#!/usr/bin/env bash
#
# bf-gui-off - Switch the field terminal back to console (multi-user) mode.
#
# Stops only the local display manager, preserves xRDP remote access, and isolates
# multi-user.target. Idempotent: already-console systems are left untouched.
#
# Install: install -m 0755 bf-gui-off /usr/local/bin/bf-gui-off
# Usage: sudo bf-gui-off
#
set -euo pipefail

usage() {
    cat <<'EOF'
Usage: bf-gui-off [--help]

Stop the graphical layer and return the device to console mode.

Options:
  --help   Show this help and exit

Behavior:
  - Stops only the local display manager (gdm3/gdm/...); xRDP and xrdp-sesman are preserved
  - Disables the local display manager so it does not restart on boot
  - Runs 'systemctl isolate multi-user.target'
EOF
}

while [[ $# -gt 0 ]]; do
    case "$1" in
        --help|-h) usage; exit 0 ;;
        *) echo "ERROR: unknown argument: $1" >&2; usage >&2; exit 2 ;;
    esac
done

if [[ "$(id -u)" -ne 0 ]]; then
    echo "ERROR: bf-gui-off must run as root (use sudo)." >&2
    exit 1
fi

log() { echo "[bf-gui-off] $*"; }

# Only the local physical display manager is controlled here. xRDP stays enabled
# and active so remote recovery is available while the console is local-default.
UNITS=(gdm3 gdm sddm lightdm)

for unit in "${UNITS[@]}"; do
    if systemctl list-unit-files --type=service 2>/dev/null | grep -q "^${unit}"; then
        if systemctl is-active --quiet "${unit}"; then
            log "Stopping ${unit} ..."
            systemctl stop "${unit}" || log "WARNING: failed to stop ${unit}."
        else
            log "${unit} already stopped."
        fi
        systemctl disable "${unit}" >/dev/null 2>&1 || true
    fi
done

log "Isolating multi-user.target ..."
systemctl isolate multi-user.target

log "GUI is OFF (console mode)."