#!/usr/bin/env sh

# Author: Janos Lenart <janos@lenart.io>

########  Public functions #####################

# Usage: dns_gcloud_add   _acme-challenge.www.domain.com   "XKrxpRBosdIKFzxW_CT3KLZNf6q0HG9i01zxXp5CPBs"
dns_gcloud_add() {
  fulldomain=$1
  txtvalue=$2
  _info "Using gcloud"
  _debug fulldomain "$fulldomain"
  _debug txtvalue "$txtvalue"

  _dns_gcloud_find_zone || return $?

  # Add an extra RR
  _dns_gcloud_start_tr || return $?
  _dns_gcloud_get_rrdatas || return $?
  echo "$rrdatas" | _dns_gcloud_remove_rrs || return $?
  echo -e "$rrdatas\n\"$txtvalue\"" | grep -v '^$' | _dns_gcloud_add_rrs || return $?
  _dns_gcloud_execute_tr || return $?

  _info "$fulldomain record added"
}

# Usage: dns_gcloud_rm   _acme-challenge.www.domain.com   "XKrxpRBosdIKFzxW_CT3KLZNf6q0HG9i01zxXp5CPBs"
# Remove the txt record after validation.
dns_gcloud_rm() {
  fulldomain=$1
  txtvalue=$2
  _info "Using gcloud"
  _debug fulldomain "$fulldomain"
  _debug txtvalue "$txtvalue"

  _dns_gcloud_find_zone || return $?

  # Remove one RR
  _dns_gcloud_start_tr || return $?
  _dns_gcloud_get_rrdatas || return $?
  echo "$rrdatas" | _dns_gcloud_remove_rrs || return $?
  echo "$rrdatas" | fgrep -v "\"$txtvalue\"" | _dns_gcloud_add_rrs || return $?
  _dns_gcloud_execute_tr || return $?

  _info "$fulldomain record added"
}

####################  Private functions below ##################################

_dns_gcloud_start_tr() {
  if ! trd=`mktemp -d`; then
    _err "_dns_gcloud_start_tr: failed to create temporary directory"
    return 1
  fi
  tr="$trd/tr.yaml"
  _debug tr "$tr"

  if ! gcloud dns record-sets transaction start \
         --transaction-file="$tr" \
         --zone="$managedZone"; then
    rm -r "$trd"
    _err "_dns_gcloud_start_tr: failed to execute transaction"
    return 1
  fi
}

_dns_gcloud_execute_tr() {
  if ! gcloud dns record-sets transaction execute \
         --transaction-file="$tr" \
         --zone="$managedZone"; then
    _debug tr "`cat \"$tr\"`"
    rm -r "$trd"
    _err "_dns_gcloud_execute_tr: failed to execute transaction"
    return 1
  fi
  rm -r "$trd"

  for i in `seq 1 120`; do
    if gcloud dns record-sets changes list \
          --zone=lenart \
          --filter='status != done' \
          | grep -q '.*'; then
       _info "_dns_gcloud_execute_tr: waiting for transaction to be comitted ..."
       sleep 5
    else
      return 0
    fi
  done

  _err "_dns_gcloud_execute_tr: transaction is still pending after 10 minutes"
  rm -r "$trd"
  return 1
}

_dns_gcloud_remove_rrs() {
  if ! xargs --no-run-if-empty gcloud dns record-sets transaction remove \
         --name="$fulldomain." \
         --ttl="$ttl" \
         --type=TXT \
         --zone="$managedZone" \
         --transaction-file="$tr"; then
    _debug tr "`cat \"$tr\"`"
    rm -r "$trd"
    _err "_dns_gcloud_remove_rrs: failed to remove RRs"
    return 1
  fi
}

_dns_gcloud_add_rrs() {
  ttl=60
  if ! xargs --no-run-if-empty gcloud dns record-sets transaction add \
         --name="$fulldomain." \
         --ttl="$ttl" \
         --type=TXT \
         --zone="$managedZone" \
         --transaction-file="$tr"; then
    _debug tr "`cat \"$tr\"`"
    rm -r "$trd"
    _err "_dns_gcloud_add_rrs: failed to add RRs"
    return 1
  fi
}

_dns_gcloud_find_zone() {
  # Prepare a filter that matches zones that are suiteable for this entry.
  # For example, _acme-challenge.something.domain.com might need to go into something.domain.com or domain.com;
  # this function finds the longest postfix that has a managed zone.
  part="$fulldomain"
  filter="dnsName=( "
  while [ "$part" != "" ]; do
    filter="$filter$part. "
    part="`echo \"$part\" | sed 's/[^.]*\.*//'`"
  done
  filter="$filter)"
  _debug filter "$filter"

  # List domains and find the longest match (in case of some levels of delegation)
  if ! match=$(gcloud dns managed-zones list \
                 --format="value(name, dnsName)" \
                 --filter="$filter" \
                 | while read dnsName name; do
                     echo -e "${#dnsName}\t$dnsName\t$name"
                   done \
                 | sort -n -r | head -n1 | cut -f2,3 | grep '.*'); then
    _err "_dns_gcloud_find_zone: Can't find a matching managed zone! Perhaps wrong project or gcloud credentials?"
    return 1
  fi

  dnsName=$(echo "$match" | cut -f2)
  _debug dnsName "$dnsName"
  managedZone=$(echo "$match" | cut -f1)
  _debug managedZone "$managedZone"
}

_dns_gcloud_get_rrdatas() {
  if ! rrdatas=$(gcloud dns record-sets list \
                   --zone="$managedZone" \
                   --name="$fulldomain." \
                   --type=TXT \
                   --format="value(ttl,rrdatas)"); then
    _err "_dns_gcloud_get_rrdatas: Failed to list record-sets"
    rm -r "$trd"
    return 1
  fi
  ttl=$(echo "$rrdatas" | cut -f1)
  rrdatas=$(echo "$rrdatas" | cut -f2 | sed 's/","/"\n"/g')
}