#!/usr/bin/env bash
set -euo pipefail

# Toggle DNS between Pi-hole and Cloudflare on all active network services.
# Usage: ./toggle_dns.sh
# Requires sudo for networksetup.

PIHOLE="192.168.1.4"
CLOUDFLARE="1.1.1.1"

# Get all hardware network services (Wi-Fi, Ethernet, Thunderbolt, USB, etc.)
services=()
while IFS= read -r line; do
  [[ "$line" == *"*"* ]] && continue  # skip disabled services
  services+=("$line")
done < <(networksetup -listallnetworkservices 2>/dev/null | tail -n +2)

if [[ ${#services[@]} -eq 0 ]]; then
  echo "No network services found"
  exit 1
fi

# Detect current mode from the first service that has a DNS set
current_dns=""
for svc in "${services[@]}"; do
  dns=$(networksetup -getdnsservers "$svc" 2>/dev/null | head -1)
  if [[ "$dns" != *"aren't any"* ]] && [[ -n "$dns" ]]; then
    current_dns="$dns"
    break
  fi
done

if [[ "$current_dns" == "$CLOUDFLARE" ]]; then
  target="$PIHOLE"
  label="Pi-hole"
else
  target="$CLOUDFLARE"
  label="Cloudflare"
fi

echo "Switching all services to ${label} (${target})..."
for svc in "${services[@]}"; do
  sudo networksetup -setdnsservers "$svc" "$target"
  echo "  ${svc} → ${target}"
done

sudo dscacheutil -flushcache
sudo killall -HUP mDNSResponder 2>/dev/null || true
echo "DNS set to ${label} (${target})"