#!/bin/bash
wspace_re='[ \t]+$'

if [ $# -ge 1 ]
then
    if [ "$1" = "-n" ]
    then
        trailingcommand=(-print)
        shift
    else
        trailingcommand=(-print -exec perl -i -pe "s/$wspace_re//;" '{}' ';')
    fi
fi

if [ $# -ne 1 ]
then
    echo "Usage:" >& 2
    echo "  $0 [-n] directory-to-purge" >& 2
    echo >& 2
    echo "  -n for \"dry-run\", to just print out files with trailing whitespace"
    exit 1
fi

find "$1" \( -name '*.sml' -o -name '*.sig' -o -name '*.tex' -o -name '*.ML' -o -name '*.lem' -o -name '*.bib' -o -name '*.doc' \) \
          \! -name '*ML.sml' \! -name '*Theory.sml' \! -name '*Theory.sig' \
          -exec perl -e "while (<>) { if (/$wspace_re/) { exit 0; }}; exit 1" \{\} \; \
          "${trailingcommand[@]}"