#! /bin/sh
# $Id$
# vim:et:ft=sh:sts=2:sw=2
#
# Copyright 2008-2016 Kate Ward. All Rights Reserved.
# Released under the Apache License.
#
# Author: kate.ward@forestent.com (Kate Ward)
#
# 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 execuatable.

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

TRUE=0
FALSE=1
ERROR=2

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

__versions_haveStrings=${ERROR}

#------------------------------------------------------------------------------
# functions
#

versions_osName()
{
  os_name_='unrecognized'
  os_system_=${UNAME_S}
  case ${os_system_} in
    CYGWIN_NT-*) os_name_='Cygwin' ;;
    Darwin) os_name_='Mac OS X' ;;
    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_
}

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)
      major_='10'
      sub_=`echo ${os_release_} |sed 's/^[0-9]*\.\([0-9]*\)\.[0-9]*$/\1/'`
      case ${os_release_} in
        8.*) minor_='4' ;;
        9.*) minor_='5' ;;
        10.*) minor_='6' ;;
        11.*) minor_='7' ;;
        12.*) minor_='8' ;;
        13.*) minor_='9' ;;
        15.*) minor_='10' ;;
        *) minor_='X'; sub_='X' ;;
      esac
      os_version_="${major_}.${minor_}.${sub_}"
      ;;
    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
          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_ sub_
}

versions_shellVersion()
{
  shell_=$1

  if [ ! -x "${shell_}" ]; then
    echo 'not installed'
    return
  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_}`
      ;;
    */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_
}

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

  # try a few different ways to figure out the version
  versions_version_=`${versions_shell_} --version : 2>&1`
  if [ $? -eq 0 ]; then
    versions_version_=`echo "${versions_version_}" \
      |sed 's/.*\([0-9][0-9][0-9][0-9]-[0-9][0-9]-[0-9][0-9]\).*/\1/'`
  else
    versions_version_=''
  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
  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
  eval strings /dev/null >/dev/null 2>&1
  if [ $? -eq 0 ]; then
    __versions_haveStrings=${TRUE}
  else
    echo 'WARN: strings not installed. try installing binutils?' >&2
    __versions_haveStrings=${FALSE}
  fi
}

#------------------------------------------------------------------------------
# main
#

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