#!/bin/bash
# adguard-register — registers this host with AdGuard Home DNS rewrites
# Deploy to each LXC/VM, run at boot via systemd oneshot or @reboot cron

set -euo pipefail

ADGUARD_URL="http://172.20.1.1"
USERNAME="newkirk"
PASSWORD="Vaxjy911!"
# Get short hostname (portable: try hostname -s, fall back to /etc/hostname or /proc)
if command -v hostname &>/dev/null; then
    HOSTNAME=$(hostname -s)
elif [ -f /etc/hostname ]; then
    HOSTNAME=$(cat /etc/hostname | cut -d. -f1)
else
    HOSTNAME=$(cat /proc/sys/kernel/hostname 2>/dev/null | cut -d. -f1)
fi

# Get primary IPv4 (non-loopback, non-docker, non-tailscale)
IP=$(ip -4 addr show scope global | grep -v 'docker\|tailscale\|br-\|veth' | grep -oP 'inet \K[\d.]+' | head -1)

if [ -z "$IP" ]; then
    echo "ERROR: Could not determine primary IPv4 address"
    exit 1
fi

DOMAIN="${HOSTNAME}.home.dustin.coffee"

# Login
COOKIE=$(curl -s -D - "${ADGUARD_URL}/control/login" \
  -H "Content-Type: application/json" \
  -d "{\"name\":\"${USERNAME}\",\"password\":\"${PASSWORD}\"}" \
  | grep -i 'set-cookie' | grep -oP 'agh_session=[a-f0-9]+' | head -1)

if [ -z "$COOKIE" ]; then
    echo "ERROR: Failed to authenticate with AdGuard Home"
    exit 1
fi

# Check if rewrite already exists
EXISTING=$(curl -s "${ADGUARD_URL}/control/rewrite/list" -b "$COOKIE")
EXISTING_ANSWER=$(echo "$EXISTING" | python3 -c "
import sys,json
data=json.load(sys.stdin)
for r in data:
    if r.get('domain') == '$DOMAIN':
        print(r.get('answer',''))
        break
" 2>/dev/null)

if [ -n "$EXISTING_ANSWER" ]; then
    if [ "$EXISTING_ANSWER" = "$IP" ]; then
        echo "OK: $DOMAIN already points to $IP — nothing to do"
        exit 0
    fi
    # Update existing
    echo "Updating $DOMAIN: $EXISTING_ANSWER → $IP"
    curl -s -X POST "${ADGUARD_URL}/control/rewrite/update" \
      -b "$COOKIE" \
      -H "Content-Type: application/json" \
      -d "{\"target\":{\"domain\":\"$DOMAIN\"},\"update\":{\"domain\":\"$DOMAIN\",\"answer\":\"$IP\"}}" \
      > /dev/null
else
    # Create new
    echo "Registering $DOMAIN → $IP"
    curl -s -X POST "${ADGUARD_URL}/control/rewrite/add" \
      -b "$COOKIE" \
      -H "Content-Type: application/json" \
      -d "{\"domain\":\"$DOMAIN\",\"answer\":\"$IP\"}" \
      > /dev/null
fi

# Verify
VERIFY=$(curl -s "${ADGUARD_URL}/control/rewrite/list" -b "$COOKIE" | python3 -c "
import sys,json
data=json.load(sys.stdin)
for r in data:
    if r.get('domain') == '$DOMAIN':
        print(r.get('answer',''))
" 2>/dev/null)

if [ "$VERIFY" = "$IP" ]; then
    echo "SUCCESS: $DOMAIN → $IP verified"
    exit 0
else
    echo "WARN: Verification failed — $DOMAIN resolves to '$VERIFY', expected '$IP'"
    exit 1
fi