gistfile1.txt

use Plack::Request;
use Plack::App::File;
use LWP::UserAgent;
use File::Basename;
use Path::Class qw/dir/;

my %cache;

return sub {
    my $env = shift;
    
    my $req = Plack::Request->new($env);
    my $res;

    if ( !defined($cache{$req->request_uri}) ) {

        my $file_path = dir('.', basename($req->path_info) )->absolute->stringify;

        if ( -f $file_path ) {
             $res = Plack::App::File->new( file => $file_path )->call($env);
        }
        else
        {
            my $_req = HTTP::Request->new(
                $req->method,
                $req->request_uri,
                $req->headers,
                $req->raw_body
            );

            my $ua = LWP::UserAgent->new;
            my $ua_res = $ua->request( $_req );

            my @res_header;
            $ua_res->headers->scan(sub{ push @res_header, @_; });
            $res = [ $ua_res->code, \@res_header, [$ua_res->content] ];
        }
        $cache{$req->request_uri} = $res;
    }
    
    $cache{$req->request_uri};
};