--- loncom/xml/lontexconvert.pm	2010/04/27 20:29:20	1.103
+++ loncom/xml/lontexconvert.pm	2019/02/15 20:56:22	1.122
@@ -1,7 +1,7 @@
 # The LearningOnline Network with CAPA
 # TeX Conversion Module
 #
-# $Id: lontexconvert.pm,v 1.103 2010/04/27 20:29:20 faziophi Exp $
+# $Id: lontexconvert.pm,v 1.122 2019/02/15 20:56:22 raeburn Exp $
 #
 # Copyright Michigan State University Board of Trustees
 #
@@ -49,7 +49,78 @@ use lib '/home/httpd/lib/perl/';
 use LONCAPA;
 use URI::Escape;
 use IO::Socket::INET;
-use IO::Socket::SSL;
+
+
+#
+# Table of substitutions to unicode characters.
+#
+
+my %unicode_harpoons = (
+                        '\rightleftharpoons'  => 0x21cc,
+                      );
+
+my %unicode_translations = (
+
+# Brackets - unicode for browsers/OS which support it.
+
+    ''             => 0x23a1,
+    ''             => 0x23a2,
+    ''             => 0x23a3,
+    ''             => 0x23a4,
+    ''             => 0x23a5,
+    ''             => 0x23a6,
+
+#  Parens - unicode for browsers/OS which support it
+
+    ''              => 0x239b,
+    ''              => 0x239c,
+    ''              => 0x239d,
+    ''              => 0x239e,
+    ''              => 0x239f,
+    ''              => 0x23a0,
+
+);
+
+my %ascii_8bit_translations = (
+
+# Brackets - pure 8-bit ascii ugliness for browsers/OS which can't handle unicode
+
+    ''              => 0x5b,
+    ''              => 0x5b,    # '['
+    ''              => 0x5b,
+    ''              => 0x5d,    # ']'
+    ''              => 0x5d,
+    ''              => 0x5d,
+
+# Parens - pure 8-bit ascii ugliness for browsers/OS which can't handle unicode
+
+    ''              => 0x28,
+    ''              => 0x28,      # '('
+    ''              => 0x28,
+    ''              => 0x29,
+    ''              => 0x29,      # '('
+    ''              => 0x29,
+
+);
+
+##
+# Utility to convert elements of a string to unicode:
+#
+# @param input - Input string
+# @param pattern - Pattern to convert
+# @param unicode - Unicode to substitute for pattern.
+#
+# @return string - resulting string.
+# 
+sub unicode_subst {
+    my ($input, $pattern, $unicode) = @_;
+    
+    my $char = pack('U', $unicode);
+
+    $input =~ s/$pattern/$char/g;
+
+    return $input;
+}
 
 # ====================================================================== Header
 
@@ -107,15 +178,38 @@ sub convert_real {
     $xmlstring=~s/^\s*\<br clear\=\"all\"/\<br/s;
     $xmlstring=~s/^\s*//;
     $xmlstring=~s/\s*$//;
+    $xmlstring=~s/^<br \/><table/<table/;
+    &Apache::lonxml::end_alarm();
+
     #
-    # \rightleftharpoons is not converted by tth but maps
-    # reasonably well to &#8660;.  If we get many more of these,
-    # we're going to need to have a translation sub.
-    #
-    my $lrharpoon = pack("U", 0x21cc);
-    $xmlstring=~s/\\rightleftharpoons/$lrharpoon/g;
+    # Several strings produced by tth require
+    # transliteration -> unicode equivalents to render reliably
+    # in browsers. %unicode_translations and %unicode_harpoons are tables of
+    # string->substitution which we now apply. (%ascii_8bit_translations used
+    # instead for Windows XP and mobile devices.
+
+    my $use_ascii;
+    if ($env{'browser.os'} eq 'win') {
+        if (($env{'browser.osversion'}) && ($env{'browser.osversion'} < 6.0)) {
+            $use_ascii = 1;
+        }
+    }
+    if ($env{'browser.mobile'}) {
+        $use_ascii = 1;
+    }
+
+    foreach my $pattern (keys(%unicode_translations)) {
+	my $unicode = $unicode_translations{$pattern};
+	if ($use_ascii) {
+	    $unicode = $ascii_8bit_translations{$pattern};
+	}
+	$xmlstring = &unicode_subst($xmlstring, $pattern, $unicode);
+    }
+
+    foreach my $pattern (keys(%unicode_harpoons)) {
+        $xmlstring = &unicode_subst($xmlstring, $pattern, $unicode_harpoons{$pattern});
+    }
 
-    &Apache::lonxml::end_alarm();
     return ($xmlstring,$errorstring);
 }
 
@@ -166,79 +260,98 @@ sub clean_out_math_mode {
 
 sub displaystyle {
     my ($texstring)=@_;
-    #has a $$ or \[ or \displaystyle in it, guessinng it's display mode
+    #has a $$ or \[ or \displaystyle or eqnarray in it, guessinng it's display mode
     if ($$texstring=~/[^\\]\$\$/ ||
-	$$texstring=~/\\\[/ ||
-	$$texstring=~/\\displaystyle/) { return 1; }
+        $$texstring=~/\\\[/ ||
+        $$texstring=~/\\displaystyle/ ||
+        $$texstring=~/eqnarray/
+       ) { return 1; }
     return 0;
 }
 
-sub jsMath_converted {
+sub MathJax_converted {
     my $texstring=shift;
-    my $tag='span';
-    if (&displaystyle($texstring)) { $tag='div'; }
+    my ($tag,$startspan,$endspan);
+    $tag='math/tex;';
+    if (&displaystyle($texstring)) {
+        $tag='math/tex; mode=display';
+        $startspan='';
+        $endspan='';
+    } else {
+        $startspan='<span style="display:inline-block;">';
+        $endspan='</span>';
+    }
     &clean_out_math_mode($texstring);
-    return &jsMath_header().
-	'<'.$tag.' class="math">'.$$texstring.'</'.$tag.'>';
+    return &MathJax_header().$startspan.
+      '<script type="'.$tag.'">'.$$texstring.'</script>'.$endspan;
 }
 
 {
-    my @jsMath_sent_header;
-    sub jsMath_reset {
-	undef(@jsMath_sent_header);
-    }
-    sub jsMath_push {
-	push(@jsMath_sent_header,0);
-    }
-    sub jsMath_header {
-	if (!@jsMath_sent_header) {
-	    &Apache::lonnet::logthis("mismatched calls of jsMath_header and jsMath_process");
-	    return '';
-	}
-	return '' if $jsMath_sent_header[-1];
-	$jsMath_sent_header[-1]=1;
-	return
-            '<script type="text/javascript">
-                     function NoFontMessage () {}
-                     jsMath = {Parser: {prototype: {environments: {\'eqnarray*\' :[\'Array\',null,null,\'rcl\',[5/18,5/18],3,\'D\']}}}};
-                   </script>'."\n".
-	    '<script type="text/javascript" src="/adm/jsMath/jsMath.js"></script>'."\n";
-    }
-    sub jsMath_process {
-	my $state = pop(@jsMath_sent_header);
-	return '' if !$state;
-	return "\n".
-	    '<script type="text/javascript">jsMath.Process()</script>'."\n";
-    }
-    sub jsMath_state {
-	my ($level) = @_;
-	return $jsMath_sent_header[$level];
-    }
+    #Relies heavily on the previous jsMath installation
+    my @MathJax_sent_header;
+    sub MathJax_reset {
+        undef(@MathJax_sent_header);
+    }
+    sub MathJax_push {
+        push(@MathJax_sent_header,0);
+    }
+    sub MathJax_header {
+        if (!@MathJax_sent_header) {
+            &Apache::lonnet::logthis("mismatched calls of MathJax_header and MathJax_process");
+            return '';
+        }
+        return '' if $MathJax_sent_header[-1];
+        $MathJax_sent_header[-1]=1;
+        return
+          '<script type="text/javascript" src="/adm/MathJax/MathJax.js?config=TeX-AMS-MML_HTMLorMML"></script>'."\n";
+    }
+    #sub MathJax_process {
+    #    my $state = pop(@MathJax_sent_header);
+    #    return '' if !$state;
+    #    return "\n".
+    #        '<script type="text/javascript">MathJax.Process()</script>'."\n";
+    #}
+    #sub MathJax_state {
+    #    my ($level) = @_;
+    #    return $MathJax_sent_header[$level];
+    #}
 }
 
 sub tex_engine {
     if (exists($env{'form.texengine'})) {
 	if ($env{'form.texengine'} ne '') {
+            if (lc($env{'form.texengine'}) eq 'jsmath') {
+                return 'MathJax';
+            }
             return $env{'form.texengine'};
         }
     }    
     if ($env{'request.course.id'}
 	&& exists($env{'course.'.$env{'request.course.id'}.'.texengine'})) {
+        if (lc($env{'course.'.$env{'request.course.id'}.'.texengine'}) eq 'jsmath') {
+            return 'MathJax';
+        }
 	return $env{'course.'.$env{'request.course.id'}.'.texengine'};
     }
     if (exists($env{'environment.texengine'})) {
+        if (lc($env{'environment.texengine'}) eq 'jsmath') {
+            return 'MathJax';
+        }
 	return $env{'environment.texengine'};
     }
-    return 'tth';
+    my $dom = $env{'request.role.domain'} || $env{'user.domain'};
+    my %domdefaults = &Apache::lonnet::get_domain_defaults($dom);
+    if ($domdefaults{'texengine'} ne '') {
+        return $domdefaults{'texengine'};
+    }
+    return $Apache::lonnet::deftex;
 }
 
 sub init_math_support {
-    my ($inherit_jsmath) = @_;
     &init_tth();
-    &Apache::lontexconvert::jsMath_push();
-    if (lc(&tex_engine()) eq 'jsmath' ||
-	($inherit_jsmath && &jsMath_state(-2))) {
-	return &Apache::lontexconvert::jsMath_header();
+    &Apache::lontexconvert::MathJax_push();
+    if (lc(&tex_engine()) eq 'mathjax') {
+        return &Apache::lontexconvert::MathJax_header();
     }
     return;
 }
@@ -246,21 +359,12 @@ sub init_math_support {
 sub mimetex_valign {
     my ($esc_texstring)=@_;
     my $valign = 0;
-    my $lonhost = $Apache::lonnet::perlvar{'lonHostID'};
-    my $hostname = &Apache::lonnet::hostname($lonhost);
-    my $protocol = $Apache::lonnet::protocol{$lonhost};
     my $path = '/cgi-bin/mimetex.cgi?'.$esc_texstring;
     my $socket;
     &Apache::lonxml::start_alarm();
-    if ($protocol eq 'https') {
-        $socket = IO::Socket::SSL->new(PeerAddr => $hostname,
-                                       PeerPort => 'https(443)',
-                                       Proto    => 'tcp');
-    } else {
-        $socket = IO::Socket::INET->new(PeerAddr => $hostname,
-                                        PeerPort => 'http(80)',
-                                        Proto    => 'tcp');
-    }
+    $socket = IO::Socket::INET->new(PeerAddr => 'localhost',
+                                    PeerPort => 'http(80)',
+                                    Proto    => 'tcp');
     if ($socket) {
         my $headreq = "HEAD $path HTTP/1.0\r\n\r\n";
         print $socket $headreq;
@@ -269,12 +373,7 @@ sub mimetex_valign {
                 $valign = $1;
             }
         }
-        if ($protocol eq 'https') {
-            $socket->close(SSL_no_shutdown => 1,
-                           SSL_ctx_free => 1);
-        } else {
-            $socket->close();
-        }
+        $socket->close();
     }
     &Apache::lonxml::end_alarm();
     return $valign;
@@ -302,7 +401,7 @@ sub mimetex_converted {
     my $valign = &mimetex_valign($esc_texstring);
     my $result='<img src="/cgi-bin/mimetex.cgi?'.$esc_texstring.'" style="vertical-align:'.$valign.'px" alt="'.$alt_string.'" />';
     if ($displaystyle) {
-	$result='<center>'.$result.'</center>';
+	$result='<div style="text-align:center">'.$result.'</div>';
     }
     return $result;
 }
@@ -313,7 +412,9 @@ sub converted {
     if ($mode =~ /tth/i) {
 	return &tth_converted($string);
     } elsif ($mode =~ /jsmath/i) {
-	return &jsMath_converted($string);
+        return &MathJax_converted($string);
+    } elsif ($mode =~ /mathjax/i) {
+	return &MathJax_converted($string);
     } elsif ($mode =~ /mimetex/i) {
 	return &mimetex_converted($string);
     } elsif ($mode =~ /raw/i) {
@@ -335,7 +436,6 @@ sub to_convert {
 
 sub smiley {
     my $expression=shift;
-    if ($env{'browser.imagesuppress'} eq 'on') { return $expression; }
     my %smileys=(
     	 '\:\-*\)' => 'face-smile.png',
 		 '8\-\)'  => 'face-cool.png',
@@ -394,7 +494,7 @@ sub msgtexconverted {
     foreach my $fragment (split(/(?:\&lt\;|\<)\/*algebra\s*(?:\&gt\;|\>)/i,
 				$message)) {
 	if ($tex) {
-        my $algebra = &algebra($fragment, 'web', undef, undef, undef, undef, 'tth');
+        my $algebra = &algebra($fragment, 'web', undef, undef, undef, 'tth');
 	    if ($email) {
 		$outmessage.='</pre><tt>'.$algebra.'</tt><pre>';
 		$tex=0;
@@ -461,7 +561,7 @@ sub postprocess_algebra {
     # $string =~s/\\fun/ /g;
 
     # sqrt(3,4) means the 4 root of 3
-    $string =~s/\\sqrt{([^,]+),([^\}]+)}/\\sqrt[$2]{$1}/gs;
+    $string =~s/\\sqrt\{([^,]+),([^\}]+)}/\\sqrt[$2]{$1}/gs;
 
     # log(3,4) means the log base 4 of 3
     $string =~s/\\log\\left\((.+?),(.+?)\\right\)/\\log_{$2}\\left($1\\right)/gs;
@@ -479,6 +579,8 @@ sub postprocess_algebra {
     $string =~s/\\lim\\left\((.+?),(.+?),(.+?)\\right\)/\\lim_{$2\\to $3}$1/gs;
     return $string;
 }
+
+
 1;
 __END__
 
@@ -521,14 +623,45 @@ Header
 =item displaystyle()
 
 
-=item jsMath_converted()
-
+=item MathJax_converted()
 
 =item tex_engine()
 
-
 =item init_math_support()
 
+=item mimetex_valign()
+
+ Makes a HEAD call to /cgi-bin/mimetex.cgi via IO:: to retrieve the 
+ vertical alignment, before the subsequent call to mimetex_converted()
+ which generates the <img> tag and the corresponding image.
+
+ Input: 1.  $esc_texstring (escaped TeX to be rendered by mimetex).
+ Output: 1. $valign - number of pixels: positive or negative integer 
+            which will be included in <img> tag for mimetex image to
+            support vertical alignment of image within a line of text.
+
+ If a server is running SSL, and Apache rewrite rules are in place 
+ to rewrite requests for http to https, modification will most likely 
+ be needed for pass through for HEAD requests for /cgi-bin/mimetex.cgi. 
+
+ Example rewrite rules which rewrite all http traffic to https, 
+ except HEAD requests for /cgi-bin/mimetex.cgi are:
+
+ <IfModule mod_rewrite.c>
+     RewriteEngine On
+     RewriteLogLevel 0
+
+     RewriteCond %{HTTPS} off
+     RewriteCond %{HTTP:Host} (.*)
+     RewriteCond %{REQUEST_METHOD} !HEAD 
+     RewriteRule ^/(.*) https://%1/$1 [R=301,L]
+
+     RewriteCond %{HTTPS} off
+     RewriteCond %{HTTP:Host} (.*)
+     RewriteCond %{REQUEST_METHOD} HEAD
+     RewriteCond %{REQUEST_URI} !^/cgi-bin/mimetex.cgi
+     RewriteRule ^/(.*) https://%1/$1 [R=301,L]
+ </IfModule>
 
 =item mimetex_converted()