te-chunked-mw.p6w

#!smack
use v6;

constant CHUNK-SIZE = 16384;
constant CRLF = "\x0a\x0d";

sub app(%env) {
    start {
        my $file = "really-big-file.txt".IO;
        200, [
            Content-Type => 'text/plain',
        ],
        on -> $out {
            my $fh = $file.open(:r);
            while my $data = $fh.read(CHUNK-SIZE) {
                $out.emit($data);
            }
            $out.done;

            ()
        };
    }
}

sub mw(%env) {
    nextsame.then(-> $p {
        if %env<SERVER_PROTOCOL> eq 'HTTP/1.1'
                && %env<TE> ~~ /\<'chunked'\>/ {

            my ($s, List() $h, Supply() $payload) = $p.result;

            return $s, $h, $payload
                if $h.first(*.key eq 'Transfer-Encoding');

            $h.append: Transfer-Encoding => 'chunked';

            $s, $h, on -> $out {
                $payload => -> $data {
                    $out.emit(CRLF ~ $data.bytes.base(16) ~ CRLF);
                    $out.emit($data);
                },
            };
        }
        else { 
            $p.result 
        }
    });
}

&app.wrap(&mw);
&app;