#!/bin/bash

commit=$1
[ "$commit" ] || {
	echo "$0: <commit id> [<top tag> [<linus branch>]]" 1>&2
	exit 1
}
commit=$(git rev-parse --verify "$commit")
[ "$commit" ] ||
	exit 1

top=$2
[ "$top" ] || top=HEAD

linus=$3
[ "$linus" ] || linus=origin/master

base=$(git merge-base "$linus" "$top")

git log --first-parent --reverse --pretty='format:%H %P' "$base".."$top" |
while read m p1 p2
do
	[ "$p1" = "$commit" ] && {
		echo "Directly committed"
		break
	}
	[ "$p2" ] ||
		continue
	git rev-list $base..$p2 | grep -q "$commit" || continue
	branch=$(git show $m | sed -n "s/[ 	]*Merge .*'\([^']*\)'\( of \([^ ]*\).*\)*$/\1|\3/p")
	tree=${branch##*|}
	branch=${branch%%|*}
	[ "$tree" ] || {
		tree=${branch%%/*}
		[ "$tree" = "quilt" ] && tree=${branch##*/}
		echo "$tree"
		break
	}
	echo "$tree#$branch"
	break
done

exit 0