Split availability windows into bookable lesson-length slots with weekly calendar views

Availability windows were stored and served as a single bookable row, so a
9:00 AM-4:00 PM window showed to students as one giant slot and booking it
consumed the whole day; past and multi-day windows also leaked into the
booking page as nonsense entries.

- Split windows into consecutive lesson-length slots on save (REST and admin
  form); each chunk is independently bookable and weekly recurrence creates a
  series per chunk so "reserve this time weekly" holds the same hour each week
- Reject windows spanning multiple days or shorter than the lesson length
  (400 invalid_window)
- Never return slots whose start has passed from GET /availability
- Migrate pre-split rows: Plugin::boot re-runs the Installer on version change
  and AvailabilityRepository::splitOversizedWindows() rewrites unbooked
  same-day oversized windows in place
- Display all times in 12-hour AM/PM form (booking page, wp-admin lists,
  editor previews)
- Add a List | Week view toggle to the student booking page and the
  instructor availability page, with previous/next-week navigation honouring
  the site's start_of_week option (new WeekCalendar helper)

Co-Authored-By: Claude Fable 5 <[email protected]>

templates/admin/availability.php

@@ -8,12 +8,33 @@ if (! defined('ABSPATH')) {
 /**
  * @var list<\Unsupervised\Schedular\Availability\AvailabilitySlot> $slots
  * @var list<\Unsupervised\Schedular\Offering\Offering>             $offeringChoices
+ * @var 'list'|'week' $view
+ * @var string $weekStart
+ * @var list<array{date: string, slots: list<\Unsupervised\Schedular\Availability\AvailabilitySlot>}> $weekDays
+ * @var string $prevWeek
+ * @var string $nextWeek
  */
+
+$baseUrl = admin_url('admin.php?page=us-availability');
+
+$deleteForm = static function (\Unsupervised\Schedular\Availability\AvailabilitySlot $slot): void {
+    ?>
+    <form method="post" style="display:inline;">
+        <?php wp_nonce_field('usc_availability_action'); ?>
+        <input type="hidden" name="usc_action" value="delete">
+        <input type="hidden" name="slot_id" value="<?php echo esc_attr((string) $slot->id); ?>">
+        <button type="submit" class="button button-small button-link-delete">
+            <?php esc_html_e('Delete', 'unsupervised-schedular'); ?>
+        </button>
+    </form>
+    <?php
+};
 ?>
 <div class="wrap">
     <h1><?php esc_html_e('My Availability', 'unsupervised-schedular'); ?></h1>
 
-    <h2><?php esc_html_e('Add Slot', 'unsupervised-schedular'); ?></h2>
+    <h2><?php esc_html_e('Add Availability', 'unsupervised-schedular'); ?></h2>
+    <p><?php esc_html_e('The window must start and end on the same day. It is split into bookable slots of the chosen lesson length — for example, 9:00 AM–4:00 PM with 60-minute lessons creates seven slots.', 'unsupervised-schedular'); ?></p>
     <form method="post">
         <?php wp_nonce_field('usc_availability_action'); ?>
         <input type="hidden" name="usc_action" value="add">
@@ -56,12 +77,63 @@ if (! defined('ABSPATH')) {
                 </td>
             </tr>
         </table>
-        <?php submit_button(esc_html__('Add Slot', 'unsupervised-schedular')); ?>
+        <?php submit_button(esc_html__('Add Availability', 'unsupervised-schedular')); ?>
     </form>
 
     <h2><?php esc_html_e('Current Slots', 'unsupervised-schedular'); ?></h2>
 
-    <?php if (empty($slots)) : ?>
+    <ul class="subsubsub" style="margin-bottom:12px;">
+        <li>
+            <a href="<?php echo esc_url($baseUrl); ?>" <?php echo 'list' === $view ? 'class="current"' : ''; ?>><?php esc_html_e('List', 'unsupervised-schedular'); ?></a> |
+        </li>
+        <li>
+            <a href="<?php echo esc_url(add_query_arg('usc_view', 'week', $baseUrl)); ?>" <?php echo 'week' === $view ? 'class="current"' : ''; ?>><?php esc_html_e('Week', 'unsupervised-schedular'); ?></a>
+        </li>
+    </ul>
+    <div class="clear"></div>
+
+    <?php if ('week' === $view) : ?>
+        <p>
+            <a class="button" href="<?php echo esc_url(add_query_arg(['usc_view' => 'week', 'usc_week' => $prevWeek], $baseUrl)); ?>">&lsaquo; <?php esc_html_e('Previous week', 'unsupervised-schedular'); ?></a>
+            <strong style="margin:0 12px;">
+                <?php
+                /* translators: %s: date of the first day of the displayed week */
+                echo esc_html(sprintf(__('Week of %s', 'unsupervised-schedular'), (string) mysql2date('M j, Y', $weekStart)));
+                ?>
+            </strong>
+            <a class="button" href="<?php echo esc_url(add_query_arg(['usc_view' => 'week', 'usc_week' => $nextWeek], $baseUrl)); ?>"><?php esc_html_e('Next week', 'unsupervised-schedular'); ?> &rsaquo;</a>
+        </p>
+        <table class="wp-list-table widefat fixed">
+            <thead>
+                <tr>
+                    <?php foreach ($weekDays as $day) : ?>
+                        <th><?php echo esc_html((string) mysql2date('D M j', $day['date'])); ?></th>
+                    <?php endforeach; ?>
+                </tr>
+            </thead>
+            <tbody>
+                <tr>
+                    <?php foreach ($weekDays as $day) : ?>
+                        <td style="vertical-align:top;">
+                            <?php if (empty($day['slots'])) : ?>
+                                <span aria-hidden="true">—</span>
+                            <?php endif; ?>
+                            <?php foreach ($day['slots'] as $slot) : ?>
+                                <p style="margin:0 0 8px;">
+                                    <?php echo esc_html((string) mysql2date('g:i A', $slot->startDt) . '–' . (string) mysql2date('g:i A', $slot->endDt)); ?><br>
+                                    <?php if ($slot->isBooked) : ?>
+                                        <em><?php esc_html_e('Booked', 'unsupervised-schedular'); ?></em>
+                                    <?php else : ?>
+                                        <?php $deleteForm($slot); ?>
+                                    <?php endif; ?>
+                                </p>
+                            <?php endforeach; ?>
+                        </td>
+                    <?php endforeach; ?>
+                </tr>
+            </tbody>
+        </table>
+    <?php elseif (empty($slots)) : ?>
         <p><?php esc_html_e('No availability slots configured.', 'unsupervised-schedular'); ?></p>
     <?php else : ?>
         <table class="wp-list-table widefat fixed striped">
@@ -77,20 +149,13 @@ if (! defined('ABSPATH')) {
             <tbody>
                 <?php foreach ($slots as $slot) : ?>
                     <tr>
-                        <td><?php echo esc_html($slot->startDt); ?></td>
-                        <td><?php echo esc_html($slot->endDt); ?></td>
+                        <td><?php echo esc_html((string) mysql2date('M j, Y g:i A', $slot->startDt)); ?></td>
+                        <td><?php echo esc_html((string) mysql2date('M j, Y g:i A', $slot->endDt)); ?></td>
                         <td><?php echo esc_html((string) $slot->durationMinutes . ' min'); ?></td>
                         <td><?php echo $slot->isBooked ? esc_html__('Booked', 'unsupervised-schedular') : esc_html__('Available', 'unsupervised-schedular'); ?></td>
                         <td>
                             <?php if (! $slot->isBooked) : ?>
-                                <form method="post" style="display:inline;">
-                                    <?php wp_nonce_field('usc_availability_action'); ?>
-                                    <input type="hidden" name="usc_action" value="delete">
-                                    <input type="hidden" name="slot_id" value="<?php echo esc_attr((string) $slot->id); ?>">
-                                    <button type="submit" class="button button-small button-link-delete">
-                                        <?php esc_html_e('Delete', 'unsupervised-schedular'); ?>
-                                    </button>
-                                </form>
+                                <?php $deleteForm($slot); ?>
                             <?php endif; ?>
                         </td>
                     </tr>