#! /bin/sh
# vim:et:ft=sh:sts=2:sw=2
#
# Versions determines the versions of all installed shells.
#
# Copyright 2008-2017 Kate Ward. All Rights Reserved.
# Released under the Apache 2.0 License.
#
# Author: kate.ward@forestent.com (Kate Ward)
# https://github.com/kward/shlib
#
# This library provides reusable functions that determine actual names and
# versions of installed shells and the OS. The library can also be run as a
# script if set executable.
#
# Disable checks that aren't fully portable (POSIX != portable).
# shellcheck disable=SC2006

ARGV0=`basename "$0"`
LSB_RELEASE='/etc/lsb-release'
VERSIONS_SHELLS="ash /bin/bash /bin/dash /bin/ksh /bin/pdksh /bin/sh /bin/zsh"

true; TRUE=$?
false; FALSE=$?
ERROR=2

UNAME_R=`uname -r`
UNAME_S=`uname -s`

__versions_haveStrings=${ERROR}

versions_osName() {
  os_name_='unrecognized'
  os_system_=${UNAME_S}
  os_release_=${UNAME_R}
  case ${os_system_} in
    CYGWIN_NT-*) os_name_='Cygwin' ;;
    Darwin)
      os_name_=`/usr/bin/sw_vers -productName`
      os_version_=`versions_osVersion`
      case ${os_version_} in
        10.4|10.4.[0-9]*) os_name_='Mac OS X Tiger' ;;
        10.5|10.5.[0-9]*) os_name_='Mac OS X Leopard' ;;
        10.6|10.6.[0-9]*) os_name_='Mac OS X Snow Leopard' ;;
        10.7|10.7.[0-9]*) os_name_='Mac OS X Lion' ;;
        10.8|10.8.[0-9]*) os_name_='Mac OS X Mountain Lion' ;;
        10.9|10.9.[0-9]*) os_name_='Mac OS X Mavericks' ;;
        10.10|10.10.[0-9]*) os_name_='Mac OS X Yosemite' ;;
        10.11|10.11.[0-9]*) os_name_='Mac OS X El Capitan' ;;
        10.12|10.12.[0-9]*) os_name_='macOS Sierra' ;;
        10.13|10.13.[0-9]*) os_name_='macOS High Sierra' ;;
        *) os_name_='macOS' ;;
      esac
      ;;
    FreeBSD) os_name_='FreeBSD' ;;
    Linux) os_name_='Linux' ;;
    SunOS)
      if grep 'OpenSolaris' /etc/release >/dev/null; then
        os_name_='OpenSolaris'
      else
        os_name_='Solaris'
      fi
      ;;
  esac

  echo ${os_name_}
  unset os_name_ os_system_ os_release_ os_version_
}

versions_osVersion() {
  os_version_='unrecognized'
  os_system_=${UNAME_S}
  os_release_=${UNAME_R}
  case ${os_system_} in
    CYGWIN_NT-*)
      os_version_=`expr "${os_release_}" : '\([0-9]*\.[0-9]\.[0-9]*\).*'`
      ;;
    Darwin)
      os_version_=`/usr/bin/sw_vers -productVersion`
      ;;
    FreeBSD)
      os_version_=`expr "${os_release_}" : '\([0-9]*\.[0-9]*\)-.*'`
      ;;
    Linux)
      if [ -r "${LSB_RELEASE}" ]; then
        if grep -q 'DISTRIB_ID=Ubuntu' "${LSB_RELEASE}"; then
          # shellcheck disable=SC2002
          os_version_=`cat "${LSB_RELEASE}" \
            |awk -F= '$1~/DISTRIB_DESCRIPTION/{print $2}' \
            |sed 's/"//g;s/ /-/g'`
        fi
      elif [ -r '/etc/redhat-release' ]; then
        os_version_=`cat /etc/redhat-release`
      fi
      ;;
    SunOS)
      if grep 'OpenSolaris' /etc/release >/dev/null; then
        os_version_=`grep 'OpenSolaris' /etc/release |awk '{print $2"("$3")"}'`
      else
        major_=`echo "${os_release_}" |sed 's/[0-9]*\.\([0-9]*\)/\1/'`
        minor_=`grep Solaris /etc/release |sed 's/[^u]*\(u[0-9]*\).*/\1/'`
        os_version_="${major_}${minor_}"
      fi
      ;;
  esac

  echo "${os_version_}"
  unset os_name_ os_release_ os_version_ major_ minor_
}

versions_shellVersion() {
  shell_=$1

  shell_present_=${FALSE}
  case "${shell_}" in
    ash)
      [ -x '/bin/busybox' ] && shell_present_=${TRUE}
      ;;
    *)
      [ -x "${shell_}" ] && shell_present_=${TRUE}
      ;;
  esac
  if [ ${shell_present_} -eq ${FALSE} ]; then
    echo 'not installed'
    return ${FALSE}
  fi

  version_=''
  case ${shell_} in
    */sh)
      # TODO(kward): fix this
      ## this could be one of any number of shells. try until one fits.
      #version_=`versions_shell_bash ${shell_}`
      ## dash cannot be self determined yet
      #[ -z "${version_}" ] && version_=`versions_shell_ksh ${shell_}`
      ## pdksh is covered in versions_shell_ksh()
      #[ -z "${version_}" ] && version_=`versions_shell_zsh ${shell_}`
      ;;
    ash) version_=`versions_shell_ash "${shell_}"` ;;
    */bash) version_=`versions_shell_bash "${shell_}"` ;;
    */dash)
      # simply assuming Ubuntu Linux until somebody comes up with a better
      # test. the following test will return an empty string if dash is not
      # installed.
      version_=`versions_shell_dash`
      ;;
    */ksh) version_=`versions_shell_ksh "${shell_}"` ;;
    */pdksh) version_=`versions_shell_pdksh "${shell_}"` ;;
    */zsh) version_=`versions_shell_zsh "${shell_}"` ;;
    *) version_='invalid'
  esac

  echo "${version_:-unknown}"
  unset shell_ version_
}

# The ash shell is included in BusyBox.
versions_shell_ash() {
  busybox --help |head -1 |sed 's/BusyBox v\([0-9.]*\) .*/\1/'
}

versions_shell_bash() {
  $1 --version 2>&1 |grep 'GNU bash' |sed 's/.*version \([^ ]*\).*/\1/'
}

versions_shell_dash() {
  eval dpkg >/dev/null 2>&1
  [ $? -eq 127 ] && return  # return if dpkg not found

  dpkg -l |grep ' dash ' |awk '{print $3}'
}

versions_shell_ksh() {
  versions_shell_=$1
  versions_version_=''

  # Try a few different ways to figure out the version.
  if versions_version_=`${versions_shell_} --version : 2>&1`; then
    versions_version_=`echo "${versions_version_}" \
      |sed 's/.*\([0-9][0-9][0-9][0-9]-[0-9][0-9]-[0-9][0-9]\).*/\1/'`
  fi
  if [ -z "${versions_version_}" ]; then
    _versions_have_strings
    versions_version_=`strings "${versions_shell_}" 2>&1 \
      |grep Version \
      |sed 's/^.*Version \(.*\)$/\1/;s/ s+ \$$//;s/ /-/g'`
  fi
  if [ -z "${versions_version_}" ]; then
    versions_version_=`versions_shell_pdksh "${versions_shell_}"`
  fi

  echo "${versions_version_}"
  unset versions_shell_ versions_version_
}

versions_shell_pdksh() {
  _versions_have_strings
  strings "$1" 2>&1 \
  |grep 'PD KSH' \
  |sed -e 's/.*PD KSH \(.*\)/\1/;s/ /-/g'
}

versions_shell_zsh() {
  versions_shell_=$1

  # Try a few different ways to figure out the version.
  # shellcheck disable=SC2016
  versions_version_=`echo 'echo ${ZSH_VERSION}' |${versions_shell_}`

  if [ -z "${versions_version_}" ]; then
    versions_version_=`${versions_shell_} --version 2>&1 |awk '{print $2}'`
  fi

  echo "${versions_version_}"
  unset versions_shell_ versions_version_
}

# Determine if the 'strings' binary installed.
_versions_have_strings() {
  [ ${__versions_haveStrings} -ne ${ERROR} ] && return
  if eval strings /dev/null >/dev/null 2>&1; then
    __versions_haveStrings=${TRUE}
    return
  fi

  echo 'WARN: strings not installed. try installing binutils?' >&2
  __versions_haveStrings=${FALSE}
}

versions_main() {
  # Treat unset variables as an error.
  set -u

  os_name=`versions_osName`
  os_version=`versions_osVersion`
  echo "os: ${os_name} version: ${os_version}"

  for shell in ${VERSIONS_SHELLS}; do
    shell_version=`versions_shellVersion "${shell}"`
    echo "shell: ${shell} version: ${shell_version}"
  done
}

if [ "${ARGV0}" = 'versions' ]; then
  versions_main "$@"
fi