#! /usr/bin/env bash

set -euo pipefail

ZONE_ID=""
ZONE_ID_FILE=""
DNS_RECORD=""
DNS_RECORD_FILE=""
DOMAIN=""
CACHED_PUBLIC_IP=""
AUTHORIZATION="$(cat .var/bearer)"

IP_URL="ifconfig.me/ip"
SEND_TELEGRAM="$(pwd)/send_telegram"
LOG_FILE_PARENT="/var/log/cloudflare_update"
LOG_FILE="${LOG_FILE_PARENT}/$(date +%d_%m_%Y_update_dns).log"

mkdir -p "${LOG_FILE_PARENT}"

function info() {
	echo "$(date --iso-8601=minutes) CLOUDFLARE_DNS_UPDATE [INFO]: ${*}"
	echo "$(date --iso-8601=minutes) CLOUDFLARE_DNS_UPDATE [INFO]: ${*}" >> "${LOG_FILE}"
}
function error() {
	echo "$(date --iso-8601=minutes) CLOUDFLARE_DNS_UPDATE [ERROR]: ${*}"
}

function check_internet_access() {
  wget -q --spider https://google.com
  if [ $? -ne 0 ]; then
    error "No internet connection. Exiting..."
    exit 1
  fi
}

function check_new_ip() {
	local new_ip
	new_ip="$(curl -s ${IP_URL})"
  if [[ "$new_ip" =~ ^([0-9]{1,3})[.]([0-9]{1,3})[.]([0-9]{1,3})[.]([0-9]{1,3})$ ]]
  then
      for (( i=1; i<${#BASH_REMATCH[@]}; ++i ))
      do
        (( ${BASH_REMATCH[$i]} <= 255 )) || { info "Bad IP from curl. ${new_ip}"; exit 1; }
      done
  else
        info "Bad IP from curl. ${new_ip}";
        exit 1;
  fi
	if [[ "${new_ip}" == "${CACHED_PUBLIC_IP}" ]]; then
		info "Public IP has not changed from ${new_ip}. Exiting..."
		exit 0;
	else
		info "Public IP has changed from ${CACHED_PUBLIC_IP} to ${new_ip}. Updating records..."
    "${SEND_TELEGRAM}" "Public IP has changed from ${CACHED_PUBLIC_IP} to ${new_ip}. Updating records..."
    CACHED_PUBLIC_IP="${new_ip}"
    echo "${new_ip}" > ${PUBLIC_IP_FILE}
	fi
}

# Parse command-line arguments
while [[ $# -gt 0 ]]; do
  case $1 in
    -z|--zone-id-file)
      ZONE_ID_FILE="$2"
      shift # past argument
      shift # past value
      ;;
    -d|--dns-record-file)
      DNS_RECORD_FILE="$2"
      shift # past argument
      shift # past value
      ;;
    --domain)
      DOMAIN="$2"
      shift # past argument
      shift # past value
      ;;
    -*|--*)
      echo "Unknown option $1"
      exit 1
      ;;
    *)
      echo "Unknown option $1"
      exit 1
      ;;
  esac
done

DNS_RECORD=$(cat "${DNS_RECORD_FILE}")
ZONE_ID=$(cat "${ZONE_ID_FILE}")
PUBLIC_IP_FILE=".var/${DOMAIN}_cached_ip"
if [ -e "$PUBLIC_IP_FILE" ]; then
    CACHED_PUBLIC_IP=$(cat "${PUBLIC_IP_FILE}")
else
    touch "${PUBLIC_IP_FILE}"
fi
check_internet_access
check_new_ip

curl_answer="$(curl --request PATCH \
  --url "https://api.cloudflare.com/client/v4/zones/${ZONE_ID}/dns_records/${DNS_RECORD}" \
  --header 'Content-Type: application/json' \
  --header 'X-Auth-Email: ' \
  --silent \
  --data '{
  "content": "'${CACHED_PUBLIC_IP}'",
  "name": "'${DOMAIN}'",
  "proxied": false,
  "type": "A",
  "comment": "Main Record",
  "ttl": 3600
}' \
-H "Authorization: Bearer ${AUTHORIZATION}")"

info "${curl_answer}"
"${SEND_TELEGRAM}" "$(echo ${curl_answer} | jq)"