#!/bin/bash

# Copyright 2011,2013 Peter Palfrader
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

set -u
set -e

get_bp_info() {
	local target="$1"; shift
	local key="$1"; shift

	local result=$(awk '$1 == "'"$target"'" {print}' << 'EOF'
#arg		versiontag	#tilde	changelogdist
lenny		d50.lenny	1
squeeze		d60.squeeze	1
wheezy		d70.wheezy	1

lenny-bpo	bpo50		1	lenny-backports
squeeze-bpo	bpo60		1	squeeze-backports
wheezy-bpo	bpo60		1	wheezy-backports

dapper		dapper		1
edgy		edgy		1
feisty		feisty		1
gutsy		gutsy		1
hardy		hardy		1
intrepid	intrepid	1
jaunty		jaunty		1
karmic		karmic		1
lucid		lucid		1
maverick	maverick	1
natty		natty		1
oneiric		oneiric		1
precise		precise		1
quantal		quantal		1
EOF
)
	if [ -z "$result" ] ; then
		echo >&2 "Do not now about target '$target'."
		exit 1
	fi
	set "nothing" $result
	shift
	if [ "$#" != "3" ] && [ "$#" != "4" ]; then
		echo >&2 "Bad result line for '$target': '$result'."
		exit 1
	fi
	shift
	case "$key" in
		versiontag) echo "$1" ;;
		tilde) echo "$2" ;;
		changelogdist) echo "${3:-}" ;;
		*)
			echo >&2 "Invalid key '$key'"
			exit 1
	esac
	return 0
}

if [ "$#" != "1" ]; then
	echo >&2 "Usage: $0 <backporttarget>"
	exit 1
fi

target="$1"

versiontag=$(get_bp_info "$target" versiontag)
tildenum=$(get_bp_info "$target" tilde)
tildes=""
while [ "$tildenum" -gt 0 ]; do
	tildes="$tildes~"
	tildenum=$((tildenum-1))
done
cldist=$(get_bp_info "$target" changelogdist)


currentdist=$(dpkg-parsechangelog | grep-dctrl -n -s Distribution '')
if [ -z "$currentdist" ]; then
	echo >&2 "Cannot figure out current distribution"
	exit 1
fi
currentver=$(dpkg-parsechangelog | grep-dctrl -n -s Version '')
#currentupstream="${currentver%-*}"
#currentdebian="${currentver##*-}"
newver="$currentver$tildes$versiontag+1"
if [ -z "$cldist" ]; then
	if [ "$currentdist" = "experimental" ]; then
		cldist="experimental-$target-backport"
	elif [ "$currentdist" = "unstable" ]; then
		cldist="$target-backport"
	else
		cldist="$currentdist-$target"
	fi
fi

dch \
	--newversion "$newver" --allow-lower-version . \
	--distribution "$cldist" --force-distribution \
	"Build for $cldist."