#!/bin/bash

moddir=""
zipdir=""
pkgcnt=0

usage()
{
  echo "Usage: $0 -m moddir [-z zipdir]"  >&2
  echo "       $0 -h|-?"  >&2
  echo "    -m moddir  The source directory containing sub-directories mods.d and modules" >&2
  echo "               If the moddir is not properly set up, it is an error." >&2
  echo "    -z zipdir  The destination directory for the zipped modules [default: /tmp/zip]" >&2
  echo "               If the zipdir does not exist it is created." >&2
  echo "    -h|-?      This usage statement" >&2
}

package_module()
{
  local conf=$1
  local modName=""
  local dataPath=""
  local count=0

  if [ ! -f $conf ] ; then
    echo "$Error: $conf does not exist" >&2
    return
  fi

  if [ ! -r $conf ] ; then
    echo "Error: $conf is not readable" >&2
    return
  fi

  # Read the conf for the section [NAME] and DataPath
  while read line
  do
    # Remove trailing \r from windows created files
    line=${line%$'\015'}

    # Check for the [NAME]
    # Use a regular expression to grab what is inside the [ ]
    if [[ $line =~ ^\[(.*)\]$ ]]
    then
       (( count++ ))
       modName=${BASH_REMATCH[1]}
    fi

    # If it is DataPath grab what follows the = sign
    if [[ $line =~ DataPath=(.*) ]]
    then
       (( count++ ))

       # Save off the match
       dataPath=${BASH_REMATCH[1]}

       # The dataPath of some modules has a prefix for filenames as the last element
       if [[ ! -d "$dataPath" ]]
       then
         # Since it is a prefix, remove the last element
         # so that it becomes a directory
         dataPath=${dataPath%/*}
       fi

       # If the path ends in a / then remove it
       dataPath=${dataPath%/}

       # If the path starts with ./ then remove it
       dataPath=${dataPath#./}
    fi

    # Quit processing the file once everything needed
    # has been seen
    if (( count == 2 ))
    then
      break
    fi
  done < $conf

  if [[ ! -d "$dataPath" ]]
  then
    echo "Error in $conf: $dataPath is not a directory" >&2
    # should we rename the conf?
    return
  fi

  # create the zip if one of the following is true
  #   - it doesn't exist
  #   - some part is newer than the existing zip
  #   - the conf is newer than the existing zip
  if [[ ! -f $zipdir/$modName.zip || -n $(find $dataPath -type f -cnewer $zipdir/$modName.zip) || $zipdir/$modName.zip -ot $conf ]]
  then
    (( pkgcnt++ ))

    # the name of the zipped file
    FINAL_ZIP=$zipdir/$modName.zip

    # Zip to a temp file so that current zip stays valid
    TMP_ZIP=$zipdir/tmp-$modName.zip

    echo zip -q -r $TMP_ZIP $conf $dataPath
    zip -q -r $TMP_ZIP $conf $dataPath

    # As long as the source and destination are on the same partition the move will be atomic
    # Note: Those that have the file prior to the move will still get it
    mv $TMP_ZIP $FINAL_ZIP
  fi
}

cache_confs()
{
  if (( pkgccnt == 0 ))
  then
    return
  fi

  # the name of the cache file
  FINAL_CACHE=mods.d.tar.gz

  # tar.gz to a temp file so that current cache stays valid
  TMP_CACHE=tmp-$FINAL_CACHE

  tar czvf $TMP_CACHE mods.d/*.conf

  # As long as the source and destination are on the same partition the move will be atomic
  # Note: Those that have the file prior to the move will still get it
  mv $TMP_CACHE $FINAL_CACHE
}

# A POSIX variable
OPTIND=1 # Reset in case getopts has been used previously in the shell.

while getopts "h?z:m:" opt
do
  case "$opt" in
    m)  moddir=$OPTARG
        ;;
    z)  zipdir=$OPTARG
        ;;
    h|\?)
        usage
        exit 0
        ;;
    esac
done

shift $((OPTIND-1))

if (( $# != 0 ))
then
  echo "Error: extra parameters: $@"
  usage
  exit 1
fi

if [[ -z $moddir ]]
then
  echo "Invalid -m has an empty argument" >&2
  usage
  exit 1
fi

# if -z parameter was not specified then set zipdir to the default
[[ -z $zipdir ]] && zipdir=/tmp/zip
[[ -d $zipdir ]] || mkdir $zipdir

if [[ ! -d "$moddir" ]]
then
  echo "Error: $moddir does not exist"  >&2
  usage
  exit 1
fi

# Work in the moddir
cd $moddir

if [[ ! -d "mods.d" ]]
then
  echo "Error: $moddir/mods.d does not exist" >&2
  usage
  exit 1
fi

if [[ ! -d "modules" ]]
then
  echo "Error: $moddir/modules does not exist" >&2
  usage
  exit 1
fi

for modconf in mods.d/*.conf
do
  package_module $modconf
done

if (( pkgcnt > 0 ))
then
  cache_confs
fi

exit 0