#!/bin/bash
#
# change-merged hook
#
# Copyright 2020 Luigi Santivetti <luigi.santivetti@gmail.com>

# Permission is hereby granted, free of charge, to any person obtaining a
# copy of this software and associated documentation files (the "Software"),
# to deal in the Software without restriction, including without limitation
# the rights to use, copy, modify, merge, publish, distribute, sublicense,
# and/or sell copies of the Software, and to permit persons to whom the
# Software is furnished to do so, subject to the following conditions:

# The above copyright notice and this permission notice (including the next
# paragraph) shall be included in all copies or substantial portions of the
# Software.

# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
# ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
# IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

# change-merged
#
#  --change <change id>
#  --change-url <change url>
#  --change-owner <change owner>
#  --change-owner-username <username>
#  --project <project name>
#  --branch <branch>
#  --topic <topic>
#  --submitter <submitter>
#  --submitter-username <username>
#  --commit <sha1>
#  --newrev <sha1>
#
# RATIONALE: change-merged can propagate one or more changes landing into
# Gerrit to an external mirror. Be noted, this is an async hook that runs
# in the background.
#
#                                    ` remote-update hook   ` TODO
#                                    `                      `
#                                    `                      `
#               (1) merge            ` (2) push             ` (3) push
#    +--------+             +--------+             +--------+
#    | Gerrit | ··········> | Gerrit | ··········> | Mirror | ··········>
#    +--------+             +--------+             +--------+
#                                    `                      `
#                                    `                      `
#                                    `                      `
#                                    `                      `

LOG_FILE=${HOOKS_LOG_DIR:-/tmp}
if [ ! -w "$LOG_FILE" ]; then
	LOG_FILE="/dev/null" # avoid permission denied
else
	LOG_FILE="$LOG_FILE/hooks.change-merged-$(date +'%d%m%Y%H%M%S').txt"
fi

# Host service where replication mirrors and deploy engine live
HOOK_HOST=${HOOKS_REMOTE_HOST:-}
if [ ! -n "$HOOK_HOST" ]; then
	echo " ****** warning: no host, skip hook" &> ${LOG_FILE}
	exit 1
fi

# User allowed t othe target host to push and eventually deploy changes
HOOK_USER=${HOOKS_REMOTE_USER:-}
if [ ! -n "$HOOK_USER" ]; then
	echo " ****** warning: no user, skip hook" &> ${LOG_FILE}
	exit 1
fi

# Directory where this hook expects the project mirror to be located
HOOK_PATH=${HOOKS_REMOTE_PATH:-}
if [ ! -n "$HOOK_PATH" ]; then
	echo " ****** warning: no path, skip hook" &> ${LOG_FILE}
	exit 1
fi

# Alias for the remote tracking a given mirror
GERRIT_R=${HOOKS_REMOTE_ALIAS:-}
if [ ! -n "$GERRIT_R" ]; then
	echo " ****** warning: no remote alias, skip hook" &> ${LOG_FILE}
	exit 1
fi

SSH_RSA_ID=${HOOKS_REMOTE_RSAID:-}
if [ ! -n "$SSH_RSA_ID" ]; then
	echo " ****** error: no rsa id file found" &> ${LOG_FILE}
	exit 1
fi

SSH_PORT=${HOOKS_REMOTE_PORT:-22}
if [ ! -n "$SSH_PORT" ]; then
	echo " ****** warning: no ssh port, default to 22" &> ${LOG_FILE}
fi

GERRIT_PORT=${HOOKS_GERRIT_PORT:-29418}
if [ ! -n "$GERRIT_PORT" ]; then
	echo " ****** warning: no Gerrit port, default to 29418" &> ${LOG_FILE}
fi

GERRIT_HOST=${HOOKS_GERRIT_HOST:-}
if [ ! -n "$GERRIT_HOST" ]; then
	echo " ****** warning: no Gerrit host, skip notify" &> ${LOG_FILE}
fi

DEPLOY_EXEC=${HOOKS_DEPLOY_EXEC:-}
if [ ! -n "${DEPLOY_EXEC}" ]; then
	echo " ****** warning: no deploy exec, skip deploy" &> ${LOG_FILE}
fi

/bin/bash <(/bin/cat <<EOF
set -x
args='${*}'

declare -A CHANGE=(
		[change]=""
		[change-url]=""
		[change-owner]=""
		[change-owner-username]=""
		[project]=""
		[branch]=""
		[topic]=""
		[submitter]=""
		[submitter-username]=""
		[commit]=""
		[newrev]=""
)

while read -a line; do
	for K in \${!CHANGE[@]}; do
		if [ "\${line[0]}" == "--\$K" ]; then
			CHANGE[\$K]="\${line[@]:1}"
			break
		fi
	done
done <<< "\$(echo -e "\${args// --/\\\\n--}")"

SSH_COMMAND="ssh"
SSH_COMMAND+=" -o StrictHostKeyChecking=no"
SSH_COMMAND+=" -o UserKnownHostsFile=/dev/null"
SSH_COMMAND+=" -i $SSH_RSA_ID"

function gerrit_cli
{
	\$SSH_COMMAND -p $GERRIT_PORT \${CHANGE[submitter-username]}@$GERRIT_HOST gerrit \${@}
}

remote_url="ssh://$HOOK_USER@$HOOK_HOST:$HOOK_PATH/\${CHANGE[project]}.git"

# Does Gerrit have \\\$git_dir remote set up?
git remote get-url "$GERRIT_R" | grep -q -- "\$remote_url"
if [ "\$?" -ne 0 ]; then
	echo >&2 " ****** error: \${CHANGE[project]} remote not found: $GERRIT_R"
	echo >&2 " ****** error: \${CHANGE[branch]} not pushed, skip hook"
	exit 1
fi

# Get patchset info
NUMBERS=\$(gerrit_cli query \${CHANGE[commit]} --patch-sets | grep -- number)

# Get patch number and patchset number
patchnum=\$(printf "%s\n" "\$NUMBERS" | head -n1 | cut -f 2 -d ':')
patchset=\$(printf "%s\n" "\$NUMBERS" | tail -n1 | cut -f 2 -d ':')

# Trim whitespaces
patchnum=\${patchnum//\ /}
patchset=\${patchset//\ /}

GIT_SSH_COMMAND="\$SSH_COMMAND"
GIT_SSH_COMMAND+=" -p $SSH_PORT"
GIT_SSH_COMMAND="\$GIT_SSH_COMMAND" git push --follow-tags $GERRIT_R refs/heads/*:refs/heads/*
if [ "\$?" -ne 0 ]; then
	echo >&2 " ****** error: failed to push \${CHANGE[branch]}"
	gerrit_cli review -m '"Gerrit failed to replicate this change ¯\\\\_(ツ)_/¯"' \$patchnum,\$patchset
	exit 1
fi

echo " ****** success: \${CHANGE[branch]} pushed to $GERRIT_R"
gerrit_cli review -m '"Gerrit has successfully replicated this change \\\\o/"' \$patchnum,\$patchset

if [ -n "$DEPLOY_EXEC" ]; then

	# If going to deploy, breathe
	sleep 1

	# Invoke deploy script
	\$SSH_COMMAND -p $SSH_PORT $HOOK_USER@$HOOK_HOST "${DEPLOY_EXEC} \${args[@]}"
	if [ \$? -ne 0 ]; then
		gerrit_cli review -m '"Gerrit failed to deploy this change ¯\\\\_(ツ)_/¯"' \$patchnum,\$patchset
		exit 1
	else
		gerrit_cli review -m '"Gerrit has successfully deployed this change \\\\o/"' \$patchnum,\$patchset
		exit 0
	fi
else
	gerrit_cli review -m '"Gerrit has skipped deploying this change ¯\\\\_(ツ)_/¯"' \$patchnum,\$patchset
	exit 0
fi
set +x
EOF
		) &> ${LOG_FILE}; RET=$?

Keep the log if the hook has failed only
[ "$RET" -ne 0 ] || rm -f ${LOG_FILE}