#!/bin/bash

function _help() {
  echo '
Usage: file-enumerate [-k] [-p #] [-o folder]

  Creates a folder "enumerated" and hard links all files in the current folder
  renamed with a number (d.ext).

  -k  Keep filename as is (d.filename)
  -p  Pad numbers, defaults to 4
  -o  Output folder name, default: enumerated
  -c  Copy instead of hard link
  -i  Offset. start from number (default 1)
  -s  Shuffle order
'
  exit
}
keep=false
pad=4
output=enumerated
hardlink="-l"
offset=1
shuf=false
for (( i=1; i<=$#; i++ )); do
  j=$(( i + 1 ))
  [[ "${!i}" = "-h" ]] && _help
  [[ "${!i}" = "--help" ]] && _help
  [[ "${!i}" = "-c" ]] && hardlink=""
  [[ "${!i}" = "-k" ]] && keep=true
  [[ "${!i}" = "-p" ]] && { pad=${!j}; i=$(( i + 1 )); }
  [[ "${!i}" = "-o" ]] && { output=${!j}; i=$(( i + 1 )); }
  [[ "${!i}" = "-i" ]] && { offset=${!j}; i=$(( i + 1 )); }
  [[ "${!i}" = "-s" ]] && { shuf=true; }
done

printf -v padstr "%%0%dd" $pad

_enum() {
  if [[ $shuf = true ]]; then
    sorting="shuf"
  else
    sorting="sort -V"
  fi
  ls -1p | grep -v "/$" | $sorting | cat -n | while read n f; do
    n=$(( n + $offset - 1 ))
    printf -v padded $padstr $n
    if [[ $keep = true ]]; then
      printf -v outname "%s.%s" "$padded" "$f"
    else
      ext=${f##*.}
      if [[ "$ext" = "$f" ]]; then
        printf -v outname "%s" "$padded"
      else
        printf -v outname "%s.%s" "$padded" "$ext"
      fi
    fi
    printf "%30s -> %s\n" "$f" "$outname"
    cp $hardlink "${f}" "${output}"/"$outname"
  done
}

mkdir -p "${output}"
_enum