#!/bin/bash

# 
# Commit patches from --spec file to git (in the curret working directory).
#
# Example:
#
#  1) clone upstrem reporitory
#     git clone git://git.kernel.org/pub/scm/utils/util-linux/util-linux.git
#
#  2) create a branch based on the same version as tarball version in your .spec file
#     git checkout -f -b rhel v2.23.2
#
#  3) create tag to remember the start point
#     git tag rhel-7-start
#
#  4) apply patches from 7.0
#     spec2git --spec /path/to/rhel/dist-git/util-linux.spec --from 0 --to 22
#
#  5) add tag to remember 7.0 (7.1, 7.2, ...)
#     git tag rhel-7.0
#
#  n) repeat 4) and 5) for each version, don't forget to update --from and --to according your spec file
#
# Notes:
#
#  * spec2git expects these lines in your spec file:
#    
#    # 123456 - description of the bug
#    Patch0: filename.patch
#
#  it means comment with relevant information before Patch<n>: 
#


TEMP=$(getopt -o f:t:p:s:e: --long patch:,spec:,from:,to:,extra: -n 'spec2git' -- "$@")

BASE=""
PATCH_NUM=""
PATCH_FROM=""
PATCH_TO=""
SPEC_FILE=""
FORCE_EDIT=""
n_patches=0

declare -a PATCHES
declare -a COMMENTS

bold=$(tput setaf 3)
normal=$(tput sgr0)

function die() {
	echo "$1"
	exit 0
}

function add_to_array() {
	local -n a=$1
	local idx=$2
	a[$idx]=$3
}

function patch_get_filename() {
	local -n a=PATCHES
	echo "${a[$1]}"
}

function patch_get_comment() {
	local -n a=COMMENTS
	echo "${a[$1]}" | sed 's/^# [0-9]*[[:blank:]]*-[[:blank:]]*//'
}

function patch_get_bz() {
	local -n a=COMMENTS
	echo "${a[$1]}" | sed 's/# \([0-9]*\).*/\1/'
}

function filename_to_commit_subject() {
	local name="$1"
	echo $name | sed 's/\.patch$//; s/-/ /g; s/^[0-9\. ]*//; s/ /\: /'
}

function bz_to_url() {
	echo "Addresses: http://bugzilla.redhat.com/show_bug.cgi?id=$1"
}

function cmd_git_commit() {
	local i=$1
	local bz=$(patch_get_bz $i)
	local file="$(patch_get_filename $i)"
	local comm="$(patch_get_comment $i)"
	local subj="$(filename_to_commit_subject $file)"
	local url="$(bz_to_url $bz)"

	for x in $(get_new_files); do
		echo "*** Add new file: $x"
		git add $x
	done

	git commit -a -m "$subj" -m "$comm" -m "$url" ${GIT_COMMIT_EXTRA}
}

function get_patch_desc() {
	local num="$1"
	local patch
	local comment

	while read line; do
		case "$line" in
			--) ;;	# ignore, empty line
			\#*)    comment="$line" ;;
			Patch*) patch="$(echo "$line" | sed 's/Patch[0-9]*\://; s/[[:blank:]]//g')" ;;
		esac
	done < <(grep -B 1 -E "^Patch$num\: .*\.patch" ${SPEC_FILE})		

	if [ -n "$patch" ]; then
		add_to_array PATCHES $n_patches "$patch"
		add_to_array COMMENTS $n_patches "$comment"
		n_patches=$(($n_patches + 1))
	fi
}

function apply_patch() {
	local file=$(patch_get_filename $1)

	patch -p1 < ${BASE}/$file
}

function get_new_files() {
	git ls-files -o
}

#
# main()
#
eval set -- "$TEMP"
while true ; do
	case "$1" in
		-p|--patch) PATCH_NUM="$2" ; shift 2 ;;
		-s|--spec)  SPEC_FILE="$2" ; shift 2 ;;
		-f|--from)  PATCH_FROM="$2" ; shift 2 ;;
		-e|--extra) GIT_COMMIT_EXTRA="$2"; shift 2 ;;
		-t|--to)    PATCH_TO="$2" ; shift 2 ;;
		--) shift ; break ;;
		*) echo "Internal error!" ; exit 1 ;;
	esac
done

[ -z "$SPEC_FILE" ] && die "No spec file specified (use --spec <path>)."
BASE="$(dirname $SPEC_FILE)"

NFILES=$(get_new_files)
[ -n "$NFILES" ] && die "Current working direcory is dirty, use 'git clean -xdf'"

if [ -n "$PATCH_NUM" ]; then
	get_patch_desc $PATCH_NUM

elif [ -n "$PATCH_FROM" -o -n "$PATCH_TO" ]; then

	[ -z "$PATCH_TO" ]   && die "use --from together with --to"
	[ -z "$PATCH_FROM" ] && die "use --to together with --from"

	for n in $(seq $PATCH_FROM $PATCH_TO); do
		get_patch_desc $n
	done
fi

[ $n_patches -eq 0 ] && die "Not found patches."

for i in $(seq 0 $(($n_patches - 1))); do
	echo "${bold}$(patch_get_filename $i)${normal}"
	apply_patch $i
	cmd_git_commit $i
	echo
done