#!/bin/sh

api_host="https://api.digitalocean.com/v2"
sleep_interval=${SLEEP_INTERVAL:-300}

die() {
    echo "$1"
    exit 1
}

test -z $DIGITALOCEAN_TOKEN && die "DIGITALOCEAN_TOKEN not set!"
test -z $DOMAIN && die "DOMAIN not set!"
test -z $NAME && die "NAME not set!"

dns_list="$api_host/domains/$DOMAIN/records"
dns_list_long="$api_host/domains/$DOMAIN/records?per_page=200"

while ( true ); do
    domain_records=$(curl -s -X GET \
        -H "Content-Type: application/json" \
        -H "Authorization: Bearer $DIGITALOCEAN_TOKEN" \
        $dns_list_long)
    record_id=$(echo $domain_records| jq ".domain_records[] | select(.type == \"A\" and .name == \"$NAME\") | .id")
    record_data=$(echo $domain_records| jq -r ".domain_records[] | select(.type == \"A\" and .name == \"$NAME\") | .data")
    
    test -z $record_id && die "No record found with given domain name!"

    ip="$(curl -s ipinfo.io/ip)"
    data="{\"type\": \"A\", \"name\": \"$NAME\", \"data\": \"$ip\"}"
    url="$dns_list/$record_id"

    if [[ -n $ip ]]; then
        if [[ "$ip" != "$record_data" ]]; then
            echo "existing DNS record address ($record_data) doesn't match current IP ($ip), sending data=$data to url=$url"

            curl -s -X PUT \
                -H "Content-Type: application/json" \
                -H "Authorization: Bearer $DIGITALOCEAN_TOKEN" \
                -d "$data" \
                "$url" &> /dev/null
        fi
    else
        echo "IP wasn't retrieved within allowed interval. Will try $sleep_interval seconds later.."
    fi

    sleep $sleep_interval
done