#!/bin/bash
# gaming-session-switch — DeckShift-compatible session-switch helper, patched
# for password-at-boot. Same path + same {gaming|desktop} interface as
# DeckShift's original (the existing sudoers rule and switch-to-gaming /
# switch-to-desktop / os-session-select callers all keep working).
#
# DeckShift's original keeps a PERMANENT SDDM autologin drop-in and only flips
# its Session= line, so the machine never shows a password screen. This version
# writes the drop-in fresh on every switch and arms a one-shot marker in /run;
# sddm-autologin-gate (ExecStartPre on sddm.service) consumes the marker so the
# autologin applies to THAT restart only. Cold boots, crashes, and manual SDDM
# restarts find no marker and get the normal password greeter.
set -u

CONF="/etc/sddm.conf.d/zz-gaming-session.conf"
MARKER="/run/deckshift-session-switch"

if [[ $EUID -ne 0 ]]; then
  echo "Error: must run as root (callers use: sudo -n $0 ...)" >&2
  exit 1
fi

# The desktop user comes from sudo (all DeckShift callers invoke via sudo -n).
USER_NAME="${SUDO_USER:-}"
if [[ -z "$USER_NAME" ]]; then
  USER_NAME=$(loginctl list-sessions --no-legend 2>/dev/null | awk '$3 != "sddm" && $3 != "" { print $3; exit }')
fi
if [[ -z "$USER_NAME" ]]; then
  echo "Error: cannot determine the user to autologin" >&2
  exit 1
fi

case "${1:-}" in
  gaming)  SESSION="gamescope-session-steam-nm" ;;
  desktop) SESSION="hyprland-uwsm" ;;
  *)
    echo "Usage: $0 {gaming|desktop}" >&2
    exit 1
    ;;
esac

cat > "$CONF" << EOF
[Autologin]
User=${USER_NAME}
Session=${SESSION}
Relogin=false
EOF
touch "$MARKER"
echo "Session set to: $1 mode (one-shot autologin armed)"