#!/usr/local/bin/perl
#
# -*- Perl -*-
#

# Dispatch the URL to one of the filter programs that makes up the DODS
# server. The filter program is executed by this script using exec. If the 
# filter program cannot be run, return an error message. 
#
# See the DODS_Dispatch.pm class for information about how environment
# variables are used.
#
# NB: This script assumes that all data is rooted in the http document
# directory subtree. If you want to access files outside that subtree, use a
# symbolic link and make sure that your server is set to follow symbolic
# links. To configure your server to follow symbolic links, add
# FollowSymLinks to the Options in the access.conf file. 
#
# $Id: nph-jg,v 1.18 1999/03/17 21:41:09 dan Exp $
#
# $Log: nph-jg,v $
# Revision 1.18  1999/03/17 21:41:09  dan
# Modified JGOFS_OBJECT and JGOFS_METHOD variables
#
# Revision 1.17  1999/03/02 19:27:27  dan
# Added the shell environment variables JGOFS_OBJECT
# and JGOFS_METHOD to the dispatch script so that
# server installations do not require a 'jgofs' user
# in /etc/passwd.
#
# Revision 1.16  1998/08/06 16:32:41  jimg
# Fixed misuse of the read(...) member function. Return true if more data
# is to be read, false is if not and error if an error is detected
#
# Revision 1.15  1997/10/04 00:33:16  jimg
# Release 2.14c fixes
#
# Revision 1.14.2.3  1997/09/22 23:50:27  jimg
# Fixed `Level_' stuff in queries; make sure to remove these fictitious
# identifiers.
#
# Revision 1.14.2.2  1997/08/20 18:32:48  jimg
# Fixed error in processing on $query; in JGOFS `,' serves as boolean AND so
# translate `&' in a DODS CE to `,'.
#
# Revision 1.14.2.1  1997/08/20 17:26:58  jimg
# Fixed bug where ancillary DAS/DDS were not found due to the presence of an
# empty constraint expression (which confused the jg_das/jg_dds filters).
#
# Revision 1.14  1997/08/11 18:01:54  jimg
# Fixed problem with PATH_INFO/$file_name where leading and trailing garbage
# was not stripped off.
#
# Revision 1.13  1997/06/12 21:13:51  jimg
# Changed the initialization of $file_name from the filename field of the Perl
# object to PATH_INFO from the httpd's environment.
#
# Revision 1.12  1997/06/12 21:00:33  jimg
# Removed the DODS_ROOT environment variable.
#
# Revision 1.11  1997/06/06 03:52:44  jimg
# Rewrote to use the new Perl DODS_Dispatch class.
#

use Env;
use DODS_Dispatch;

# Set the DODS_ROOT environment variable. This is done so that the filter
# programs which do the real work of the server can find gzip when it is not
# on the user's PATH but *is* in DODS_ROOT/etc. NB: The filter program
# appends the `etc'.  
# $ENV{'DODS_ROOT'} = "/usr/local/DODS-2.13"; NOT USED

# Set the JGOFS_OBJECT_PATH environment variable.  This variable can be
# used to find the location of the JGOFS object dictionary without
# requiring a 'jgofs' user defined in the passwd file.
$ENV{'JGOFS_OBJECT'} = "/usr/local/apache/cgi-bin/";

# Set the JGOFS_METHOD_PATH environment variable.  This variable can be
# used to find the location of the JGOFS methods directory without
# requiring a 'jgofs' user defined in the passwd file.
$ENV{'JGOFS_METHOD'} = "/usr/local/apache/cgi-bin/";

# The DODS_Dispatch object reads information from the environment variables
# and builds up a command based on the format of a DODS URL. 
$dispatch = new DODS_Dispatch;

$query = $dispatch->query();

# Query must be munged for JGOFS.
$query =~ s@&@,@;
# The `Level_' names are synthesized by the JGOFS servers. Strip them off
# before handing the queries to the JGOFS servers for processing.
$query =~ s@Level_[^.]*\.@@g;

$cgi_dir = $dispatch->cgi_dir();
$script = $dispatch->script();

# Dan pointed out that we don't want to use PATH_TRANSLATED with the jgofs
# server. I made this change, but have no easy way to test it. jhrg 6/12/97
#$file_name = $dispatch->filename();

$filename = $ENV{'PATH_INFO'};
$ext = $dispatch->extension();

# Strip leading `/' and the trailing extension (e.g., `.das') from $filename
# Nasty... jhrg 8/9/97
$filename =~ s@/(.*)\.$ext@$1@;

# OK, the filter program to run is as follows:
if ($ext eq "info") {
    # If the user wants to run the usage filter ($extension is `.html'), then
    # select that filter and send the cgi directory and API prefix as the
    # second argument (which is passed using $query). Note that the form of
    # the query is also different.
    $server_pgm = $cgi_dir . "usage";
    $query = $cgi_dir . $script;
    $command = $server_pgm . " '" . $filename . "()' " . $query;
} elsif ($ext eq "ver" || $ext eq "/version") {
    $script_rev = '$Revision: 1.18 $ ';
    $script_rev =~ s@\$([A-z]*): (.*) \$@$2@;
    $server_pgm = $cgi_dir . $script . "_dods";
    $command = $server_pgm . " -v " . $script_rev . " " . $filename;
} elsif ($ext eq "asc" || $ext eq "ascii") {
    $server_pgm = $cgi_dir . $script . "_dods";
    $command = $server_pgm . " '" . $filename . "(" . $query . ")'";
    # Never compress ASCII.
    local($ascii_srvr) = $cgi_dir . "asciival";
    $command .= " | " . $ascii_srvr . " -m -- -";
} elsif ($ext eq "das" || $ext eq "dds" || $ext eq "dods") {
    # Otherwise, form the name of the filter program to run by catenating the
    # script name, underscore and the extension.
    $server_pgm = $cgi_dir . $script . "_" . $ext;

    # Note that the DAS and DDS filters should not have the ()'s if $query
    # is empty. If a query is passed, then those filters won't be able to 
    # access ancillary DAS/DDS files (as of 8/20/97). jhrg
    if ($ext ne "dods" && $query eq "") {
	$command = $server_pgm . " " . $filename;
    } 
    else {
	$command = $server_pgm . " '" . $filename . "(" . $query . ")'";
    }
} else {
    $command = "";
}

if ($command ne "") {		# if no error...
    exec($command);
} else {
    my $script_rev = '$Revision: 1.18 $ ';
    $script_rev =~ s@\$([A-z]*): (.*) \$@$2@;

    $dispatch->print_error_message($script_rev);
}