#!/bin/bash
#
#   pkgdelta - create delta files for use with pacman and repo-add
#   @configure_input@
#
#   Copyright (c) 2009 Xavier Chantry <shiningxc@gmail.com>
#
#   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 2 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/>.
#

# bash options
set -o errexit

# gettext initialization
export TEXTDOMAIN='pacman-scripts'
export TEXTDOMAINDIR='@localedir@'

declare -r myver='@PACKAGE_VERSION@'

QUIET=0

# minimal of package before deltas are generated (bytes)
min_pkg_size=$((1024*1024))

# percent of new package above which the delta will be discarded
max_delta_size=70


# ensure we have a sane umask set
umask 0022

m4_include(library/output_format.sh)

# print usage instructions
usage() {
	printf "pkgdelta (pacman) %s\n\n" "$myver"
	printf -- "$(gettext "Usage: pkgdelta [options] <package1> <package2>\n")"
	printf -- "$(gettext "\
	pkgdelta will create a delta file between two packages.\n\
This delta file can then be added to a database using repo-add.\n\n")"
	printf -- "$(gettext "Example:  pkgdelta pacman-3.0.0.pkg.tar.gz pacman-3.0.1.pkg.tar.gz")\n"
	echo
	printf -- "$(gettext "Options:\n")"
	printf -- "  -q                ""$(gettext "quiet\n")"
	printf -- "  --min-pkg-size    ""$(gettext "minimal of package before deltas are generated (bytes)\n")"
	printf -- "  --max-delta-size  ""$(gettext "percent of new package above which the delta will be discarded\n")"
}

version() {
	printf "pkgdelta (pacman) %s\n\n" "$myver"
	printf -- "$(gettext "\
Copyright (c) 2009 Xavier Chantry <shiningxc@gmail.com>.\n\n\
This is free software; see the source for copying conditions.\n\
There is NO WARRANTY, to the extent permitted by law.\n")"
}

isnumeric() {
	[[ $1 != *[!0-9]* ]]
}

read_pkginfo()
{
	pkgname= pkgver= arch=
	local OLDIFS=$IFS
	# IFS (field separator) is only the newline character
	IFS="
"
	local line var val
	for line in $(bsdtar -xOqf "$1" .PKGINFO 2>/dev/null |
		grep -v "^#" | sed 's|\(\w*\)\s*=\s*\(.*\)|\1="\2"|'); do
		eval "$line"
		if [[ -n $pkgname && -n $pkgver && -n $arch ]]; then
			IFS=$OLDIFS
			return 0
		fi
	done
	IFS=$OLDIFS
	error "$(gettext "Invalid package file '%s'.")" "$1"
	return 1
}

# $oldfile $oldmd5 $newfile $newmd5 $deltafile $deltamd5 $deltasize
create_xdelta()
{
	local oldfile=$1
	local newfile=$2
	local \
	oldname oldver oldarch \
	newname newver newarch \
	deltafile

	read_pkginfo "$oldfile" || return 1
	oldname="$pkgname"
	oldver="$pkgver"
	oldarch="$arch"
	read_pkginfo "$newfile" || return 1
	newname="$pkgname"
	newver="$pkgver"
	newarch="$arch"

	pkgsize="$(@SIZECMD@ -L "$newfile")"

	if ((pkgsize < min_pkg_size)); then
		msg "$(gettext "Skipping delta creation for small package: %s - size %s")" "$newname" "$pkgsize"
		return 0
	fi

	if [[ $oldname != "$newname" ]]; then
		error "$(gettext "The package names don't match : '%s' and '%s'")" "$oldname" "$newname"
		return 1
	fi

	if [[ $oldarch != "$newarch" ]]; then
		error "$(gettext "The package architectures don't match : '%s' and '%s'")" "$oldarch" "$newarch"
		return 1
	fi

	if [[ $oldver == "$newver" ]]; then
		error "$(gettext "Both packages have the same version : '%s'")" "$newver"
		return 1
	fi

	msg "$(gettext "Generating delta from version %s to version %s")" "$oldver" "$newver"
	deltafile=$(dirname "$newfile")/$pkgname-${oldver}_to_${newver}-$arch.delta
	local ret=0

	xdelta3 -q -f -s "$oldfile" "$newfile" "$deltafile" || ret=$?
	if (( ret )); then
		error "$(gettext "Delta could not be created.")"
		return 1
	fi

	deltasize="$(@SIZECMD@ -L "$deltafile")"

	if ((max_delta_size * pkgsize / 100 < deltasize)); then
		msg "$(gettext "Delta package larger than maximum size. Removing.")"
		rm -f "$deltafile"
		return 0
	fi

	msg "$(gettext "Generated delta : '%s'")" "$deltafile"
	(( QUIET )) && echo "$deltafile"

	return 0
}

declare -a args

# parse arguments
while (( $# )); do
	case "$1" in
		-h|--help)    usage; exit 0 ;;
		-V|--version) version; exit 0 ;;
		-q|--quiet) QUIET=1;;
		--min-pkg-size)
			if ! isnumeric "$2"; then
				echo "invalid argument '$2' for option -- '$1'"
				exit 1
			fi
			min_pkg_size=$2
			shift
			;;
		--max-delta-size)
			arg=$(echo "$2" | awk '{print $1 * 100}')
			if ! isnumeric "$arg" || (($arg > 200)); then
				echo "invalid argument '$2' for option -- '$1'"
				exit 1
			fi
			max_delta_size=$arg
			shift
			;;
		--) shift; args+=("$@"); break 2 ;;
		-*) echo "invalid option -- '$1'"; usage; exit 1 ;;
		*) args+=("$1");;
	esac
	shift
done

if (( ${#args[@]} != 2 )); then
	usage
	exit 1
fi

for i in "${args[@]}"; do
	if [[ ! -f $i ]]; then
		error "$(gettext "File '%s' does not exist")" "$i"
		exit 1
	fi
done

if ! type xdelta3 &>/dev/null; then
	error "$(gettext "Cannot find the xdelta3 binary! Is xdelta3 installed?")"
	exit 1
fi

create_xdelta "${args[@]}"

# vim: set ts=2 sw=2 noet: