=encoding utf8

=head1 NAME

Net::OAuth2::Profile::WebServer - OAuth2 for web-server use

=head1 INHERITANCE

 Net::OAuth2::Profile::WebServer
   is a Net::OAuth2::Profile

=head1 SYNOPSIS

  # See examples/psgi/
  my $auth = Net::OAuth2::Profile::WebServer->new
    ( name           => 'Google Contacts'
    , client_id      => $id
    , client_secret  => $secret
    , site           => 'https://accounts.google.com'
    , scope          => 'https://www.google.com/m8/feeds/'
    , authorize_path    => '/o/oauth2/auth'
    , access_token_path => '/o/oauth2/token'
    , protected_resource_url
        =>  'https://www.google.com/m8/feeds/contacts/default/full'
    );

  # Let user ask for a grant from the resource owner
  print $auth->authorize_response->as_string;
  # or, in Plack:   redirect $auth->authorize;

  # Prove your identity at the authorization server
  # The $info are the parameters from the callback to your service, it
  # will contain a 'code' value.
  my $access_token  = $auth->get_access_token($info->{code});

  # communicate with the resource serve
  my $response      = $access_token->get('/me');
  $response->is_success
      or die "error: " . $response->status_line;

  print "Yay, it worked: " . $response->decoded_content;

=head1 DESCRIPTION

Use OAuth2 in a WebServer context.  Read the DETAILS section, far below
this man-page before you start implementing this interface.

Extends L<"DESCRIPTION" in Net::OAuth2::Profile|Net::OAuth2::Profile/"DESCRIPTION">.
 
=head1 METHODS

Extends L<"METHODS" in Net::OAuth2::Profile|Net::OAuth2::Profile/"METHODS">.
 
=head2 Constructors

Extends L<"Constructors" in Net::OAuth2::Profile|Net::OAuth2::Profile/"Constructors">.
 
=over 4

=item Net::OAuth2::Profile::WebServer-E<gt>B<new>(%options)

 -Option           --Defined in          --Default
  auto_save                                <set token's changed flag>
  client_id          Net::OAuth2::Profile  <required>
  client_secret      Net::OAuth2::Profile  <required>
  grant_type         Net::OAuth2::Profile  'authorization_code'
  hd                 Net::OAuth2::Profile  undef
  redirect_uri                             undef
  referer                                  undef
  scope              Net::OAuth2::Profile  undef
  secrets_in_params  Net::OAuth2::Profile  <true>
  site               Net::OAuth2::Profile  undef
  state              Net::OAuth2::Profile  undef
  token_scheme       Net::OAuth2::Profile  'auth-header:Bearer'
  user_agent         Net::OAuth2::Profile  <created internally>

=over 2

=item auto_save => CODE

When a new token is received or refreshed, it usually needs to get
save into a database or file.  The moment you receive a new token is
clear, but being aware of refreshes in your main program is a hassle.
Read more about configuring this in the L</DETAILS> section below.

=item client_id => STRING

=item client_secret => STRING

=item grant_type => STRING

=item hd => STRING

=item redirect_uri => URI

=item referer => URI

Adds a C<Referer> header to each request.  Some servers check whether
provided redirection uris point to the same server the page where the
link was found.

=item scope => STRING

=item secrets_in_params => BOOLEAN

=item site => URI

=item state => STRING

=item token_scheme => SCHEME

=item user_agent => LWP::UserAgent object

=back

=back

=head2 Accessors

Extends L<"Accessors" in Net::OAuth2::Profile|Net::OAuth2::Profile/"Accessors">.
 
=over 4

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

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

Inherited, see L<Net::OAuth2::Profile/"Accessors">

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

Inherited, see L<Net::OAuth2::Profile/"Accessors">

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

Inherited, see L<Net::OAuth2::Profile/"Accessors">

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

Inherited, see L<Net::OAuth2::Profile/"Accessors">

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

=item $obj-E<gt>B<referer>( [$uri] )

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

Inherited, see L<Net::OAuth2::Profile/"Accessors">

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

Inherited, see L<Net::OAuth2::Profile/"Accessors">

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

Inherited, see L<Net::OAuth2::Profile/"Accessors">

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

Inherited, see L<Net::OAuth2::Profile/"Accessors">

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

Inherited, see L<Net::OAuth2::Profile/"Accessors">

=back

=head2 Actions

Extends L<"Actions" in Net::OAuth2::Profile|Net::OAuth2::Profile/"Actions">.
 
=over 4

=item $obj-E<gt>B<authorize>(%options)

On initial contact of a new user, you have to redirect to the resource
owner.  Somewhere in the near future, your application will be contacted
again by the same user but then with an authorization grant code.

Only the most common %options are listed... there may be more: read the
docs on what your server expects.

 -Option       --Default
  client_id      new(client_id)
  response_type  'code'
  scope          undef
  state          undef

=over 2

=item client_id => STRING

=item response_type => STRING

=item scope => STRING

=item state => STRING

=back

example: 

  my $auth = Net::OAuth2::Profile::WebServer->new(...);

  # From the Plack demo, included in this distribution (on CPAN)
  get '/get' => sub { redirect $auth->authorize };

  # In generic HTTP, see method authorize_response
  use HTTP::Status 'HTTP_TEMPORARY_REDIRECT';   # 307
  print HTTP::Response->new
    ( HTTP_TEMPORARY_REDIRECT => 'Get authorization grant'
    , [ Location => $auth->authorize ]
    )->as_string;

=item $obj-E<gt>B<authorize_response>( [$request] )

Convenience wrapper around L<authorize()|Net::OAuth2::Profile::WebServer/"Actions">, to produce a complete
HTTP::Response object to be sent back.

=item $obj-E<gt>B<get_access_token>(CODE, %options)

 -Option       --Default
  client_id      new(client_id)
  client_secret  new(client_secret)

=over 2

=item client_id => STRING

=item client_secret => STRING

=back

=item $obj-E<gt>B<update_access_token>($token, %options)

Ask the server for a new token.  You may pass additional %options as
pairs.  However, this method is often triggered automatically, in which
case you can to use the C<refresh_token_params> option of L<new()|Net::OAuth2::Profile::WebServer/"Constructors">.

example: 

  $auth->update_access_token($token);
  $token->refresh;   # nicer

=back

=head2 Helpers

Extends L<"Helpers" in Net::OAuth2::Profile|Net::OAuth2::Profile/"Helpers">.
 
=over 4

=item $obj-E<gt>B<add_token>($request, $token, $scheme)

Inherited, see L<Net::OAuth2::Profile/"Helpers">

=item $obj-E<gt>B<build_request>($method, $uri, $params)

Inherited, see L<Net::OAuth2::Profile/"Helpers">

=item $obj-E<gt>B<params_from_response>($response, $reason)

Inherited, see L<Net::OAuth2::Profile/"Helpers">

=item $obj-E<gt>B<site_url>( <$uri|$path>, $params )

Inherited, see L<Net::OAuth2::Profile/"Helpers">

=back

=head1 DETAILS

OAuth2 is a server-server protocol, not the usual client-server
set-up. The consequence is that the protocol handlers on both sides will
not wait for another during the communication: the remote uses callback
urls to pass on the response.  Your side of the communication, your
webservice, needs to re-group these separate processing steps into
logical sessions.

=head2 The process

The client side of the process has
three steps, nicely described in
L<https://tools.ietf.org/html/rfc6749|RFC6749>

=over 4

=item 1. Send an authorization request to resource owner

It needs a C<client_id>: usually the name of the service where you want
get access to.  The answer is a redirect, based on the C<redirection_uri>
which you usually pass on.  Additional C<scope>, C<state>, and C<hd> parameters
can be needed or useful.  The redirect will provide you with (amongst other
things) a C<code> parameter.

=item 2. Translate the code into an access token

With the code, you go to an authorization server which will validate
your existence.  An access token (and sometimes a refresh token) are
returned.

=item 3. Address the protected resource

The access token, usually a 'bearer' token, is added to each request to
the resource you want to address.  The token may refresh itself when
needed.

=back

=head2 Saving the token

Your application must implement a persistent session, probably
in a database or file.  The session information is kept in an
L<Net::OAuth2::AccessToken|Net::OAuth2::AccessToken> object, and does contain more facts than
just the access token.

Let's discuss the three approaches.

=head3 no saving

The Plack example contained in the CPAN distribution of this module
is a single process server.  The tokens are administered in the memory
of the process.  It is nice to test your settings, but probably not
realistic for any real-life application.

=head3 automatic saving

When your own code is imperative:

  my $auth = Net::OAuth2::Profile::WebServer->new
    ( ...
    , auto_save => \&save_session
    );

  sub save_session($$)
  {   my ($profile, $token) = @_;
      ...
  }

When your own code is object oriented:

  sub init(...)
  {  my ($self, ...) = @_;
     my $auth = Net::OAuth2::Profile::WebServer->new
       ( ...
       , auto_save => sub { $self->save_session(@_) }
       );
  }

  sub save_session($$)
  {   my ($self, $profile, $token) = @_;
      ...
  }

=head3 explicit saving

In this case, do not use L<new(auto_save)|Net::OAuth2::Profile::WebServer/"Constructors">.

=head1 COPYRIGHTS

Copyrights 2013-2019 on the perl code and the related documentation
 by [Mark Overmeer <markov@cpan.org>] for SURFnet bv, The Netherlands.  For other contributors see L</Changes>.

Copyrights 2011-2012 by Keith Grennan.

This program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
See F<http://dev.perl.org/licenses/>