#!/bin/bash

TITLE="Tailscale"
DESCRIPTION="Join your Core's Tailscale network"

CORE_CONF="$HOME/.config/coredesktop/core.conf"
TAILSCALE_CONF="$HOME/.config/coredesktop/tailscale.conf"
[ -f "$CORE_CONF" ] && source "$CORE_CONF"
[ -f "$TAILSCALE_CONF" ] && source "$TAILSCALE_CONF"

is_installed() {
  command -v tailscale
}

# Tailscale has no status field naming its login server, so tailscale.conf
# records which Core it was set up for
joined() {
  [ -n "$TAILSCALE_DOMAIN" ] \
    && tailscale status --json 2> /dev/null | jq -e '.BackendState == "Running"' > /dev/null
}

# Done when on the main Core's network
is_configured() {
  [ -n "$CORE_DOMAIN" ] && [ "$TAILSCALE_DOMAIN" = "$CORE_DOMAIN" ] && joined
}

# Log out rather than only go down, so this computer's key is expired on
# headscale and it's off the network until it joins again
leave_network() {
  sudo tailscale logout || return 1
  rm -f "$TAILSCALE_CONF"
  echo "This computer has left your Core's Tailscale network. To join again: configure tailscale"
}

run_configure() {
  local choice
  if joined &> /dev/null; then
    echo "This computer is on $TAILSCALE_DOMAIN's Tailscale network (headscale.$TAILSCALE_DOMAIN)."
    echo
    if [ "$TAILSCALE_DOMAIN" = "$CORE_DOMAIN" ]; then
      echo "  1) Join it again"
    else
      echo "  1) Join your main Core's network instead (headscale.$CORE_DOMAIN)"
    fi
    echo "  2) Leave the network"
    echo "  q) Leave it as it is"
    echo
    read -rp "Choose: " choice
    case "$choice" in
      1) ;;
      2) leave_network; return ;;
      *) return 0 ;;
    esac
  fi

  if [ -z "$CORE_DOMAIN" ]; then
    echo "This joins your Core's Tailscale network, so set up your Core first: configure core"
    return 1
  fi

  # --reset and --force-reauth move the machine from any other tailnet;
  # --operator lets you, and the Tailscale GNOME extension, use it without sudo
  if ! systemctl is-active -q tailscaled; then
    sudo systemctl enable --now tailscaled || return 1
  fi
  echo "Open the link below to sign in to your Core's Tailscale network (headscale.$CORE_DOMAIN)."
  sudo tailscale up --reset --force-reauth --login-server "https://headscale.$CORE_DOMAIN" \
    --accept-routes --operator="$USER" || return 1

  mkdir -p "$(dirname "$TAILSCALE_CONF")"
  printf 'TAILSCALE_DOMAIN=%q\n' "$CORE_DOMAIN" > "$TAILSCALE_CONF"
  echo "This computer is on your Core's Tailscale network."
}