fetch writeable calendars of user and display a dropdown in confirm dialog with list of calendars to choose for the event

templates/confirm.php

@@ -100,6 +100,24 @@ $h = static function (string $value): string {
                 method="post"
                 action="<?= $h($_['createUrl']) ?>"
             >
+                <?php if ($_['calendars'] !== []): ?>
+                    <div class="atocal-row">
+                        <label for="atocal-calendar">
+                            <strong>Calendar</strong>
+                        </label>
+                        <select id="atocal-calendar" name="calendarId">
+                            <?php foreach ($_['calendars'] as $calendar): ?>
+                                <option
+                                    value="<?= $h($calendar['id']) ?>"
+                                    <?= $calendar['id'] === $_['calendarId'] ? 'selected' : '' ?>
+                                >
+                                    <?= $h($calendar['displayName']) ?>
+                                </option>
+                            <?php endforeach; ?>
+                        </select>
+                    </div>
+                <?php endif; ?>
+
                 <input
                     type="hidden"
                     name="requesttoken"