#!/bin/bash

# version #VERSION#

set -e

stty &> /dev/null || \
  sleep $[$RANDOM%60]

if ! ipCmd="$(which ip 2> /dev/null)"
then
  for p1 in / /usr/
  do
    for p2 in bin/ sbin/
    do
      ipCmd="${p1}${p2}ip"
      [ -x "${ipCmd}" ] && break
    done
    [ -x "${ipCmd}" ] && break
  done
fi

unset ignoreIps

i=0

while read -r ipVer updateUrl dnsName
do

  if [[ "${ipVer}" = '#'* ]] || [ -z "${ipVer}" ]
  then
    continue
  fi

  if [[ "${ipVer}" == 'ignore' ]]
  then
    ignoreIps="${ignoreIps} ${updateUrl} ${dnsName}"
    continue
  fi

  if [[ "${ipVer}" == *"?" ]]
  then
    ipVer="${ipVer%?}"
    [ -z "$(${ipCmd} -o -${ipVer} addr show scope global)" ] && continue
  fi

  if [ "${ipVer}" == '4' ]
  then
    dnsVers[${i}]='A'
    inetVers[${i}]='inet'
    ipCmdVers[${i}]='-4'
  elif [ "${ipVer}" == '6' ]
  then
    dnsVers[${i}]='AAAA'
    inetVers[${i}]='inet6'
    ipCmdVers[${i}]='-6'
  elif [ "${ipVer}" == '46' ] || [ "${ipVer}" == '64' ]
  then
    dnsVers[${i}]='A'
    inetVers[${i}]='inet'
    ipCmdVers[${i}]='-4'

    updateUrls[${i}]="${updateUrl}"
    dnsNamen[${i}]="${dnsName}"
    i=$[${i}+1]

    dnsVers[${i}]='AAAA'
    inetVers[${i}]='inet6'
    ipCmdVers[${i}]='-6'
  else
    >&2 echo 'Error: First column in "#ETCDIR#/update-ddns.conf" needs to be "4", "6", "46" or "64"!'
    exit 1
  fi

  updateUrls[${i}]="${updateUrl}"
  dnsNamen[${i}]="${dnsName}"

  i=$[${i}+1]

done < #ETCDIR#/update-ddns.conf

ignoreIps='^\('"$(
  echo ${ignoreIps} | \
    tr '[:space:]' '\n' | \
    grep -vxF '' | \
    sort -u | \
    sed '
      s@$@\\|@
    ' | \
    tr -d '\n' | \
    sed '
      s@\\|$@@
    '
)"'\)$'

for dnsName in $( \
  echo "${dnsNamen[@]}" | \
    tr ' ' '\n' | \
    sort -u
)
do
  unset updateIps
  unset updateUrl
  unset curlForceIpVer
  needsUpdate=false

  for ((j=0; j<${i}; j++))
  do
    [ "${dnsName}" != "${dnsNamen[${j}]}" ] && continue

    updateUrl="${updateUrls[${j}]}"

    if [[ "${dnsName}" == *'/'* ]]
    then
      dnsIps="$(
        curl ${ipCmdVers[${j}]} "${dnsName}" 2> /dev/null
      )"
      ips='1'
      updateIps="${updateIps}"',auto'
      if [ -n "${curlForceIpVer}" ] && [ "${curlForceIpVer}" != "${ipCmdVers[${j}]}" ]
      then
        >&2 echo 'Error: I cannot determine two different ip versions automatically (because Erich didn'"'"'t need it).'
        exit 1
      fi
      curlForceIpVer="${ipCmdVers[${j}]}"
    else
      dnsIps="$(
        dig $1 "${dnsName}" ${dnsVers[${j}]} | \
          sed '/^;; AUTHORITY SECTION:$/Q' | \
          grep '^[^;]' | \
          grep "\s${dnsVers[${j}]}\s" | \
          awk '{print $5}' | \
          sort -u
      )"

      ips="$(
        "${ipCmd}" -o ${ipCmdVers[${j}]} addr show scope global | \
          awk '{print $4}' | \
          cut -d/ -f1 | \
          grep -vx "${ignoreIps}" | \
          sort -u
      )"

      if [ $(echo "${ips}" | grep -c '.') -eq 0 ]
      then
        updateIps="${updateIps}"',auto'
        if [ -n "${curlForceIpVer}" ] && [ "${curlForceIpVer}" != "${ipCmdVers[${j}]}" ]
        then
          >&2 echo 'Error: I cannot determine two different ip versions automatically (because Erich didn'"'"'t need it).'
          exit 1
        fi
        curlForceIpVer="${ipCmdVers[${j}]}"
      else
        updateIps="${updateIps},$(echo -n "${ips}" | tr '\n' ',')"
      fi
    fi

    if [ "${dnsIps}" != "${ips}" ]
    then
      needsUpdate=true
    fi
  done

  if ${needsUpdate}
  then
    if [[ "${updateUrl}" = *'?'* ]]
    then
      updateIps='&address='"${updateIps#,}"
    else
      updateIps='?address='"${updateIps#,}"
    fi
    curl ${curlForceIpVer} -sS "${updateUrl}${updateIps}" 2> /dev/null
  fi
done