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

auth_email="email"                                       # The email used to login 'https://dash.cloudflare.com'
auth_method="global"                                 # Set to "global" for Global API Key or "token" for Scoped API Token
auth_key="key"                                         # Your API Token or Global API Key
zone_identifier="key"                                  # Can be found in the "Overview" tab of your domain
record_name="domain name"                                      # Which record you want to be synced
ttl="0"                                          # Set the DNS TTL (seconds)
proxy="true"                                       # Set the proxy to true or false
sitename="domain name"                                         # Title of site "Example Site"
slackchannel=""                                     # Slack Channel #example
slackuri=""                                         # URI for Slack WebHook "https://hooks.slack.com/services/xxxxx"
discorduri="webhook url"                                       # URI for Discord WebHook "https://discordapp.com/api/webhooks/xxxxx"


###########################################
## Check if we have a public IP
###########################################
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

###########################################
## Check and set the proper auth header
###########################################
if [[ "${auth_method}" == "global" ]]; then
  auth_header="X-Auth-Key:"
else
  auth_header="Authorization: Bearer"
fi

###########################################
## Seek for the A record
###########################################

logger "DDNS Updater: Check Initiated"
record=$(curl --write-out "%{http_code}" -s -X GET "https://api.cloudflare.com/client/v4/zones/$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")

record_status=$(echo $record | tail -c 4)

if (( $record_status >= 400 && $record_status <= 530 )); then
  logger -s "DDNS Updater: Error while checking record identifier!"
  exit 1
fi

###########################################
## Check if the domain has an A record
###########################################
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 existing IP
###########################################
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

###########################################
## Set the record identifier from result
###########################################
record_identifier=$(echo "$record" | sed -E 's/.*"id":"(\w+)".*/\1/')

###########################################
## Change the IP@Cloudflare using the API
###########################################
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}}")

###########################################
## Report the status
###########################################
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 [[ $discorduri != "" ]]; then
    curl -i -H "Accept: application/json" -H "Content-Type:application/json" -X POST \
    --data-raw '{
      "content" : "<@&discordruleid> We'"'"''""'ve detected a new IP address for the following domain name ||`'"$sitename"'`|| we'"'"''""'ve gone ahead and updated the A record for the following DNS record ||`'$record_name'`|| with the new IP address ||`'$ip'`||"
    }' $discorduri
  fi
  exit 0;;
esac