#################################
#	Module for making conference programs
#	Based on HSSbot.pm
#	so it carries a lot of excess baggage
#	3 apr 20002 -- kcb
##################################

#	Package declaration
package Conference;

##################################

#	Exported variables and other symbols

use vars qw(
 @ISA @EXPORT @EXPORT_OK %EXPORT_TAGS
 $DivHome $SSHome $HumHome $CITHome
 $hss_url $html_pub 
 $database_mod_date 
 $weekday $today $weekday_num $month
 $today_serial 
);


use Exporter();

@ISA = ( "Exporter" );

@EXPORT = qw($DivHome $SSHome $HumHome $hss_url $html_pub $CITHome
		);

@EXPORT_OK = qw(
 		$weekday $today $weekday_num $today_serial
		$month
		);

%EXPORT_TAGS = (
	Times => [ qw($weekday $today $weekday_num $today_serial $month) ], 
		);

use Time::Local;

##################################
#	CONSTANTS 
##################################

#	Paths:

my $db_dir		= '.';
my $log_dir		= '.';
my $prog_dir		= '.';


$html_pub		= '/infosys/www/www.hss.caltech.edu/docroot';


#	URLs:
$hss_url	= 'http://www.hss.caltech.edu';

$CITHome	= qq(<a href="http://www.caltech.edu/">Caltech Home Page</a>);

$DivHome	= qq(<a href="$hss_url/HSSHome.html">Division Home Page</a>);

$SSHome		= qq(<a href="$hss_url/SSHome.html">Social Science Home Page</a>);

$HumHome	= qq(<a href="$hss_url/HumHome.html">Humanities Home Page</a>);


##################################
#	MISC GLOBAL VARIABLE DECLARATION
##################################

my @months = qw(January February March April May June July August September October November December);

my @days = qw(Sunday Monday Tuesday Wednesday Thursday Friday Saturday);

#	flag for logging
my $silent;

#	for saved file handle
my $prev_fh;


##################################
#	DEFAULT FUNCTION ARGUMENTS
##################################

my %default = (
'record_separator'	=> "\n", 
'field_separator'	=> "\t", 
'banner_icon'		=> 'hss.jpg', 
'cleanup'		=> \&cleanup, 
'top_links_ref'		=> [], 
'bottom_links_ref'	=> [], 
'logfile'		=> 0, 
'background'		=> "http://www.caltech.edu/pics/background.jpg",
'bgcolor'		=> '#ffffcc',
'group_id'		=> 104,
);	#	end %default


##################################
#	TOOLS FOR FUNCTION ARGUMENTS
##################################

#	Usage: %p = my_args(@_);
#	returns parameter hash for a function
#	filling in default values for missing args

sub my_args {
	
	my %p = %default;	#	set initial parameters to default values
	my %in = @_;		#	read in additional parameters and overrides

#	replace parameters with new values using hash slice
@p{ keys %in } = values %in;	

return %p;
	
}	#	END sub my_args


##################################

#	Usage: fatal_omissions('function name', \%p, 'arg1', 'arg2', ... );
#	dies with diagnostic if args missing

sub fatal_omissions {
	my ($fn, $href, @args) = @_;
	my $arg;
	
foreach $arg (@args) {
	die qq($0 Fatal Error:  No "$arg" => "value" supplied to $fn.)
		unless $href->{$arg};
}

} 	#	END sub fatal_omissions


##################################

sub venial_omissions {
	my ($fn, $href, @args) = @_;
	my $arg;
	
	
foreach $arg (@args) {
	warn qq($0 Warning:  No "$arg" => "value" supplied to $fn.  
    Using default value = $default{$arg}.)
		unless $href->{$arg};
}

}	#	END	sub venial_omissions


##################################
#	READ DATA AND CREATE ARRAY REFERENCE
##################################

#	Usage: 
#		$recordset_ref = Conference::create_recordset(
#			database		=> 'papers' , 
#			db_fields_ref		=> \@db_fields, 
#			required_fields_ref 	=> \@required_fields, 
#			sort_routine		=> \&by_Session, 				
#			record_separator	=> "\n", 
#			field_separator		=> "\t", 
#			);


sub create_recordset {
	
	#	Get arguments
	my %p = my_args(@_);
	
	#	Check argument list for completeness
	fatal_omissions('create_recordset', \%p, 'database', 'db_fields_ref');
	
	#	accept a list of databases
	my @database			= split /, / , $p{'database'};	

	#	make nicknames
	my $db_fields_ref		= $p{'db_fields_ref'};
	my $required_fields_ref		= $p{'required_fields_ref'};
	my $sort_routine_ref		= $p{'sort_routine'};
	my $cleanup = $p{'cleanup'};
	
	#	Use proper input separators.
	$/		= $p{'record_separator'};
	my $fs		= $p{'field_separator'};

	#	scratch variables
	my ($database, $field, @records, $rec);
	my ($num_processed, $num_warnings) = (0, 0);
	my @padding = ("") x scalar @{$p{'db_fields_ref'}};
	
	local $_;

#	Next, open each $database or die.

foreach $database ( @database ) {
	open (DB, "$db_dir/$database") 
		or die qq(Cannot open file "$db_dir/$database": $!);
	log_msg("\tProcessing $db_dir/$database database:");

	#	While reading each record ...
	while (<DB>) {

		next if /^\s*$/; 	#	ignore blank lines
		next if /^\s*#/; 	#	ignore comments

		chomp;
		my %hash = ();		#	Keep this private to this loop
					#	cf. page 263 of the Camel book

		#	create a hash reference for each record, using @db_fields for keys
		#	Initialize to "" if missing from database
		
		@hash{ @$db_fields_ref } = 
				( 
			 	( split /$fs/, &$cleanup($_) ), 
			 	@padding
				);

		#	push a reference to this private hash
		
		push @records, \%hash;
	
		#	Generate warnings for missing data
		
		foreach $field ( @$required_fields_ref ) {
		
			log_msg("HEY!: Record $. " . (exists $hash{'Name'} ? "$hash{'Name'} ": "") . "in $database database is missing $field"), 
				++$num_warnings if ! $hash{$field};

		}	#	end foreach $field ( @$required_fields_ref ), 


	}	#	end of: while (<DB>)


	#	Get record count before closing 
	$num_processed += $.;
	close (DB);
}	#	 end foreach $database ( @database ) 


#	Report record count and warning count

log_msg("\t$num_processed in recordset. \t$num_warnings warning" . ($num_warnings ==1 ? "": "s") . ".\n");


#	Sort the record list and return a reference to it

return [ sort { &$sort_routine_ref } @records ] ;


}	#	end sub create_recordset


##################################
#	 Sorting Routines
##################################

sub by_Session {
	
	"\l$a->{'Session'}" cmp "\l$b->{'Session'}";

}


##################################

sub by_time {
	#	this is a real kludge

my ($a_raw, $a_ampm) = split /\s+/, $a;
my ($b_raw, $b_ampm) = split /\s+/, $b;

my ($a_hour, $a_min) = split /:/, $a_raw;
my ($b_hour, $b_min) = split /:/, $b_raw;

$a_hour ||= 0;
$b_hour ||= 0;
$a_min ||= 0;
$b_min ||= 0;

$a_hour += 12 if ($a_ampm =~ /P/i and $a_hour < 12);
$b_hour += 12 if ($b_ampm =~ /P/i and $b_hour < 12);

$a_hour + ($a_min/60) <=> $b_hour + ($a_min/60);

}	#	END sub by_time

##################################

sub by_duration_end {
	#	this is a worse kludge

my ($a_start, $a_end) = split /-/, $a;
my ($b_start, $b_end) = split /-/, $b;

my ($a_raw, $a_ampm) = split /\s+/, $a_end;
my ($b_raw, $b_ampm) = split /\s+/, $b_end;

my ($a_hour, $a_min) = split /:/, $a_raw;
my ($b_hour, $b_min) = split /:/, $b_raw;

$a_hour += 12 if ($a_ampm =~ /PM/i and $a_hour < 12);
$b_hour += 12 if ($b_ampm =~ /PM/i and $b_hour < 12);

$a_hour + ($a_min/60) <=> $b_hour + ($a_min/60);

}	#	END sub by_duration_end

##################################
#	 Clean up the data
##################################

sub cleanup {
#	Clean up data before splitting on tabs

	local $_ = shift(@_);

	#	Fix some data entry glitches:

	s/[ ]+/ /g;		#	multiple spaces
	s/[ ]+, /, /g;		#	space before comma
	s/[ ]+$//g;		#	trailing space in a field
	s/[ ]+\t/\t/g;		#	trailing space in a field
	s/^[ ]+//g;		#	leading space in a field
	s/\t[ ]+/\t/g;		#	leading space in a field

	#	Convert the FilemakePro special characters.

	#	Convert "smart" quotes to dumb ones.

	s/\322/"/g;		#	(double right) aka ²
	s/\323/"/g;		#	(double left) aka ³
	s/\324/`/g;		#	(single left) aka Œ
	s/\325/'/g;		#	(single right) aka ¹

	#	Separator for repeating fields is ASCII 29 = \035 octal
	#	Newline within a field is ASCII 11 = \013 octal

	s/(\035|\013)+(\t|$)/$2/g;	#	remove leading separators
	s/(^|\t)(\035|\013)+/$1/g;	#	remove trailing separators


	return $_;

}	#	end sub cleanup


##################################

sub high_ascii_to_html {
	local $_ = shift;

	s/\330/&eacute;/g;
	s/\216/&eacute;/g;

	return $_;
}

##################################

sub high_ascii_to_tex {
	local $_ = shift;

	s/\330/\\'{e}/g;
	s/\216/\\'{e}/g;

	return $_;
}


##################################
#	OUTPUT PAGE TYPES
##################################

sub create_html_program {
	#	get argument list
	my %p = my_args(@_);

	#	check argument list for completeness
	fatal_omissions('create_html_program', \%p, 'filename', 'paperlist_ref', 
		'sessionlist_ref');
	venial_omissions('create_html_program', \%p, 'maintainer', 
		'maintainertitle', 'window_title');


	#	scratch variables
	my $session;
	my $paper;
	my $times;
	my $d;
	my $t;


open_out("$p{'filename'}", $silent);

html_head(
	'window_title'	=> "$p{'window_title'}", 
	'background'	=> "$p{'background'}",
	'bgcolor'	=> "$p{'bgcolor'}",
);

banner("$p{'page_heading_a'}", "$p{'page_heading_b'}", "$p{'banner_icon'}");
running_list(@{$p{'top_links_ref'}});
hrule(4);

#	Print a disclaimer about the papers
	print qq(<p><font size="3">Links are provided to pdf versions of the papers where available.  These pdf files are supplied by the authors.  Any problems reading them should be reported to the author, not to the conference organizer.  Thank you.</font></p><hr />);


#	Make a List of Session Dates and Times

foreach $session ( @{$p{'sessionlist_ref'}} ) {
	++$times{$session->{'Date'}}->{$session->{'Start_Time'}}->{$session->{'Time'}};
}



#	Create a Session List
print qq(<h3 align="center">Overview of Sessions</h3>\n);
hrule(3);

foreach $d ( sort keys %times ) {
	print "<b>", slash_to_day("$d"), "</b><hr />\n";

	foreach $t ( sort by_time keys %{$times{$d}} ) {
		print qq(<b>$t</b><br />\n);
		foreach $s ( @{$p{'sessionlist_ref'}} ) {
			print qq(<a href="#$s->{'Session'}">$s->{'Session'}</a>: $s->{'Title'}<br />\n) if ($s->{'Date'} eq $d and $s->{'Start_Time'} eq $t);
		}	# END foreach $s
		br();
	}	# END foreach $t

	br(); hrule(3);

}	# END foreach $d




#	Group papers by session

print qq(<h3 align="center">Session Details</h3>\n<hr />\n);

foreach $session ( @{$p{'sessionlist_ref'}} ) {
	my @list;

	print html_session_heading($session);	


	#	format each paper entry
	foreach $paper (@{$p{'paperlist_ref'}}) {

		next unless ($paper->{'Session'} eq $session->{'Session'});

		push @list, html_program_format($paper);


	}	#	end foreach ($paper)


	print ("<h4>Papers</h4>")	if scalar @list > 1;
	print (join "<br />", @list)	if scalar @list;

	hrule(3);
	
}	#	END foreach $session



running_list(@{$p{'bottom_links_ref'}});

#	Print a disclaimer about the papers
	print qq(<hr />\n<p><font size="3">\nLinks are provided to pdf versions of the papers where available.  These pdf files are supplied by the authors.  Any problems reading them should be reported to the author, not to the conference organizer.<br />\nThank you.</font></p>\n\n);


address("$p{'maintainer'}", "$p{'maintainertitle'}");

close_out();
set_group_and_permissions("$p{'group_id'}", '0664', "$p{'filename'}");

}	#	end sub create_html_program


##################################


sub create_tex_program {
	#	get argument list
	my %p = my_args(@_);

	#	check argument list for completeness
	fatal_omissions('create_tex_program', \%p, 'filename', 'paperlist_ref', 
		'sessionlist_ref');

	#	scratch variables
	my $session;
	my $paper;
	my %times;
	my $d;
	my $s;
	my $e;
	my $first;
	my $f;

open_out("$p{'filename'}.tex", $silent);

#	LaTeX Preamble
print qq(\\documentclass[twoside]{article}
\\usepackage{conference}

\\makeindex

\\title{$p{'page_heading_a'}}
\\date{$p{'page_heading_c'}}
\\author{}

\\begin{document}

\\pagestyle{headings}
\\pagenumbering{roman}
\\thispagestyle{plain}
\\tableofcontents
\\clearpage
\\thispagestyle{plain}
\\input{ack}
\\clearpage\\markboth{}{}\\cleardoublepage
\\markboth{}{}
\\setcounter{page}{0}
\\pagenumbering{arabic}

);


#	Make a List of Session Dates and Times

foreach $session ( @{$p{'sessionlist_ref'}} ) {
	++$times->{$session->{'Date'}}->{$session->{'Start_Time'}}->{$session->{'Time'}};
}


#	Group papers by session

#	Group by Date
foreach $d ( sort keys %{$times} ) {
	print "\\clearpage\n\\thispagestyle{plain}\n\\section{", slash_to_day("$d"), "}\n";

#	Group by Start Time
foreach $s ( sort by_time keys %{$times->{$d}} ) {

#	Group by Duration (just in case they aren't all the same)
foreach $e ( sort by_duration_end keys %{ $times->{$d}->{$s} } ) {

	($f = $e) =~ s/-/--/;	#	KLUDGE
	print "\\filbreak\n\\subsection{$f}\n\n";
	$first = 1;

foreach $session ( @{$p{'sessionlist_ref'}} ) {
	my @list;

	if ($session->{'Date'} eq $d and $session->{'Start_Time'} eq $s and $session->{'Time'} eq $e) {

	print tex_session_heading($first, $session);
	$first = 0;
	print "\\medskip\n";

	#	format each paper entry
	foreach $paper (@{$p{'paperlist_ref'}}) {

		next unless ($paper->{'Session'} eq $session->{'Session'});

		push @list, tex_program_format($paper);


	}	#	end foreach ($paper)


	print (join "\n\n\\smallskip\n", @list)	if scalar @list;

	}	# END if
}	#	END foreach $session
}	#	END foreach time $e
}	#	END foreach start time $s
}	#	END foreach date $d



print "\\clearpage
\\markright{Committees}
\\input{committees}
\\input{$p{'filename'}.ind}
\\end{document}
";

close_out();
set_group_and_permissions("$p{'group_id'}", '0664', "$p{'filename'}.tex");

}	#	end sub create_tex_program




##################################
#	LIST ITEM FORMATS
##################################

sub html_session_heading {	
	my $s = shift;

return join "",
	qq(<h3><a name="$s->{'Session'}" href="#Top">Session $s->{'Session'}</a>: $s->{'Title'}</h3>\n), 
	qq(  <table>\n),
	if_nonnull("    <tr><td><b>", slash_to_day("$s->{'Date'}"), "</b></td>"), 
	if_nonnull(q(    <td width="18"></td><td>), $s->{'Time'}, "</td>\n"), 
	if_nonnull(q(    <tr><td colspan="3">), $s->{'Location'}, "</td></tr>\n"), 
	if_nonnull(q(    <tr><td><b>Chair:</b></td><td colspan="2">), $s->{'Chair'}, "</td></tr>\n"), 
	"  </table><br />\n", 
;

}	#	end sub html_session_heading


################################

sub tex_session_heading {	
	my ($first, $s) = @_;
	my ($l, $f) = ("", "");
	my $chair = idx_name($s->{'Chair'});

return join "",
	( $first ? "" : qq(\\filbreak\n) ),
	qq(\\subsubsection[\\hbox to 2.25em {$s->{'Session'}:\\hfill\\hss} $s->{'Title'}]),
	qq({$s->{'Session'}: $s->{'Title'}),
	if_nonnull(" \\newblock(", $s->{'Location'}, ")"),
	"}\n", 

	if_nonnull("Chair: \\textbf{", $chair, "} "),
	"\n\n", 
;

}	#	end sub tex_session_heading


################################

sub html_program_format {		
	my $rec = shift(@_);
	my $col;

	my $title =  ( -e "../Papers/$rec->{'FileName'}.pdf" ? 
		qq(<a href="Papers/$rec->{'FileName'}.pdf"><i>$rec->{'PaperTitle'}</i></a>) :
		qq(<i>$rec->{'PaperTitle'}</i>) 
		);


return join "", 
	"<table>\n", 
	if_nonnull("      <tr><td>", $title, "</td></tr>\n"), 
	if_nonnull("      <tr><td><b>", "$rec->{'FirstName'} $rec->{'LastName'}", "</b>\n"), 
	if_nonnull("              (", high_ascii_to_html($rec->{'Institution'}), ")\n"), 

	if_nonnull( "<br />\n     <tr><td>",, $rec->{'Coauthor1'}, "\n"),
 	if_nonnull(' (', $rec->{'Coauthor1Affil'}, ")\n"),
	if_nonnull( "<br />\n       <tr><td>",, $rec->{'Coauthor2'}, "\n"),
 	if_nonnull(' (', $rec->{'Coauthor2Affil'}, ")\n"),
	if_nonnull( "<br />\n       <tr><td>",, $rec->{'Coauthor3'}, "\n"),
 	if_nonnull(' (', $rec->{'Coauthor3Affil'}, ")\n"),


	"</td></tr>

   </table>", 
;

}	#	end sub html_program_format


################################

sub tex_program_format {		
	my $rec = shift(@_);
	my $col;

return join "", 
	'\begin{tabular}{p{\\titlewidth}}',
	"\n", 
	if_nonnull("{\\slshape ", $rec->{'PaperTitle'}, "}\\\\ \n"), 
	if_nonnull('{\bfseries ', "$rec->{'FirstName'} $rec->{'LastName'}}\\index{$rec->{'LastName'}, $rec->{'FirstName'}}", ''), 
	if_nonnull(' (', $rec->{'Institution'}, ")\n"),

	if_nonnull( "\\\\\n", idx_name($rec->{'Coauthor1'}), "\n"),
 	if_nonnull(' (', $rec->{'Coauthor1Affil'}, ")\n"),
	if_nonnull( "\\\\\n", idx_name($rec->{'Coauthor2'}), "\n"),
 	if_nonnull(' (', $rec->{'Coauthor2Affil'}, ")\n"),
	if_nonnull( "\\\\\n", idx_name($rec->{'Coauthor3'}), "\n"),
 	if_nonnull(' (', $rec->{'Coauthor3Affil'}, ")\n"),

	'\end{tabular}',
	"\n\n", 
;

}	#	end sub tex_program_format



##################################
# 	Miscellaneous
##################################
#  Kludge to deal with names where first, last are not separate fields
sub idx_name {
		my $name = shift @_;

		return "" unless $name;

		$name =~ s/, Jr/,~Jr/;

		my @names = split /\s+/, $name;
		my $l = pop @names;
		$l =~ s/~/ /;
		my $f = join " ", @names;
		return $name .= "\\index{$l, $f}";

}



##################################

sub if_nonnull {
	my ($prefix, $text, $suffix, $sep, $newsep) = (@_, '', '');

	$sep ||= "\013";
	$newsep ||= "<br />\n";
	
if ($text) {
	$text =~ s/$sep+/$newsep/eg; 

	return "$prefix$text$suffix";
}

}	#	end sub if_nonnull


##################################
#	HTML subroutines
##################################

sub html_head {
#	make the html header with window title
	
	#	Get arguments
	my %p = my_args(@_);
	
	#	Check argument list for completeness
	venial_omissions('html_head', \%p, 'window_title');

	my $background	= ($p{'background'} ? qq(background="$p{'background'}") : "");
	my $bgcolor	= ($p{'bgcolor'} ? qq(bgcolor="$p{'bgcolor'}") : "");

print <<End_of_html_head;
<html>
<head>
<title>
$p{'window_title'}
</title>
<link rev="author" href="mailto:www\@hss.caltech.edu">
<meta name="Title" content="$p{'window_title'}">
<meta name="Author" content="mailto:www\@hss.caltech.edu">
<meta name="Generator" content="Conference.pm">
<meta http-equiv="Content-Type" content="text/html; charset=us-ascii">
</head>

<body link="#006600" vlink="#003300" alink="#669966" $bgcolor $background >
<a name="Top"></a>

End_of_html_head

}	#	end sub html_head


##################################

sub running_list {
	my @list = @_;

	my $list;
	my $spacer = ' &#183; ';

$list = join "$spacer", @list;

print "<center>\n&#183; $list &#183;\n</center>\n";

}	#	end sub running_list


##################################

sub address {

my ($maintainer, $maintainertitle)= @_;

print <<End_of_address;

<hr />


<address>
This page is maintained by <a href="mailto:$maintainer">$maintainertitle</a>, and is current as of as $database_mod_date.  
</address>

</body>
</html>

End_of_address

}	#	end sub address


##################################

sub banner {

#	make a page banner heading 

	my ($page_heading_a, $page_heading_b, $banner_icon) = @_ ;
	my $alt;
	my $img = "";

	if ($banner_icon =~ /hss.jpg/) { $alt="The Humanities and Social Sciences";}
	elsif ($banner_icon =~ /ss.jpg/) { $alt="Social Sciences";}
	elsif ($banner_icon =~ /th.jpg/ ) { $alt="The Humanities";}
	else {$alt = "";}

	$img = qq(<img src="$banner_icon" 
	alt="California Institute of Technology: $alt" />\n) if $banner_icon;


	print <<End_of_banner;

<p align="center">
$img
<a name="Top"></a>

</p>

<h2 align="center">$page_heading_a</h2>
<h1 align="center">$page_heading_b</h1>

<hr />

End_of_banner

}	#	END sub banner




##################################

sub br {
	print "<br />\n";
}	#	end sub br

##################################

sub p {
	print "<p>\n";
}	#	end sub p

##################################

sub end_p {
	print "</p>\n";
}	#	end sub end_p

##################################

sub emph {
	my $string = shift(@_);

	print "<em>$string</em>";
}	#	end sub emph

##################################

sub bold {
	my $string = shift(@_);

	print "<b>$string</b>";
}	#	end sub bold



##################################

sub hrule {
	my ($size) = @_;

	print "\n<hr", ($size ? qq( size="$size") : ""), " />\n\n";

}	#	end sub hrule




##################################
#	FILE MANIPULATION
##################################

sub open_out {
	my ($filename, $silent) = (@_, '');

	if ( open (OUT, ">$filename") ) {log_msg("\tCreating $filename.") unless $silent ;} 
	else {warn "WHOA!!!! cannot create $filename: $!" ; return;}

	#	store previous handle in global variable
	$prev_fh = select (OUT);
	
	return \*OUT;

}	#	end sub open_out


##################################

sub close_out {

	close (OUT);
	select ($prev_fh);


}	#	end sub close_out


##################################

sub set_group_and_permissions {
	my ($gid, $permissions, @filelist) = @_ ;

#	The $< variable contains the current user's user ID.
#	must use oct function for chmod, see p.148--149 of Camel book

	chown ($<, $gid, @filelist);
	chmod (oct($permissions), @filelist);

}	#	end subroutine set_group_and_permissions


##################################

sub get_mod_date {
#	get modification date of $filename

	my $filename = shift(@_);

	return '?' unless -e $filename;

#	Get the file stats from the database file.
my ($dev, $ino, $mode, $nlink, $uid, $gid, $rdev, $size, $atime, $mtime, $ctime, $blksize, $blocks) = stat $filename ;

return long_date($mtime);

}	#	end get_mod_date


################################
#		Time and date
################################


#	Find number of complete days in so many seconds:
#	Used to convert UNIX time (nonleap seconds since epoch) to a 
#	UNIX  date serial. (December 31, 1960 = day 0)

sub seconds_to_days {
	my $seconds = shift(@_) ;
	
	return int($seconds/86400);
}


################################

sub long_date {

	my $epoch_seconds = shift (@_);

my ($sec, $min, $hour, $mday, $mon, $year, $wday, $yday, $isdst) = localtime($epoch_seconds);

my $Month = $months[$mon];
my $Year = 1900 + $year;
 
return "$Month $mday, $Year";

}	#	end sub long_date




##################################

sub slash_to_day {
	my ($m, $d, $y) = split /\//, shift @_;
	--$m;

	my $epoch_seconds = timelocal(0, 0, 0, $d, $m, $y);
	my ($sec, $min, $hour, $mday, $mon, $year, $wday, $yday, $isdst) = 
		localtime($epoch_seconds);

return "$days[$wday], $months[$m] $d";

}	#	END sub slash_to_day


##################################

sub weekday {
my $epoch_seconds = shift (@_);
my ($sec, $min, $hour, $mday, $mon, $year, $wday, $yday, $isdst) = localtime($epoch_seconds);

return $days[$wday];

}



##################################

sub time_of_day {

	my $epoch_seconds = shift (@_);
my ($sec, $min, $hour, $mday, $mon, $year, $wday, $yday, $isdst) = localtime($epoch_seconds);

$min = "0$min" if $min < 10;
$sec = "0$sec" if $sec < 10;

return "$hour:$min.$sec";

}	#	end sub time_of_day


################################

sub get_time_vars {

	my $instant = time;
	my ($sec, $min, $hour, $mday, $mon, $year, $wday, $yday, $isdst) =
		localtime($instant);
	my ($today, $today_serial, $month);

	$today = long_date($instant);
	$today_serial = seconds_to_days($instant);
	$weekday = weekday($instant);

	$month = ++$mon;

	return ($today, $today_serial, $wday, $weekday, $month);

}	#	END sub get_time_vars



##################################
#	LOGGING
##################################
#	Usage: start_log(logfile => 'faculty', silent => 0);

sub start_log {
	my %p = my_args(@_);
	venial_omissions('start_log', \%p, 'logfile', 'database');
		
	#	set this global flag
	$silent		= $p{'silent'};
	
	#	nicknames
	my $logfile		= $p{'logfile'};
	my $database	= $p{'database'};


unless ($logfile) {
	warn "$0 error: logfile => filename supplied to start_log. Logging on error.log";
	$logfile = 'error';
}

#	Initalize certain package and private variables

($today, $today_serial, $weekday_num, $weekday, $month) = get_time_vars();

my $prog_mod_date = get_mod_date($0);
my $bot_mod_date = get_mod_date("$prog_dir/Conference.pm");
my $user = getpwuid($<);
my $now = time_of_day(time);


$database_mod_date = get_mod_date("$db_dir/$database");

open (LOGFILE, ">$log_dir/$logfile.log") or warn "Cannot open log file. $!";

print LOGFILE <<End_of_log_prolog;
Message log from $0 (rev. $prog_mod_date)
Uses Conference.pm (rev. $bot_mod_date). Author: KCB.


Operator: $user.
Messages re $database as of $today at $now:

End_of_log_prolog

}	#	end start_log


##################################

sub log_msg {
	my ($error_msg, $shh) = (@_, '') ;

print LOGFILE "$error_msg\n";
print STDERR  "$error_msg\n" unless $silent or $shh;

}	#	end sub log_msg

##################################

sub logout {
	my %p = my_args(@_);
	
	my $logfile = $p{'logfile'};
	my $database = $p{'database'};

	#	Set group and permissions.
	#	Group = dbmaint (106), no other read permssion
	set_group_and_permissions("$p{'group_id'}", '0664', "$db_dir/$database");
	
	#	close the log file last
	log_msg("\nDONE\tMessage log available in file $log_dir/$logfile.log");
	close (LOGFILE);
	set_group_and_permissions("$p{'group_id'}", "0664", "$log_dir/$logfile.log");

}	#	end sub log



##################################
#	FINISH
##################################

1;