# create or check checksums for all files in current directory.
# usage: checksum <ACTION>
# actions: "new", "check".
checksum()
{
  local action="$1"          # what to do with checksum.
  local file="checksum.sha1" # file name to store checksums.

  if [[ "$action" =~ ^(n|new)$  ]]; then
    # create checksums for all files.
    find -type f | parallel sha1sum {} >> "$file"
    
    # remove checksum file from resulting hashes.
    sed -i "/$file/d" "$file"
    
    return 0
  fi

  if [[ "$action" =~ ^(c|check)$ ]]; then
    # check checsums for all files.
    sha1sum --quiet -c ./checksum.sha1
    
    return 0
  fi
  
  # error on wrong action.
  echo "supported actions: new (n), check (c)."
  return 2
}

# autocomplete.
_checksum()
{
  _autocomplete_first "{new,check}"
}

complete -F _checksum checksum