#!/usr/bin/perl

# Read an ASCII format STL file
# Report if it is not a solid.
# Report issues with the facet normals.

# solid 1170Handle
# facet normal -0.000148266570749099 -0.00460401291523558 0.999989390484769
#   outer loop
#     vertex 0.000140744572064588 1.4493726055151 0.146
#     vertex -0.0370754460367823 1.67815054731263 0.146999999999999
#     vertex -0.0413711642044813 1.68852132837323 0.146999999999999
#   endloop
# endfacet
# endsolid 1170Handle

# That normal isn't a proper unit normal.  Should be:
# facet normal 0.0 0.0 1.0

#
# Sort two points into an appropriately ordered edge with 
# standardized precision.
sub mkedge {
  local($p, $t) = @_;
  ($x1, $y1, $z1) = split(/\s+/, $p);
  ($x2, $y2, $z2) = split(/\s+/, $t);
# # Round each coordinate to the desired resolution.
# $resolution = 1000;
# $x1 = int($x1*$resolution+0.5);
# $y1 = int($y1*$resolution+0.5);
# $z1 = int($z1*$resolution+0.5);
# $x2 = int($x2*$resolution+0.5);
# $y2 = int($y2*$resolution+0.5);
# $z2 = int($z2*$resolution+0.5);
  $cmp = $x1 <=> $x2;
  $cmp = $y1 <=> $y2 unless $cmp;
  $cmp = $z1 <=> $z2 unless $cmp;
  if ($cmp > 0) {
    # Swap them
    ($p, $t) = ($t, $p);
    ($x1, $y1, $z1, $x2, $y2, $z2) = ($x2, $y2, $z2, $x1, $y1, $z1);
  }
# return "($x1 $y1 $z1) ($x2, $y2, $z2)";
  return "$p $t";
}

# Check that every line segment joins two faces.

$badfiles = 0;
foreach $f (@ARGV) {
  open(INPUT, $f) || die "$f: $!";
  $_ = <INPUT>;
  unless (/^solid /) {
    warn "$f: Not an ASCII STL file\n";
    $badfiles++;
    next;
  }
  $previous = undef;
  %edge = ();
  $bad = 0;
  while (<INPUT>) {
    s/\r$//; chop;
    last if /^\s*endsolid /;
    if (/^\s*facet /) {
      next unless /-0[.]0 /;
      warn "$f: bad normal: $_\n";
      $bad++;
      next;
    }
    next if /^\s*endloop/;
    next if /^\s*outer loop/;
    if (/^\s*endfacet/) {
      $edge = &mkedge($first, $this);
      $edge{$edge} = 0 unless defined $edge{$edge};
      $edge{$edge}++;
      $edges++;
      $previous = undef;
      next;
    }
    die "syntax error: $_" unless /\s*vertex ([-e\d.\s]+)$/i;
    $this = $1;
    if (defined $previous) {
      $edge = &mkedge($previous, $this);
      $edge{$edge} = 0 unless defined $edge{$edge};
      $edge{$edge}++;
      $edges++;
    } else {
      $first = $this;
    }
    $previous = $this;
  }

  foreach $edge (keys %edge) {
    if ($edge{$edge} != 2) {
      print "$edge occurs $edge{$edge} times\n";
      $bad++;
    }
  }

  if ($bad) {
    print "$f: $bad out of $edges edges were open\n";
    $badfiles++;
  }

}

exit $badfiles;