#!/bin/sh

# Post merge hook to automerge branch to branches which

vercomp () {
    if [[ $1 == $2 ]]
    then
        return 0
    fi
    local IFS=.
    local i ver1=($1) ver2=($2)
    # fill empty fields in ver1 with zeros
    for ((i=${#ver1[@]}; i<${#ver2[@]}; i++))
    do
        ver1[i]=0
    done
    for ((i=0; i<${#ver1[@]}; i++))
    do
        if [[ -z ${ver2[i]} ]]
        then
            # fill empty fields in ver2 with zeros
            ver2[i]=0
        fi
        if ((10#${ver1[i]} > 10#${ver2[i]}))
        then
            return 1
        fi
        if ((10#${ver1[i]} < 10#${ver2[i]}))
        then
            return 2
        fi
    done
    return 0
}


PATTERN='release/*'

CURRENT_BRANCH=$(git rev-parse --abbrev-ref HEAD)
LAST_COMMIT=$(git rev-list -1 HEAD)

#echo $CURRENT_BRANCH
#echo $LAST_COMMIT

# Get current branch version, exit if no match (no release branch)
if [[ $CURRENT_BRANCH =~ ^release\/v?([0-9\.]+)$ ]]; then
	CURRENT_VERSION=${BASH_REMATCH[1]}
else
	echo 'Current branch does not match pattern.';
	exit 0;
fi

# Find first next version in all branches
# Loop through all branches and compare each item to current and next versions
eval "$(git for-each-ref --shell --format='branches+=(%(refname:strip=2))' refs/heads/)"
for branch in "${branches[@]}"; do
	if [[ $branch =~ ^release\/v?([0-9\.]+)$ ]]; then
		version=${BASH_REMATCH[1]}

		# is branch version greater then current version? Should be 1
		vercomp $version $CURRENT_VERSION
		current_comp=$?

		# is branch version lower then current next version? Should be 2
		vercomp $version $NEXT_VERSION
		next_comp=$?

		if [[ $current_comp = 1 && ( $next_comp = 2 || -z "$NEXT_VERSION" ) ]]; then
			NEXT_VERSION=$version
			NEXT_BRANCH=$branch
		fi
	fi
done
echo "Next version after $CURRENT_VERSION is $NEXT_VERSION"


# Now merge branch to new next branch
#
if [[ -n "$NEXT_VERSION" ]]; then
	git checkout $NEXT_VERSION && git merge $LAST_COMMIT
	git checkout $CURRENT_BRANCH
fi