#!/usr/bin/env bash
#=============================================================================
# Copyright 2010-2012 Kitware, Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#=============================================================================

. "${BASH_SOURCE%/*}/hooks-config.bash"

# Start with project-specific hook.
hooks_start commit-msg "$@"

# Prepare a copy of the message:
#  - strip comment lines
#  - stop at "diff --git" (git commit -v)
commit_msg="$GIT_DIR/COMMIT_MSG"
sed -n -e '/^#/d' -e '/^diff --git/q' -e 'p;d' "$1" > "$commit_msg"

die_advice='
To continue editing, run the command
  git commit -e -F '"$commit_msg"'
(assuming your working directory is at the top).'

die() {
	echo 'commit-msg hook failure' 1>&2
	echo '-----------------------' 1>&2
	echo '' 1>&2
	echo "$@" 1>&2
	test -n "$die_advice" && echo "$die_advice" 1>&2
	exit 1
}

#-----------------------------------------------------------------------------
# Check the commit message layout with a simple state machine.

msg_is_merge() {
	echo "$line" | grep "^Merge " >/dev/null 2>&1
}

msg_is_revert() {
	echo "$line" | grep "^Revert " >/dev/null 2>&1
}

msg_first() {
	len=$(echo -n "$line" | wc -c)
	if test $len -eq 0; then
		# not yet first line
		return
	elif test $len -lt 8; then
		die 'The first line must be at least 8 characters:
--------
'"$line"'
--------'
	elif test $len -gt 78 && ! msg_is_merge && ! msg_is_revert; then
		die 'The first line may be at most 78 characters:
------------------------------------------------------------------------------
'"$line"'
------------------------------------------------------------------------------'
	elif echo "$line" | grep "^[	 ]\|[	 ]$" >/dev/null 2>&1; then
		die 'The first line may not have leading or trailing space:
['"$line"']'
	else
		# first line okay
		state=second
	fi
}

msg_second() {
	if test "x$line" != "x"; then
		die 'The second line must be empty:
'"$line"
	else
		state=rest
	fi
}

msg_rest() {
	if echo "$line" | grep -q "^Change-Id:"; then
		state=gerrit
	fi
}

msg_gerrit() {
	test "x$line" = "x" && return
	echo "$line" | grep -q '^[A-Za-z0-9-][A-Za-z0-9-]*:' && return
	die 'The Change-Id line must appear in a footer at the bottom.'
}

# Pipe commit message into the state machine.
state=first
cat "$commit_msg" |
while IFS='' read line; do
	msg_$state || break
done &&
rm -f "$commit_msg" || exit 1
die_advice='' # No more temporary message file.

#-----------------------------------------------------------------------------
# Optionally run Gerrit's commit-msg hook to add a Change-Id line.

gerrit_advice() {
	gerrits=$(git config -l |grep '^remote\.[^=]\+url=.*review.*$')
	test "x$gerrits" != "x" || return 0

	echo 'Some config values look like Gerrit Code Review URLs:'
	echo ''
	echo "$gerrits" | sed 's/^/  /'
	echo '
This hook can automatically add a "Change-Id" footer to commit messages
to make interaction with Gerrit easier.  To enable this feature, run

  git config hooks.GerritId true

Then run "git commit --amend" to fix this commit.  Otherwise, run

  git config hooks.GerritId false

to disable the feature and this message.'
}

gerrit_error() {
	die 'non-bool config value hooks.GerritId = '"$hooks_GerritId"
}

gerrit_hook() {
	"$HOOKS_DIR/gerrit/commit-msg" "$@" ||
	die 'gerrit/commit-msg failed'
}

hooks_GerritId=$(git config --get hooks.GerritId)
case "$hooks_GerritId" in
	'true')  gerrit_hook "$@" ;;
	'false') ;;
	'')      gerrit_advice ;;
	*)       gerrit_error ;;
esac

#-----------------------------------------------------------------------------
# Chain to project-specific hook.
hooks_chain commit-msg "$@"