################################################################################
# WeBWorK mod_perl (c) 1995-2002 WeBWorK Team, Univeristy of Rochester
# $Id$
################################################################################

package WeBWorK::Utils;

=head1 NAME

WeBWorK::Utils - useful utilities used by other WeBWorK modules.

=cut

use strict;
use warnings;
use base qw(Exporter);
use Date::Format;
use Date::Parse;

our @EXPORT    = ();
our @EXPORT_OK = qw(
	runtime_use
	readFile
	formatDateTime
	parseDateTime
	dbDecode
	dbEncode
	decodeAnswers
	encodeAnswers
	ref2string
);

sub runtime_use($) {
	return unless @_;
	eval "package Main; require $_[0]; import $_[0]";
	die $@ if $@;
}

sub readFile($) {
	my $fileName = shift;
	open INPUTFILE, "<", $fileName
		or die "Failed to read $fileName: $!";
	local $/ = undef;
	my $result = <INPUTFILE>;
	close INPUTFILE;
	return $result;
}

sub formatDateTime($) {
	my $dateTime = shift;
	# "standard" WeBWorK date/time format:
	# %m 	month number, starting with 01
	# %d 	numeric day of the month, with leading zeros (eg 01..31)
	# %y	year (2 digits)
	# %I 	hour, 12 hour clock, leading 0's)
	# %M 	minute, leading 0's
	# %P 	am or pm (Yes %p and %P are backwards :)
	return time2str "%m/%d/%y %I:%M%P", $dateTime;
}

sub parseDateTime($) {
	my $string = shift;
	return str2time $string;
}

# -----

sub dbDecode($) {
	my $string = shift;
	return unless defined $string and $string;
	my %hash = $string =~ /(.*?)(?<!\\)=(.*?)(?:(?<!\\)&|$)/g;
	$hash{$_} =~ s/\\(&|=)/$1/g foreach keys %hash; # unescape & and =
	return %hash;
}

sub dbEncode(@) {
	my %hash = @_;
	my $string;
	foreach (keys %hash) {
		$hash{$_} = "" unless defined $hash{$_}; # promote undef to ""
		$hash{$_} =~ s/(=|&)/\\$1/g; # escape & and =
		$string .= "$_=$hash{$_}&";
	}
	chop $string; # remove final '&' from string for old code :p
	return $string;
}

sub decodeAnswers($) {
	my $string = shift;
	return unless defined $string and $string;
	my @array = split m/##/, $string;
	$array[$_] =~ s/\\#\\/#/g foreach 0 .. $#array;
	push @array, "" if @array%2;
	return @array; # it's actually a hash ;)
}

sub encodeAnswers(\%\@) {
	my %hash = %{ shift() };
	my @order = @{ shift() };
	my $string;
	foreach my $name (@order) {
		my $value = defined $hash{$name} ? $hash{$name} : "";
		$name  =~ s/#/\\#\\/g; # this is a WEIRD way to escape things
		$value =~ s/#/\\#\\/g; # and it's not my fault!
		$string .= "$name##$value##"; # this is also not my fault
	}
	$string =~ s/##$//; # remove last pair of hashs
	return $string;
}

# -----

sub ref2string($;$);
sub ref2string($;$) {
	my $ref = shift;
	my $dontExpand = shift || {};
	my $refType = ref $ref;
	my $result;
	if ($refType and not $dontExpand->{$refType}) {
		my $baseType = refBaseType($ref);
		$result .= '<font size="1" color="grey">' . $refType;
		$result .= " ($baseType)" if $baseType and $refType ne $baseType;
		$result .= ":</font><br>";
		$result .= '<table border="1" cellpadding="2">';
		if ($baseType eq "HASH") {
			my %hash = %$ref;
			foreach (sort keys %hash) {
				$result .= '<tr valign="top">';
				$result .= "<td>$_</td>";
				$result .= "<td>" . ref2string($hash{$_}, $dontExpand) . "</td>";
				$result .= "</tr>";
			}
		} elsif ($baseType eq "ARRAY") {
			my @array = @$ref;
			# special case for Problem, Set, and User objects, which are defined
			# using lists and contain a @FIELDS package variable:
			no strict 'refs';
			my @FIELDS = eval { @{$refType."::FIELDS"} };
			use strict 'refs';
			undef @FIELDS unless scalar @FIELDS == scalar @array and not $@;
			foreach (0 .. $#array) {
				$result .= '<tr valign="top">';
				$result .= "<td>$_</td>";
				$result .= "<td>".$FIELDS[$_]."</td>" if @FIELDS;
				$result .= "<td>" . ref2string($array[$_], $dontExpand) . "</td>";
				$result .= "</tr>";
			}
		} elsif ($baseType eq "SCALAR") {
			my $scalar = $$ref;
			$result .= '<tr valign="top">';
			$result .= "<td>$scalar</td>";
			$result .= "</tr>";
		} else {
			# perhaps a coderef? in any case, i don't feel like dealing with it!
			$result .= '<tr valign="top">';
			$result .= "<td>$ref</td>";
			$result .= "</tr>";
		}
		$result .= "</table>"
	} else {
		$result .= defined $ref ? $ref : '<font color="red">undef</font>';
	}	
}

sub refBaseType($) {
	my $ref = shift;
	local $SIG{__DIE__} = 'IGNORE';
	return "HASH"   if eval { $_ = %$ref; 1 };
	return "ARRAY"  if eval { $_ = @$ref; 1 };
	return "SCALAR" if eval { $_ = $$ref; 1 };
	return 0;
}

1;