#!/usr/bin/env perl

use strict;
use warnings;
use 5.020;
use autodie;
use Data::Dumper;

use JSON;
use CGI; 
use CGI::Carp qw(fatalsToBrowser);


if (my $content_len = $ENV{CONTENT_LENGTH}) {

    read(STDIN, my $json, $content_len);
    my $href = decode_json($json);
    my $a = $href->{a};
    my $b = $href->{b};

    my $q = CGI->new; #Doesn't work with inets httpd server

    print $q->header,
          $q->start_html("Test Page"),
          $q->div("json=$json"),
          $q->div("a=$a"),
          $q->div("b=$b"),
          $q->end_html;

    #print 'Content-type: text/html';
    #print  "\r\n\r\n";
    #print  "<div>a=$a</div>";
    #print  "<div>b=$b</div>";

} 
else {
    my $error = "Could not read json: No Content-Length header in request.";
    #print 'Content-type: text/html';
    #print "\r\n\r\n";
    #print "<div>$error</div>";

    my $q = CGI->new;
    print $q->header,
          $q->start_html("Test Page"),
          $q->h1($error),
          $q->end_html;
}

##</code><code>##

~$ curl -v -H 'Content-Type: application/json' --data '{"a": 1, "b": 2}' http://localhost:65451/cgi-bin/1.pl
*   Trying ::1...
* TCP_NODELAY set
* Connection failed
* connect to ::1 port 65451 failed: Connection refused
*   Trying 127.0.0.1...
* TCP_NODELAY set
* Connected to localhost (127.0.0.1) port 65451 (#0)
> POST /cgi-bin/1.pl HTTP/1.1
> Host: localhost:65451
> User-Agent: curl/7.58.0
> Accept: */*
> Content-Type: application/json
> Content-Length: 16
> 
* upload completely sent off: 16 out of 16 bytes

==== Hangs here for about 5 sseconds =======

< HTTP/1.1 504 Gateway Time-out
< Date: Fri, 09 Mar 2018 14:40:55 GMT
< Content-Type: text/html
< Server: inets/6.4.5
* no chunk, no close, no size. Assume close to signal end
< 
* Closing connection 0
~$ 


##</code><code>##

~$ curl -v -H 'Content-Type: application/json' --data '{"a": 1, "b": 2}' http://localhost:65451/cgi-bin/1.pl
*   Trying ::1...
* TCP_NODELAY set
* Connection failed
* connect to ::1 port 65451 failed: Connection refused
*   Trying 127.0.0.1...
* TCP_NODELAY set
* Connected to localhost (127.0.0.1) port 65451 (#0)
> POST /cgi-bin/1.pl HTTP/1.1
> Host: localhost:65451
> User-Agent: curl/7.58.0
> Accept: */*
> Content-Type: application/json
> Content-Length: 16
> 
* upload completely sent off: 16 out of 16 bytes
< HTTP/1.1 200 OK
< Date: Fri, 09 Mar 2018 14:52:03 GMT
< Server: inets/6.4.5
< Transfer-Encoding: chunked
< Content-Type: text/html
< 
* Connection #0 to host localhost left intact
<div>a=1</div><div>b=2</div>~$ 
</div>