#!/bin/bash
## change to "bin/sh" when necessary

auth_email=""                                       # The email used to login 'https://dash.cloudflare.com'
auth_method="token"                                 # Set to "global" for Global API Key or "token" for Scoped API Token
auth_key=""                                         # Your API Token or Global API Key
zone_identifier=""                                  # Can be found in the "Overview" tab of your domain
record_name=""                                      # Which record you want to be synced
ttl="3600"                                          # Set the DNS TTL (seconds)
proxy="false"                                       # Set the proxy to true or false
sitename=""                                         # Title of site "Example Site"
slackchannel=""                                     # Slack Channel #example
slackuri=""                                         # URI for Slack WebHook "https://hooks.slack.com/services/xxxxx"
discorduri=""                                       # URI for Discord WebHook "https://discordapp.com/api/webhooks/xxxxx"


validate_variables(){
  # Validate required variables
  if [[ -z $auth_email || -z $auth_key || -z $zone_identifier || -z $record_name ]]; then
    echo "Missing required variables. Please provide values for 'auth_email', 'auth_key', 'zone_identifier', and 'record_name'."
    exit 1
  fi
}

check_ipv4_is_available(){
  ipv4_regex='([01]?[0-9]?[0-9]|2[0-4][0-9]|25[0-5])\.([01]?[0-9]?[0-9]|2[0-4][0-9]|25[0-5])\.([01]?[0-9]?[0-9]|2[0-4][0-9]|25[0-5])\.([01]?[0-9]?[0-9]|2[0-4][0-9]|25[0-5])'

  ip=$(curl -s -4 https://cloudflare.com/cdn-cgi/trace | grep -E '^ip'); ret=$?
  if [[ ! $ret == 0 ]]; then # In the case that cloudflare failed to return an ip.
      # Attempt to get the ip from other websites.
      ip=$(curl -s https://api.ipify.org || curl -s https://ipv4.icanhazip.com)
  else
      # Extract just the ip from the ip line from cloudflare.
      ip=$(echo $ip | sed -E "s/^ip=($ipv4_regex)$/\1/")
  fi

  # Use regex to check for proper IPv4 format.
  if [[ ! $ip =~ ^$ipv4_regex$ ]]; then
      logger -s "DDNS Updater: Failed to find a valid IP."
      exit 2
  fi
}

set_auth_headers(){
  if [[ "${auth_method}" == "global" ]]; then
    auth_header="X-Auth-Key:"
  else
    auth_header="Authorization: Bearer"
  fi
}


check_if_a_record_exists(){
  logger "DDNS Updater: Check Initiated"
  record=$(curl -s -X GET "https://api.cloudflare.com/client/v4/zones/$zone_identifier/dns_records?type=A&name=$record_name" \
                        -H "X-Auth-Email: $auth_email" \
                        -H "$auth_header $auth_key" \
                        -H "Content-Type: application/json")

  if [[ $record == *"\"count\":0"* ]]; then
    logger -s "DDNS Updater: Record does not exist, perhaps create one first? (${ip} for ${record_name})"
    exit 1
  fi
}

get_current_ip_from_cloudflare(){
  old_ip=$(echo "$record" | sed -E 's/.*"content":"(([0-9]{1,3}\.){3}[0-9]{1,3})".*/\1/')
  # Compare if they're the same
  if [[ $ip == $old_ip ]]; then
    logger "DDNS Updater: IP ($ip) for ${record_name} has not changed."
    exit 0
  fi
}

update_ip_on_cloudflare(){
  record_identifier=$(echo "$record" | sed -E 's/.*"id":"([A-Za-z0-9_]+)".*/\1/')


  update=$(curl -s -X PATCH "https://api.cloudflare.com/client/v4/zones/$zone_identifier/dns_records/$record_identifier" \
                      -H "X-Auth-Email: $auth_email" \
                      -H "$auth_header $auth_key" \
                      -H "Content-Type: application/json" \
                      --data "{\"type\":\"A\",\"name\":\"$record_name\",\"content\":\"$ip\",\"ttl\":\"$ttl\",\"proxied\":${proxy}}")
}

send_webhooks(){
  case "$update" in
  *"\"success\":false"*)
    echo -e "DDNS Updater: $ip $record_name DDNS failed for $record_identifier ($ip). DUMPING RESULTS:\n$update" | logger -s 
    if [[ $slackuri != "" ]]; then
      curl -L -X POST $slackuri \
      --data-raw '{
        "channel": "'$slackchannel'",
        "text" : "'"$sitename"' DDNS Update Failed: '$record_name': '$record_identifier' ('$ip')."
      }'
    fi
    if [[ $discorduri != "" ]]; then
      curl -i -H "Accept: application/json" -H "Content-Type:application/json" -X POST \
      --data-raw '{
        "content" : "'"$sitename"' DDNS Update Failed: '$record_name': '$record_identifier' ('$ip')."
      }' $discorduri
    fi
    exit 1;;
  *)
    logger "DDNS Updater: $ip $record_name DDNS updated."
    if [[ $slackuri != "" ]]; then
      curl -L -X POST $slackuri \
      --data-raw '{
        "channel": "'$slackchannel'",
        "text" : "'"$sitename"' Updated: '$record_name''"'"'s'""' new IP Address is '$ip'"
      }'
    fi
    if [[ $discorduri != "" ]]; then
      curl -i -H "Accept: application/json" -H "Content-Type:application/json" -X POST \
      --data-raw '{
        "content" : "'"$sitename"' Updated: '$record_name''"'"'s'""' new IP Address is '$ip'"
      }' $discorduri
    fi
    exit 0;;
  esac
}

main(){
  validate_variables
  check_ipv4_is_available
  set_auth_headers
  check_if_a_record_exists
  get_current_ip_from_cloudflare
  update_ip_on_cloudflare
  send_webhooks
}