#!/usr/bin/perl
# 
# Copyright © 2015-2020 by Vincent Slyngstad
# 
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
# 
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
# 
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS LISTED ABOVE BE LIABLE
# FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
# CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
# 
# Except as contained in this notice, the names of the authors above
# shall not be used in advertising or otherwise to promote the sale, use
# or other dealings in this Software without prior written authorization
# from those authors.

#
# Look for files that might be paper tape images, with similar content.
# For now, "might be paper tape images" means a size less than $toobig
# and "similar content" means the same result from &hash.
#
$toobig = 100*1000;

#
# Read in the file and compute the hash function on it's contents.
# For now, just sum the words loaded, ignoring 0000 and 0200, and
# stopping at 0232.
sub hash {
  local($f) = @_;
  return undef unless (-s $f) < $toobig;
#warn "in hash, $f: " . (-s $f) . "\n";
  open(INPUT, $f) || die "$f: $!";
  $sum = 0;
  while (read(INPUT, $buf, 1)) {
    $buf = unpack("C", $buf);
    next if $buf == 0200;
    last if $buf == 0232;
    # 0000 is harmless here.
    $sum += $buf;
  }
  return sprintf("%0o", $sum);
}

#
# Walk the directories and files given, building a hash table.
$status = 0;
@todo = @ARGV;
%hash = (); # Nothing hashed yet
while  (@todo) {
  $f = shift @todo;
#warn "processing $f\n";
  if (-d $f) {
    $d = $f;
    # It is really a directory; enumerate it.
    opendir(DIR, $d) || die "$d: $!";
    while (($f = readdir(DIR))) {
      if (-d "$d/$f") {
        # Examine it later
#warn "unshift $d/$f\n" unless $f =~ /^[.]/;
        unshift(@todo, "$d/$f") unless $f =~ /^[.]/;
        next;
      }
#warn "unshift $d/$f\n";
      unshift(@todo, "$d/$f"); # Examine it later
    }
    next;
  }
  # It is a file.
  $h = &hash($f);
#warn "hash of $d/$f is $h\n";
  next unless defined $h;
  if (defined $hash{$h}) {
    print "Hash collsion of $f with $hash{$h}\n";
    $hash{$h} .= ":$f";
  } else {
    $hash{$h} = $f;
  }
}
exit $status;