#!/bin/bash 

set -e

length=50

die() {
	echo "E: $@" >&2
	exit 1
}

warn() {
	echo "W: $@" >&2
}

uncompress_patch() {
	patch=$1
	case "$patch" in
		*.bz2) bzcat $patch ;;
		*.gz) zcat $patch ;;
		*) cat $patch ;;
	esac
}

find_patch() {
	patch=$1

	if [ -f "$patch" ]; then
		echo "$patch"
	elif [ -f "$patch.bz2" ]; then
		echo "$patch.bz2"
	elif [ -f "$patch.gz" ]; then
		echo "$patch.gz"
	else
		die "$patch is in the series, but doesn't exist!"
	fi
}
		
apply_patch() {
	patch=$(find_patch $home/$1)
	base=$1
	if uncompress_patch "$patch" | patch -p1 --fuzz=1 -f -s -t --no-backup-if-mismatch; then
		printf "%-${length}s\tOK (+)\n" "$base"
	else
		printf "%-${length}s\tFAIL (+)\n" "$base"
		exit 1
	fi
}

deapply_patch() {
	patch=$(find_patch $home/$1)
	base=$1
	if uncompress_patch "$patch" | patch -p1 -f -s -t -R --no-backup-if-mismatch; then
		printf "%-${length}s\tOK (-)\n" "$base"
	else
		printf "%-${length}s\tFAIL (-)\n" "$base"
		exit 1
	fi
}

unpatch_series() {
	series=$1

	tac $series | while read action patch; do
		case "$action" in
			+) deapply_patch $patch ;;
			-) apply_patch $patch ;;
			X)
				bakfile="$(dirname $patch)/.$(basename $patch).bak"
				if [ -f "$bakfile" ]; then
					mv -f "$bakfile" "$patch"
					printf "%-${length}s\tRESTORED (X)\n" "$patch"
				else
					printf "%-${length}s\tNO BACKUP (X)\n" "$patch"
				fi
			;;
		esac
	done 
	echo "--> $(basename $series) fully unapplied."
}

patch_series() {
	series=$1
	[ -f "$series" ] || return

	while read action patch; do
		case "$action" in
			+) apply_patch $patch ;;
			-) deapply_patch $patch ;;
			X)
				bakfile="$(dirname $patch)/.$(basename $patch).bak"
				if [ -f "$patch" ]; then
					mv -f "$patch" "$bakfile"
					printf "%-${length}s\tREMOVED (X)\n" "$patch"
				else
					printf "%-${length}s\tNO FILE (X)\n" "$patch"
				fi
			;;
		esac
	done < $series
	echo "--> $(basename $series) fully applied."
}

if ! [ -d Documentation ] || ! [ -d kernel ]; then
	die 'Not in kernel top level directory.  Exiting'
	exit 1
fi

# for THIS particular version of the source package
version=${override_version:-@version@}
revision=$(echo $version | sed -ne 's,^\(.*\)-\([^-]*\)$,\2,p')
upstream=$(echo $version | sed -ne 's,^\(.*\)-\([^-]*\)$,\1,p')
revisions_count=0
for i in ${override_revisions:-@revisions@}; do
    revisions[$revisions_count]=$i
	revisions_count=$(($revisions_count + 1))
done

home=${home:-/usr/src/kernel-patches/all/$upstream/debian}

if [ -f version.Debian ]; then
	current=$(cat version.Debian)
    current_rev=$(echo $current | sed -ne 's,^\(.*\)-\([^-]*\)$,\2,p')
    current_up=$(echo $current | sed -ne 's,^\(.*\)-\([^-]*\)$,\1,p')

	if [ "$current" = "$upstream" ]; then
		current_rev=0
	fi
else
	warn "No version.Debian file, assuming pristine Linux $upstream"
	current=$upstream
	current_rev=0
fi

target=${1:-$version}

target_rev=$(echo $target | sed -ne 's,^\(.*\)-\([^-]*\)$,\2,p')
target_up=$(echo $target | sed -ne 's,^\(.*\)-\([^-]*\)$,\1,p')

# Sanity checks
if dpkg --compare-versions "$target_up" ne "$upstream"; then
	die "Upstream $target_up doesn't match $upstream!"
# We don't have that version out yet!
elif [ ! -n "$target_rev" ] || 
		( dpkg --compare-versions "$target_rev" ne "$target" && 
			dpkg --compare-versions "$target_rev" gt "$revision" ); then
	year=$(($(date +%Y) + 1))
	die "Can't patch to nonexistent revision $target_rev (wait until $year)"
fi

# At this point, we must handle three cases.
# 1. $target_rev is greater than $current_rev. We must patch forward for this.
# 2. $target_rev is less than $current_rev. We must reverse the list of series,
#    reverse each used series (tac) and unapply applied patches and vice versa.
# 3. $target_rev is undefined, and $target is $upstream.

if dpkg --compare-versions "$target_rev" eq "$current_rev"; then
	echo "Nothing to do, exiting."
	exit 0
else
	cur_index=$revisions_count
	while [ $cur_index -gt 0 ]; do
		[ ${revisions[$(($cur_index - 1))]} == $current_rev ] && break
		cur_index=$(($cur_index - 1))
	done
	target_index=$revisions_count
	while [ $target_index -gt 0 ]; do
		[ ${revisions[$(($target_index - 1))]} == $target_rev ] && break
		target_index=$(($target_index - 1))
	done
	if [ $target_index -gt $cur_index ]; then
		while [ $target_index -gt $cur_index ]; do
			series="$home/series/${upstream}-${revisions[$cur_index]}"
			[ -f "$series" ] && patch_series $series
			cur_index=$(($cur_index + 1))
		done
	elif [ $target_index -lt $cur_index ]; then
		while [ $target_index -lt $cur_index ]; do
			cur_index=$(($cur_index - 1))
			series="$home/series/${upstream}-${revisions[$cur_index]}"
			[ -f "$series" ] && unpatch_series $series
		done
	fi
fi

echo $target > version.Debian

# vim:noet:ai:ts=4