#!/bin/bash -e

usage(){
	echo >&2 'Usage: release-branch-from-master --release <version> [ --release-suffix <suffix> ]'
	echo >&2 '                                  --master <version>  [ --master-suffix <suffix> ]'
	echo >&2 'Creates a release branch, and updates the version number in both the branch and master.'
	echo >&2 '<version> should be a two-part version number, such as 3.6 or 4.0.'
	echo >&2 '<suffix> will normally be of the form ".patchlevel", plus "-RC1" or similar if required,'
	echo >&2 'plus "-SNAPSHOT". Example: ".0.RC1-SNAPSHOT". The defaults for the suffix are normally sensible.'
	echo >&2 'This command will preview what it is going to do and require confirmation before it makes changes.'
}

release_ver=
release_ver_suffix=.0-RC1-SNAPSHOT
master_ver=
master_ver_suffix=.0-SNAPSHOT

[ $# -eq 0 ] && echo >&2 "No arguments given, so I'm going to try and figure it out myself. Invoke with the --help option if you want to find how to invoke this script."

while [ $# -gt 0 ]; do
	case $1 in
		--release)			shift; release_ver=$1;;
		--release-suffix)	shift; release_ver_suffix=$1;;
		--master)			shift; master_ver=$1;;
		--master-suffix)	shift; master_ver_suffix=$1;;
		*)					usage; exit 1;;
	esac
	shift
done

# Use xpath to query the current version number in the pom
xpath='xpath'
type -P $xpath &>/dev/null && {
	set +e
	current_version=$( xpath pom.xml '/project/version/text()' 2>/dev/null )
	( echo ${current_version} | grep -qE '^([0-9]+).([0-9]+).0-SNAPSHOT$' )
	current_version_valid=$?
	set -e 
} || { 
	echo "Cannot guess version number as $xpath command not found."
	current_version_valid=1
}

if [ "${current_version_valid}" -ne 0 -a -z "${release_ver}" -a -z "${master_ver}" ]; then
	echo >&2 "Detected current version as '${current_version}', but I can't parse this. Please supply --release and --master parameters."
	exit 1
fi

[ -z "${release_ver}" ] && {
	release_ver=${current_version%-SNAPSHOT}
	release_ver=${release_ver%.0}
	[ -z "${release_ver}" ] && { echo >&2 Could not determine the version of the release branch. Please use the --release parameter. ; exit 1 ; }
}

[ -z "${master_ver}" ] && {
	master_ver=$( echo ${current_version} | perl -n -e 'if (/^(\d+).(\d+)(.*)$/) { printf "%s.%s\n", $1, $2+1 }' )
	[ -z "${master_ver}" ] && { echo >&2 Could not determine the version of the master branch. Please use the --master parameter. ; exit 1 ; }
}

version_on_branch=${release_ver}${release_ver_suffix}
version_on_master=${master_ver}${master_ver_suffix}
branch_name=${version_on_branch}

# Show the details and get confirmation
echo "The current version is:                                  ${current_version}"
echo "The release branch will be named:                        ${branch_name}"
echo "The version number on the release branch will be set to: ${version_on_branch}"
echo "The version number on 'master' will be set to:           ${version_on_master}"
echo "If you proceed, the new branch and version number changes will be pushed to GitHub."
echo -n 'Enter "y" if this is correct, anything else to abort: '
read input
[ "$input" == "y" ] || { echo >&2 Aborted. ; exit 1 ; }

# Fail if not in a Git repository
[ -d .git ] || {
	echo >&2 Error: this directory is not a git repository root. Nothing happened.
	exit 1
}

# Warn if the current branch isn't master
current_branch=$( git name-rev --name-only HEAD )
[ ${current_branch} == "master" ] || {
	echo Current branch is ${current_branch}. Usually, release branches are made from master.
	echo -n 'Enter "y" if this is correct, anything else to abort: '
	read input
	[ "$input" == "y" ] || { echo >&2 Aborted. ; exit 1 ; }
}

# Get Maven to make the branch
set -x
mvn release:clean release:branch -P Brooklyn,Console,Example,Launcher,Acceptance,Documentation --batch-mode -DautoVersionSubmodules=true -DbranchName=${branch_name} -DupdateBranchVersions=true -DreleaseVersion=${version_on_branch} -DdevelopmentVersion=${version_on_master}
set +x

# Done!
echo Completed. Your repository is still looking at ${current_branch}. To switch to the release branch, enter:
echo git checkout ${branch_name}