#!/bin/sh

#
# When tagging the candidate branch, and commit "A"
# has gone onto a topic branch that we previously
# merged, reject the tag.
#
# * -- * -- * -- A   topic A
#  \        \
#   * -- *           topic B
#          \ \
#            *       candidate
#
# We want to detect A when trying to tag candidate.
#
# This also implements candidate protection, e.g.
# only merges are allowed on candidate branches.

# Command line
refname="$1"
oldrev="$2"
newrev="$3"

echo "updating $refname $oldrev $newrev"
fail=0

case "$refname" in
	refs/tags/*)
		# First make sure stable hasn't moved on us
		baserev=$(git merge-base stable $newrev)
		stablerev=$(git rev-parse stable)
		if [ "$baserev" != "$stablerev" ] ; then
			echo "----------------------------------------------------"
			echo
			echo " Rejecting $refname because you need to merge:"
			echo
			git rev-list "$baserev..$stablerev" | xargs git name-rev
			echo
			echo "----------------------------------------------------"
			fail=1
		else

			# Now go back to stable and iterate through looking for commits on
			# our merge parents that are not within us
			git rev-list --first-parent "stable..$newrev" | while read commit ; do
				number_of_parents=$(git rev-list -n 1 --parents $commit | sed 's/ /\n/g' | grep -v $commit | wc -l)
				if [[ $number_of_parents > 1 ]] ; then
					# For each parent
					git rev-list --no-walk --parents $commit | sed 's/ /\n/g' | grep -v $commit | while read parent ; do
						# Does this parent have any children besides us?
						#
						# List the parents of all branch commits (after stable/parent), find
						# those that include our parent, get their sha1, remove our merge
						git rev-list --parents --branches ^stable "^$parent" | grep $parent | gawk '{print $1}' | grep -v $commit | while read child ; do
							number_missing=$(git rev-list "$child" "^$newrev" | wc -l)
							if [[ $number_missing > 0 ]] ; then
								echo "----------------------------------------------------"
								echo
								echo " Rejecting $refname because you need to merge:"
								echo
								git rev-list "$child" "^$newrev" | xargs git name-rev
								echo
								echo "----------------------------------------------------"
								fail=1
							fi
						done

						# Find any commits in the parent (and another branch) but not us--that means we need it
						# number_missing=$(git rev-list "$parent" --all "^$newrev" | wc -l)
						# if [[ $number_missing > 0 ]] ; then
						# 	echo "----------------------------------------------------"
						# 	echo
						# 	echo " Rejecting $refname because you need to merge:"
						# 	echo
						# 	git rev-list "$parent" --all "^$newrev" | xargs git name-rev
						# 	echo
						# 	echo "----------------------------------------------------"
						# 	exit 1
						# fi
					done
				fi
			done

		fi
		;;

	refs/heads/candidate*)
		# Look at commits between stable and us--ignoring those brought in by merges
		git rev-list --first-parent "$newrev" ^stable | while read commit ; do
			number_of_parents=$(git rev-list -n 1 --parents $commit | sed 's/ /\n/g' | grep -v $commit | wc -l)
			if [[ $number_of_parents == 1 ]] ; then
				echo "----------------------------------------------------"
				echo
				echo " Candidate branches must be only merges"
				echo
				echo "----------------------------------------------------"
				fail=1
			fi
		done
		;;

	*)
		;;
esac

exit "$fail"