: %s" "$cmd" "$*" >&2
				usage >&2
				return 2
			fi
			if [[ $# = 1 ]]; then
				if ! in_array "$1" "${repos[@]}"; then
					die "The specified Parabola repo \"%s\" cannot be compared.  It's not in the list of repos in the configuration variable \"repos\"." "$1"
				fi
			fi
			main_compare "$@"
			;;
	esac
}

main_update() {
	if [[ $EUID != 0 ]]; then
		die "To initialize %s or update %s pacman databases, %s must be run as root (without arguments).  Nothing done." \
		    "$name" \
		    "$name" \
		    "$cmd"
	fi
	check_vars libredbdiff statedir mirror_prbl mirror_arch || exit 1

	createdir "$statedir"
	{
		msg "Generating %s %q" Parabola pacman.conf
		cp -T /usr/share/pacman/defaults/pacman.conf.x86_64 "$conffile_prbl"
		sed -r \
		    -e "s|/etc/pacman\.d/mirrorlist$|$mirrorlist_prbl|" \
		    -e "s|^#?DBPath\s*=.*|DBPath = $dbpath_prbl|" \
		    -e "s|^#?Architecture\s*=.*|Architecture = x86_64|" \
		    -i "$conffile_prbl"
		local repo
		for repo in multilib {libre,pcr,nonprism}{,-multilib}; do
			enablerepo "$repo" "$conffile_prbl"
		done

		msg "Generating %s %q" Arch pacman.conf
		wget -q \
		     -O "$conffile_arch" \
		     "https://git.archlinux.org/svntogit/packages.git/plain/pacman/repos/core-x86_64/pacman.conf.x86_64" ||
			die "Failed to download %q.  Exiting." "$conffile_arch"
		sed -r \
		    -e "s|/etc/pacman\.d/mirrorlist$|$mirrorlist_arch|" \
		    -e "s|^#?DBPath\s*=.*|DBPath = $dbpath_arch|" \
		    -e "s|^#?Architecture\s*=.*|Architecture = x86_64|" \
		    -i "$conffile_arch"
		enablerepo multilib "$conffile_arch"

		printf 'Server = %s\n' "$mirror_prbl" > "$mirrorlist_prbl"

		printf 'Server = %s\n' "$mirror_arch" > "$mirrorlist_arch"
	}

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

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

	msg "%s pacman databases are updated.  %s is ready.  Run %q -n to print results." \
	    "$name" "$name" "$cmd"
}

main_compare() {
	check_vars libredbdiff statedir repos || exit 1

	local conffiles=(
		"$dbpath_prbl/sync/libre.db"
		"$dbpath_arch/sync/core.db"
		"$conffile_prbl"
		"$conffile_arch"
	)
	local file
	for file in "${conffiles[@]}"; do
		if ! [[ -f "$file" && -r "$file" ]]; then
			error "Could not read %q." "$file"
			die "Nothing done.  It may be necessary to run %q without \
arguments as root to initialize %s." "$cmd" "$name"
		fi
	done

	local tmpdir
	tmpdir="$(mktemp --tmpdir -d "$cmd.XXXXXXXXXX")" || die "Could not create temporary working directory"
	trap "rm -rf -- $(printf %q "$tmpdir")" RETURN
	local arch_packages_tmp="$tmpdir/arch-packages"
	local prbl_packages_tmp="$tmpdir/parabola-packages"

	unset provides ver_prbl ver_arch
	declare -gA provides ver_prbl ver_arch

	expac --config "$conffile_arch" -S '%n %v' \
		> "$arch_packages_tmp" || \
		die "expac command to get %s package data has failed.  Exiting." Arch

	local pkgname pkgver
	while read -r pkgname pkgver; do
		ver_arch["$pkgname"]="$pkgver"
	done < "$arch_packages_tmp"

	expac --config "$conffile_prbl" -S '%r/%n %v %S' \
		> "$prbl_packages_tmp" || \
		die "expac command to get %s package data has failed.  Exiting." Parabola

	if [[ $# == 1 ]]; then
		print_cmp "$1"
	else
		for repo in "${repos[@]}" ; do
			echo "[$repo]"
			print_cmp "$repo"
		done
	fi
}

main "$@"