#compdef unexpand gunexpand expand gexpand

local all tabs
local -a args

all="convert all whitespace, instead of just initial whitespace"
tabs="[use comma separated list of tab positions]:list of tab positions"

if _pick_variant gnu='(Free Soft|uutils)' unix --version; then
  if [[ $service = *un* ]]; then
    args=(
      "(-a --help --version)--all[$all]"
      '(--help --version)--first-only[convert only leading sequences of whitespace]'
    )
  else
    args=(
      '(-i --initial --help --version)'{-i,--initial}"[don't convert tabs after non blanks]"
    )
  fi

  args+=(
    "(-t --help --version)--tabs=${tabs}"
    '(* -)--help[display usage information]'
    '(* -)--version[display version information]'
  )
elif [[ $OSTYPE = (*bsd*|dragonfly*|darwin*) ]]; then
  args=( -A "-*" )
fi
[[ $service = *un* ]] && args+=(  "(--all --help --version)-a[$all]" )

# Most (un)expand variants, excluding BusyBox, allow e.g. -4 instead of -t4
[[ $_cmd_variant[$service] == *busybox* ]] ||
args+=( '!(-0 -1 -2 -3 -4 -5 -6 -7 -8 -9 -t --tabs)-'{0..9} )

_arguments -s -S "$args[@]" \
  "(--tabs --help)-t+${tabs}" \
  '*:file:_files'
