Subscribe to events from calendar applications

_define.php

@@ -47,6 +47,8 @@
         'event_bookings_export'     => 'groupmanager',
         'events_bookings_export'    => 'groupmanager',
         'events_calendar'           => 'member',
+        'events_feed_subscribe'     => 'member',
+        'events_feed_regenerate'    => 'member',
         'ajax-events_calendar'      => 'member'
     ],
     dbver: 1.2

_routes.php

@@ -174,6 +174,22 @@
     [EventsController::class, 'calendar']
 )->setName('events_calendar')->add(Authenticate::class);
 
+$app->post(
+    '/events/feed',
+    [EventsController::class, 'subscribe']
+)->setName('events_feed_subscribe')->add(Authenticate::class);
+
+$app->post(
+    '/events/feed/regenerate',
+    [EventsController::class, 'regenerateFeed']
+)->setName('events_feed_regenerate')->add(Authenticate::class);
+
+//calendar applications have no session: the secret token is the only credential
+$app->get(
+    '/events/feed/{token:' . GaletteEvents\Feeds::TOKEN_PATTERN . '}.ics',
+    [EventsController::class, 'feed']
+)->setName('events_feed');
+
 $app->get(
     '/ajax/events/calendar',
     [EventsController::class, 'ajaxCalendar']

js/calendar.js

@@ -61,4 +61,18 @@ $(function() {
   });
 
   calendar.render();
+
+  var $feed = $('#calendar_feed');
+  $('#calendar_subscribe').on('click', function() {
+    $feed.modal('show');
+  });
+  $('#feed_regenerate').on('submit', function(event) {
+    if (!window.confirm($(this).data('confirm'))) {
+      event.preventDefault();
+    }
+  });
+  //back from getting or changing the subscription address
+  if (options.show_subscription) {
+    $feed.modal('show');
+  }
 });

lib/GaletteEvents/Booking.php

@@ -635,7 +635,7 @@ private function canBook(Event $event): bool
             return true;
         }
 
-        return $event->isOpen() && Events::isVisible($event->getGroup(), $this->login);
+        return $event->isOpen() && Events::isVisible($event->getGroup(), Viewer::fromLogin($this->login));
     }
 
     /**

lib/GaletteEvents/Controllers/Crud/EventsController.php

@@ -14,8 +14,11 @@
 use Galette\Repository\Groups;
 use Galette\Core\Pagination;
 use GaletteEvents\Filters\EventsList;
+use Galette\Entity\Adherent;
 use GaletteEvents\Event;
+use GaletteEvents\Feeds;
 use GaletteEvents\Ics;
+use GaletteEvents\Viewer;
 use GaletteEvents\NotFoundException;
 use GaletteEvents\Repository\Events;
 use Slim\Psr7\Request;
@@ -37,6 +40,9 @@
 
 class EventsController extends AbstractController
 {
+    /** Ended events kept in calendar subscriptions */
+    public const int FEED_PAST_MONTHS = 12;
+
     /**
      * Entity name, for session keys and logs
      */
@@ -139,19 +145,128 @@ public function calendar(
             );
         }
 
+        //calendar subscription, for members only
+        $viewer = Viewer::fromLogin($this->login);
+        $token = $viewer->id === null ? null : (new Feeds($this->zdb))->getToken($viewer->id);
+
         // display page
         $this->view->render(
             $response,
             $this->getTemplate('calendar'),
             [
                 'page_title'            => _T("Events calendar", "events"),
                 'require_dialog'        => true,
-                'module_id'             => $this->getModuleId()
+                'module_id'             => $this->getModuleId(),
+                'can_subscribe'         => $viewer->id !== null,
+                'feed_urls'             => $token === null ? null : $this->getFeedUrls($token),
+                'show_subscription'     => isset($request->getQueryParams()['subscription']),
             ]
         );
         return $response;
     }
 
+    /**
+     * Subscription URLs of a calendar
+     *
+     * @param string $token Subscription token
+     *
+     * @return array{https: string, webcal: string}
+     */
+    private function getFeedUrls(string $token): array
+    {
+        $url = rtrim($this->preferences->getURL(), '/')
+            . $this->routeparser->urlFor('events_feed', ['token' => $token]);
+        return [
+            'https'     => $url,
+            'webcal'    => (string)preg_replace('#^https?://#', 'webcal://', $url),
+        ];
+    }
+
+    /**
+     * Get, or create, the calendar subscription of logged-in member
+     */
+    public function subscribe(Request $request, Response $response): Response
+    {
+        return $this->storeFeedToken($response, false);
+    }
+
+    /**
+     * Change calendar subscription of logged-in member
+     */
+    public function regenerateFeed(Request $request, Response $response): Response
+    {
+        return $this->storeFeedToken($response, true);
+    }
+
+    /**
+     * Create or change calendar subscription token of logged-in member
+     *
+     * @param bool $regenerate Replace an existing token
+     */
+    private function storeFeedToken(Response $response, bool $regenerate): Response
+    {
+        $viewer = Viewer::fromLogin($this->login);
+        if ($viewer->id === null) {
+            //superadmin is not a member
+            return $this->redirectWithErrors(
+                response: $response,
+                errors: [_T("You do not have permission for requested URL.")],
+                redirect_url: $this->routeparser->urlFor('events_calendar')
+            );
+        }
+
+        $feeds = new Feeds($this->zdb);
+        $successes = [];
+        if ($regenerate) {
+            $feeds->regenerate($viewer->id);
+            $successes[] = _T(
+                'Your subscription address has been changed: calendar applications subscribed to the previous one no longer get updates.',
+                'events'
+            );
+        } else {
+            $feeds->getOrCreateToken($viewer->id);
+        }
+
+        return $this->redirect(
+            response: $response,
+            redirect_url: $this->routeparser->urlFor('events_calendar') . '?subscription',
+            successes: $successes
+        );
+    }
+
+    /**
+     * Calendar subscription, as fetched by calendar applications, without session
+     *
+     * Unknown tokens and inactive members get the same answer.
+     *
+     * @param string $token Subscription token
+     */
+    public function feed(Request $request, Response $response, string $token): Response
+    {
+        $id = (new Feeds($this->zdb))->getMember($token);
+        $member = $id === null ? null : new Adherent($this->zdb, $id);
+        if ($member === null || !$member->isActive()) {
+            return $response->withStatus(404);
+        }
+
+        //descriptions are in the member language
+        $this->i18n->changeLanguage($member->language);
+
+        $events = new Events($this->zdb, $this->login, $this->history, $this->preferences);
+        $list = $events->getFeed(
+            Viewer::fromMember($member),
+            (new \DateTimeImmutable('-' . self::FEED_PAST_MONTHS . ' months'))->format('Y-m-d')
+        );
+
+        $ics = new Ics($this->preferences, $this->routeparser);
+        $name = $this->preferences->pref_nom . ' – ' . _T('Events', 'events');
+        $response->getBody()->write($ics->getCalendar($list, $name)->serialize());
+        return $response
+            ->withHeader('Content-Type', Ics::CONTENT_TYPE)
+            ->withHeader('Content-Disposition', 'inline; filename="events.ics"')
+            ->withHeader('Cache-Control', 'private, no-cache');
+    }
+
     /**
      * Calendar view
      */

lib/GaletteEvents/Event.php

@@ -740,7 +740,7 @@ public function canEdit(Login $login): bool
      */
     public function canShow(Login $login): bool
     {
-        if (Events::isVisible($this->group, $login)) {
+        if (Events::isVisible($this->group, Viewer::fromLogin($login))) {
             return true;
         }
 

lib/GaletteEvents/Feeds.php

@@ -0,0 +1,104 @@
+<?php
+
+/**
+ * This file is part of Galette Events plugin (https://galette.eu).
+ * SPDX-FileCopyrightText: Copyright © 2018-2026 The Galette Team
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+declare(strict_types=1);
+
+namespace GaletteEvents;
+
+use Galette\Core\Db;
+use Galette\Entity\Adherent;
+
+/**
+ * Personal calendar subscriptions
+ *
+ * Each member may get a secret token, that gives read access to the events
+ * they can see, without session. Tokens are stored as is, so that members
+ * can display their subscription URL again; they are only created on demand.
+ *
+ * @author Johan Cwiklinski <johan@x-tnd.be>
+ */
+class Feeds
+{
+    public const string TABLE = 'feeds';
+    public const string TOKEN_PATTERN = '[0-9a-f]{64}';
+
+    /**
+     * Constructor
+     *
+     * @param Db $zdb Database instance
+     */
+    public function __construct(private readonly Db $zdb)
+    {
+    }
+
+    /**
+     * Get token of a member, if any
+     *
+     * @param int $member Member identifier
+     */
+    public function getToken(int $member): ?string
+    {
+        $select = $this->zdb->select(EVENTS_PREFIX . self::TABLE);
+        $select->where([Adherent::PK => $member]);
+        $row = $this->zdb->execute($select)->current();
+        return $row ? (string)$row['token'] : null;
+    }
+
+    /**
+     * Get token of a member, create it if missing
+     *
+     * @param int $member Member identifier
+     */
+    public function getOrCreateToken(int $member): string
+    {
+        return $this->getToken($member) ?? $this->regenerate($member);
+    }
+
+    /**
+     * Give a member a new token; the previous one, if any, no longer works
+     *
+     * @param int $member Member identifier
+     */
+    public function regenerate(int $member): string
+    {
+        $token = bin2hex(random_bytes(32));
+        $values = [
+            'token'         => $token,
+            'creation_date' => date('Y-m-d'),
+        ];
+
+        if ($this->getToken($member) === null) {
+            $insert = $this->zdb->insert(EVENTS_PREFIX . self::TABLE);
+            $insert->values($values + [Adherent::PK => $member]);
+            $this->zdb->execute($insert);
+        } else {
+            $update = $this->zdb->update(EVENTS_PREFIX . self::TABLE);
+            $update->set($values)->where([Adherent::PK => $member]);
+            $this->zdb->execute($update);
+        }
+
+        return $token;
+    }
+
+    /**
+     * Get member a token belongs to
+     *
+     * @param string $token Token
+     */
+    public function getMember(string $token): ?int
+    {
+        if (!preg_match('/^' . self::TOKEN_PATTERN . '$/', $token)) {
+            return null;
+        }
+
+        $select = $this->zdb->select(EVENTS_PREFIX . self::TABLE);
+        $select->where(['token' => $token]);
+        $row = $this->zdb->execute($select)->current();
+        return $row ? (int)$row[Adherent::PK] : null;
+    }
+}

lib/GaletteEvents/Ics.php

@@ -46,14 +46,22 @@ public function __construct(
      * Build calendar
      *
      * @param array<Event> $events Events to include
+     * @param ?string      $name   Name of a subscribed calendar, refreshed by calendar applications
      */
-    public function getCalendar(array $events): VCalendar
+    public function getCalendar(array $events, ?string $name = null): VCalendar
     {
         $calendar = new VCalendar([
             'PRODID'    => '-//Galette//Galette Events//EN',
             'CALSCALE'  => 'GREGORIAN',
             'METHOD'    => 'PUBLISH',
         ]);
+        if ($name !== null) {
+            //RFC 7986 properties, and their widely used predecessors
+            $calendar->add('NAME', $name);
+            $calendar->add('X-WR-CALNAME', $name);
+            $calendar->add('REFRESH-INTERVAL', 'PT1H', ['VALUE' => 'DURATION']);
+            $calendar->add('X-PUBLISHED-TTL', 'PT1H');
+        }
 
         $now = new DateTimeImmutable('now', new DateTimeZone('UTC'));
         $domain = $this->getUidDomain();