#!/bin/sh
# Installs hammerhead as a systemd service from the files in this folder.
#
#   sudo ./install.sh              install or upgrade (your settings and data are kept)
#   sudo ./install.sh --start      the same, then start (or restart) the service
#   sudo ./install.sh --uninstall  remove the service and binary (keeps the settings and data)
#
# Files: /usr/local/lib/hammerhead/hammerhead (linked from /usr/local/bin/hammerhead), /etc/systemd/system/hammerhead.service,
#        /etc/hammerhead/hammerhead.env (your settings and secrets), /var/lib/hammerhead (data).
# Set DESTDIR=/some/dir to stage everything there without touching the system.
set -eu
NAME=hammerhead
HERE=$(cd "$(dirname "$0")" && pwd)
ROOT=${DESTDIR:-}
BIN=$ROOT/usr/local/bin/$NAME
UNIT=$ROOT/etc/systemd/system/$NAME.service
CONF=$ROOT/etc/$NAME
ENVFILE=$CONF/$NAME.env
DATA=$ROOT/var/lib/$NAME
LIB=$ROOT/usr/local/lib/$NAME # the program lives here, owned by the service, so auto-update can replace it

say() { printf '%s\n' "$*"; }
real() { [ -z "${DESTDIR:-}" ]; } # are we touching the real system?

if real; then
	[ "$(id -u)" = 0 ] || { say "Run this as root:  sudo $0 $*"; exit 1; }
	command -v systemctl > /dev/null 2>&1 || { say "systemd wasn't found. Run $NAME directly (see the README) or use Docker."; exit 1; }
fi

if [ "${1:-}" = "--uninstall" ]; then
	if real; then
		systemctl disable --now "$NAME" > /dev/null 2>&1 || true
	fi
	rm -f "$UNIT" "$BIN" "$LIB/$NAME"
	if real; then
		systemctl daemon-reload || true
	fi
	say "Removed $NAME. Left in place: $CONF and $DATA (delete them yourself if you want them gone)."
	exit 0
fi

[ -f "$HERE/$NAME" ] || { say "Can't find the $NAME binary next to this script."; exit 1; }

if real && ! id "$NAME" > /dev/null 2>&1; then
	useradd --system --home-dir "/var/lib/$NAME" --shell /usr/sbin/nologin "$NAME"
	say "Created the system user '$NAME'."
fi

mkdir -p "$ROOT/usr/local/bin" "$ROOT/etc/systemd/system" "$CONF" "$DATA"
mkdir -p "$LIB"
install -m 0755 "$HERE/$NAME" "$LIB/$NAME.new"
mv -f "$LIB/$NAME.new" "$LIB/$NAME" # atomic, so upgrading a running service is safe
rm -f "$BIN"
LINK=/usr/local/lib/$NAME/$NAME
[ -z "${DESTDIR:-}" ] || LINK=$LIB/$NAME # staging: point inside the staging folder
ln -s "$LINK" "$BIN"
install -m 0644 "$HERE/$NAME.service" "$UNIT"
if [ ! -f "$ENVFILE" ]; then
	install -m 0600 "$HERE/.env.example" "$ENVFILE"
	say "Created $ENVFILE. Edit it before starting."
fi
if real; then
	chown -R "$NAME:$NAME" "$DATA" "$LIB"
fi

if real; then
	systemctl daemon-reload
	systemctl enable "$NAME" > /dev/null 2>&1
	if [ "${1:-}" = "--start" ] || systemctl is-active --quiet "$NAME"; then
		systemctl restart "$NAME"
		say "$NAME is running."
	fi
fi

say "Installed $("$LIB/$NAME" -version 2> /dev/null || echo "$NAME")."
say "Next:"
say "  1. edit $ENVFILE"
say "  2. systemctl start $NAME      (or run this again with --start)"
say "  3. journalctl -u $NAME -f     to watch it"