#!/usr/local/bin/perl -w
=pod

mark-no v. 11 Jul 1996, Dave Schweisguth <dcs@proton.chem.yale.edu>

Marks chemical shifts which are expected to be non-observable in an ssd

=cut

### Preliminaries

require 5.002;			    # Perl 5.002 required
use strict;			    # Require optional-but-desirable practices
use vars qw($whatami);		    # Exempt globals from 'use strict'
use Churn qw(retrieve_ssd store_fd);

### Parameters

# Environment

($whatami = $0) =~ s|.*/||;	    # `basename $0`
my $isatty	= -t STDIN;

# Configuration

my %nos = (			    # Non-observable spins for each residue
    a => [qw(h61 h62)],
    g => [qw(h21 h22)]
);

# Initialization (don't change these)

$| = 1;				    # Interleave STDOUT and STDERR properly
my($ssd, $seg, $res, $type, $no);

### Arguments and error-checking

# Parse args

my($arg, $sign, $first, $rest);
while (@ARGV and ($sign, $first, $rest) = ($ARGV[0] =~ /^([\-+])(.)(.*)/)) {
    if ($sign eq '+' && $first !~ /[\0]/) { # -/+ switches
	&usage("$sign$first is not an option.\n");
    }
    if ($first =~ /[\0]/) {	# Switches with arguments (none at the moment)
    	shift;
    	$arg = $rest ne '' ? $rest : @ARGV ? shift :
      	    &usage("$sign$first requires an argument.\n");
    } elsif ($rest eq '') {
	shift;
    } else {
    	$ARGV[0] = "$sign$rest";
    }
    if    ($first eq 'u') { &usage(0); }
    else	          { &usage("$sign$first is not an option.\n"); }
}

sub usage {
    warn $_[0] ? "$whatami: $_[0]" : '', <<EOP;
Usage: $whatami [-u] [ssd]
ssd may be '-' or omitted to read from standard input.
-u	This message
EOP
    exit !! $_[0];
}

# Post-process args

if (@ARGV > 1 || @ARGV == 0 && $isatty) {
    &usage("Specify or provide on standard input a single spin-system database.\n");
} elsif (@ARGV == 0) {
    $ARGV[0] = '-';
}

### Do it

$ssd = &retrieve_ssd(shift) || exit 1;   # Read spin system database or die

foreach $seg (keys %{$$ssd{segs}}) {
    foreach $res (keys %{$$ssd{segs}{$seg}}) {
	$type = $$ssd{segs}{$seg}{$res}{type};
	if ($nos{$type}) {
	    foreach $no (@{$nos{$type}}) {
		$$ssd{segs}{$seg}{$res}{spins}{$no} = 'no';
	    }
	}
    }
}

&store_fd($ssd, 'STDOUT');

exit;