#!/bin/sh

clean= next=next
branch=`git symbolic-ref HEAD`
while case $# in 0) break ;; esac
do
	case "$1" in
	--clean)
		test refs/heads/master = "$branch" || {
			echo >&2 Not on master 
			exit 1
		}
		clean=t
		;;
	--next)
		test 2 -le $# || {
			echo >&2 "Need argument"
			exit 1
		}
		next="$2"
		git rev-parse --verify "$next" >/dev/null || exit
		shift
		;;
	*)
		echo >&2 "$0 [--clean | --next test-next ]"
		exit 1
		;;
	esac
	shift
done

master_sha1=`git rev-parse --verify refs/heads/master`
LF='
'
(cd .git/refs/heads && find -type f) |
sed -n \
    -e 's/^\.\///' \
    -e '/^[^\/][^\/]\//p' |
sort |
while read topic
do
	rebase= done= not_done= trouble= date=
	topic_sha1=`git rev-parse --verify "refs/heads/$topic"`
	is_current=
	if test "refs/heads/$topic" = "$branch"
	then
		is_current=" *"
	fi

	date=`
		git-rev-list -1 --pretty "$topic" |
		sed -ne 's/^Date: *\(.*\)/ (\1)/p'
	`
	# (1)
	only_next_1=`git-rev-list ^master "^$topic" ${next} | sort`
	only_next_2=`git-rev-list ^master           ${next} | sort`
	if test "$only_next_1" = "$only_next_2"
	then
		not_in_topic=`git-rev-list "^$topic" master`
		if test -z "$not_in_topic"
		then
			rebase=" (vanilla)"
		else
			rebase=" (can be rebased)"
		fi
	fi

	# (2)
	not_in_master=`
		git-rev-list ^master "$topic"
	`
	test -z "$not_in_master" &&
	done="${LF}Fully merged -- delete."

	# (3)
	not_in_next=`
		git-rev-list --pretty=oneline ^${next} "$topic" |
		sed -e 's/^[0-9a-f]* / - /'
	`
	if test -n "$not_in_next"
	then
	    	if test -n "$done"
		then
			# If $topic and master are the same,
			# it is fine.
			test "$master_sha1" = "$topic_sha1" ||
			trouble="${LF}### MODIFIED AFTER COOKED ###"
		fi
		not_done="${LF}Still not merged in ${next}$rebase.$LF$not_in_next"
	elif test -n "$done"
	then
		not_done=
	else
		not_done="${LF}Up to date."
	fi

	echo "*** $topic ***$date$is_current$trouble$done$not_done"

	if test -z "$trouble$not_done" &&
	    test -n "$done" &&
	    test t = "$clean"
	then
		git branch -d "$topic"
	fi
done

exit

################################################################
Using Topic Branches

Some important disciplines first.

 * Once a topic branch forks from "master", never merge "master"
   updates into the topic branch.

 * Once a topic branch is fully cooked and merged into "master",
   delete it.  If you need to build on top of it to correct
   earlier mistakes, create a new topic branch by forking at the
   tip of the "master".  This is not strictly necessary, but it
   makes it easier to keep your history simple.

 * Whenever you need to test or publish your changes to topic
   branches, merge them into "next" branch.

So, you would want to know:

(1) ... if a topic branch has ever been merged to "next".  Young
    topic branches can have stupid mistakes you would rather
    clean up, and things that have not been merged into other
    branches can be easily rebased without affecting others.

(2) ... if a topic branch has been fully merged to "master".
    Then you can delete it.  More importantly, you can tell you
    should not build on top of it.

(3) ... if a topic branch has commits unmerged to "next".  You
    need to merge them to test and/or publish.

Let's look at this example:

		   o---o---o---o---o---o---o---o---o---o "next"
		  /       /           /           /
		 /   a---a---b A     /           /
		/   /               /           /
	       /   /   c---c---c---c B         /
	      /   /   /             \         /
	     /   /   /   b---b C     \       /
	    /   /   /   /             \     /
    ---o---o---o---o---o---o---o---o---o---o---o "master"


A, B and C are topic branches.

 * A has one fix since it was merged up to "next".

 * B has finished.  It has been fully merged up to "master" and "next",
   and is ready to be deleted.

 * C has not merged to "next" at all.

To compute (1):

	git-rev-list ^master ^topic next
	git-rev-list ^master        next

	if these match, topic has not merged in next at all.

To compute (2):

	git-rev-list master..topic

	if this is empty, it is fully merged to "master".

To compute (3):

	git-rev-list next..topic

	if this is empty, there is nothing to merge to "next".