#!/usr/bin/perl
#
# $Id: citations.pl,v 1.1 1997/03/19 20:20:50 alberto Exp alberto $
#
# Test program for the ADS WWW library.
#
# Searcheable fields are:
#    au = author
#    kw = keyword
#    ti = title
#    ab = abstract text
# 
# Example:
#    citations.pl au=geller and ti="(structure bubble)"
#
# Written by Alberto Accomazzi <alberto@cfa.harvard.edu>,
#                              http://cfa-www.harvard.edu/~alberto  
#
# $Log: citations.pl,v $
# Revision 1.1  1997/03/19  20:20:50  alberto
# Initial revision
#
#
#

unshift(@INC, $libloc) if ($libloc = $ENV{'LIBWWW_PERL'});
push(@INC,"/opt/local/lib/perl") if (-d "/opt/local/lib/perl");

require "adswww.pl";

while ($ARGV[0] =~ /^\-/) {
    $_ = shift(@ARGV);
    if (/^\-debug/) {
	$debug++;
    } elsif (/^\-db/) {
	&Usage("missing argument for \"-db\" option")
	    unless ($opts{'db_key'} = shift(@ARGV));
    } elsif (/^-totref/) {
	&Usage("missing argument for \"-totref\" option")
	    unless (($opts{'nr_to_return'} = shift(@ARGV)) > 0);
    } else {
	&Usage("unknown option \"$_\"");
    }
}

$ads'debug = 1                              #'
    if ($debug > 1);

# process keyword=value pairs on the command line or STDIN
# interpreting them as WAIS syntax
($waisq = join(' ',@ARGV)) =~ s/^\s+|\s+$//g;
if (! $waisq) {
    while (<STDIN>) {
        chop;
        $waisq .= "$_ ";
    }
    chop($waisq);
}
# translate original WAIS query into an ADS fielded query
%query = &ads'wais2ads($waisq);                      #'

# add options specified on the command line
foreach (keys(%opts)) {
    $query{$_} = $opts{$_};    
}


$query{'data_type'} = 'PORTABLE'; # force refer style output
$query{'query_type'} = 'CITES';	  # return citations
$totref = $query{'nr_to_return'}; # tot number of references we want returned

# loop here to repeatedly retrieve references until we have as many 
# as we want
while ($references < $totref) {

    # now issue the WWW query
    print STDERR "$0: retrieving references...";
    ($result,$status) = &ads'abstract_query(%query);    #'
    print STDERR "done!\n";

    # did an error occurr?
    die "$0: ADS query returned the following error status: $status\n" .
	"$0: HTTP error message follows:\n$result\n"
	    if ($status);

    print STDERR "$0: parsing references..."; 
    push(@references,&ads'parse_bib($result,*score,*title,*author,*pubdate) #'
	 );	      
    print STDERR "done!\n";

    # here we are saving all references in arrays instead of
    # printing them out out right away, but keep in mind that if
    # you're doing any of this from inside an nph CGI script, you
    # should do the printing as soon as you can, so that the user
    # will start recieving results right after the first pass.

    print STDERR "$0: total number of references selected: ",
         $ads'ref_selected,                             #'
	 "\n$0: total number of references returned: ",
         $ads'ref_returned,                             #'
	 "\n$0: references start from sequence number ",
         $ads'ref_start,                                #'
         "\n"
	     if ($debug);

    # increase reference counters
    $references += $ads'ref_returned;                   #'
    $selected = $ads'ref_selected                       #'
	unless($selected);

    # exit loop when no more references are returned or if all
    # selected references have been returned this time around
    last unless $ads'ref_returned;                      #'
    last if ($ads'ref_selected == $ads'ref_returned);

    print STDERR "$0: parsed references $ads'ref_start - ", #'
	$ads'ref_start + $ads'ref_returned - 1 , "\n";

    # update start reference counter
    $query{'start_nr'} = $ads'ref_start + $ads'ref_returned; #'

}    

# sort, and print out citations array
foreach (@references) {
    &PrintBib($_);
}


sub PrintBib {
    local($b) = $_[0];
    return unless($b);

    print "Bibliographic Code: $b\n";
    print "Score:              $score{$b}\n"       if ($score{$b});
    print "Title:              $title{$b}\n"       if ($title{$b});
    print "Authors:            $author{$b}\n"      if ($author{$b});
    print "Publication Date:   $pubdate{$b}\n"     if ($pubdate{$b});
    print "\n";
}


sub Usage {
    print STDERR "$0: @_\n" if (@_);
    print STDERR <<"EOF";
Usage: $0 [-debug] [-db database] [-totref number] [query ...]
If no query terms are specified on the command line, they are read from STDIN.
EOF

    exit(1);
}