#! /bin/bash
commit_id=$(git rev-parse --short=7 HEAD 2>/dev/null)
[ -z "$commit_id" ] && commit_id="0000001"
commit_message=$(git show -s --format="%<(52,trunc)%s" $commit_id 2>/dev/null | sed -e 's/[[:space:]]*$//')
[ -z "$commit_message" ] && commit_message="unable to get the commit message"
commit_id_old=$(cat ./source/gitver.c 2>/dev/null | tr -d '\n' | sed -r 's/.*([0-9a-f]{7}).*/\1/')

if [ "$commit_id" != "$commit_id_old" ] || [ ! -f ./source/gitver.c ]; then

cat <<EOF > ./source/gitver.c
#define GIT_HASH "$commit_id"

const char *commitID()
{
	return GIT_HASH;
}
EOF

	if [ -z "$commit_id_old" ]; then
		echo "Created gitver.c and set the commit ID to $commit_id ($commit_message)" >&2
	else
		echo "Changed the commit ID from $commit_id_old to $commit_id ($commit_message)" >&2
	fi
	echo >&2
fi