package Catalyst::Engine::CGI;

use Moose;
extends 'Catalyst::Engine';

has _header_buf => (is => 'rw', clearer => '_clear_header_buf', predicate => '_has_header_buf');

=head1 NAME

Catalyst::Engine::CGI - The CGI Engine

=head1 SYNOPSIS

A script using the Catalyst::Engine::CGI module might look like:

    #!/usr/bin/perl -w

    use strict;
    use lib '/path/to/MyApp/lib';
    use MyApp;

    MyApp->run;

The application module (C<MyApp>) would use C<Catalyst>, which loads the
appropriate engine module.

=head1 DESCRIPTION

This is the Catalyst engine specialized for the CGI environment.

=head1 OVERLOADED METHODS

This class overloads some methods from C<Catalyst::Engine>.

=head2 $self->finalize_headers($c)

=cut

sub finalize_headers {
    my ( $self, $c ) = @_;

    $c->response->header( Status => $c->response->status );

    $self->_header_buf($c->response->headers->as_string("\015\012") . "\015\012");
}

=head2 $self->prepare_connection($c)

=cut

sub prepare_connection {
    my ( $self, $c ) = @_;
    local (*ENV) = $self->env || \%ENV;

    my $request = $c->request;
    $request->address( $ENV{REMOTE_ADDR} );

  PROXY_CHECK:
    {
        unless ( ref($c)->config->{using_frontend_proxy} ) {
            last PROXY_CHECK if $ENV{REMOTE_ADDR} ne '127.0.0.1';
            last PROXY_CHECK if ref($c)->config->{ignore_frontend_proxy};
        }
        last PROXY_CHECK unless $ENV{HTTP_X_FORWARDED_FOR};

        # If we are running as a backend server, the user will always appear
        # as 127.0.0.1. Select the most recent upstream IP (last in the list)
        my ($ip) = $ENV{HTTP_X_FORWARDED_FOR} =~ /([^,\s]+)$/;
        $request->address($ip);
        if ( defined $ENV{HTTP_X_FORWARDED_PORT} ) {
            $ENV{SERVER_PORT} = $ENV{HTTP_X_FORWARDED_PORT};
        }
    }

    $request->hostname( $ENV{REMOTE_HOST} ) if exists $ENV{REMOTE_HOST};
    $request->protocol( $ENV{SERVER_PROTOCOL} );
    $request->user( $ENV{REMOTE_USER} );  # XXX: Deprecated. See Catalyst::Request for removal information
    $request->remote_user( $ENV{REMOTE_USER} );
    $request->method( $ENV{REQUEST_METHOD} );

    if ( $ENV{HTTPS} && uc( $ENV{HTTPS} ) eq 'ON' ) {
        $request->secure(1);
    }

    if ( $ENV{SERVER_PORT} == 443 ) {
        $request->secure(1);
    }
    binmode(STDOUT); # Ensure we are sending bytes.
}

=head2 $self->prepare_headers($c)

=cut

sub prepare_headers {
    my ( $self, $c ) = @_;
    local (*ENV) = $self->env || \%ENV;
    my $headers = $c->request->headers;
    # Read headers from %ENV
    foreach my $header ( keys %ENV ) {
        next unless $header =~ /^(?:HTTP|CONTENT|COOKIE)/i;
        ( my $field = $header ) =~ s/^HTTPS?_//;
        $headers->header( $field => $ENV{$header} );
    }
}

=head2 $self->prepare_path($c)

=cut

# Please don't touch this method without adding tests in
# t/aggregate/unit_core_engine_cgi-prepare_path.t
sub prepare_path {
    my ( $self, $c ) = @_;
    local (*ENV) = $self->env || \%ENV;

    my $scheme = $c->request->secure ? 'https' : 'http';
    my $host      = $ENV{HTTP_HOST}   || $ENV{SERVER_NAME};
    my $port      = $ENV{SERVER_PORT} || 80;
    my $script_name = $ENV{SCRIPT_NAME};
    $script_name =~ s/([^$URI::uric])/$URI::Escape::escapes{$1}/go if $script_name;

    my $base_path;
    if ( exists $ENV{REDIRECT_URL} ) {
        $base_path = $ENV{REDIRECT_URL};
        $base_path =~ s/$ENV{PATH_INFO}$//;
    }
    else {
        $base_path = $script_name || '/';
    }

    # If we are running as a backend proxy, get the true hostname
  PROXY_CHECK:
    {
        unless ( ref($c)->config->{using_frontend_proxy} ) {
            last PROXY_CHECK if $host !~ /localhost|127.0.0.1/;
            last PROXY_CHECK if ref($c)->config->{ignore_frontend_proxy};
        }
        last PROXY_CHECK unless $ENV{HTTP_X_FORWARDED_HOST};

        $host = $ENV{HTTP_X_FORWARDED_HOST};

        # backend could be on any port, so
        # assume frontend is on the default port
        $port = $c->request->secure ? 443 : 80;
        if ( $ENV{HTTP_X_FORWARDED_PORT} ) {
            $port = $ENV{HTTP_X_FORWARDED_PORT};
        }
    }

    # RFC 3875: "Unlike a URI path, the PATH_INFO is not URL-encoded,
    # and cannot contain path-segment parameters." This means PATH_INFO
    # is always decoded, and the script can't distinguish / vs %2F.
    # See https://issues.apache.org/bugzilla/show_bug.cgi?id=35256
    # Here we try to resurrect the original encoded URI from REQUEST_URI.
    my $path_info   = $ENV{PATH_INFO};
    if (my $req_uri = $ENV{REQUEST_URI}) {
        $req_uri =~ s/^\Q$base_path\E//;
        $req_uri =~ s/\?.*$//;
        if ($req_uri) {
            # Note that if REQUEST_URI doesn't start with a /, then the user
            # is probably using mod_rewrite or something to rewrite requests
            # into a sub-path of their application..
            # This means that REQUEST_URI needs information from PATH_INFO
            # prepending to it to be useful, otherwise the sub path which is
            # being redirected to becomes the app base address which is
            # incorrect.
            if (substr($req_uri, 0, 1) ne '/') {
                my ($match) = $req_uri =~ m|^([^/]+)|;
                my ($path_info_part) = $path_info =~ m|^(.*?\Q$match\E)|;
                substr($req_uri, 0, length($match), $path_info_part);
            }
            $path_info = $req_uri;
        }
    }

    # set the request URI
    my $path = $base_path . ( $path_info || '' );
    $path =~ s{^/+}{};

    # Using URI directly is way too slow, so we construct the URLs manually
    my $uri_class = "URI::$scheme";

    # HTTP_HOST will include the port even if it's 80/443
    $host =~ s/:(?:80|443)$//;

    if ( $port !~ /^(?:80|443)$/ && $host !~ /:/ ) {
        $host .= ":$port";
    }

    # Escape the path
    $path =~ s/([^$URI::uric])/$URI::Escape::escapes{$1}/go;
    $path =~ s/\?/%3F/g; # STUPID STUPID SPECIAL CASE

    my $query = $ENV{QUERY_STRING} ? '?' . $ENV{QUERY_STRING} : '';
    my $uri   = $scheme . '://' . $host . '/' . $path . $query;

    $c->request->uri( bless(\$uri, $uri_class)->canonical );

    # set the base URI
    # base must end in a slash
    $base_path .= '/' unless $base_path =~ m{/$};

    my $base_uri = $scheme . '://' . $host . $base_path;

    $c->request->base( bless \$base_uri, $uri_class );
}

=head2 $self->prepare_query_parameters($c)

=cut

around prepare_query_parameters => sub {
    my $orig = shift;
    my ( $self, $c ) = @_;
    local (*ENV) = $self->env || \%ENV;

    if ( $ENV{QUERY_STRING} ) {
        $self->$orig( $c, $ENV{QUERY_STRING} );
    }
};

=head2 $self->prepare_request($c, (env => \%env))

=cut

sub prepare_request {
    my ( $self, $c, %args ) = @_;

    if ( $args{env} ) {
        $self->env( $args{env} );
    }
}

=head2 $self->prepare_write($c)

Enable autoflush on the output handle for CGI-based engines.

=cut

around prepare_write => sub {
    *STDOUT->autoflush(1);
    return shift->(@_);
};

=head2 $self->write($c, $buffer)

Writes the buffer to the client.

=cut

around write => sub {
    my $orig = shift;
    my ( $self, $c, $buffer ) = @_;

    # Prepend the headers if they have not yet been sent
    if ( $self->_has_header_buf ) {
        $buffer = $self->_clear_header_buf . $buffer;
    }

    return $self->$orig( $c, $buffer );
};

=head2 $self->read_chunk($c, $buffer, $length)

=cut

sub read_chunk { shift; shift; *STDIN->sysread(@_); }

=head2 $self->run

=cut

sub run { shift; shift->handle_request( env => \%ENV ) }

=head1 SEE ALSO

L<Catalyst>, L<Catalyst::Engine>

=head1 AUTHORS

Catalyst Contributors, see Catalyst.pm

=head1 COPYRIGHT

This library is free software. You can redistribute it and/or modify it under
the same terms as Perl itself.

=cut
no Moose;

1;
