#!/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="systemd openrc lsb initd runit"
PLATFORM="$(uname -s)"
SHOW_SVC_TYPE=0
SVC_SOURCE="@libsysdir_POST@"
SVC_TYPE="detect"
WSL_ERROR_MSG="We appear to be running in WSL and were unable to find a usable service manager. We currently support systemd, LSB init scripts, and traditional init.d style init scripts when running under WSL."

# =====================================================================
# 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}" "${svc_file}"; 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.
  --show-type   Display information about what service managers are detected.
  --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

_check_systemd() {
  pids=''
  p=''
  myns=''
  ns=''

  # 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
    echo "NO" && return 0
  fi

  # if there is no systemctl command, it is not systemd
  [ -z "$(command -v systemctl 2>/dev/null || true)" ] && echo "NO" && return 0

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

  # it ‘is’ systemd at this point, but systemd might not be running
  # if not, return 2 to indicate ‘systemd, but not running’
  pids=$(safe_pidof systemd 2> /dev/null)
  [ -z "${pids}" ] && echo "OFFLINE" && return 0

  # 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}" ] && echo "YES" && return 0
  done

  # else, it is not systemd
  echo "NO"
}

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

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

    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 [ "$(check_systemd)" = "YES" ]; then
    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
  fi
}

systemd_cmds() {
  if [ "$(check_systemd)" = "YES" ]; then
    NETDATA_START_CMD='systemctl start netdata'
    NETDATA_STOP_CMD='systemctl stop netdata'
  else # systemd is not running, use external defaults by providing no commands
    warning "Detected systemd, but not booted using systemd. Unable to provide commands to start or stop Netdata using the service manager."
  fi
}

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

_check_openrc() {
  # if /lib/rc/sh/functions.sh does not exist, it's not OpenRC
  [ ! -f /lib/rc/sh/functions.sh ] && echo "NO" && return 0

  # if there is no /etc/init.d, it's not OpenRC
  [ ! -d /etc/init.d ] && echo "NO" && return 0

  # if there is no rc-update command, it's not OpenRC
  [ -z "$(command -v rc-update 2>/dev/null || true)" ] && echo "NO" && return 0

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

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

  # if there is an openrc command, it's OpenRC, but not booted as such
  [ -n "$(command -v openrc 2>/dev/null || true)" ] && echo "OFFLINE" && return 0

  # if /etc/init.d/local exists and has `openrc-run` in it's shebang line, it’s OpenRC, but not booted as such
  [ -r /etc/init.d/local ] && head -n 1 /etc/init.d/local | grep -q openrc-run && echo "OFFLINE" && return 0

  # Otherwise, it’s not OpenRC
  echo "NO" && return 0
}

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

  echo "${IS_OPENRC}"
}

enable_openrc() {
  if [ "$(check_openrc)" = "YES" ]; then
    runlevel="$(rc-status -r)"
  fi

  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() {
  if [ "$(check_openrc)" = "YES" ]; then
    NETDATA_START_CMD='rc-service netdata start'
    NETDATA_STOP_CMD='rc-service netdata stop'
  else # Not booted using OpenRC, use external defaults by not providing commands.
    warning "Detected OpenRC, but the system is not booted using OpenRC. Unable to provide commands to start or stop Netdata using the service manager."
  fi
}

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

_check_lsb_ignore_systemd() {
  # if there is no /etc/init.d directory, it’s not an LSB system
  [ ! -d /etc/init.d ] && echo "NO" && return 0

  # If it's an OpenRC system, then it's not an LSB system
  [ "$(check_openrc)" != "NO" ] && echo "NO" && return 0

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

  echo "NO" && return 0
}

_check_lsb() {
  # if there is _any_ systemd, it’s not an LSB system
  [ "$(check_systemd)" != "NO" ] && echo "NO" && return 0

  _check_lsb_ignore_systemd
}

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

  echo "${IS_LSB}"
}

enable_lsb() {
  if ! update-rc.d netdata defaults; then
    warning "Failed to enable Netdata service."
  elif ! update-rc.d netdata defaults-disabled; 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() {
  NETDATA_START_CMD='/etc/init.d/netdata start'
  NETDATA_STOP_CMD='/etc/init.d/netdata stop'
}

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

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

  # if there is no chkconfig command, it's not a (usable) init.d system
  [ -z "$(command -v chkconfig 2>/dev/null || true)" ] && echo "NO" && return 0

  # if there is _any_ openrc, it’s not init.d
  [ "$(check_openrc)" != "NO" ] && echo "NO" && return 0

  # if it's not an LSB setup, it’s init.d
  [ "$(check_lsb)" != "NO" ] && echo "NO" && return 0

  echo "YES" && return 0
}

_check_initd() {
  # if there is _any_ systemd, it’s not init.d
  [ "$(check_systemd)" != "NO" ] && echo "NO" && return 0

  _check_initd_ignore_systemd
}

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

  echo "${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() {
  NETDATA_START_CMD='/etc/init.d/netdata start'
  NETDATA_STOP_CMD='/etc/init.d/netdata stop'
}

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

_check_runit() {
  # if there is no runsvdir command, then it's not runit
  [ -z "$(command -v runsvdir 2>/dev/null || true)" ] && echo "NO" && return 0

  # if there is no runit command, then it's not runit
  [ -z "$(command -v runit 2>/dev/null || true)" ] && echo "NO" && return 0

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

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

  echo "NO" && return 0
}

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

  echo "${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.

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

  echo "NO" && return 0
}

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

  echo "${IS_WSL}"
}

install_wsl_service() {
  error "${WSL_ERROR_MSG}"
  exit 3
}

wsl_cmds() {
  error "${WSL_ERROR_MSG}"
  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
    found_types=''

    for t in wsl ${LINUX_INIT_TYPES}; do
      case "$("check_${t}")" in
        YES)
          SVC_TYPE="${t}"
          break
          ;;
        NO) continue ;;
        OFFLINE)
          if [ -z "${found_types}" ]; then
            found_types="${t}"
          else
            found_types="${found_types} ${t}"
          fi
          ;;
      esac
    done

    if [ "${SVC_TYPE}" = "detect" ]; then
      if [ -z "${found_types}" ]; then
        error "Failed to detect what type of service manager is in use."
      else
        SVC_TYPE="$(echo "${found_types}" | cut -f 1 -d ' ')"
        warning "Failed to detect a running service manager, using detected (but not running) ${SVC_TYPE}."
      fi
    elif [ "${SVC_TYPE}" = "wsl" ]; then
      if [ "$(check_systemd)" = "YES" ]; then
        # Support for systemd in WSL.
        SVC_TYPE="systemd"
      elif [ "$(_check_lsb_ignore_systemd)" = "YES" ]; then
        # Support for LSB init.d in WSL.
        SVC_TYPE="lsb"
      elif [ "$(_check_initd_ignore_systemd)" = "YES" ]; then
        # Support for ‘generic’ init.d in WSL.
        SVC_TYPE="initd"
      fi
    fi
  fi

  echo "${SVC_TYPE}"
}

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"
}

# =====================================================================
# Service type display function

show_service_type() {
  info "Detected platform: ${PLATFORM}"

  case "${PLATFORM}" in
    FreeBSD)
      info "Detected service managers:"
      info "  - freebsd: YES"
      info "Would use freebsd service management."
      ;;
    Darwin)
      info "Detected service managers:"
      info "  - launchd: YES"
      info "Would use launchd service management."
      ;;
    Linux)
      [ "$(check_wsl)" = "YES" ] && info "Detected WSL environment."
      info "Detected service managers:"
      for t in ${LINUX_INIT_TYPES}; do
        info "  - ${t}: $("check_${t}")"
      done
      info "Would use $(detect_linux_svc_type) service management."
      ;;
    *)
      info "${PLATFORM} is not supported by this script. No service file would be installed."
  esac

  exit 0
}

# =====================================================================
# 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="${2}"
          shift 1
        fi
        ;;
      "--show-type") SHOW_SVC_TYPE=1 ; INSTALL=0 ;;
      "--save-cmds")
        if [ -z "${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 "${@}"

  if [ "${SHOW_SVC_TYPE}" -eq 1 ]; then
    show_service_type
  else
    case "${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
  fi

  exit 0
}

main "${@}"