#!/bin/bash
display_help() {
    (>&2 echo "Usage: $(basename "$0") [-chqv] [-o outfile] indir iseq")
    (>&2 echo "UCF tar scalar packer")
    (>&2 echo)
    (>&2 echo "   indir                   path to input directory")
    (>&2 echo "   iseq                    sequence number with leading zeros")
    (>&2 echo "   -c, --checksum          compares checksums after the archive is created")
    (>&2 echo "   -h, --help              display this help message")
    (>&2 echo "   -o, --outfile           output file (default: snapshot_XXXX.ucf.tar)")
    (>&2 echo "   -q, --quicksum          same as --checksum, but compares only first bytes")
    (>&2 echo "   -v, --verbose           verbose output")
}
exit_script() {
    #trap - SIGINT SIGTERM  # clear the trap
    #kill -- -$$            # Sends SIGTERM to child/sub processes
    (>&2 echo "SIGINT/SIGTERM received: removing archive")
    rm $fout
}
# Parse command line arguments
if [ $# -eq 0 ]; then
  display_help
  exit -1
fi
fout=""
verbose=0
checksum=0
quicksum=0
POSITIONAL=()
while [[ $# -gt 0 ]]
do
key="$1"
case $key in
    -h|--help)
    display_help
    exit 0
    shift # past argument
    ;;
    -o|--outfile)
    fout="$2"
    shift # past argument
    shift # past value
    ;;
    -v|--verbose)
    verbose=1
    shift # past argument
    ;;
    -c|--checksum)
    checksum=1
    shift # past argument
    ;;
    -q|--quicksum)
    quicksum=1
    shift # past argument
    ;;
    *)    # unknown option
    POSITIONAL+=("$1") # save it in an array for later
    shift # past argument
    ;;
esac
done
set -- "${POSITIONAL[@]}"

# Parse input filename
din=$1
seqnum=$2 

# Construct output filename if not specified
if [ -z "$fout" ]; then
  fout="snapshot_scal_${seqnum}.ucf.tar"
fi

# Display verbose info
if [ $verbose -eq 1 ]; then
  (>&2 echo "Creating archive: $fout")
fi

# Check input files
fparam="parameters_${seqnum}.asc"
fgrid="grid_${seqnum}.bin"
fproc="proc_${seqnum}.bin"
fpart="particles_${seqnum}.bin"
fbscal="scal_"

# Check if obligatory files are present
if [ ! -s ${din}/${fparam} ]; then
  (>&2 echo "[Error] File not found or empty: ${din}/${fparam}")
  exit 1
fi
if [ ! -s ${din}/${fgrid} ]; then
  (>&2 echo "[Error] File not found or empty: ${din}/${fgrid}")
  exit 1
fi
if [ ! -s ${din}/${fproc} ]; then
  (>&2 echo "[Error] File not found or empty: ${din}/${fproc}")
  exit 1
fi
if [ ! -s ${din}/${fpart} ]; then
  (>&2 echo "[Error] File not found or empty: ${din}/${fpart}")
  exit 1
fi

# Check if all velocity fields exist and are not empty
nproc=$(cat ${din}/${fparam} | grep "nprocs" | awk '{print $NF}')
if [ $verbose -eq 1 ]; then
  (>&2 echo "Number of processors: $nproc")
fi

# Check if all scalar fields exist (if any) and are not empty
fscal=()
for (( ii=0; ii<$nproc; ii++ )); do
  ftmp=$(printf ${fbscal}${seqnum}.%05d $ii)
  if [ ! -s ${din}/${ftmp} ]; then
    (>&2 echo "[Error] File not found or empty: ${din}/${ftmp}")
    exit 1
  fi
  fscal+=($ftmp)
done

# Verbose info
if [ $verbose -eq 1 ]; then
  (>&2 echo "[x] parameters")
  (>&2 echo "[x] grid")
  (>&2 echo "[x] processor grid")
  (>&2 echo "[x] particles")
  (>&2 echo "[x] scalar fields")
fi

# Create a full file list for the archive
flist=(${fparam} ${fgrid} ${fproc} ${fpart} ${fscal[@]})

# Now tar them and remove seqence number from file names while doing so
flagtar=""
if [ $verbose -eq 1 ]; then
  flagtar="$flagtar --verbose"
fi
trap exit_script SIGINT SIGTERM
tar $flagtar --format ustar --transform="flags=r;s|_$seqnum||" --directory=${din} -cf ${fout} ${flist[@]}
tarexit=$?
# Set exit status accoring to tar
if [ $tarexit -ne 0 ]; then
  (>&2 echo "tar failed with exit code $tarexit")
  exit 254
fi

# Compare checksums (CNC32), if flag is set
#din="./archive/" #for testing
flistx=($(echo ${flist[@]} | sed s/"_$seqnum"/""/g))
if [ $checksum -eq 1 ]; then
  for ii in "${!flistx[@]}"; do 
    if [ $verbose -eq 1 ]; then
      (>&2 echo "Verifying checksum: ${flist[$ii]}")
    fi
    crcori=$(cksum ${din}/${flist[$ii]} | awk '{ print $1, $2 }')
    crctar=$(tar --to-command='cksum -' -xf ${fout} ${flistx[$ii]} | awk '{ print $1, $2 }')
    if [ "$crcori" != "$crctar" ]; then
      (>&2 echo "Verification failed: ${flist[$ii]} ${flistx[$ii]}")
      exit 5
    fi
  done
elif [ $quicksum -eq 1 ]; then
  for ii in "${!flistx[@]}"; do
    if [ $verbose -eq 1 ]; then
      (>&2 echo "Verifying partial checksum: ${flist[$ii]}")
    fi
    crcori=$(head -c 1M ${din}/${flist[$ii]} | cksum -)
    crctar=$(tar --to-command='head -c 1M' -xf ${fout} ${flistx[$ii]} | cksum -)
    if [ "$crcori" != "$crctar" ]; then
      (>&2 echo "Verification failed: ${flist[$ii]} ${flistx[$ii]}")
      exit 5
    fi
  done
fi

exit 0