#!/bin/bash

#

# createmodule.sh - Takes the name of a environment init script and 

# produces a modulefile that duplicates the changes made by the init script

#

# Copyright (C) 2010-2012 by Orion E. Poplawski <orion@cora.nwra.com>

#

# This program is free software: you can redistribute it and/or modify

# it under the terms of the GNU General Public License as published by

# the Free Software Foundation, either version 2 of the License, or

# (at your option) any later version.

# This program is distributed in the hope that it will be useful,

# but WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

# GNU General Public License for more details.

# You should have received a copy of the GNU General Public License

# along with this program.  If not, see <http://www.gnu.org/licenses/>.

usage="Usage: $0 [-p prefix] <initscript> [args]"

usage() {

  echo $usage 1>&2

  exit 1

}

while getopts "p:" opt

do

  case $opt in

    p) prefix=$OPTARG; shift 2;;

    *) usage;;

  esac

done

# Need a script name

[ -z "$1" ] && usage

# Need to be a readable script

if [ ! -r "$1" ]

then

  echo "ERROR: Cannot read $1" 1>&2

  exit 1 

fi

#Will print out array assignment list

printenvarray () {

  env | while read x

  do

    key=${x%%=*}

    value=`printenv "$key"`

    if [ $? -eq 0 ]

    then

      echo [$key]="'$value'"

    fi

  done

}

#Apparently we need to declare the associative arrays

declare -A env1 env2

#Record starting environment

eval env1=(`printenvarray`)

#Source the environment script

. "$@"

#Record ending environment

eval env2=(`printenvarray`)

#Print out the modulefile

echo "#%Module 1.0"

#Prefix

[ -n "$prefix" ] && echo -e "\nset prefix $prefix\n"

# dedup - remove duplicate entries from a list

#Subshell so we can sort the output

(

dedup() {

  list=`mktemp`

  [ -n "$2" ] && sep=$2 || sep=:

  echo $1 | sed -r -e 's,[^/]+/\.\./,,g' -e 's,[^/]+/\.\./,,g' -e "s/\\$sep/\n/g" |

    while read x

    do

      grep -Fx ${x} $list && continue

      if [ -n "$prefix" ]

      then

        echo $x | sed -e s,$prefix,\$prefix,

      else

        echo $x

      fi

      echo $x >> $list

    done | tr '\n' $sep | sed -e "s/\\$sep\$//"

  rm $list

} 

#Keys that changed

for key in "${!env1[@]}"

do

  if [ "${env1[$key]}" != "${env2[$key]}" ]

  then

    #Working directory change

    if [ "$key" = PWD ]

    then

      if [ -n "$prefix" ]

      then

        echo -e "chdir\t\t${env2[PWD]}" | sed -e s,$prefix,\$prefix,g

      else

        echo -e "chdir\t\t${env2[PWD]}"

      fi

    #Test for delete

    elif [ -z "${env2[$key]}" ]

    then

      echo -e "unsetenv\t${key}\t${env2[$key]}"

    #Test for prepend

    elif [ "${env2[$key]%${env1[$key]}}" != "${env2[$key]}" ]

    then

      added=${env2[$key]%${env1[$key]}}

      sep=${added: -1}

      added=${added%$sep}

      added=$(dedup $added $sep)

      if [ $sep = : ]

      then

        echo -e "prepend-path\t$key\t${added}"

      else

        echo -e "prepend-path\t--delim $sep\t$key\t${added}"

      fi

    #Test for prepend plus : added at end (MANPATH)

    elif [ "${key: -4}" = PATH -a "${env2[$key]%${env1[$key]}:}" != "${env2[$key]}" ]

    then

      added=$(dedup ${env2[$key]%${env1[$key]}:})

      echo -e "prepend-path\t$key\t${added}"

    #Test for append

    elif [ "${env2[$key]#${env1[$key]}}" != "${env2[$key]}" ]

    then

      added=${env2[$key]#${env1[$key]}}

      sep=${added:0:1}

      added=${added#$sep}

      added=$(dedup $added $sep)

      if [ $sep = : ]

      then

        echo -e "append-path\t$key\t${added}"

      else

        echo -e "append-path\t--delim $sep\t$key\t${added}"

      fi

    #Test for prepend plus append

    elif [ "${env2[$key]%${env1[$key]}*}" != "${env2[$key]}" ]

    then

      prepended=${env2[$key]%${env1[$key]}*}

      presep=${prepended: -1}

      prepended=${prepended%$presep}

      prepended=$(dedup $prepended $presep)

      appended=${env2[$key]#*${env1[$key]}}

      appsep=${appended:0:1}

      appended=${appended#$appsep}

      appended=$(dedup $appended $appsep)

      if [ $presep != $appsep -o -z "$prepended" -o -z "$appended" ]

      then

        #Unhandled

        echo "Unhandled change of $key" 1>&2

        echo "Before <${env1[$key]}>" 1>&2

        echo "After  <${env2[$key]}>" 1>&2

      else

        if [ $presep = : ]

        then

          echo -e "prepend-path\t$key\t${prepended}"

          echo -e "append-path\t$key\t${appended}"

        else

          echo -e "prepend-path\t--delim $presep\t$key\t${prepended}"

          echo -e "append-path\t--delim $appsep\t$key\t${appended}"

        fi

      fi

    else

      #Unhandled

      echo "Unhandled change of $key" 1>&2

      echo "Before <${env1[$key]}>" 1>&2

      echo "After  <${env2[$key]}>" 1>&2

    fi

  fi

  #Delete keys we have handled

  unset env1[$key]

  unset env2[$key]

done

#New keys

for key in "${!env2[@]}"

do

  if [ "$key" = OLDPWD ]

  then

    continue

  fi

  #Use prepend-path for new paths

  if [ "${key: -4}" = PATH -o "${key: -4}" = DIRS -o "${key: -4}" = FILES ]

  then

    # TODO - Need to handle stripping of default MANPATH

    echo -e "prepend-path\t${key}\t"$(dedup ${env2[$key]})

  else

    if [ -n "$prefix" ]

    then

      echo -e "setenv\t\t${key}\t${env2[$key]}" | sed -e s,$prefix,\$prefix,g

    else

      echo -e "setenv\t\t${key}\t${env2[$key]}"

    fi

  fi

done

) | sort