lib/Kalamar/Plugin/Auth.pm

package Kalamar::Plugin::Auth;
use Mojo::Base 'Mojolicious::Plugin';
use File::Basename 'dirname';
use File::Spec::Functions qw/catdir/;
use Mojo::ByteStream 'b';
use Mojo::File qw!path!;
use Mojo::Util qw!b64_encode encode!;
use Mojo::JSON qw'decode_json encode_json';
use Encode 'is_utf8';

# This is a plugin to deal with the Kustvakt OAuth server.
# All tokens are stored in the session. Access tokens are short-lived,
# which limits the effects of misuse.
# Refresh tokens are bound to client id and client secret,
# which again limits the effects of misuse.

# TODO:
#   Establish a plugin 'OAuth' that works independent of 'Auth'.

# TODO:
#   CSRF-protect logout!

# TODO:
#   Remove the Bearer prefix from auth.

# In case no expiration time is returned by the server,
# take this time.
our $EXPECTED_EXPIRATION_IN = 259200;

# Register the plugin
sub register {
  my ($plugin, $app, $param) = @_;

  # Load parameter from config file
  if (my $config_param = $app->config('Kalamar-Auth')) {
    $param = { %$param, %$config_param };
  };

  if ($param->{jwt}) {
    $app->log->error('JWT flow is no longer supported');
    return;
  };

  # Load 'notifications' plugin
  unless (exists $app->renderer->helpers->{notify}) {
    $app->plugin(Notifications => {
      HTML => 1
    });
  };

  # Set session default timeout
  for ($app->sessions) {
    $_->default_expiration(60*60*24*3); # Session expires after 3 days of non-use
  };

  # Get client_id and client_secret from client file
  if ($param->{client_file} || $main::ENV{KALAMAR_CLIENT_FILE}) {
    $param->{client_file} ||= $main::ENV{KALAMAR_CLIENT_FILE};
    my $client_json = decode_json(path($param->{client_file})->slurp);
    $param->{client_id} //= $client_json->{client_id};
    $param->{client_secret} //= $client_json->{client_secret};
  };

  # Get the client id and the client_secret as a requirement
  unless ($param->{client_id} && $param->{client_secret}) {
    $app->log->error('client_id or client_secret not defined');
  };

  # Load localize
  $app->plugin('Localize' => {
    dict => {
      de => {
        abort => 'Abbrechen'
      },
      -en => {
        abort => 'Abort'
      },
      Auth => {
        _ => sub { $_->locale },
        de => {
          loginPlease => 'Bitte melden Sie sich an!',
          loginSuccess => 'Anmeldung erfolgreich',
          loginFail => 'Anmeldung fehlgeschlagen',
          logoutSuccess => 'Abmeldung erfolgreich',
          logoutFail => 'Abmeldung fehlgeschlagen',
          authenticationFail => 'Nicht authentifiziert',
          csrfFail => 'Fehlerhafter CSRF Token',
          scopeFail => 'Scope nicht definiert',
          clientIDFail => 'Client ID nicht definiert',
          invalidChar => 'Ungültiges Zeichen in Anfrage',
          openRedirectFail => 'Weiterleitungsfehler',
          tokenExpired => 'Zugriffstoken abgelaufen',
          tokenInvalid => 'Zugriffstoken ungültig',
          refreshFail => 'Fehlerhafter Refresh-Token',
          responseError => 'Unbekannter Autorisierungsfehler',
          serverError => 'Unbekannter Serverfehler',
          revokeFail => 'Der Token kann nicht widerrufen werden',
          revokeSuccess => 'Der Token wurde erfolgreich widerrufen',
          paramError => 'Einige Eingaben sind fehlerhaft',
          redirectUri => 'Weiterleitungsadresse',
          pluginSrc => 'Beschreibung des Plugins (*.json-Datei)',
          homepage => 'Webseite',
          desc => 'Kurzbeschreibung',
          revoke => 'Widerrufen',
          clientCredentials => 'Client Daten',
          clientType => 'Art der Client-Applikation',
          clientName => 'Name der Client-Applikation',
          clientID => 'ID der Client-Applikation',
          clientSecret => 'Client-Secret',
          clientRegister => 'Neue Client-Applikation registrieren',
          registerSuccess => 'Registrierung erfolgreich',
          registerFail => 'Registrierung fehlgeschlagen',
          oauthSettings => 'OAuth',
          #for marketplace settings
          marketplace => 'Marktplatz',
          mp_regby => "Registriert von",
          mp_regdate => "Registrierungsdatum",

          oauthUnregister => {
            -long => 'Möchten sie <span class="client-name"><%= $client_name %></span> wirklich löschen?',
            short => 'Löschen'
          },
          oauthHint => 'Die folgende Registrierung (und alle Angaben) für API-Clients folgen der <a href="https://oauth.net/" class="external">OAuth-2.0-Spezifikation</a>.',
          loginHint => 'Möglicherweise müssen sie sich zunächst einloggen.',
          oauthIssueToken => {
            -long => 'Stelle einen neuen Token für <span class="client-name"><%= $client_name %></span> aus',
            short => 'Neuen Token ausstellen'
          },
          accessToken => 'Access Token',
          oauthRevokeToken => {
            -long => 'Widerrufe einen Token für <span class="client-name"><%= $client_name %></span>',
            short => 'Widerrufe'
          },
          oauthGrantScope => {
            -long => '<span class="client-name"><%= $client_name %></span> möchte Zugriffsrechte',
            short => 'Zugriffsrechte erteilen'
          },
          oauthGrantPublicWarn => 'Achtung - dies ist ein öffentlicher Client!',
          oauthGrantRedirectWarn => 'Die Weiterleitung findet an eine unbekannte Adresse statt',
          createdAt => 'Erstellt am <time datetime="<%= stash("date") %>"><%= stash("date") %></date>.',
          expiresIn => 'Läuft in <%= stash("seconds") %> Sekunden ab.',
          fileSizeExceeded => 'Dateigröße überschritten'
        },
        -en => {
          loginPlease => 'Please log in!',
          loginSuccess => 'Login successful',
          loginFail => 'Access denied',
          logoutSuccess => 'Logout successful',
          logoutFail => 'Logout failed',
          authenticationFail => 'Not authenticated',
          csrfFail => 'Bad CSRF token',
          scopeFail => 'Scope required',
          clientIDFail => 'Client ID required',
          invalidChar => 'Invalid character in request',
          openRedirectFail => 'Redirect failure',
          tokenExpired => 'Access token expired',
          tokenInvalid => 'Access token invalid',
          refreshFail => 'Bad refresh token',
          responseError => 'Unknown authorization error',
          serverError => 'Unknown server error',
          revokeFail => 'Token can\'t be revoked',
          revokeSuccess => 'Token was revoked successfully',
          paramError => 'Some fields are invalid',
          redirectUri => 'Redirect URI',
          pluginSrc => 'Declaration of the plugin (*.json file)',
          homepage => 'Homepage',
          desc => 'Short description',
          revoke => 'Revoke',
          clientCredentials => 'Client Credentials',
          clientType => 'Type of the client application',
          clientName => 'Name of the client application',
          clientID => 'ID of the client application',
          clientSecret => 'Client secret',
          clientRegister => 'Register new client application',
          registerSuccess => 'Registration successful',
          registerFail => 'Registration denied',
          oauthSettings => 'OAuth',
          #for marketplace settings
          marketplace => 'Marketplace',
          mp_regby =>"Registered by",
          mp_regdate =>"Registration date",
          oauthUnregister => {
            -long => 'Do you really want to unregister <span class="client-name"><%= $client_name %></span>?',
            short => 'Unregister'
          },
          oauthHint => 'The following registration of API clients follows the <a href="https://oauth.net/" class="external">OAuth 2.0 specification</a>.',
          loginHint => 'Maybe you need to log in first?',
          oauthIssueToken => {
            -long => 'Issue a new token for <span class="client-name"><%= $client_name %></span>',
            short => 'Issue new token'
          },
          accessToken => 'Access Token',
          oauthRevokeToken => {
            -long => 'Revoke a token for <span class="client-name"><%= $client_name %></span>',
            short => 'Revoke'
          },
          oauthGrantScope => {
            -long => '<span class="client-name"><%= $client_name %></span> wants to have access',
            short => 'Grant access'
          },
          oauthGrantPublicWarn => 'Warning - this is a public client!',
          oauthGrantRedirectWarn => 'The redirect points to an unknown location',
          createdAt => 'Created at <time datetime="<%= stash("date") %>"><%= stash("date") %></date>.',
          expiresIn => 'Expires in <%= stash("seconds") %> seconds.',
          fileSizeExceeded => 'File size exceeded',
          confidentialRequired => 'Plugins need to be confidential',
          jsonRequired => 'Plugin declarations need to be json files',
        }
      }
    }
  });


  # Add login frame to sidebar
  $app->content_block(
    sidebar => {
      template => 'partial/auth/login'
    }
  );


  # Add logout button to header button list
  $app->content_block(
    headerButtonGroup => {
      template => 'partial/auth/logout'
    }
  );


  # Add hook after search
  $app->hook(
    after_search => sub {
      my $c = shift;

      # User is not logged in
      if ($c->stash('results')->size == 0 && !$c->auth->token) {
        $c->content_for(
          'after_search_results' =>
            $c->render_to_string(
              inline => '<p class="hint"><%= loc "Auth_loginHint" %></p>'
            )
          );
      };
    }
  );

  # The plugin path
  my $path = catdir(dirname(__FILE__), 'Auth');

  # Append "templates"
  push @{$app->renderer->paths}, catdir($path, 'templates');

  # Get or set the user token necessary for authorization
  $app->helper(
    'auth.token' => sub {
      my ($c, $token, $expires_in) = @_;

      if ($token) {
        # Set auth token
        $c->stash(auth => $token);
        $c->session(auth => $token);
        $c->session(auth_exp => time + $expires_in);
        return 1;
      };

      # Get token from stash
      $token = $c->stash('auth');

      return $token if $token;

      # Get auth from session
      $token = $c->session('auth') or return;
      $c->stash(auth => $token);

      # Return stashed value
      return $token;
    }
  );

  # Log in to the system
  my $r = $app->routes;

  my $client_id = $param->{client_id};
  my $client_secret = $param->{client_secret};


  # Sets a requested token and returns
  # an error, if it didn't work
  $app->helper(
    'auth.set_tokens_p' => sub {
      my ($c, $json) = @_;
      my $promise = Mojo::Promise->new;

      # No json object
      unless ($json) {
        return $promise->reject({
          message => 'Response is no valid JSON object (remote)'
        });
      };

      # There is an error here
      # Dealing with errors here
      if ($json->{error} && ref $json->{error} ne 'ARRAY') {
        return $promise->reject(
          {
            message => $json->{error} . ($json->{error_description} ? ': ' . $json->{error_description} : '')
          }
        );
      }

      # There is an array of errors
      elsif (my $error = $json->{errors} // $json->{error}) {
        if (ref $error eq 'ARRAY') {
          my @errors = ();
          foreach (@{$error}) {
            if ($_->[1]) {
              push @errors, { code => $_->[0], message => $_->[1]}
            };
          };
          return $promise->reject(@errors);
        };

        return $promise->reject({message => $error});
      };

      # Everything is fine
      my $access_token  = $json->{access_token};
      my $token_type    = $json->{token_type};
      my $refresh_token = $json->{refresh_token};
      my $expires_in    = $json->{"expires_in"} // $EXPECTED_EXPIRATION_IN;
      my $auth          = $token_type . ' ' . $access_token;
      # my $scope       = $json->{scope};

      # Set session info
      $c->session(auth => $auth);

      # Expiration of the token minus tolerance
      $c->session(auth_exp => time + $expires_in - 60);

      # Set session info for refresh token
      # This can be stored in the session, as it is useless
      # unless the client secret is stolen
      $c->session(auth_r => $refresh_token) if $refresh_token;

      # Set stash info
      $c->stash(auth => $auth);

      return $promise->resolve;
    }
  );


  # Refresh tokens and return a promise
  $app->helper(
    'auth.refresh_p' => sub {
      my $c = shift;
      my $refresh_token = shift;

      # Get OAuth access token
      state $r_url = Mojo::URL->new($c->korap->api)->path('oauth2/token');

      $c->app->log->debug("Refresh at $r_url");

      return $c->kalamar_ua->post_p($r_url, {} => form => {
        grant_type => 'refresh_token',
        client_id => $client_id,
        client_secret => $client_secret,
        refresh_token => $refresh_token
      })->then(
        sub {
          my $tx = shift;
          my $json = $tx->result->json;

          # Response is fine
          if ($tx->res->is_success) {

            $c->app->log->info("Refresh was successful");

            # Set the tokens and return a promise
            return $c->auth->set_tokens_p($json);
          };

          # There is a client error - refresh fails
          if ($tx->res->is_client_error && $json) {

            $c->stash(auth => undef);
            $c->stash(auth_exp => undef);
            delete $c->session->{user};
            delete $c->session->{auth};
            delete $c->session->{auth_r};
            delete $c->session->{auth_exp};

            # Response is 400
            return Mojo::Promise->reject(
              $json->{error_description} // $c->loc('Auth_refreshFail')
            );
          };

          if ($tx->res->is_server_error) {
            return Mojo::Promise->reject(
              '600'
            )
          };

          $c->notify(error => $c->loc('Auth_responseError'));
          return Mojo::Promise->reject;
        }
      )
    }
  );


  # Get a list of registered clients
  $app->helper(
    'auth.client_list_p' => sub {
      my $c = shift;


      # Get list of registered clients
      state $r_url = Mojo::URL->new($c->korap->api)->path('oauth2/client/list');

      # Get the list of all clients
      return $c->korap_request(post => $r_url, {} => form => {
        super_client_id => $client_id,
        super_client_secret => $client_secret,
        authorized_only => 'no'
      })->then(
        sub {
          my $tx = shift;
          my $json = $tx->result->json;

          # Response is fine
          if ($tx->res->is_success) {
            return Mojo::Promise->resolve($json);
          };

          $c->log->error($c->dumper($tx->res->to_string));

          # Failure
          $c->notify(error => $c->loc('Auth_responseError'));
          return Mojo::Promise->reject($json // 'No response');
        }
      );
    }
  );

  # Get info for registered client
  $app->helper(
    'auth.client_info_p' => sub {
      my $c = shift;
      my $req_client_id = shift;

      # Get list of registered clients
      my $r_url = Mojo::URL->new($c->korap->api)->path('oauth2/client/')->path($req_client_id);

      my $form = {
        super_client_id => $client_id,
        super_client_secret => $client_secret,
      };

      # Get the list of all clients
      return $c->korap_request(POST => $r_url, {} => form => $form)->then(
        sub {
          my $tx = shift;
          my $json = $tx->result->json // {};

          # Response is fine
          if ($tx->res->is_success) {
            return Mojo::Promise->resolve($json);
          };

          $c->log->error($c->dumper($tx->res->to_string));

          # Failure
          return Mojo::Promise->reject($json->{error_description} // 'Client unknown');
        }
      );
    }
  );


  # Get a list of registered clients
  $app->helper(
    'auth.token_list_p' => sub {
      my $c = shift;
      my $user_client_id = shift;

      # Revoke the token
      state $r_url = Mojo::URL->new($c->korap->api)->path('oauth2/token/list');

      my $form = {
        super_client_id => $client_id,
        super_client_secret => $client_secret,
        token_type => 'access_token',
      };

      if ($user_client_id) {
        $form->{client_id} = $user_client_id;
      };

      # Get the list of all clients
      return $c->korap_request(post => $r_url, {} => form => $form)->then(
        sub {
          my $tx = shift;
          my $json = $tx->result->json;

          # Response is fine
          if ($tx->res->is_success) {
            return Mojo::Promise->resolve($json);
          };

          $c->log->error($c->dumper($tx->res->to_string));

          # Failure
          $c->notify(error => $c->loc('Auth_responseError'));
          return Mojo::Promise->reject($json // 'No response');
        }
      );
    }
  );


  # Issue a korap request with "oauth"orization
  # This will override the core request helper
  $app->helper(
    korap_request => sub {
      my $c      = shift;

      # Get plugin user agent
      my $ua = $c->kalamar_ua;

      # Override if UA is granted
      if (ref $_[0] eq 'Mojo::UserAgent') {
        $ua = shift;
      };

      my $method = shift;
      my $path   = shift;

      my @param = @_;

      # TODO:
      #   Check if $tx is not leaked!

      my $url = Mojo::URL->new($path);
      my $tx = $ua->build_tx(uc($method), $url->clone, @param);

      # Set X-Forwarded for
      $tx->req->headers->header(
        'X-Forwarded-For' => $c->client_ip
      );

      # Emit Hook to alter request
      $c->app->plugins->emit_hook(
        before_korap_request => ($c, $tx)
      );

      my $h = $tx->req->headers;

      # If the request already has an Authorization
      # header, respect it!
      if ($h->authorization) {
        return $ua->start_p($tx);
      };

      # Get auth token
      if (my $auth_token = $c->auth->token) {

        # The token is already expired!
        my $exp = $c->session('auth_exp');
        if (defined $exp && $exp < time) {

          # Remove auth ...
          $c->stash(auth => undef);

          # And get refresh token from session
          if (my $refresh_token = $c->session('auth_r')) {

            $c->app->log->debug("Refresh is required");

            # Refresh
            return $c->auth->refresh_p($refresh_token)->then(
              sub {
                $c->app->log->debug("Search with refreshed tokens");

                # Tokens were set - now send the request the first time!
                $tx->req->headers->authorization($c->stash('auth'));
                return $ua->start_p($tx);
              }
            );
          }

          # The token is expired and no refresh token is
          # available - issue an unauthorized request!
          else {

            $c->stash(auth => undef);
            $c->stash(auth_exp => undef);
            delete $c->session->{user};
            delete $c->session->{auth};
            delete $c->session->{auth_r};
            delete $c->session->{auth_exp};

            # Warn on Error!
            $c->notify(warn => $c->loc('Auth_tokenExpired'));
            return $ua->start_p($tx);
          };
        }

        # Auth token is fine
        else {

          # Set auth
          $h->authorization($auth_token);
        }
      }

      # No token set
      else {

        # Return unauthorized request
        return $ua->start_p($tx);
      };

      # Issue an authorized request and automatically
      # refresh the token on expiration!
      return $ua->start_p($tx)->then(
        sub {
          my $tx = shift;

          # Response is fine
          if ($tx->res->is_success || $tx->res->is_redirect) {
            return Mojo::Promise->resolve($tx);
          }

          # There is a client error - maybe refresh!
          elsif ($tx->res->is_client_error) {

            # Check the error
            my $json = $tx->res->json('/errors/0/1');
            if ($json && ($json =~ /expired|invalid/)) {
              $c->stash(auth => undef);
              $c->stash(auth_exp => undef);
              delete $c->session->{user};
              delete $c->session->{auth};

              # And get refresh token from session
              if (my $refresh_token = $c->session('auth_r')) {

                # Refresh
                return $c->auth->refresh_p($refresh_token)->then(
                  sub {
                    $c->app->log->debug("Search with refreshed tokens");

                    my $tx = $ua->build_tx(uc($method), $url->clone, @param);

                    # Set X-Forwarded for
                    $tx->req->headers->header(
                      'X-Forwarded-For' => $c->client_ip
                    );

                    # Tokens were set - now send the request the first time!
                    $tx->req->headers->authorization($c->stash('auth'));
                    return $ua->start_p($tx);
                  }
                )
              };

              # Reject the invalid token
              $c->notify(error => $c->loc('Auth_tokenInvalid'));
              return Mojo::Promise->reject;
            };

            return Mojo::Promise->resolve($tx);
          }

          # There is a server error - just report
          elsif ($tx->res->is_server_error) {
            my $err = $tx->res->error;
            if ($err) {
              return Mojo::Promise->reject($err->{code} . ': ' . $err->{message});
            }
            else {
              $c->notify(error => $c->loc('Auth_serverError'));
              return Mojo::Promise->reject;
            };
          };

          $c->notify(error => $c->loc('Auth_responseError'));
          return Mojo::Promise->reject;
        }
      );
    }
  );

  # Password flow for OAuth
  $r->post('/user/login')->to(
    cb => sub {
      my $c = shift;

      # Validate input
      my $v = $c->validation;
      $v->required('handle_or_email', 'trim');
      $v->required('pwd', 'trim');
      $v->csrf_protect;
      $v->optional('fwd')->closed_redirect;

      my $user = check_decode($v->param('handle_or_email'));
      unless ($user) {
        $c->notify(error => $c->loc('Auth_invalidChar'));
        $c->param(handle_or_email => '');
        return $c->relative_redirect_to('index');
      };

      my $fwd = $v->param('fwd');

      # Set flash for redirect
      $c->flash(handle_or_email => $user);

      if ($v->has_error || index($user, ':') >= 0) {
        if ($v->has_error('fwd')) {
          $c->notify(error => $c->loc('Auth_openRedirectFail'));
        }
        elsif ($v->has_error('csrf_token')) {
          $c->notify(error => $c->loc('Auth_csrfFail'));
        }
        else {
          $c->notify(error => $c->loc('Auth_loginFail'));
        };

        return $c->relative_redirect_to($fwd // 'index');
      }

      my $pwd = $v->param('pwd');

      $c->app->log->debug("Login from user $user");

      # <specific>

      # Get OAuth access token
      my $url = Mojo::URL->new($c->korap->api)->path('oauth2/token');

      # Korap request for login
      $c->korap_request('post', $url, {}, form => {
        grant_type => 'password',
        username => $user,
        password => $pwd,
        client_id => $client_id,
        client_secret => $client_secret
      })->then(
        sub {
          # Set the tokens and return a promise
          return $c->auth->set_tokens_p(shift->result->json)
        }
      )->then(
        sub {
          # Set user info
          $c->session(user => $user);
          $c->stash(user => $user);

          # Notify on success
          $c->app->log->debug(qq!Login successful: "$user"!);
          $c->notify(success => $c->loc('Auth_loginSuccess'));
        }
      )->catch(
        sub {

          # Notify the user on login failure
          unless (@_) {
            $c->notify(error => $c->loc('Auth_loginFail'));
          }

          # There are known errors
          foreach (@_) {
            if (ref $_ eq 'HASH') {
              my $err = ($_->{code} ? $_->{code} . ': ' : '') .
                $_->{message};
              $c->notify(error => $err);
              # Log failure
              $c->app->log->debug($err);
            }
            else {
              $c->notify(error => $_);
              $c->app->log->debug($_);
            };
          };

          $c->app->log->debug(qq!Login fail: "$user"!);
        }
      )->finally(
        sub {
          # Redirect to slash
          return $c->relative_redirect_to($fwd // 'index');
        }
      )

      # Start IOLoop
      ->wait;

      return 1;
    }
  )->name('login');


  # Log out of the session
  $r->get('/user/logout')->to(
    cb => sub {
      my $c = shift;

      # TODO: csrf-protection!

      my $refresh_token = $c->session('auth_r');

      # Revoke the token
      state $url = Mojo::URL->new($c->korap->api)->path('oauth2/revoke');

      $c->kalamar_ua->post_p($url => {} => form => {
        client_id => $client_id,
        client_secret => $client_secret,
        token => $refresh_token,
        token_type => 'refresh_token'
      })->then(
        sub {
          my $tx = shift;
          my $json = $tx->result->json;

          my $promise;

          # Response is fine
          if ($tx->res->is_success) {
            $c->app->log->info("Revocation was successful");
            $c->notify(success => $c->loc('Auth_logoutSuccess'));

            $c->stash(auth => undef);
            $c->stash(auth_exp => undef);
            $c->flash(handle_or_email => delete $c->session->{user});
            delete $c->session->{auth};
            delete $c->session->{auth_r};
            delete $c->session->{auth_exp};
            return Mojo::Promise->resolve;
          };

          # Token may be invalid
          $c->notify('error', $c->loc('Auth_logoutFail'));

          # There is a client error - refresh fails
          if ($tx->res->is_client_error && $json) {

            return Mojo::Promise->reject(
              $json->{error_description}
            );
          };

          # Resource may not be found (404)
          return Mojo::Promise->reject

        }
      )->catch(
        sub {
          my $err = shift;

          # Server may be irresponsible
          $c->notify('error', $c->loc('Auth_logoutFail'));
          return Mojo::Promise->reject($err);
        }
      )->finally(
        sub {
          return $c->redirect_to('index');
        }
      )->wait;
    }
  )->name('logout');




  # If "experimental_registration" is set, open
  # OAuth registration dialogues.
  if ($param->{experimental_client_registration}) {

    # Add settings
    $app->navi->add(settings => (
      $app->loc('Auth_oauthSettings'), 'oauth'
    )
    );
    #$app->navi->add(settings => (
    #  $app->loc('Auth_marketplace'), 'marketplace'
    #));


    # Lists all permitted registered plugins
    $app->helper(
    'auth.plugin_list_m' => sub {

      my $c = shift;
      state $r_url = Mojo::URL->new($c->korap->api)->path('plugins');
      return $c->korap_request(post => $r_url, {} => form => {
        super_client_id => $client_id,
        super_client_secret => $client_secret,
        #list only permitted plugins
        permitted_only => 'true'
      })->then( 
          sub {
          my $tx = shift;
          my $json = $tx->result->json;

          # Response is fine
          if ($tx->res->is_success) {
            return Mojo::Promise->resolve($json);
          };

          $c->log->error($c->dumper($tx->res->to_string));

          # Failure
          $c->notify(error => $c->loc('Auth_responseError'));
          return Mojo::Promise->reject($json // 'No response');
        }
      );
     }
   );

    # Route to marketplace settings
    $r->get('/settings/marketplace')->to(
      cb => sub {
      my $c = shift;
      _set_no_cache($c->res->headers);
      
      unless ($c->auth->token) {
      #TODO: Handle authorization (forward to Login for example)
        return $c->render(
            template => 'exception',
            msg => $c->loc('Auth_authenticationFail'),
            status => 401
          );
        };

      $c->render_later;
      $c->auth->plugin_list_m->then(
        sub {
          $c->stash('plugin_list' => shift);
          }
        )->catch(
         sub {
            return;
          }
       )->finally(
         sub {
           return $c->render(template => 'auth/marketplace');
         }
       );
      }
     )->name('marketplace');



    # Route to OAuth settings
    $r->get('/settings/oauth')->to(
      cb => sub {
        my $c = shift;

        _set_no_cache($c->res->headers);

        unless ($c->auth->token) {
          return $c->render(
            template => 'exception',
            msg => $c->loc('Auth_authenticationFail'),
            status => 401
          );
        };

        # Wait for async result
        $c->render_later;

        $c->auth->client_list_p->then(
          sub {
            $c->stash('client_list' => shift);
          }
        )->catch(
          sub {
            return;
          }
        )->finally(
          sub {
            return $c->render(template => 'auth/clients')
          }
        );
      }
    )->name('oauth-settings');

    # Route to oauth client registration
    $r->post('/settings/oauth/register')->to(
      cb => sub {
        my $c = shift;

        _set_no_cache($c->res->headers);

        my $v = $c->validation;

        unless ($c->auth->token) {
          return $c->render(
            content => 'Unauthorized',
            status => 401
          );
        };

        $v->csrf_protect;
        $v->required('name', 'trim', 'not_empty')->size(3, 255);
        $v->required('type')->in('PUBLIC', 'CONFIDENTIAL');
        $v->required('desc', 'trim', 'not_empty')->size(3, 255);
        $v->optional('url', 'trim', 'not_empty')->like(qr/^(http|$)/i);
        $v->optional('redirect_uri', 'trim', 'not_empty')->like(qr/^(http|$)/i);
        $v->optional('src', 'not_empty');

        $c->stash(template => 'auth/clients');

        # Render with error
        if ($v->has_error) {
          if ($v->has_error('csrf_token')) {
            $c->notify(error => $c->loc('Auth_csrfFail'));
          }
          else {
            $c->notify(error => $c->loc('Auth_paramError'));
          };
          return $c->render;
        } elsif ($c->req->is_limit_exceeded) {
          $c->notify(error => $c->loc('Auth_fileSizeExceeded'));
          return $c->render;
        };

        my $type = $v->param('type');
        my $src = $v->param('src');
        my $src_json;

        my $json_obj = {
          name         => $v->param('name'),
          type         => $type,
          description  => $v->param('desc'),
          url          => $v->param('url'),
          redirect_uri => $v->param('redirect_uri')
        };

        # Check plugin source
        if ($src) {

          # Source need to be a file upload
          if (!ref $src || !$src->isa('Mojo::Upload')) {
            $c->notify(error => $c->loc('Auth_jsonRequired'));
            return $c->render;
          };

          # Uploads can't be too large
          if ($src->size > 1_000_000) {
            $c->notify(error => $c->loc('Auth_fileSizeExceeded'));
            return $c->render;
          };

          # Check upload is not empty
          if ($src->size > 0 && $src->filename ne '') {

            # Plugins need to be confidential
            if ($type ne 'CONFIDENTIAL') {
              $c->notify(error => $c->loc('Auth_confidentialRequired'));
              return $c->render;
            }

            my $asset = $src->asset;

            # Check for json
            eval {
              $src_json = decode_json($asset->slurp);
            };

            if ($@ || !ref $src_json || ref $src_json ne 'HASH') {
              $c->notify(error => $c->loc('Auth_jsonRequired'));
              return $c->render;
            };

            $json_obj->{source} = $src_json;
          };
        };

        # Wait for async result
        $c->render_later;

        # Register on server
        state $url = Mojo::URL->new($c->korap->api)->path('oauth2/client/register');
        $c->korap_request('POST', $url => {} => json => $json_obj)->then(
          sub {
            my $tx = shift;
            my $result = $tx->result;

            if ($result->is_error) {
              my $json = $result->json;
              if ($json && $json->{error}) {
                $c->notify(
                  error => $json->{error} .
                    ($json->{error_description} ? ': ' . $json->{error_description} : '')
                  )
              };

              return Mojo::Promise->reject;
            };

            my $json = $result->json;

            my $client_id = $json->{client_id};
            my $client_secret = $json->{client_secret};

            $c->stash('client_name' => $v->param('name'));
            $c->stash('client_desc' => $v->param('desc'));
            $c->stash('client_type' => $v->param('type'));
            $c->stash('client_url'  => $v->param('url'));
            $c->stash('client_src'  => $v->param('source'));
            $c->stash('client_redirect_uri' => $v->param('redirect_uri'));
            $c->stash('client_id' => $client_id);

            if ($client_secret) {
              $c->stash('client_secret' => $client_secret);
            };

            $c->notify(success => $c->loc('Auth_en_registerSuccess'));

            return $c->render(template => 'auth/client');
          }
        )->catch(
          sub {
            $c->notify('error' => $c->loc('Auth_en_registerFail'));
          }
        )->finally(
          sub {
            return $c->redirect_to('settings' => { scope => 'oauth' });
          }
        );
      }
    )->name('oauth-register');


    # Unregister client page
    $r->get('/settings/oauth/:client_id/unregister')->to(
      cb => sub {
        my $c = shift;
        _set_no_cache($c->res->headers);
        $c->render(template => 'auth/unregister');
      }
    )->name('oauth-unregister');


    # Unregister client
    $r->post('/settings/oauth/:client_id/unregister')->to(
      cb => sub {
        my $c = shift;
        _set_no_cache($c->res->headers);

        my $v = $c->validation;

        unless ($c->auth->token) {
          return $c->render(
            content => 'Unauthorized',
            status => 401
          );
        };

        $v->csrf_protect;
        $v->required('client-name', 'trim')->size(3, 255);

        # Render with error
        if ($v->has_error) {
          if ($v->has_error('csrf_token')) {
            $c->notify(error => $c->loc('Auth_csrfFail'));
          }
          else {
            $c->notify(error => $c->loc('Auth_paramError'));
          };
          return $c->redirect_to('oauth-settings');
        };

        my $client_id =     $c->stash('client_id');
        my $client_name =   $v->param('client-name');
        my $client_secret = $v->param('client-secret');

        # Get list of registered clients
        my $r_url = Mojo::URL->new($c->korap->api)->path('oauth2/client/deregister/')->path(
          $client_id
        );

        my $send = {};

        if ($client_secret) {
          $send->{client_secret} = $client_secret;
        };

        # Get the list of all clients
        return $c->korap_request(delete => $r_url, {} => form => $send)->then(
          sub {
            my $tx = shift;

            # Response is fine
            if ($tx->res->is_success) {
              # Okay
              $c->notify(success => 'Successfully deleted ' . $client_name);
            }
            else {

              # Failure
              my $json = $tx->result->json;
              if ($json && $json->{error_description}) {
                $c->notify(error => $json->{error_description});
              } else {
                $c->notify(error => $c->loc('Auth_responseError'));
              };
            };

            return $c->redirect_to('oauth-settings');
          }
        );
      }
    )->name('oauth-unregister-post');


    # OAuth Client authorization
    $r->get('/settings/oauth/authorize')->to(
      cb => sub {
        my $c = shift;

        _set_no_cache($c->res->headers);

        my $v = $c->validation;
        $v->required('client_id', 'trim');
        $v->required('scope', 'trim');
        $v->optional('state', 'trim');
        $v->optional('redirect_uri', 'trim', 'not_empty')->like(qr/^(http|$)/i);

        # Redirect with error
        if ($v->has_error) {

          if ($v->has_error('client_id')) {
            $c->notify(error => $c->loc('Auth_clientIDFail'));
          }
          elsif ($v->has_error('scope')) {
            $c->notify(error => $c->loc('Auth_scopeFail'));
          }
          else {
            $c->notify(error => $c->loc('Auth_paramError'));
          };

          # If logged in, go to oauth settings - otherwise to index
          return $c->redirect_to($c->auth->token ? 'oauth-settings' : 'index');
        };

        foreach (qw!scope client_id state redirect_uri!) {
          $c->stash($_, $v->param($_));
        };

        # Wait for async result
        $c->render_later;

        my $client_id = $v->param('client_id');

        my $client_information = $c->auth->client_info_p($client_id)->then(
          sub {
            my $cl = shift;
            $c->stash(client_name => $cl->{'client_name'});
            $c->stash(client_type => $cl->{'client_type'});
            $c->stash(client_desc => $cl->{'client_description'});
            $c->stash(client_url => $cl->{'client_url'});
            $c->stash(redirect_uri_server => $cl->{'client_redirect_uri'});
          }
        )->then(
          sub {

            # Check, if the client redirect_uri is valid
            my $redirect_uri_server = $c->stash('redirect_uri_server');
            my $redirect_uri = $v->param('redirect_uri');
            my ($server_o, $client_o);

            # Both exist
            if ($redirect_uri_server && $redirect_uri) {
              $server_o = Mojo::URL->new($redirect_uri_server);
              $client_o = Mojo::URL->new($redirect_uri);

              # Host not valid - take registered URI
              if ($server_o->host ne $client_o->host) {
                $c->notify(warn => 'redirect_uri host differs from registered host');
                $client_o = $server_o;
              }

              # Port not valid - take registered URI
              elsif (($server_o->port // '') ne ($client_o->port // '')) {
                $c->notify(warn => 'redirect_uri port differs from registered port');
                $client_o = $server_o;
              };
            }

            # Client sent exists
            elsif ($redirect_uri) {
              $client_o = Mojo::URL->new($redirect_uri);
              $c->stash(redirect_warning => $c->loc('oauthGrantRedirectWarn'))
            }

            # Server registered exists
            elsif ($redirect_uri_server) {
              $client_o = Mojo::URL->new($redirect_uri_server);
            }

            # Redirect unknown
            else {
              $c->notify(error => 'redirect_uri not set');

              # If logged in, go to oauth settings - otherwise to index
              return $c->redirect_to($c->auth->token ? 'oauth-settings' : 'index');
            };

            # No userinfo allowed
            if ($client_o->userinfo) {
              $c->notify(warn => 'redirect_uri contains userinfo');
              $client_o->userinfo('');
            };

            # HTTPS warning
            # if ($client_o->scheme ne 'https') {
            #   $c->notify(warn => 'redirect_uri is not HTTPS');
            # };

            # Sign redirection URL
            $c->stash(redirect_uri => $client_o->to_string);
            $c->stash(close_redirect_uri => '' . $c->close_redirect_to($client_o));

            # Get auth token
            my $auth_token = $c->auth->token;

            # User is not logged in - log in before!
            unless ($auth_token) {
              return $c->render(template => 'auth/login');
            };

            # Grant authorization
            return $c->render(template => 'auth/grant_scope');
          }
        )->catch(
          sub {
            my $error = shift;
            $c->notify(error => $error);

            # If logged in, go to oauth settings - otherwise to index
            return $c->redirect_to($c->auth->token ? 'oauth-settings' : 'index');
          }
        );
      }
    )->name('oauth-grant-scope');


    # OAuth Client authorization
    # This will return a location information including some info
    $r->post('/settings/oauth/authorize')->to(
      cb => sub {
        my $c = shift;

        _set_no_cache($c->res->headers);

        # It's necessary that it's clear this was triggered by
        # KorAP and not by the client!
        my $v = $c->validation;
        $v->csrf_protect;
        $v->required('client_id', 'trim');
        $v->required('scope', 'trim');
        $v->optional('state', 'trim');

        # Only signed redirects are allowed
        $v->required('redirect_uri', 'trim', 'not_empty')->closed_redirect;

        # Render with error
        if ($v->has_error) {

          # If logged in, go to oauth settings - otherwise to index
          my $url = $c->url_for($c->auth->token ? 'oauth-settings' : 'index');

          if ($v->has_error('client_id')) {
            $url->query([error_description => $c->loc('Auth_clientIDFail')]);
          }
          elsif ($v->has_error('scope')) {
            $url->query([error_description => $c->loc('Auth_scopeFail')]);
          }
          elsif ($v->has_error('csrf_token')) {
            $url->query([error_description => $c->loc('Auth_csrfFail')]);
          }
          else {
            $url->query([error_description => $c->loc('Auth_paramError')]);
          };

          return $c->redirect_to($url);
        };

        state $r_url = Mojo::URL->new($c->korap->api)->path('oauth2/authorize');
        $c->stash(redirect_uri => Mojo::URL->new($v->param('redirect_uri')));

        my $ua = Mojo::UserAgent->new(
          connect_timeout => 30,
          inactivity_timeout => 30,
          max_redirects => 0
        );

        $ua->server->app($app);

        return $c->korap_request($ua, post => $r_url, { } => form => {
          response_type => 'code',
          client_id => $v->param('client_id'),
          redirect_uri => $c->stash('redirect_uri'),
          state => $v->param('state'),
          scope => $v->param('scope'),
        })->then(
          sub {
            my $tx = shift;

            unless (ref($tx)) {
              return Mojo::Promise->reject('Something went wrong');
            };

            # Check for location header with code in redirects
            my $loc;

            # Look for code in location URL
            if ($loc = $tx->res->headers->header('Location')) {
              my $url = Mojo::URL->new($loc);

              if ($url->query->param('code')) {
                return Mojo::Promise->resolve($loc);
              } elsif (my $err = $url->query->param('error_description')) {
                return Mojo::Promise->reject($err);
              }
            };

            # Check for location header with code in redirects
            # This should be dead code tbh
            foreach (@{$tx->redirects}) {
              $loc = $_->res->headers->header('Location');

              my $url = Mojo::URL->new($loc);

              if ($url->query->param('code')) {
                last;
              } elsif (my $err = $url->query->param('error_description')) {
                return Mojo::Promise->reject($err);
              }
            };

            return Mojo::Promise->resolve($loc) if $loc;

            # Failed redirect, but location set
            if ($tx->res->headers->location) {
              my $url = Mojo::URL->new($tx->res->headers->location);
              if (my $err = $url->query->param('error_description'))  {
                return Mojo::Promise->reject($err);
              };
            }

            $c->stash(redirect_uri => undef);

            # Maybe json
            my $json = $tx->res->json;
            if ($json && $json->{error_description}) {
              return Mojo::Promise->reject($json->{error_description});
            };

            # No location code
            return Mojo::Promise->reject('no location response');
          }
        )->catch(
          sub {
            my $err_msg = shift;
            my $url = $c->stash('redirect_uri');

            # Redirect!
            if ($url) {
              if ($err_msg) {
                $url = $url->query([error_description => $err_msg]);
              };
            }

            # Do not redirect!
            else {
              $c->notify(error => $err_msg);

              # If logged in, go to oauth settings - otherwise to index
              $url = $c->url_for($c->auth->token ? 'oauth-settings' : 'index');
            };

            return Mojo::Promise->resolve($url);
          }
        )->then(
          sub {
            my $loc = shift;
            return $c->redirect_to($loc);
          }
        )->wait;
        return $c->rendered;
      }
    )->name('oauth-grant-scope-post');


    # Show information of a client
    $r->get('/settings/oauth/:client_id')->to(
      cb => sub {
        my $c = shift;

        _set_no_cache($c->res->headers);

        $c->render_later;

        $c->auth->client_list_p->then(
          sub {
            my $json = shift;

            my ($item) = grep {
              $c->stash('client_id') eq $_->{client_id}
            } @$json;

            unless ($item) {
              return Mojo::Promise->reject;
            };

            $c->stash(client_name => $item->{client_name});
            $c->stash(client_desc => $item->{client_description});
            $c->stash(client_url  => $item->{client_url});
            $c->stash(client_type => ($item->{client_type} // 'PUBLIC'));
            $c->stash(client_redirect_uri => $item->{client_redirect_uri});
            $c->stash(client_src  => encode_json($item->{source})) if $item->{source};

            $c->auth->token_list_p($c->stash('client_id'));
          }
        )->then(
          sub {
            my $json = shift;

            $c->stash(tokens => $json);

            return Mojo::Promise->resolve;
          }
        )->catch(
          sub {
            return $c->reply->not_found;
          }
        )->finally(
          sub {
            return $c->render(template => 'auth/client')
          }
        );

        return;
      }
    )->name('oauth-tokens');
  };


  # Ask if new token should be issued
  $r->get('/settings/oauth/:client_id/token')->to(
    cb => sub {
      my $c = shift;
      _set_no_cache($c->res->headers);
      $c->render(template => 'auth/issue-token');
    }
  )->name('oauth-issue-token');


  # Ask if a token should be revoked
  $r->post('/settings/oauth/:client_id/token/revoke')->to(
    cb => sub {
      shift->render(template => 'auth/revoke-token');
    }
  )->name('oauth-revoke-token');


  # Issue new token
  $r->post('/settings/oauth/:client_id/token')->to(
    cb => sub {
      my $c = shift;
      _set_no_cache($c->res->headers);

      my $v = $c->validation;

      unless ($c->auth->token) {
        return $c->render(
          content => 'Unauthorized',
          status => 401
        );
      };

      $v->csrf_protect;
      $v->optional('client-secret');
      $v->required('name', 'trim');

      # Render with error
      if ($v->has_error) {
        if ($v->has_error('csrf_token')) {
          $c->notify(error => $c->loc('Auth_csrfFail'));
        }
        else {
          $c->notify(error => $c->loc('Auth_paramError'));
        };
        return $c->redirect_to('oauth-settings')
      };

      # Get authorization token
      state $r_url = Mojo::URL->new($c->korap->api)->path('oauth2/authorize');
      my $client_id = $c->stash('client_id');
      my $name = $v->param('name');
      my $redirect_url = $c->url_for->query({name => $name});

      return $c->korap_request(post => $r_url, {} => form => {
        response_type => 'code',
        client_id => $client_id,
        redirect_uri => $redirect_url,
        # TODO: State
      })->then(
        sub {
          my $tx = shift;

          # Strip the token from the location header of the fake redirect
          # TODO: Alternatively redirect!
          my ($code, $scope, $loc, $name);
          foreach (@{$tx->redirects}) {
            $loc = $_->res->headers->header('Location');
            if (index($loc, 'code') > 0) {
              my $q = Mojo::URL->new($loc)->query;
              $code  = $q->param('code');
              $scope = $q->param('scope');
              $name  = $q->param('name');
              last;
            };
          };

          # Fine!
          if ($code) {
            return Mojo::Promise->resolve(
              $client_id,
              $redirect_url,
              $code,
              $scope,
              $name
            );
          };
          return Mojo::Promise->reject;
        }
      )->then(
        sub {
          my ($client_id, $redirect_url, $code, $scope, $name) = @_;

          # Get OAuth access token
          state $r_url = Mojo::URL->new($c->korap->api)->path('oauth2/token');
          return $c->kalamar_ua->post_p($r_url, {} => form => {
            client_id => $client_id,
            # NO CLIENT_SECRET YET SUPPORTED
            grant_type => 'authorization_code',
            code => $code,
            redirect_uri => $redirect_url
          })->then(
            sub {
              my $tx = shift;
              my $json = $tx->res->json;

              if ($tx->res->is_error) {
                $c->notify(error => 'Unable to fetch new token');
                return Mojo::Promise->reject;
              };

              $c->notify(success => 'New access token created');

              $c->redirect_to('oauth-tokens' => { client_id => $client_id })
            }
          )->catch(
            sub {
              my $err_msg = shift;

              # Only raised in case of connection errors
              if ($err_msg) {
                $c->notify(error => { src => 'Backend' } => $err_msg)
              };

              $c->render(
                status => 400,
                template => 'failure'
              );
            }
          )

          # Start IOLoop
          ->wait;

        }
      )->catch(
        sub {
          my $err_msg = shift;

          # Only raised in case of connection errors
          if ($err_msg) {
            $c->notify(error => { src => 'Backend' } => $err_msg)
          };

          return $c->render(
            status => 400,
            template => 'failure'
          );
        }
      )

      # Start IOLoop
      ->wait;

      return 1;
    }
  )->name('oauth-issue-token-post');


  # Revoke token
  $r->delete('/settings/oauth/:client_id/token')->to(
    cb => sub {
      my $c = shift;

      my $v = $c->validation;

      unless ($c->auth->token) {
        return $c->render(
          content => 'Unauthorized',
          status => 401
        );
      };

      $v->csrf_protect;
      $v->required('token', 'trim');
      $v->optional('name', 'trim');
      my $private_client_id = $c->stash('client_id');

      # Render with error
      if ($v->has_error) {
        if ($v->has_error('csrf_token')) {
          $c->notify(error => $c->loc('Auth_csrfFail'));
        }
        else {
          $c->notify(error => $c->loc('Auth_paramError'));
        };
        return $c->redirect_to('oauth-tokens', client_id => $private_client_id);
      };

      # Revoke token using super client privileges
      state $r_url = Mojo::URL->new($c->korap->api)->path('oauth2/revoke/super');

      my $token = $v->param('token');

      return $c->korap_request(post => $r_url, {} => form => {
        super_client_id => $client_id,
        super_client_secret => $client_secret,
        token => $token
      })->then(
        sub {
          my $tx = shift;

          # Response is fine
          if ($tx->res->is_success) {
            $c->notify(success => $c->loc('Auth_revokeSuccess'));
            return Mojo::Promise->resolve;
          };

          return Mojo::Promise->reject;
        }
      )->catch(
        sub {
          my $err_msg = shift;
          if ($err_msg) {
            $c->notify(error => { src => 'Backend' } => $err_msg );
          }
          else {
            $c->notify(error => $c->loc('Auth_revokeFail'));
          };
        }
      )->finally(
        sub {
          return $c->redirect_to('oauth-tokens', client_id => $private_client_id);
        }
      )

      # Start IOLoop
      ->wait;
    }
  )->name('oauth-revoke-token-delete');

  $app->log->info('Successfully registered Auth plugin');
};


# Set 'no caching' headers
sub _set_no_cache {
  my $h = shift;
  $h->cache_control('max-age=0, no-cache, no-store, must-revalidate');
  $h->expires('Thu, 01 Jan 1970 00:00:00 GMT');
  $h->header('Pragma','no-cache');
};


sub check_decode {
  no warnings 'uninitialized';
  my $str = shift;
  my $str2 = is_utf8($str) ? b($str)->decode : $str;
  if (defined($str2) && $str2 && length($str2) > 1) {
    return $str2
  };
  return;
};


1;


__END__

=pod

=encoding utf8

=head1 NAME

Kalamar::Plugin::Auth - OAuth-2.0-based authorization plugin

=head1 DESCRIPTION

L<Kalamar::Plugin::Auth> is an OAuth-2.0-based authorization
plugin for L<Kalamar>. It requires a C<Kustvakt> full server
with OAuth 2.0 capabilities.
It is activated by loading C<Auth> as a plugin in the C<Kalamar.plugins>
parameter in the Kalamar configuration.

=head1 CONFIGURATION

L<Kalamar::Plugin::Auth> supports the following parameter for the
C<Kalamar-Auth> configuration section in the Kalamar configuration:

=over 2

=item B<client_id>

The client identifier of Kalamar to be send with every OAuth 2.0
management request.

=item B<client_secret>

The client secret of Kalamar to be send with every OAuth 2.0
management request.

=item B<experimental_client_registration>

Activates the oauth client registration flow.

=back

=head2 COPYRIGHT AND LICENSE

Copyright (C) 2015-2022, L<IDS Mannheim|http://www.ids-mannheim.de/>
Author: L<Nils Diewald|http://nils-diewald.de/>

Kalamar is developed as part of the L<KorAP|http://korap.ids-mannheim.de/>
Corpus Analysis Platform at the
L<Leibniz Institute for the German Language (IDS)|http://ids-mannheim.de/>,
member of the
L<Leibniz-Gemeinschaft|http://www.leibniz-gemeinschaft.de>
and supported by the L<KobRA|http://www.kobra.tu-dortmund.de> project,
funded by the
L<Federal Ministry of Education and Research (BMBF)|http://www.bmbf.de/en/>.

Kalamar is free software published under the
L<BSD-2 License|https://raw.githubusercontent.com/KorAP/Kalamar/master/LICENSE>.

=cut