#! /bin/sh
# $Id$
#
# Encapsulates set/access of a components file, which records set of
# components that were built in a library.  Intended to be used by
# Makefiles and scripts.  See ACE_wrappers/PACE/pace/Makefile for an
# example.
#
usage="usage: $0 --pace [--remove | --set \" <components list> \"]"

####
#### Make sure that PACE_ROOT is set.
####
if [ ! "$ACE_ROOT" ]; then
  echo $0': your ACE_ROOT environment variable is not set!' 1>&2
  exit -1
fi
if [ ! "$PACE_ROOT" ]; then
  PACE_ROOT=$ACE_ROOT/PACE
  export PACE_ROOT
fi

####
#### Process command line arguments.
####
if [ $# -ge 1 ]; then
  case $1 in
    --pace) components_file=$PACE_ROOT/PACE_COMPONENTS.list ;;
    *) echo $usage; exit -1 ;;
  esac
  shift
else
  echo $usage
  exit -1
fi

set_components=0
if [ $# -ge 1 ]; then
  if [ $1 = '--set' ]; then
    set_components=1
    shift
    if [ $# -eq 1 ]; then
      components=$1
      shift
    else
      echo $usage
      exit -1
    fi
  elif [ $1 = '--remove' ]; then
    rm -f $components_file
  else
    echo $usage
    exit -1
  fi
fi

if [ $set_components -eq 1 ]; then
  ####
  #### Update the components file, if it has changed since last set.
  ####
  if [ -f $components_file ]; then
    if echo "$components" | diff - $components_file > /dev/null; then
      :
    else
      echo "$components" > $components_file
    fi
  else
    echo "$components" > $components_file
  fi
else
  ####
  #### Access the contents of the components file, if it exists.
  ####
  if [ -f $components_file ]; then
    cat $components_file
  fi
fi