Add parallel, queueable curl implementation

... which needs some more parameters, like "wait-for-finish" etc.

script/curl.pl

@@ -0,0 +1,172 @@
+use 5.020;
+use COWS::Crawler;
+use experimental 'signatures';
+use experimental 'try';
+
+#use COWS 'scrape';
+use URI;
+#use lib '../Term-Output-List/lib';
+use Term::Output::List;
+use HTTP::Request::FromCurl;
+
+use Getopt::Long ':config' => 'pass_through';
+use Encode 'decode';
+use URI;
+use YAML 'LoadFile';
+use File::Spec;
+use JSON;
+use JobFunnel;
+use JobFunnel::ProgressItem;
+
+GetOptions(
+    'h|help' => \my $help,
+    'target-directory=s' => \my $target_directory,
+);
+# XXX do we want a sleep option to wait between requests?
+#     between all requests?! what about requests from mungers?!
+#     or should effective_url not be a munger but an action?!
+
+$target_directory //= '.';
+
+binmode STDOUT, ':encoding(utf8)';
+
+# The progress output
+my $printer = Term::Output::List->new();
+my $funnel = JobFunnel->new(
+    new_job => \&submit_download,
+);
+$funnel->on( update => sub { output_scoreboard() });
+$funnel->on( added => sub { msg("Added item" )});
+$funnel->on( idle => sub { Mojo::IOLoop->stop_gracefully });
+
+my $ua = Mojo::UserAgent->new();
+
+my @running;
+
+sub submit_download( $request ) {
+    my $method = $request->{method};
+    my $url = $request->{url};
+    my %headers = %{ $request->{headers} // {} };
+    my $filename = $request->{target};
+    msg("$method $url");
+
+    my $progress = JobFunnel::ProgressItem->new(
+        visual => $url,
+        action => 'dl',
+        total  => undef,
+    );
+
+    # See also LWP::UserAgent
+    # If the file exists, add a cache-related header
+    if ( -e $filename ) {
+        my ($mtime) = ( stat($filename) )[9];
+        if ($mtime) {
+            $headers{ 'If-Modified-Since' } = HTTP::Date::time2str($mtime);
+        }
+    }
+
+    my $req = $ua->build_tx( $method => "$url", \%headers, '' );
+    $req->res->on( 'progress' => sub($res,@rest) {
+        return unless my $len = $res->headers->content_length;
+        $progress->total( $len ) if $len;
+        $progress->progress($res->content->progress);
+    });
+
+    $req->res->on( 'finish' => sub($res,@rest) {
+
+        # Only save if successful and not already there:
+        if( $res->code =~ /^2\d\d/ ) {
+            $res->save_to( $filename );
+            # Update utime from the server Last-Changed header, if we know it
+            if ( my $lm = $res->headers->last_modified ) {
+                $lm = HTTP::Date::str2time( $lm );
+                utime $lm, $lm, $filename
+                    or warn "Cannot update modification time of '$filename': $!\n";
+            }
+
+        } elsif( $res->code == 304 ) {
+            # unchanged
+        } elsif( $res->code =~ /^3\d\d/ ) {
+            # what do we do about 301 redirects?!
+            msg(sprintf "Got %d status for $url", $res->code);
+        }
+        $progress->finish();
+    });
+
+    push @running, $ua->start_p( $req );
+
+    return $progress
+}
+
+sub status($item) {
+    my $perc = $item->percent;
+    $perc = defined $perc ? sprintf "% 3d%%", $perc : ' -- ';
+    my $vis = $item->visual // '?';
+    return sprintf "%s %s %s", $perc, $item->action, $vis;
+}
+
+sub output_scoreboard(@) {
+    my @scoreboard;
+    if( $funnel ) {
+        @scoreboard = $funnel->jobs->@*;
+    };
+    $printer->output_list(
+        map { status( $_ ) } @scoreboard
+    );
+}
+
+sub msg($msg) {
+    $printer->output_permanent($msg);
+    output_scoreboard();
+}
+
+my @known_extensions = (qw(
+    gif
+    jpg
+    jpeg
+    json
+    pdf
+    png
+    tar.gz
+));
+my $re_known_extensions = join "|", @known_extensions;
+
+sub handle_download( $req ) {
+    my $url = $req->uri;
+
+    my $filename = $req->output;
+
+    if( !$filename) {
+        if( $url =~ m!\b([^/?=]+\.($re_known_extensions))\b! ) {
+            $filename = $1;
+        } else {
+            die "Couldn't guess filename from '$url'";
+        }
+    }
+
+    my $target = File::Spec->catfile( $target_directory, $filename );
+    if( -e $target ) {
+        msg( "$target already exists, resuming" );
+        $req->headers->{Range} = -s( $filename ). "-";
+    };
+
+    if( ! -d $target_directory ) {
+        mkpath $target_directory;
+    };
+
+    my $job = {
+        filename => $filename,
+        target   => $target,
+        method   => $req->method,
+        headers  => $req->headers,
+        url      => $req->uri,
+    };
+    $funnel->add($job);
+}
+
+my @requests = HTTP::Request::FromCurl->new( argv => \@ARGV );
+for my $r (@requests) {
+    handle_download( $r );
+}
+
+Mojo::IOLoop->start unless Mojo::IOLoop->is_running;