#!/bin/sh

set -eu

# we only want to run this script as root
if [ ! $(id -u) = 0 ]; then
   echo "This script must be run as root" 1>&2
   exit 1
fi

# use environment variable for user
# or fallback to logname
USER="${SOURCE_USER:-$(logname)}"

# get user home directory and preferred shell
HOME="$(getent passwd "$USER" | cut -d: -f6)"
SHELL="$(getent passwd "$USER" | cut -d: -f7)"

# in case the users preferred shell defaulted to this
# script we fallback to bash
if [ "$SHELL" = "$0" ]; then
	SHELL=/bin/bash
fi

# if the user has a custom gitconfig we use it to define the
# git author and email
if [ -n "$HOME" ] && [ -e "$HOME/.gitconfig" ]; then
	GIT_AUTHOR_NAME="$(git config -f "$HOME/.gitconfig" user.name)"
	GIT_AUTHOR_EMAIL="$(git config -f "$HOME/.gitconfig" user.email)"
# in case no custom gitconfig has been provided we fallback to
# the username and a dynamically created mail address
else
	GIT_AUTHOR_NAME="$USER"
	GIT_AUTHOR_EMAIL="$USER@$(hostname -a)"
fi

# export the git authorship information into the environment
export GIT_AUTHOR_NAME
export GIT_AUTHOR_EMAIL

# finally execute the preferred shell
exec "$SHELL"