#!/usr/bin/env sh

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

# Usage: add  _acme-challenge.www.domain.com   "XKrxpRBosdIKFzxW_CT3KLZNf6q0HG9i01zxXp5CPBs"
# Used to add txt record
#
# Ref: https://docs.microsoft.com/en-us/rest/api/dns/recordsets/createorupdate
#
dns_azure_add() {
  fulldomain=$1
  txtvalue=$2

  AZUREDNS_SUBSCRIPTIONID="${AZUREDNS_SUBSCRIPTIONID:-$(_readaccountconf_mutable AZUREDNS_SUBSCRIPTIONID)}"
  AZUREDNS_TENANTID="${AZUREDNS_TENANTID:-$(_readaccountconf_mutable AZUREDNS_TENANTID)}"
  AZUREDNS_APPID="${AZUREDNS_APPID:-$(_readaccountconf_mutable AZUREDNS_APPID)}"
  AZUREDNS_CLIENTSECRET="${AZUREDNS_CLIENTSECRET:-$(_readaccountconf_mutable AZUREDNS_CLIENTSECRET)}"

  if [ -z "$AZUREDNS_SUBSCRIPTIONID" ]; then
    AZUREDNS_SUBSCRIPTIONID=""
    AZUREDNS_TENANTID=""
    AZUREDNS_APPID=""
    AZUREDNS_CLIENTSECRET=""
    _err "You didn't specify the Azure Subscription ID "
    return 1
  fi

  if [ -z "$AZUREDNS_TENANTID" ]; then
    AZUREDNS_SUBSCRIPTIONID=""
    AZUREDNS_TENANTID=""
    AZUREDNS_APPID=""
    AZUREDNS_CLIENTSECRET=""
    _err "You didn't specify the Azure Tenant ID "
    return 1
  fi

  if [ -z "$AZUREDNS_APPID" ]; then
    AZUREDNS_SUBSCRIPTIONID=""
    AZUREDNS_TENANTID=""
    AZUREDNS_APPID=""
    AZUREDNS_CLIENTSECRET=""
    _err "You didn't specify the Azure App ID"
    return 1
  fi

  if [ -z "$AZUREDNS_CLIENTSECRET" ]; then
    AZUREDNS_SUBSCRIPTIONID=""
    AZUREDNS_TENANTID=""
    AZUREDNS_APPID=""
    AZUREDNS_CLIENTSECRET=""
    _err "You didn't specify the Azure Client Secret"
    return 1
  fi
  #save account details to account conf file.
  _saveaccountconf_mutable AZUREDNS_SUBSCRIPTIONID "$AZUREDNS_SUBSCRIPTIONID"
  _saveaccountconf_mutable AZUREDNS_TENANTID "$AZUREDNS_TENANTID"
  _saveaccountconf_mutable AZUREDNS_APPID "$AZUREDNS_APPID"
  _saveaccountconf_mutable AZUREDNS_CLIENTSECRET "$AZUREDNS_CLIENTSECRET"

  accesstoken=$(_azure_getaccess_token "$AZUREDNS_TENANTID" "$AZUREDNS_APPID" "$AZUREDNS_CLIENTSECRET")

  if ! _get_root "$fulldomain" "$AZUREDNS_SUBSCRIPTIONID" "$accesstoken"; then
    _err "invalid domain"
    return 1
  fi
  _debug _domain_id "$_domain_id"
  _debug _sub_domain "$_sub_domain"
  _debug _domain "$_domain"

  acmeRecordURI="https://management.azure.com$(printf '%s' "$_domain_id" | sed 's/\\//g')/TXT/$_sub_domain?api-version=2017-09-01"
  _debug "$acmeRecordURI"
  body="{\"properties\": {\"TTL\": 3600, \"TXTRecords\": [{\"value\": [\"$txtvalue\"]}]}}"
  _azure_rest PUT "$acmeRecordURI" "$body" "$accesstoken"
  if [ "$_code" = "200" ] || [ "$_code" = '201' ]; then
    _info "validation record added"
  else
    _err "error adding validation record ($_code)"
    return 1
  fi
}

# Usage: fulldomain txtvalue
# Used to remove the txt record after validation
#
# Ref: https://docs.microsoft.com/en-us/rest/api/dns/recordsets/delete
#
dns_azure_rm() {
  fulldomain=$1
  txtvalue=$2

  AZUREDNS_SUBSCRIPTIONID="${AZUREDNS_SUBSCRIPTIONID:-$(_readaccountconf_mutable AZUREDNS_SUBSCRIPTIONID)}"
  AZUREDNS_TENANTID="${AZUREDNS_TENANTID:-$(_readaccountconf_mutable AZUREDNS_TENANTID)}"
  AZUREDNS_APPID="${AZUREDNS_APPID:-$(_readaccountconf_mutable AZUREDNS_APPID)}"
  AZUREDNS_CLIENTSECRET="${AZUREDNS_CLIENTSECRET:-$(_readaccountconf_mutable AZUREDNS_CLIENTSECRET)}"

  if [ -z "$AZUREDNS_SUBSCRIPTIONID" ]; then
    AZUREDNS_SUBSCRIPTIONID=""
    AZUREDNS_TENANTID=""
    AZUREDNS_APPID=""
    AZUREDNS_CLIENTSECRET=""
    _err "You didn't specify the Azure Subscription ID "
    return 1
  fi

  if [ -z "$AZUREDNS_TENANTID" ]; then
    AZUREDNS_SUBSCRIPTIONID=""
    AZUREDNS_TENANTID=""
    AZUREDNS_APPID=""
    AZUREDNS_CLIENTSECRET=""
    _err "You didn't specify the Azure Tenant ID "
    return 1
  fi

  if [ -z "$AZUREDNS_APPID" ]; then
    AZUREDNS_SUBSCRIPTIONID=""
    AZUREDNS_TENANTID=""
    AZUREDNS_APPID=""
    AZUREDNS_CLIENTSECRET=""
    _err "You didn't specify the Azure App ID"
    return 1
  fi

  if [ -z "$AZUREDNS_CLIENTSECRET" ]; then
    AZUREDNS_SUBSCRIPTIONID=""
    AZUREDNS_TENANTID=""
    AZUREDNS_APPID=""
    AZUREDNS_CLIENTSECRET=""
    _err "You didn't specify the Azure Client Secret"
    return 1
  fi

  accesstoken=$(_azure_getaccess_token "$AZUREDNS_TENANTID" "$AZUREDNS_APPID" "$AZUREDNS_CLIENTSECRET")

  if ! _get_root "$fulldomain" "$AZUREDNS_SUBSCRIPTIONID" "$accesstoken"; then
    _err "invalid domain"
    return 1
  fi
  _debug _domain_id "$_domain_id"
  _debug _sub_domain "$_sub_domain"
  _debug _domain "$_domain"

  acmeRecordURI="https://management.azure.com$(printf '%s' "$_domain_id" | sed 's/\\//g')/TXT/$_sub_domain?api-version=2017-09-01"
  _debug "$acmeRecordURI"
  body="{\"properties\": {\"TTL\": 3600, \"TXTRecords\": [{\"value\": [\"$txtvalue\"]}]}}"
  _azure_rest DELETE "$acmeRecordURI" "" "$accesstoken"
  if [ "$_code" = "200" ] || [ "$_code" = '204' ]; then
    _info "validation record removed"
  else
    _err "error removing validation record ($_code)"
    return 1
  fi
}

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

_azure_rest() {
  m=$1
  ep="$2"
  data="$3"
  accesstoken="$4"

  export _H1="authorization: Bearer $accesstoken"
  export _H2="accept: application/json"
  export _H3="Content-Type: application/json"

  _debug "$ep"
  if [ "$m" != "GET" ]; then
    _debug data "$data"
    response="$(_post "$data" "$ep" "" "$m")"
  else
    response="$(_get "$ep")"
  fi
  _debug2 response "$response"

  _code="$(grep "^HTTP" "$HTTP_HEADER" | _tail_n 1 | cut -d " " -f 2 | tr -d "\r\n")"
  _debug2 "http response code $_code"

  if [ "$?" != "0" ]; then
    _err "error $ep"
    return 1
  fi
  return 0
}

## Ref: https://docs.microsoft.com/en-us/azure/active-directory/develop/active-directory-protocols-oauth-service-to-service#request-an-access-token
_azure_getaccess_token() {
  TENANTID=$1
  clientID=$2
  clientSecret=$3

  export _H1="accept: application/json"
  export _H2="Content-Type: application/x-www-form-urlencoded"

  body="resource=$(printf "%s" 'https://management.core.windows.net/' | _url_encode)&client_id=$(printf "%s" "$clientID" | _url_encode)&client_secret=$(printf "%s" "$clientSecret" | _url_encode)&grant_type=client_credentials"
  _debug data "$body"
  response="$(_post "$body" "https://login.windows.net/$TENANTID/oauth2/token" "" "POST")"
  accesstoken=$(echo "$response" | _egrep_o "\"access_token\":\"[^\"]*\"" | _head_n 1 | cut -d : -f 2 | tr -d \")
  _debug2 "response $response"

  if [ -z "$accesstoken" ]; then
    _err "no acccess token received"
    return 1
  fi
  if [ "$?" != "0" ]; then
    _err "error $response"
    return 1
  fi
  printf "%s" "$accesstoken"
  return 0
}

_get_root() {
  domain=$1
  subscriptionId=$2
  accesstoken=$3
  i=2
  p=1

  ## Ref: https://docs.microsoft.com/en-us/rest/api/dns/zones/list
  ## returns up to 100 zones in one response therefore handling more results is not not implemented
  ## (ZoneListResult with  continuation token for the next page of results)
  ## Per https://docs.microsoft.com/en-us/azure/azure-subscription-service-limits#dns-limits you are limited to 100 Zone/subscriptions anyways
  ##
  _azure_rest GET "https://management.azure.com/subscriptions/$subscriptionId/providers/Microsoft.Network/dnszones?api-version=2017-09-01" "" "$accesstoken"

  # Find matching domain name is Json response
  while true; do
    h=$(printf "%s" "$domain" | cut -d . -f $i-100)
    _debug2 "Checking domain: $h"
    if [ -z "$h" ]; then
      #not valid
      _err "Invalid domain"
      return 1
    fi

    if _contains "$response" "\"name\":\"$h\"" >/dev/null; then
      _domain_id=$(echo "$response" | _egrep_o "\{\"id\":\"[^\"]*$h\"" | head -n 1 | cut -d : -f 2 | tr -d \")
      if [ "$_domain_id" ]; then
        _sub_domain=$(printf "%s" "$domain" | cut -d . -f 1-$p)
        _domain=$h
        return 0
      fi
      return 1
    fi
    p=$i
    i=$(_math "$i" + 1)
  done
  return 1
}