#!/bin/bash
set -euo pipefail

WIFI_IFACE="wlan0"
PRIMARY_CONN="netplan-wlan0-eskimue.de"
SECONDARY_CONN="4pi"
FALLBACK_AP_CONN="CUNO-AP"
CHECK_INTERVAL=20

get_active_connection() {
  nmcli -t -f GENERAL.CONNECTION device show "$WIFI_IFACE" 2>/dev/null | head -n 1 | cut -d: -f2-
}

activate_connection() {
  local connection_name="$1"
  nmcli --wait 15 connection up "$connection_name" ifname "$WIFI_IFACE" >/dev/null 2>&1
}

ensure_best_connection() {
  local active_connection
  active_connection="$(get_active_connection)"

  if [[ "$active_connection" == "$PRIMARY_CONN" ]]; then
    return
  fi

  if activate_connection "$PRIMARY_CONN"; then
    return
  fi

  active_connection="$(get_active_connection)"
  if [[ "$active_connection" == "$SECONDARY_CONN" ]]; then
    return
  fi

  if activate_connection "$SECONDARY_CONN"; then
    return
  fi

  active_connection="$(get_active_connection)"
  if [[ "$active_connection" != "$FALLBACK_AP_CONN" ]]; then
    activate_connection "$FALLBACK_AP_CONN" || true
  fi
}

while true; do
  ensure_best_connection
  sleep "$CHECK_INTERVAL"
done