=encoding utf8

=head1 NAME

Any::Daemon::HTTP::VirtualHost - webserver virtual hosts

=head1 SYNOPSIS

 my $vhost  = Any::Daemon::HTTP::VirtualHost->new
  ( directories => ...
  , rewrite     => ...
  , handlers    => ...
  );
 my $daemon = Any::Daemon::HTTP->new
   ( @other_options
   , vhosts  => $vhost  # or \@vhosts
   );

 # or
 my $daemon = Any::Daemon::HTTP->new(@other_opts);
 $daemon->addVirtualHost($vhost);
 $daemon->addVirtualHost(@vhost2_opts);

 # create object which extends Any::Daemon::HTTP::VirtualHost
 my $myvhost = MyVHost->new(...);
 $daemon->addVirtualHost($myvhost);

=head1 DESCRIPTION

These virtual host definitions are used by L<Any::Daemon::HTTP|Any::Daemon::HTTP>, to
implement (server) name based data seperation.  Its features resemble those
of Apache virtual hosts.

Each virtual host usually has to L<Any::Daemon::HTTP::Directory|Any::Daemon::HTTP::Directory> slaves: one
which describes the permissions for user directories (url paths in the
form C< /~user/ >) and one for data outside the user space.

=head1 METHODS

=head2 Constructors

You may avoid the creation of extension classes for each virtual host,
by using these options.

=over 4

=item Any::Daemon::HTTP::VirtualHost-E<gt>B<new>(OPTIONS|HASH-of-OPTIONS)

 -Option     --Default
  aliases      []
  directories  <see text>
  documents    <undef>
  handlers     {}
  name         <required>
  redirect     <undef>
  rewrite      <undef>
  user_dirs    undef

=over 2

=item aliases => HOSTNAME|ARRAY-of-HOSTNAMES

=item directories => OBJECT|HASH|ARRAY

Pass one or more L<Any::Daemon::HTTP::Directory|Any::Daemon::HTTP::Directory> OBJECTS, or HASHes which will
be used to initialize them.

=item documents => DIRECTORY

An absolute DIRECTORY for the location of the source files.  Creates the
most free L<Any::Daemon::HTTP::Directory|Any::Daemon::HTTP::Directory> object.  If you need things like
access restrictions, then do not use this option but the C<directories>
option.

=item handlers => CODE|HASH

The keys are path names, part of the request URIs.  The values are
CODE-references, called when that URI is addressed.  The access rules
are taken from the directory definition which is selected by the path.
Read L</DETAILS> for the details.

=item name => HOSTNAME

=item redirect => CODE|METHOD|HASH

[0.21] Automatically redirect the browser to some other url, maybe to
an other host.  Configuration like for C<rewrite>.

=item rewrite => CODE|METHOD|HASH

When a request arrives, the URI can be rewritten to become an other
request. See L</URI rewrite>.

[0.21] When a METHOD name is specified, that will be called on
the virtual host object.  An HASH as parameter is interpreted as a
simple lookup table.

=item user_dirs => undef|OBJECT|HASH

With an (empty?) HASH which contains instantiation parameter, an
L<Any::Daemon::HTTP::UserDirs|Any::Daemon::HTTP::UserDirs> is created for you, with
standard Apache behavior.  You may provide your own OBJECT.  Without
this parameter, there are no public user pages.

=back

=back

=head2 Attributes

=over 4

=item $obj-E<gt>B<aliases>()

Returns a list of all aliases (alternative names) for this server.

=item $obj-E<gt>B<name>()

Returns the primary name for this server.

=back

=head2 Handler

=over 4

=item $obj-E<gt>B<addHandler>(CODE|(PATH => CODE)-LIST|HASH)

Handlers are called to dynamically generate responses, for instance
to fill-in templates.  The L</DETAILS> section below explains how
handlers work.

When only CODE is given, then this will be the default handler for all
paths (under '/', top).  You may also pass a list or HASH of PAIRS.
[0.21] CODE may also be a method name.

example: 

  $vhost->addHandler('/' => \&default_handler,
      '/upload' => \&upload_handler);

  $vhost->addHandler(\&default_handler);

  # [0.21] will call $vhost->formHandle
  $vhost->addHandler('/form' => 'formHandler');

=item $obj-E<gt>B<addHandlers>(PARAMS)

Same as L<addHandler()|Any::Daemon::HTTP::VirtualHost/"Handler">.

=item $obj-E<gt>B<findHandler>(URI|PATH|PATH-SEGMENTS)

=back

=head2 Access permissions

=over 4

=item $obj-E<gt>B<handleRequest>(SERVER, SESSION, REQUEST, [URI])

=back

=head2 Basic daemon actions

=over 4

=item $obj-E<gt>B<allow>(SESSION, REQUEST, URI)

BE WARNED that the URI is the rewrite of the REQUEST uri, and therefore
you should use that URI.  The SESSION represents a user.

See L</Allow access>.

=item $obj-E<gt>B<mustRedirect>(URI)

[0.21] Returns an HTTP::Response object if the URI needs to be
redirected, according to the vhost configuration.

=item $obj-E<gt>B<redirect>(URI, [HTTP_CODE])

[0.21] Returns an HTTP::Response object of the URI.

=item $obj-E<gt>B<rewrite>(URI)

Returns an URI object as result, which may be the original in case of
no rewrite was needed.  See L</URI Rewrite>.

=back

=head2 Directories

=over 4

=item $obj-E<gt>B<addDirectory>(OBJECT|HASH|OPTIONS)

Either pass a L<Any::Daemon::HTTP::Directory|Any::Daemon::HTTP::Directory> OBJECT or the OPTIONS to
create the object.  When OPTIONS are provided, they are passed to
L<Any::Daemon::HTTP::Directory::new()|Any::Daemon::HTTP::Directory/"Constructors"> to create the OBJECT.

=item $obj-E<gt>B<directoryOf>(PATH|PATH_SEGMENTS)

Find the best matching L<Any::Daemon::HTTP::Directory|Any::Daemon::HTTP::Directory> object.

=item $obj-E<gt>B<filename>(URI)

Translate the URI into a filename, without checking for existence.  Returns
C<undef> is not possible.

=back

=head1 DETAILS

=head2 Handlers

Handlers are called to dynamically generate responses, for instance
to fill-in templates.

When a request for an URI is received, it is first checked whether
a static file can fulfil the request.  If not, a search is started
for the handler with the longest path.

  # /upload($|/*) goes to the upload_handler
  $vhost->addHandler
    ( '/'       => \&default_handler
    , '/upload' => \&upload_handler
    );

  # Missing files go to the default_handler
  # which is actually replacing the existing one
  $vhost->addHandler(\&default_handler);

  # [0.21] This will call $vhost->formHandle(...), especially
  # useful in your virtual host sub-class.
  $vhost->addHandler('/form' => 'formHandler');

The handlers are called with many arguments, and should return an
HTTP::Response object:

  $vhost->addHandler('/upload' => $handler);
  my $resp = $hander->($vhost, $session, $req, $uri, $tree);

  $vhost->addHandler('/form' => $method);
  my $resp = $vhost->$method($session, $req, $uri, $tree);

In which

=over 4

=item * C<$vhost> is an C<Any::Daemon::HTTP::VirtualHost>,

=item * C<$session> is an L<Any::Daemon::HTTP::Session|Any::Daemon::HTTP::Session>,

=item * C<$req> is an HTTP::Request,

=item * C<$uri> an URI after rewrite rules, and

=item * C<$tree> the selected C<Any::Daemon::HTTP::Directory>.

=back

The handler could work like this:

  sub formHandler($$$$)
  {   my ($vhost, $session, $req, $uri, $tree) = @_;
      # in OO extended vhosts, then $vhost => $self

      # Decode path parameters in Plack style
      # ignore two components: '/' and 'form' from the path
      my (undef, undef, $name, @more) = $uri->path_segments;

      HTTP::Response->new(HTTP_OK, ...);
  }

=head2 Your virtual host as class

When your virtual host has larger configuration or many handlers --or when
you like clean programming--, it may be a good choice to put your code
in a separate package with the normal Object Oriented extension mechanism.

You may need to implement your own information persistence via databases
or configation files.  For that, extend L<Any::Daemon::HTTP::Session|Any::Daemon::HTTP::Session>.

=head2 URI Rewrite

For each request, the L<rewrite()|Any::Daemon::HTTP::VirtualHost/"Basic daemon actions"> method is called to see whether a
rewrite of the URI is required.  The method must return the original URI
object (the only parameter) or a new URI object.

=head1 SEE ALSO

This module is part of Any-Daemon-HTTP distribution version 0.21,
built on October 15, 2013. Website: F<http://perl.overmeer.net/any-daemon/>

=head1 LICENSE

Copyrights 2013 by [Mark Overmeer]. For other contributors see ChangeLog.

This program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
See F<http://www.perl.com/perl/misc/Artistic.html>

