#!/usr/bin/env sh

# SPDX-License-Identifier: GPL-3.0-or-later

# Handle installation of the Netdata agent as a system service.
#
# Exit codes:
# 0 - Successfully installed service.
# 1 - Invalid arguments or other internal error.
# 2 - Unable to detect system service type.
# 3 - Detected system service type, but type not supported.
# 4 - Detected system service type, but could not install due to other issues.
# 5 - Platform not supported.

set -e

SCRIPT_SOURCE="$(
    self=${0}
    while [ -L "${self}" ]
    do
        cd "${self%/*}" || exit 1
        self=$(readlink "${self}")
    done
    cd "${self%/*}" || exit 1
    echo "$(pwd -P)/${self##*/}"
)"

DUMP_CMDS=0
ENABLE="auto"
EXPORT_CMDS=0
INSTALL=1
LINUX_INIT_TYPES="wsl systemd openrc lsb initd runit"
PLATFORM="$(uname -s)"
SVC_SOURCE="@libsysdir_POST@"
SVC_TYPE="detect"

# =====================================================================
# Utility functions

cleanup() {
  ec="${?}"

  if [ -n "${NETDATA_SAVE_WARNINGS}" ]; then
    if [ -n "${NETDATA_PROPAGATE_WARNINGS}" ]; then
      export NETDATA_WARNINGS="${NETDATA_WARNINGS}${SAVED_WARNINGS}"
    fi
  fi

  trap - EXIT

  exit "${ec}"
}

info() {
  printf >&2 "%s\n" "${*}"
}

warning() {
  if [ -n "${NETDATA_SAVE_WARNINGS}" ]; then
    SAVED_WARNINGS="${SAVED_WARNINGS}\n  - ${*}"
  fi
  printf >&2 "WARNING: %s\n" "${*}"
}

error() {
  if [ -n "${NETDATA_SAVE_WARNINGS}" ]; then
    SAVED_WARNINGS="${SAVED_WARNINGS}\n  - ${*}"
  fi
  printf >&2 "ERROR: %s\n" "${*}"
}

get_os_key() {
  if [ -f /etc/os-release ]; then
    # shellcheck disable=SC1091
    . /etc/os-release || return 1
    echo "${ID}-${VERSION_ID}"

  elif [ -f /etc/redhat-release ]; then
    cat /etc/redhat-release
  else
    echo "unknown"
  fi
}

valid_types() {
  case "${PLATFORM}" in
    Linux)
      echo "detect systemd openrc lsb initd"
      ;;
    FreeBSD)
      echo "detect freebsd"
      ;;
    Darwin)
      echo "detect launchd"
      ;;
    *)
      echo "detect"
      ;;
  esac
}

install_generic_service() {
  svc_type="${1}"
  svc_type_name="${2}"
  svc_file="${3}"
  svc_enable_hook="${4}"
  svc_disable_hook="${5}"

  info "Installing ${svc_type_name} service file."
  if [ ! -f "${svc_file}" ] && [ "${ENABLE}" = "auto" ]; then
    ENABLE="enable"
  fi

  if ! install -p -m 0755 -o 0 -g 0 "${SVC_SOURCE}/netdata-${svc_type}" /etc/init.d/netdata; then
    error "Failed to install service file."
    exit 4
  fi

  case "${ENABLE}" in
    auto) true ;;
    disable)
      info "Disabling Netdata service."
      ${svc_disable_hook}
      ;;
    enable)
      info "Enabling Netdata service."
      ${svc_enable_hook}
      ;;
  esac
}

dump_cmds() {
  [ -n "${NETDATA_START_CMD}" ] && echo "NETDATA_START_CMD='${NETDATA_START_CMD}'"
  [ -n "${NETDATA_STOP_CMD}" ] && echo "NETDATA_STOP_CMD='${NETDATA_STOP_CMD}'"
  [ -n "${NETDATA_INSTALLER_START_CMD}" ] && echo "NETDATA_INSTALLER_START_CMD='${NETDATA_INSTALLER_START_CMD}'"
  return 0
}

export_cmds() {
  [ -n "${NETDATA_START_CMD}" ] && export NETDATA_START_CMD="${NETDATA_START_CMD}"
  [ -n "${NETDATA_STOP_CMD}" ] && export NETDATA_STOP_CMD="${NETDATA_STOP_CMD}"
  [ -n "${NETDATA_INSTALLER_START_CMD}" ] && export NETDATA_INSTALLER_START_CMD="${NETDATA_INSTALLER_START_COMMAND}"
  return 0
}

save_cmds() {
  dump_cmds > "${SAVE_CMDS_PATH}"
}

# =====================================================================
# Help functions

usage() {
  cat << HEREDOC
USAGE: install-service.sh [options]
       where options include:

  --source      Specify where to find the service files to install (default ${SVC_SOURCE}).
  --type        Specify the type of service file to install. Specify a type of 'help' to get a list of valid types for your platform.
  --cmds        Additionally print a list of commands for starting and stopping the agent with the detected service type.
  --export-cmds Export the variables that would be printed by the --cmds option.
  --cmds-only   Don't install, just handle the --cmds or --export-cmds option.
  --enable      Explicitly enable the service on install (default is to enable if not already installed).
  --disable     Explicitly disable the service on install.
  --help        Print this help information.
HEREDOC
}

help_types() {
  cat << HEREDOC
Valid service types for ${PLATFORM} are:
$(valid_types)
HEREDOC
}

# =====================================================================
# systemd support functions

issystemd() {
  pids=''
  p=''
  myns=''
  ns=''
  systemctl=''

  # if the directory /lib/systemd/system OR /usr/lib/systemd/system (SLES 12.x) does not exit, it is not systemd
  if [ ! -d /lib/systemd/system ] && [ ! -d /usr/lib/systemd/system ]; then
    return 1
  fi

  # if there is no systemctl command, it is not systemd
  systemctl=$(command -v systemctl 2> /dev/null)
  if [ -z "${systemctl}" ] || [ ! -x "${systemctl}" ]; then
    return 1
  fi

  # if pid 1 is systemd, it is systemd
  [ "$(basename "$(readlink /proc/1/exe)" 2> /dev/null)" = "systemd" ] && return 0

  # if systemd is not running, it is not systemd
  pids=$(safe_pidof systemd 2> /dev/null)
  [ -z "${pids}" ] && return 1

  # check if the running systemd processes are not in our namespace
  myns="$(readlink /proc/self/ns/pid 2> /dev/null)"
  for p in ${pids}; do
    ns="$(readlink "/proc/${p}/ns/pid" 2> /dev/null)"

    # if pid of systemd is in our namespace, it is systemd
    [ -n "${myns}" ] && [ "${myns}" = "${ns}" ] && return 0
  done

  # else, it is not systemd
  return 1
}

check_systemd() {
  if [ -z "${IS_SYSTEMD}" ]; then
    issystemd
    IS_SYSTEMD="$?"
  fi

  return "${IS_SYSTEMD}"
}

get_systemd_service_dir() {
  if [ -w "/lib/systemd/system" ]; then
    echo "/lib/systemd/system"
  elif [ -w "/usr/lib/systemd/system" ]; then
    echo "/usr/lib/systemd/system"
  elif [ -w "/etc/systemd/system" ]; then
    echo "/etc/systemd/system"
  else
    error "Unable to detect systemd service directory."
    exit 4
  fi
}

install_systemd_service() {
  SRCFILE="${SVC_SOURCE}/netdata.service"

  if [ "$(systemctl --version | head -n 1 | cut -f 2 -d ' ')" -le 235 ]; then
    SRCFILE="${SVC_SOURCE}/netdata.service.v235"
  fi

  if [ "${ENABLE}" = "auto" ]; then
    IS_NETDATA_ENABLED="$(systemctl is-enabled netdata 2> /dev/null || echo "Netdata not there")"

    if [ "${IS_NETDATA_ENABLED}" = "disabled" ]; then
      ENABLE="disable"
    else
      ENABLE="enable"
    fi
  fi

  info "Installing systemd service..."
  if ! install -p -m 0644 -o 0 -g 0 "${SRCFILE}" "$(get_systemd_service_dir)/netdata.service"; then
    error "Failed to install systemd service file."
    exit 4
  fi

  if ! systemctl daemon-reload; then
    warning "Failed to reload systemd unit files."
  fi

  if ! systemctl ${ENABLE} netdata; then
    warning "Failed to ${ENABLE} Netdata service."
  fi
}

systemd_cmds() {
  NETDATA_START_CMD='systemctl start netdata'
  NETDATA_STOP_CMD='systemctl stop netdata'
}

# =====================================================================
# OpenRC support functions

isopenrc() {
  # if /lib/rc/sh/functions.sh does not exist, it's not OpenRC
  [ ! -f /lib/rc/sh/functions.sh ] && return 1

  # if there is no /etc/init.d, it's not OpenRC
  [ ! -d /etc/init.d ] && return 1

  # if PID 1 is openrc-init, it's OpenRC
  [ "$(basename "$(readlink /proc/1/exe)" 2> /dev/null)" = "openrc-init" ] && return 0

  # If /run/openrc/softlevel exists, it's OpenRC
  [ -f /run/openrc/softlevel ] && return 0

  # if there is an openrc command, it's OpenRC
  command -v openrc > /dev/null 2>&1 && return 0

  # Otherwise, it’s not OpenRC
  return 1
}

check_openrc() {
  if [ -z "${IS_OPENRC}" ]; then
    isopenrc
    IS_OPENRC="$?"
  fi

  return "${IS_OPENRC}"
}

enable_openrc() {
  runlevel="$(rc-status -r)"
  runlevel="${runlevel:-default}"
  if ! rc-update add netdata "${runlevel}"; then
    warning "Failed to enable Netdata service in runlevel ${runlevel}."
  fi
}

disable_openrc() {
  for runlevel in /etc/runlevels/*; do
    if [ -e "${runlevel}/netdata" ]; then
      runlevel="$(basename "${runlevel}")"
      if ! rc-update del netdata "${runlevel}"; then
        warning "Failed to disable Netdata service in runlevel ${runlevel}."
      fi
    fi
  done
}

install_openrc_service() {
  install_generic_service openrc OpenRC /etc/init.d/netdata enable_openrc disable_openrc
}

openrc_cmds() {
  NETDATA_START_CMD='rc-service netdata start'
  NETDATA_STOP_CMD='rc-service netdata stop'
}

# =====================================================================
# LSB init script support functions

islsb() {
  # if there is no /etc/init.d directory, it’s not an LSB system
  [ ! -d /etc/init.d ] && return 1

  # If it's an OpenRC system, then it's not an LSB system
  check_openrc && return 1

  # If /lib/lsb/init-functions exists, it’s an LSB system
  [ -f /lib/lsb/init-functions ] && return 0

  return 1
}

check_lsb() {
  if [ -z "${IS_LSB}" ]; then
    islsb
    IS_LSB="$?"
  fi

  return "${IS_LSB}"
}

enable_lsb() {
  if ! update-rc.d netdata defaults; then
    warning "Failed to enable Netdata service."
  elif ! update-rc.d netdata defaults-disable; then
    warning "Failed to fully enable Netdata service."
  fi
}

disable_lsb() {
  if ! update-rc.d netdata remove; then
    warning "Failed to disable Netdata service."
  fi
}

install_lsb_service() {
  install_generic_service lsb LSB /etc/init.d/netdata enable_lsb disable_lsb
}

lsb_cmds() {
  if command -v service >/dev/null 2>&1; then
    NETDATA_START_CMD='service netdata start'
    NETDATA_STOP_CMD='service netdata stop'
  else
    NETDATA_START_CMD='/etc/init.d/netdata start'
    NETDATA_STOP_CMD='/etc/init.d/netdata stop'
  fi
}

# =====================================================================
# init.d init script support functions

isinitd() {
  # if there is no /etc/init.d directory, it’s not an init.d system
  [ ! -d /etc/init.d ] && return 1

  # if there is no chkconfig command, it's not a (usable) init.d system
  command -v chkconfig >/dev/null 2>&1 || return 1

  # if it's not an LSB setup, it’s init.d
  check_initd || return 0

  return 1
}

check_initd() {
  if [ -z "${IS_INITD}" ]; then
    isinitd
    IS_INITD="$?"
  fi

  return "${IS_INITD}"
}

enable_initd() {
  if ! chkconfig netdata on; then
    warning "Failed to enable Netdata service."
  fi
}

disable_initd() {
  if ! chkconfig netdata off; then
    warning "Failed to disable Netdata service."
  fi
}

install_initd_service() {
  install_generic_service init-d init.d /etc/init.d/netdata enable_initd disable_initd
}

initd_cmds() {
  if command -v service >/dev/null 2>&1; then
    NETDATA_START_CMD='service netdata start'
    NETDATA_STOP_CMD='service netdata stop'
  else
    NETDATA_START_CMD='/etc/init.d/netdata start'
    NETDATA_STOP_CMD='/etc/init.d/netdata stop'
  fi
}

# =====================================================================
# runit support functions
#
# Currently not supported, this exists to provide useful error messages.

isrunit() {
  # if there is no /lib/rc/sv.d, then it's not runit
  [ ! -d /lib/rc/sv.d ] && return 1

  # if there is no runit command, then it's not runit
  command -v runit >/dev/null 2>&1 || return 1

  # if /run/runit exists, then it's runit
  [ -d /run/runit ] && return 0

  # if /etc/runit/1 exists and is executable, then it's runit
  [ -x /etc/runit/1 ] && return 0

  return 1
}

check_runit() {
  if [ -z "${IS_RUNIT}" ]; then
    isrunit
    IS_RUNIT="$?"
  fi

  return "${IS_RUNIT}"
}

install_runit_service() {
  error "Detected runit, which we do not currently support."
  exit 3
}

runit_cmds() {
  error "Detected runit, which we do not currently support."
  exit 3
}

# =====================================================================
# WSL support functions
#
# Cannot be supported, this exists to provide useful error messages.

iswsl() {
  # If uname -r contains the string WSL, then it's WSL.
  uname -r | grep -q 'WSL' && return 0

  # If uname -r contains the string Microsoft, then it's WSL.
  # This probably throws a false positive on CBL-Mariner, but it's part of what MS officially recommends for
  # detecting if you're running under WSL.
  uname -r | grep -q "Microsoft" && return 0

  return 1
}

check_wsl() {
  if [ -z "${IS_WSL}" ]; then
    iswsl
    IS_WSL="$?"
  fi

  return "${IS_WSL}"
}

install_wsl_service() {
  error "We appear to be running in WSL. Netdata cannot be automatically installed as a service under WSL."
  exit 3
}

wsl_cmds() {
  error "We appear to be running in WSL. Netdata cannot be automatically installed as a service under WSL."
  exit 3
}

# =====================================================================
# FreeBSD support functions

enable_freebsd() {
  if ! sysrc netdata_enable=YES; then
    warning "Failed to enable netdata service."
  fi
}

disable_freebsd() {
  if ! sysrc netdata_enable=NO; then
    warning "Failed to disable netdata service."
  fi
}

install_freebsd_service() {
  install_generic_service freebsd "FreeBSD rc.d" /usr/local/etc/rc.d/netdata enable_freebsd disable_freebsd
}

freebsd_cmds() {
  NETDATA_START_CMD='service netdata start'
  NETDATA_STOP_CMD='service netdata stop'
  NETDATA_INSTALLER_START_CMD='service netdata onestart'
}

# =====================================================================
# macOS support functions

install_darwin_service() {
  info "Installing macOS plist file for launchd."
  if ! install -C -S -p -m 0644 -o 0 -g 0 system/netdata.plist /Library/LaunchDaemons/com.github.netdata.plist; then
    error "Failed to copy plist file."
    exit 4
  fi

  if ! launchctl load /Library/LaunchDaemons/com.github.netdata.plist; then
    error "Failed to load plist file."
    exit 4
  fi
}

darwin_cmds() {
  NETDATA_START_CMD='launchctl start com.github.netdata'
  NETDATA_STOP_CMD='launchctl stop com.github.netdata'
}

# =====================================================================
# Linux support functions

detect_linux_svc_type() {
  if [ "${SVC_TYPE}" = "detect" ]; then
    for t in ${LINUX_INIT_TYPES}; do
      if "check_${t}"; then
        SVC_TYPE="${t}"
        break
      fi
    done

    if [ "${SVC_TYPE}" = "detect" ]; then
      error "Failed to detect what type of service manager is in use."
    else
      echo "${SVC_TYPE}"
    fi
  else
    echo "${SVC_TYPE}"
  fi
}

install_linux_service() {
  t="$(detect_linux_svc_type)"

  if [ -z "${t}" ]; then
    exit 2
  fi

  "install_${t}_service"
}

linux_cmds() {
  t="$(detect_linux_svc_type)"

  if [ -z "${t}" ]; then
    exit 2
  fi

  "${t}_cmds"
}

# =====================================================================
# Argument handling

parse_args() {
  while [ -n "${1}" ]; do
    case "${1}" in
      "--source" | "-s")
        SVC_SOURCE="${2}"
        shift 1
        ;;
      "--type" | "-t")
        if [ "${2}" = "help" ]; then
          help_types
          exit 0
        else
          SVC_TYPE="${2}"
          shift 1
        fi
        ;;
      "--save-cmds")
        if [ -z "${2}" ]; then
          info "No path specified to save command variables."
          exit 1
        else
          SAVE_CMDS_PATH="${2}"
          shift 1
        fi
        ;;
      "--cmds" | "-c") DUMP_CMDS=1 ;;
      "--cmds-only") INSTALL=0 ;;
      "--export-cmds") EXPORT_CMDS=1 ;;
      "--enable" | "-e") ENABLE="enable" ;;
      "--disable" | "-d") ENABLE="disable" ;;
      "--help" | "-h")
        usage
        exit 0
        ;;
      *)
        info "Unrecognized option '${1}'."
        exit 1
        ;;
    esac
    shift 1
  done

  if [ "${SVC_SOURCE#@}" = "libsysdir_POST@" ]; then
    SVC_SOURCE="$(dirname "${SCRIPT_SOURCE}")/../../lib/netdata/system"
    warning "SVC_SOURCE not templated, using ${SVC_SOURCE} as source directory."
  fi

  if [ ! -d "${SVC_SOURCE}" ] && [ "${INSTALL}" -eq 1 ]; then
    error "${SVC_SOURCE} does not appear to be a directory. Please specify a valid source for service files with the --source option."
    exit 1
  fi

  if valid_types | grep -vw "${SVC_TYPE}"; then
    error "${SVC_TYPE} is not supported on this platform."
    help_types
    exit 1
  fi
}

# =====================================================================
# Core logic

main() {
  trap "cleanup" EXIT

  parse_args "${@}"

  case "${PLATFORM}" in
    FreeBSD)
      [ "${INSTALL}" -eq 1 ] && install_freebsd_service
      freebsd_cmds
      ;;
    Darwin)
      [ "${INSTALL}" -eq 1 ] && install_darwin_service
      darwin_cmds
      ;;
    Linux)
      [ "${INSTALL}" -eq 1 ] && install_linux_service
      linux_cmds
      ;;
    *)
      error "${PLATFORM} is not supported by this script."
      exit 5
      ;;
  esac

  [ "${DUMP_CMDS}" -eq 1 ] && dump_cmds
  [ "${EXPORT_CMDS}" -eq 1 ] && export_cmds
  [ -n "${SAVE_CMDS_PATH}" ] && save_cmds
  exit 0
}

main "${@}"