#!/usr/bin/env sh
#
# Acme.sh DNS API plugin for Oracle Cloud Infrastructure
# Copyright (c) 2021, Oracle and/or its affiliates
#
# The plugin will automatically use the default profile from an OCI SDK and CLI
# configuration file, if it exists.
#
# Alternatively, set the following environment variables:
# - OCI_CLI_TENANCY : OCID of tenancy that contains the target DNS zone
# - OCI_CLI_USER    : OCID of user with permission to add/remove records from zones
# - OCI_CLI_REGION  : Should point to the tenancy home region
#
# One of the following two variables is required:
# - OCI_CLI_KEY_FILE: Path to private API signing key file in PEM format; or
# - OCI_CLI_KEY     : The private API signing key in PEM format
#
# NOTE: using an encrypted private key that needs a passphrase is not supported.
#

dns_oci_add() {
  _fqdn="$1"
  _rdata="$2"

  if _get_oci_zone; then

    _add_record_body="{\"items\":[{\"domain\":\"${_sub_domain}.${_domain}\",\"rdata\":\"$_rdata\",\"rtype\":\"TXT\",\"ttl\": 30,\"operation\":\"ADD\"}]}"
    response=$(_signed_request "PATCH" "/20180115/zones/${_domain}/records" "$_add_record_body")
    if [ "$response" ]; then
      _info "Success: added TXT record for ${_sub_domain}.${_domain}."
    else
      _err "Error: failed to add TXT record for ${_sub_domain}.${_domain}."
      _err "Check that the user has permission to add records to this zone."
      return 1
    fi

  else
    return 1
  fi

}

dns_oci_rm() {
  _fqdn="$1"
  _rdata="$2"

  if _get_oci_zone; then

    _remove_record_body="{\"items\":[{\"domain\":\"${_sub_domain}.${_domain}\",\"rdata\":\"$_rdata\",\"rtype\":\"TXT\",\"operation\":\"REMOVE\"}]}"
    response=$(_signed_request "PATCH" "/20180115/zones/${_domain}/records" "$_remove_record_body")
    if [ "$response" ]; then
      _info "Success: removed TXT record for ${_sub_domain}.${_domain}."
    else
      _err "Error: failed to remove TXT record for ${_sub_domain}.${_domain}."
      _err "Check that the user has permission to remove records from this zone."
      return 1
    fi

  else
    return 1
  fi

}

####################  Private functions below ##################################
_get_oci_zone() {

  if ! _oci_config; then
    return 1
  fi

  if ! _get_zone "$_fqdn"; then
    _err "Error: DNS Zone not found for $_fqdn in $OCI_CLI_TENANCY"
    return 1
  fi

  return 0

}

_oci_config() {

  OCI_CLI_CONFIG_FILE="${OCI_CLI_CONFIG_FILE:-$HOME/.oci/config}"
  OCI_CLI_PROFILE="${OCI_CLI_PROFILE:-DEFAULT}"

  # Let's try and find the values automagically first
  # But still let any environment variables take precendence
  if [ -f "$OCI_CLI_CONFIG_FILE" ]; then
    _info "Reading OCI configuration file: $(_green "$OCI_CLI_CONFIG_FILE")"
    OCI_CLI_TENANCY="${OCI_CLI_TENANCY:-$(_read_oci_config tenancy)}"
    OCI_CLI_USER="${OCI_CLI_USER:-$(_read_oci_config user)}"
    OCI_CLI_KEY_FILE="${OCI_CLI_KEY_FILE:-$(_read_oci_config key_file)}"
    OCI_CLI_REGION="${OCI_CLI_REGION:-$(_read_oci_config region)}"
  else
    OCI_CLI_TENANCY="${OCI_CLI_TENANCY:-$(_readaccountconf_mutable OCI_CLI_TENANCY)}"
    OCI_CLI_USER="${OCI_CLI_USER:-$(_readaccountconf_mutable OCI_CLI_USER)}"
    OCI_CLI_KEY="${OCI_CLI_KEY:-$(_readaccountconf_mutable OCI_CLI_KEY)}"
    OCI_CLI_REGION="${OCI_CLI_REGION:-$(_readaccountconf_mutable OCI_CLI_REGION)}"
    _save_config="true"
  fi

  _not_set=""
  _ret=0

  if [ -z "$OCI_CLI_KEY_FILE" ] && [ -z "$OCI_CLI_KEY" ]; then
    _err "Fatal: you must provide a value for either OCI_CLI_KEY_FILE or OCI_CLI_KEY."
    return 1
  fi

  if [ "$OCI_CLI_KEY_FILE" ] && [ -z "$OCI_CLI_KEY" ]; then
    if [ -f "$OCI_CLI_KEY_FILE" ]; then
      OCI_CLI_KEY=$(_base64 <"$OCI_CLI_KEY_FILE")
    else
      _err "Fatal: unable to read key file: $OCI_CLI_KEY_FILE"
      return 1
    fi
  fi

  if [ -z "$OCI_CLI_TENANCY" ]; then
    _not_set="${_not_set}OCI_CLI_TENANCY "
  fi

  if [ -z "$OCI_CLI_USER" ]; then
    _not_set="${_not_set}OCI_CLI_USER "
  fi

  if [ -z "$OCI_CLI_REGION" ]; then
    _not_set="${_not_set}OCI_CLI_REGION "
  fi

  if [ "$_not_set" ]; then
    _err "Fatal: required environment variable(s): ${_not_set} not set."
    _ret=1
  else
    if [ "$_save_config" ]; then
      _saveaccountconf_mutable OCI_CLI_TENANCY "$OCI_CLI_TENANCY"
      _saveaccountconf_mutable OCI_CLI_USER "$OCI_CLI_USER"
      _saveaccountconf_mutable OCI_CLI_KEY "$OCI_CLI_KEY"
      _saveaccountconf_mutable OCI_CLI_REGION "$OCI_CLI_REGION"
    else
      _info "Success: OCI configuration retrieved from $OCI_CLI_CONFIG_FILE."
    fi
  fi

  if ! _contains "PRIVATE KEY" "$OCI_CLI_KEY"; then
    OCI_CLI_KEY=$(printf "%s" "$OCI_CLI_KEY" | _dbase64 multiline)
  fi

  return $_ret

}

# _get_zone(): retrieves the Zone name and OCID
#
# _sub_domain=_acme-challenge.www
# _domain=domain.com
# _domain_ociid=ocid1.dns-zone.oc1..
_get_zone() {
  domain=$1
  i=1
  p=1

  while true; do
    h=$(printf "%s" "$domain" | cut -d . -f $i-100)
    _debug h "$h"
    if [ -z "$h" ]; then
      # not valid
      return 1
    fi

    _domain_id=$(_signed_request "GET" "/20180115/zones/$h" "" "id")
    if [ "$_domain_id" ]; then
      _sub_domain=$(printf "%s" "$domain" | cut -d . -f 1-$p)
      _domain=$h

      _debug _domain_id "$_domain_id"
      _debug _sub_domain "$_sub_domain"
      _debug _domain "$_domain"
      return 0
    fi

    p=$i
    i=$(_math "$i" + 1)
  done
  return 1

}

#Usage: privatekey
#Output MD5 fingerprint
_fingerprint() {
  pkey="$1"
  if [ -z "$pkey" ]; then
    _usage "Usage: _fingerprint privkey"
    return 1
  fi

  printf "%s" "$pkey" | ${ACME_OPENSSL_BIN:-openssl} rsa -pubout -outform DER 2>/dev/null | ${ACME_OPENSSL_BIN:-openssl} md5 -c | cut -d = -f 2 | tr -d ' '

}

_signed_request() {

  _sig_method="$1"
  _sig_target="$2"
  _sig_body="$3"
  _return_field="$4"

  _key_fingerprint=$(_fingerprint "$OCI_CLI_KEY")
  _sig_host="dns.$OCI_CLI_REGION.oraclecloud.com"
  _sig_keyId="$OCI_CLI_TENANCY/$OCI_CLI_USER/$_key_fingerprint"
  _sig_alg="rsa-sha256"
  _sig_version="1"
  _sig_now="$(LC_ALL=C \date -u "+%a, %d %h %Y %H:%M:%S GMT")"

  _request_method=$(printf %s "$_sig_method" | _lower_case)
  _curl_method=$(printf %s "$_sig_method" | _upper_case)

  _request_target="(request-target): $_request_method $_sig_target"
  _date_header="date: $_sig_now"
  _host_header="host: $_sig_host"

  _string_to_sign="$_request_target\n$_date_header\n$_host_header"
  _sig_headers="(request-target) date host"

  if [ "$_sig_body" ]; then
    _secure_debug3 _sig_body "$_sig_body"
    _sig_body_sha256="x-content-sha256: $(printf %s "$_sig_body" | _digest sha256)"
    _sig_body_type="content-type: application/json"
    _sig_body_length="content-length: ${#_sig_body}"
    _string_to_sign="$_string_to_sign\n$_sig_body_sha256\n$_sig_body_type\n$_sig_body_length"
    _sig_headers="$_sig_headers x-content-sha256 content-type content-length"
  fi

  _tmp_file=$(_mktemp)
  if [ -f "$_tmp_file" ]; then
    printf '%s' "$OCI_CLI_KEY" >"$_tmp_file"
    _signature=$(printf '%b' "$_string_to_sign" | _sign "$_tmp_file" sha256 | tr -d '\r\n')
    rm -f "$_tmp_file"
  fi

  _signed_header="Authorization: Signature version=\"$_sig_version\",keyId=\"$_sig_keyId\",algorithm=\"$_sig_alg\",headers=\"$_sig_headers\",signature=\"$_signature\""
  _secure_debug3 _signed_header "$_signed_header"

  if [ "$_curl_method" = "GET" ]; then
    export _H1="$_date_header"
    export _H2="$_signed_header"
    _response="$(_get "https://${_sig_host}${_sig_target}")"
  elif [ "$_curl_method" = "PATCH" ]; then
    export _H1="$_date_header"
    export _H2="$_sig_body_sha256"
    export _H3="$_sig_body_type"
    export _H4="$_sig_body_length"
    export _H5="$_signed_header"
    _response="$(_post "$_sig_body" "https://${_sig_host}${_sig_target}" "" "PATCH")"
  else
    _err "Unable to process method: $_curl_method."
  fi

  _ret="$?"
  if [ "$_return_field" ]; then
    _response="$(echo "$_response" | sed 's/\\\"//g'))"
    _return=$(echo "${_response}" | _egrep_o "\"$_return_field\"\\s*:\\s*\"[^\"]*\"" | _head_n 1 | cut -d : -f 2 | tr -d "\"")
  else
    _return="$_response"
  fi

  printf "%s" "$_return"
  return $_ret

}

# file  key  [section]
_read_oci_config() {
  _key="$1"

  _start_n=$(grep -n '\['"$OCI_CLI_PROFILE"']' "$OCI_CLI_CONFIG_FILE" | cut -d : -f 1)
  _debug2 _start_n "$_start_n"
  if [ -z "$_start_n" ]; then
    _err "Can not find section: $OCI_CLI_PROFILE"
    return 1
  fi

  _start_nn=$(_math "$_start_n" + 1)
  _debug2 "_start_nn" "$_start_nn"

  _left="$(sed -n "${_start_nn},99999p" "$OCI_CLI_CONFIG_FILE")"
  _debug2 _left "$_left"
  _end="$(echo "$_left" | grep -n "^\[" | _head_n 1)"
  _debug2 "_end" "$_end"
  if [ "$_end" ]; then
    _end_n=$(echo "$_end" | cut -d : -f 1)
    _debug "_end_n" "$_end_n"
    _seg_n=$(echo "$_left" | sed -n "1,${_end_n}p")
  else
    _seg_n="$_left"
  fi

  _debug2 "_seg_n" "$_seg_n"
  _lineini="$(echo "$_seg_n" | grep "^ *$_key *= *")"

  _debug2 "_lineini" "$_lineini"
  printf "%b" "$(eval "echo $_lineini | sed -e \"s/${_key}[[:space:]]*=[[:space:]]*//g\"")"

}