#!/usr/bin/env bash
set -eo pipefail; [[ $DOKKU_TRACE ]] && set -x

has_tty() {
  if [[ "$(/usr/bin/tty || true)" == "not a tty" ]]; then
    return 1
  else
    return 0
  fi
}

dokku_apps() {
  local INSTALLED_APPS=$(find "$DOKKU_ROOT" -follow -maxdepth 1 -mindepth 1 -type d ! -name 'tls' ! -name '.*' -printf "%f\n" | sort) || (dokku_log_fail "You haven't deployed any applications yet")
  [[ $INSTALLED_APPS ]] && echo "$INSTALLED_APPS"
}

dokku_log_info1() {
  echo "-----> $*"
}

dokku_log_info2() {
  echo "=====> $*"
}

dokku_log_info1_quiet() {
  if [[ -z "$DOKKU_QUIET_OUTPUT" ]]; then
    echo "-----> $*"
  else
    return 0
  fi
}

dokku_log_info2_quiet() {
  if [[ -z "$DOKKU_QUIET_OUTPUT" ]]; then
    echo "=====> $*"
  else
    return 0
  fi
}

dokku_col_log_info1() {
  printf "%-6s %-18s %-25s %-25s %-25s\n" "----->" "$@"
}

dokku_col_log_info1_quiet() {
  if [[ -z "$DOKKU_QUIET_OUTPUT" ]]; then
    printf "%-6s %-18s %-25s %-25s %-25s\n" "----->" "$@"
  else
    return 0
  fi
}

dokku_col_log_info2() {
  printf "%-6s %-18s %-25s %-25s %-25s\n" "=====>" "$@"
}

dokku_col_log_info2_quiet() {
  if [[ -z "$DOKKU_QUIET_OUTPUT" ]]; then
    printf "%-6s %-18s %-25s %-25s %-25s\n" "=====>" "$@"
  else
    return 0
  fi
}

dokku_col_log_msg() {
  printf "%-25s %-25s %-25s %-25s\n" "$@"
}

dokku_col_log_msg_quiet() {
  if [[ -z "$DOKKU_QUIET_OUTPUT" ]]; then
    printf "%-25s %-25s %-25s %-25s\n" "$@"
  else
    return 0
  fi
}

dokku_log_verbose_quiet() {
  if [[ -z "$DOKKU_QUIET_OUTPUT" ]]; then
    echo "       $*"
  else
    return 0
  fi
}

dokku_log_verbose() {
  echo "       $*"
}

dokku_log_warn() {
  echo " !     $*"
}

dokku_log_fail() {
  echo "$@" 1>&2
  exit 1
}

dokku_log_event() {
  logger -t dokku -i -- "$@"
}

dokku_log_plugn_trigger_call() {
  local l_hook

  l_hook="$1" ; shift
  dokku_log_event "INVOKED: ${l_hook}( $* ) NAME=$NAME FINGERPRINT=$FINGERPRINT"
}

dokku_container_log_verbose_quiet() {
  local CID=$1;
  shift

  OIFS=$IFS
  IFS=$'\n'
  for line in $(docker logs "$CID" 2>&1); do
    dokku_log_verbose_quiet "$line"
  done
  IFS=$OIFS
}

verify_app_name() {
  local APP="$1"
  [[ ! -n "$APP" ]] && dokku_log_fail "(verify_app_name) APP must not be null"
  if [[ ! "$APP" =~ ^[a-z].* && ! "$APP" =~ ^[0-9].* ]]; then
    [[ -d "$DOKKU_ROOT/$APP" ]] && rm -rf "$DOKKU_ROOT/$APP"
    dokku_log_fail "App name must begin with lowercase alphanumeric character"
  fi
  [[ ! -d "$DOKKU_ROOT/$APP" ]] && dokku_log_fail "App $APP does not exist"

  return 0
}

verify_image() {
  local IMAGE="$1"
  if (docker inspect "$IMAGE" &>/dev/null); then
    return 0
  else
    return 1
  fi
}

get_app_image_repo() {
  # central definition of our image repo pattern
  local APP="$1"; local IMAGE_REPO="dokku/$APP"
  [[ -z "$APP" ]] && dokku_log_fail "(get_app_image_repo) APP must not be null"
  echo "$IMAGE_REPO"
}

get_app_image_name() {
  # return image identifier for a given app, tag tuple. validate if tag is presented
  local APP="$1"; local IMAGE_TAG="$2"; local IMAGE_REPO=$(get_app_image_repo "$APP")
  [[ -z "$APP" ]] && dokku_log_fail "(get_app_image_name) APP must not be null"

  if [[ -n "$IMAGE_TAG" ]]; then
    IMAGE="$IMAGE_REPO:$IMAGE_TAG"
    verify_image "$IMAGE" || dokku_log_fail "app image ($IMAGE) not found"
  else
    IMAGE="$IMAGE_REPO:latest"
  fi
  echo "$IMAGE"
}

get_running_image_tag() {
  # retrieve current image tag for a given app. returns empty string if no deployed containers are found
  local APP="$1"
  [[ ! -n "$APP" ]] && dokku_log_fail "(get_running_image_tag) APP must not be null"
  verify_app_name "$APP"

  CIDS=( $(get_app_container_ids "$APP") )
  RUNNING_IMAGE_TAG=$(docker inspect -f '{{ .Config.Image }}' ${CIDS[0]} 2>/dev/null | awk -F: '{ print $2 }' || echo '')
  echo "$RUNNING_IMAGE_TAG"
}

is_image_herokuish_based() {
  # circleci can't support --rm as they run lxc in lxc
  [[ ! -f "/home/ubuntu/.circlerc" ]] && local DOCKER_ARGS="--rm"
  docker run "$DOKKU_GLOBAL_RUN_ARGS" --entrypoint="/bin/sh" $DOCKER_ARGS "$@" -c "test -f /exec"
}

is_number() {
  local NUMBER=$1; local NUM_RE='^[0-9]+$'
  if [[ $NUMBER =~ $NUM_RE ]]; then
    return 0
  else
    return 1
  fi
}

is_abs_path() {
  local TEST_PATH=$1
  if [[ "$TEST_PATH" = /* ]]; then
      return 0
    else
      return 1
  fi
}

parse_args() {
  for arg in "$@"; do
    case "$arg" in
      --quiet)
        export DOKKU_QUIET_OUTPUT=1
        ;;
      --trace)
        export DOKKU_TRACE=1
        ;;
      --rm-container|--rm)
        export DOKKU_RM_CONTAINER=1
        ;;
      --force)
        export DOKKU_APPS_FORCE_DELETE=1
        ;;
    esac
  done
  return 0
}

copy_from_image() {
  local IMAGE="$1"; local SRC_FILE="$2"; local DST_DIR="$3"
  verify_app_name "$APP"

  if verify_image "$IMAGE"; then
    if ! is_abs_path "$SRC_FILE"; then
      local WORKDIR=$(docker inspect -f '{{.Config.WorkingDir}}' "$IMAGE")
      [[ -z "$WORKDIR" ]] && WORKDIR=/app
      SRC_FILE="$WORKDIR/$SRC_FILE"
    fi
    CID=$(docker run "$DOKKU_GLOBAL_RUN_ARGS" -d "$IMAGE" bash)
    docker cp "$CID:$SRC_FILE" "$DST_DIR"
    docker rm -f "$CID" &> /dev/null
  else
    return 1
  fi
}

get_app_container_ids() {
  local APP="$1"; local CONTAINER_TYPE="$2"
  verify_app_name "$APP"
  [[ -f $DOKKU_ROOT/$APP/CONTAINER ]] && DOKKU_CIDS+=$(< "$DOKKU_ROOT/$APP/CONTAINER")

  if [[ -n "$CONTAINER_TYPE" ]]; then
    CONTAINER_PATTERN="$DOKKU_ROOT/$APP/CONTAINER.$CONTAINER_TYPE.*"
    if [[ $CONTAINER_TYPE == *.* ]]; then
      CONTAINER_PATTERN="$DOKKU_ROOT/$APP/CONTAINER.$CONTAINER_TYPE"
      [[ ! -f $CONTAINER_PATTERN ]] && echo "" && return 0
    fi
  else
    CONTAINER_PATTERN="$DOKKU_ROOT/$APP/CONTAINER.*"
  fi

  shopt -s nullglob
  for DOKKU_CID_FILE in $CONTAINER_PATTERN; do
    DOKKU_CIDS+=" "
    DOKKU_CIDS+=$(< "$DOKKU_CID_FILE")
    DOKKU_CIDS+=" "
  done
  shopt -u nullglob
  echo "$DOKKU_CIDS"
}

get_app_running_container_ids() {
  local APP=$1
  verify_app_name "$APP"

  ! (is_deployed "$APP") && dokku_log_fail "App $APP has not been deployed"
  local CIDS=$(get_app_container_ids "$APP")

  for CID in $CIDS; do
    local APP_CONTAINER_STATUS=$(docker inspect -f '{{.State.Running}}' "$CID" || true)
    [[ "$APP_CONTAINER_STATUS" == "true" ]] && local APP_RUNNING_CONTAINER_IDS+="$CID "
  done

  echo "$APP_RUNNING_CONTAINER_IDS"
}

get_cmd_from_procfile() {
  local APP=$1; local PROC_TYPE=$2; local DOKKU_PROCFILE="$DOKKU_ROOT/$APP/DOKKU_PROCFILE"
  local name; local command;
  verify_app_name "$APP"

  if [[ -f $DOKKU_PROCFILE ]]; then
    while read line || [[ -n "$line" ]]; do
      if [[ -z "$line" ]] || [[ "$line" == "#"* ]]; then
        continue
      fi
      name="${line%%:*}"
      command="${line#*:[[:space:]]}"
      [[ "$name" == "$PROC_TYPE" ]] && echo "$command" && break
    done < "$DOKKU_PROCFILE"
  fi
}

is_deployed() {
  local APP="$1"
  if [[ -f "$DOKKU_ROOT/$APP/CONTAINER" ]] || [[ $(ls "$DOKKU_ROOT/$APP"/CONTAINER.* &> /dev/null; echo $?) -eq 0 ]]; then
    return 0
  else
    return 1
  fi
}

is_container_running () {
  local CID=$1
  local CONTAINER_STATUS=$(docker inspect -f '{{.State.Running}}' "$CID" || true)

  if [[ "$CONTAINER_STATUS" == "true" ]]; then
    return 0
  else
    return 1
  fi
}

is_container_status () {
  local CID=$1
  local TEMPLATE="{{.State.$2}}"
  local CONTAINER_STATUS=$(docker inspect -f "$TEMPLATE" "$CID" || true)

  if [[ "$CONTAINER_STATUS" == "true" ]]; then
    return 0
  else
    return 1
  fi
}

is_app_running() {
  local APP="$1"
  verify_app_name "$APP"

  local APP_RUNNING_CONTAINER_IDS=$(get_app_running_container_ids "$APP")

  if [[ -n "$APP_RUNNING_CONTAINER_IDS" ]]; then
    return 0
  else
    return 1
  fi
}

release_and_deploy() {
  local APP="$1"; local IMAGE_TAG="$2"; local IMAGE=$(get_app_image_name "$APP" "$IMAGE_TAG")
  verify_app_name "$APP"

  if verify_image "$IMAGE"; then
    if is_image_herokuish_based "$IMAGE"; then
      IMAGE_SOURCE_TYPE="herokuish"
    else
      IMAGE_SOURCE_TYPE="dockerfile"
    fi

    DOKKU_APP_SKIP_DEPLOY="$(dokku config:get "$APP" DOKKU_SKIP_DEPLOY || true)"
    DOKKU_GLOBAL_SKIP_DEPLOY="$(dokku config:get --global DOKKU_SKIP_DEPLOY || true)"

    DOKKU_SKIP_DEPLOY=${DOKKU_APP_SKIP_DEPLOY:="$DOKKU_GLOBAL_SKIP_DEPLOY"}

    dokku_log_info1 "Releasing $APP ($IMAGE)..."
    dokku release "$APP" "$IMAGE_SOURCE_TYPE" "$IMAGE_TAG"

    if [[ "$DOKKU_SKIP_DEPLOY" != "true" ]]; then
      dokku_log_info1 "Deploying $APP ($IMAGE)..."
      dokku deploy "$APP" "$IMAGE_TAG"
      dokku_log_info2 "Application deployed:"
      dokku urls "$APP" | sed "s/^/       /"
    else
      dokku_log_info1 "Skipping deployment"
    fi

    echo
  fi
}

docker_cleanup() {
  # delete all non-running containers
  # shellcheck disable=SC2046
  docker rm $(docker ps -a -f 'status=exited' -q) &> /dev/null || true

  # delete all dead containers
  # shellcheck disable=SC2046
  docker rm $(docker ps -a -f 'status=dead' -q) &> /dev/null || true

  # delete unused images
  # shellcheck disable=SC2046
  docker rmi $(docker images -f 'dangling=true' -q) &> /dev/null &
}

get_available_port() {
  while true; do
    local port=$(shuf -i 1025-65535 -n 1)
    if ! nc -z 0.0.0.0 "$port"; then
      echo "$port"
      return 0
    else
      continue
    fi
  done
}

dokku_auth() {
  export SSH_USER=${SSH_USER:=$USER}
  export SSH_NAME=${NAME:="default"}
  if ! plugn trigger user-auth "$SSH_USER" "$SSH_NAME" "$@" ; then
    return 1
  fi
  return 0
}

_ipv4_regex() {
  echo "([0-9]{1,3}[\.]){3}[0-9]{1,3}"
}

_ipv6_regex() {
  local RE_IPV4="$(_ipv4_regex)"
  local RE_IPV6="([0-9a-fA-F]{1,4}:){7,7}[0-9a-fA-F]{1,4}|"              # TEST: 1:2:3:4:5:6:7:8
  RE_IPV6="${RE_IPV6}([0-9a-fA-F]{1,4}:){1,7}:|"                         # TEST: 1::                              1:2:3:4:5:6:7::
  RE_IPV6="${RE_IPV6}([0-9a-fA-F]{1,4}:){1,6}:[0-9a-fA-F]{1,4}|"         # TEST: 1::8             1:2:3:4:5:6::8  1:2:3:4:5:6::8
  RE_IPV6="${RE_IPV6}([0-9a-fA-F]{1,4}:){1,5}(:[0-9a-fA-F]{1,4}){1,2}|"  # TEST: 1::7:8           1:2:3:4:5::7:8  1:2:3:4:5::8
  RE_IPV6="${RE_IPV6}([0-9a-fA-F]{1,4}:){1,4}(:[0-9a-fA-F]{1,4}){1,3}|"  # TEST: 1::6:7:8         1:2:3:4::6:7:8  1:2:3:4::8
  RE_IPV6="${RE_IPV6}([0-9a-fA-F]{1,4}:){1,3}(:[0-9a-fA-F]{1,4}){1,4}|"  # TEST: 1::5:6:7:8       1:2:3::5:6:7:8  1:2:3::8
  RE_IPV6="${RE_IPV6}([0-9a-fA-F]{1,4}:){1,2}(:[0-9a-fA-F]{1,4}){1,5}|"  # TEST: 1::4:5:6:7:8     1:2::4:5:6:7:8  1:2::8
  RE_IPV6="${RE_IPV6}[0-9a-fA-F]{1,4}:((:[0-9a-fA-F]{1,4}){1,6})|"       # TEST: 1::3:4:5:6:7:8   1::3:4:5:6:7:8  1::8
  RE_IPV6="${RE_IPV6}:((:[0-9a-fA-F]{1,4}){1,7}|:)|"                     # TEST: ::2:3:4:5:6:7:8  ::2:3:4:5:6:7:8 ::8       ::
  RE_IPV6="${RE_IPV6}fe08:(:[0-9a-fA-F]{1,4}){2,2}%[0-9a-zA-Z]{1,}|"     # TEST: fe08::7:8%eth0      fe08::7:8%1                                      (link-local IPv6 addresses with zone index)
  RE_IPV6="${RE_IPV6}::(ffff(:0{1,4}){0,1}:){0,1}${RE_IPV4}|"            # TEST: ::255.255.255.255   ::ffff:255.255.255.255  ::ffff:0:255.255.255.255 (IPv4-mapped IPv6 addresses and IPv4-translated addresses)
  RE_IPV6="${RE_IPV6}([0-9a-fA-F]{1,4}:){1,4}:${RE_IPV4}"                # TEST: 2001:db8:3:4::192.0.2.33  64:ff9b::192.0.2.33
  echo "$RE_IPV6"
}

get_ipv4_regex() {
  local RE_IPV4="$(_ipv4_regex)"
  # Ensure the ip address continues to the end of the line
  # Fixes using a wildcard dns service such as xip.io which allows for *.<ip address>.xip.io
  echo "${RE_IPV4}\$"
}

get_ipv6_regex() {
  local RE_IPV6="$(_ipv6_regex)"
  # Ensure the ip address continues to the end of the line
  # Fixes using a wildcard dns service such as xip.io which allows for *.<ip address>.xip.io
  echo "${RE_IPV6}\$"
}

get_global_vhost() {
 local GLOBAL_VHOST_FILE="$DOKKU_ROOT/VHOST"
 [[ -f "$GLOBAL_VHOST_FILE" ]] && local GLOBAL_VHOST=$(< "$GLOBAL_VHOST_FILE")
 echo "$GLOBAL_VHOST"
}

is_global_vhost_enabled() {
  local desc="returns true if we have a valid global vhost set; otherwise returns false"
  local GLOBAL_VHOST=$(get_global_vhost)
  local GLOBAL_VHOST_ENABLED=true
  local RE_IPV4="$(get_ipv4_regex)"
  local RE_IPV6="$(get_ipv6_regex)"

  if [[ -z "$GLOBAL_VHOST" ]] || [[ "$GLOBAL_VHOST" =~ $RE_IPV4 ]] || [[ "$GLOBAL_VHOST" =~ $RE_IPV6 ]]; then
    local GLOBAL_VHOST_ENABLED=false
  fi
  echo $GLOBAL_VHOST_ENABLED
}

is_app_vhost_enabled() {
  local desc="returns true or false if vhost support is enabled for a given application"
  local APP=$1; verify_app_name "$APP"

  local NO_VHOST=$(config_get "$APP" NO_VHOST)
  local APP_VHOST_ENABLED=true

  if [[ "$NO_VHOST" == "1" ]]; then
    local APP_VHOST_ENABLED=false
  fi

  echo $APP_VHOST_ENABLED
}

disable_app_vhost() {
  local desc="disable vhost support for given application"
  local APP=$1; verify_app_name "$APP"
  local APP_VHOST_FILE="$DOKKU_ROOT/$APP/VHOST"
  local APP_URLS_FILE="$DOKKU_ROOT/$APP/URLS"
  local DOKKU_NGINX_PORT=$(config_get "$APP" DOKKU_NGINX_PORT)
  local DOKKU_NGINX_SSL_PORT=$(config_get "$APP" DOKKU_NGINX_SSL_PORT)

  if [[ -f "$APP_VHOST_FILE" ]]; then
    dokku_log_info1 "VHOST support disabled, deleting $APP/VHOST"
    rm "$APP_VHOST_FILE"
  fi
  if [[ -f "$APP_URLS_FILE" ]]; then
    dokku_log_info1 "VHOST support disabled, deleting $APP/URLS"
    rm "$APP_URLS_FILE"
  fi
  if [[ "$DOKKU_NGINX_PORT" == "80" ]]; then
    config_unset --no-restart "$APP" DOKKU_NGINX_PORT
  fi
  if [[ "$DOKKU_NGINX_SSL_PORT" == "443" ]]; then
    config_unset --no-restart "$APP" DOKKU_NGINX_SSL_PORT
  fi

  [[ "$2" == "--no-restart" ]] && local CONFIG_SET_ARGS=$2
  # shellcheck disable=SC2086
  config_set $CONFIG_SET_ARGS $APP NO_VHOST=1
}

enable_app_vhost() {
  local desc="enable vhost support for given application"
  local APP=$1; verify_app_name "$APP"

  config_unset --no-restart "$APP" DOKKU_NGINX_PORT DOKKU_NGINX_SSL_PORT
  [[ "$2" == "--no-restart" ]] && local CONFIG_SET_ARGS=$2
  # shellcheck disable=SC2086
  config_set $CONFIG_SET_ARGS "$APP" NO_VHOST=0
}

get_dockerfile_exposed_ports() {
  local DOCKERFILE_PORTS=$(egrep "^EXPOSE " "$1" | awk '{ print $2 }' | xargs) || true
  echo "$DOCKERFILE_PORTS"
}

get_app_raw_tcp_ports() {
  local APP="$1"; verify_app_name "$APP"
  local DOCKERFILE_PORTS="$(config_get "$APP" DOKKU_DOCKERFILE_PORTS)"
  for p in $DOCKERFILE_PORTS; do
    if [[ ! "$p" =~ .*udp.* ]]; then
      p=${p//\/tcp}
      raw_tcp_ports+="$p "
    fi
  done
  raw_tcp_ports="$(echo "$raw_tcp_ports"| xargs)"
  echo "$raw_tcp_ports"
}

get_container_ports() {
  local APP="$1"; verify_app_name "$APP"
  local APP_CIDS="$(get_app_container_ids "$APP")"
  local cid

  for cid in $APP_CIDS; do
    local container_ports="$(docker port "$cid" | awk '{ print $3 "->" $1}' | awk -F ":" '{ print $2 }')"
  done

  echo "$container_ports"
}

get_app_urls() {
  local APP="$2"; verify_app_name "$APP"
  local RAW_TCP_PORTS="$(get_app_raw_tcp_ports "$APP")"
  local URLS_FILE="$DOKKU_ROOT/$APP/URLS"

  if [[ -s "$URLS_FILE" ]]; then
    local app_urls="$(egrep -v "^#" "$URLS_FILE")"
    if [[ -n "$RAW_TCP_PORTS" ]]; then
      for url in ${app_urls[*]}; do
        for p in $RAW_TCP_PORTS; do
          local port_urls+="$url:$p "
        done
      done
      local port_urls="$(echo "$port_urls"| xargs)"
    fi
    local URLS=${port_urls:=$app_urls}
    case "$1" in
      url)
        echo "$URLS" | tr ' ' '\n' | head -n1
      ;;
      urls)
        echo "$URLS" | tr ' ' '\n'
      ;;
    esac
  else
    local SCHEME="http"; local SSL="$DOKKU_ROOT/$APP/tls"
    local DOKKU_NGINX_PORT=$(config_get "$APP" DOKKU_NGINX_PORT || true)
    local DOKKU_NGINX_SSL_PORT=$(config_get "$APP" DOKKU_NGINX_SSL_PORT || true)

    if [[ -e "$SSL/server.crt" && -e "$SSL/server.key" ]]; then
      local SCHEME="https"
    fi

    if [[ "$(is_app_proxy_enabled "$APP")" == "false" ]]; then
      if [[ -n "$RAW_TCP_PORTS" ]]; then
        local APP_CONTAINER_PORTS="$(get_container_ports "$APP")"
        local app_port
        for app_port in $APP_CONTAINER_PORTS; do
          echo "$(< "$DOKKU_ROOT/HOSTNAME"):$app_port (container)"
        done
      else
        shopt -s nullglob
        for PORT_FILE in $DOKKU_ROOT/$APP/PORT.*; do
          echo "$SCHEME://$(< "$DOKKU_ROOT/HOSTNAME"):$(< "$PORT_FILE") (container)"
        done
        shopt -u nullglob
      fi
    elif [[ -n "$DOKKU_NGINX_PORT" ]] || [[ -n "$DOKKU_NGINX_SSL_PORT" ]]; then
      if [[ -n "$DOKKU_NGINX_PORT" ]];then
        echo "http://$(< "$DOKKU_ROOT/HOSTNAME"):$DOKKU_NGINX_PORT ($(get_app_proxy_type "$APP"))"
      fi
      if [[ -n "$DOKKU_NGINX_SSL_PORT" ]]; then
        echo "https://$(< "$DOKKU_ROOT/HOSTNAME"):$DOKKU_NGINX_SSL_PORT ($(get_app_proxy_type "$APP")-ssl)"
      fi
    elif [[ -n "$RAW_TCP_PORTS" ]]; then
      for p in $RAW_TCP_PORTS; do
        echo "http://$(< "$DOKKU_ROOT/HOSTNAME"):$p"
      done
    else
      echo "$SCHEME://$(< "$DOKKU_ROOT/VHOST")"
    fi
  fi
}

get_json_value() {
  # return value of provided json key from a json stream on stdin
  # JSON_NODE should be expresses as either a top-level object that has no children
  # or in the format of json.node.path
  local JSON_NODE="$1"
  local JSON_NODE=${JSON_NODE//\./\"][\"}
  local JSON_NODE="[\"${JSON_NODE}\"]"
  cat | python -c 'import json,sys;obj=json.load(sys.stdin);print json.dumps(obj'"${JSON_NODE}"').strip("\"")';
}

get_json_keys() {
  # return space-separated list of json keys from json provided on stdin
  # JSON_NODE should be expressed as json.node.path and is expected to have children
  local JSON_NODE="$1"
  local JSON_NODE=${JSON_NODE//\./\"][\"}
  local JSON_NODE="[\"${JSON_NODE}\"]"
  if [[ "$JSON_NODE" == "[\"\"]" ]]; then
    cat | python -c 'import json,sys;obj=json.load(sys.stdin);print " ".join(obj.keys())';
  else
    cat | python -c 'import json,sys;obj=json.load(sys.stdin);print " ".join(obj'"${JSON_NODE}"'.keys())';
  fi
}