Improve account validation and feedback

app/Views/auth/register.php

@@ -1,16 +1,63 @@
+<?php
+
+$values = $values ?? ['name' => '', 'email' => ''];
+$errors = $errors ?? [];
+?>
+
 <section class="auth-panel">
     <h1>Registrieren</h1>
+    <?php if (!empty($errors['form'])): ?>
+        <p class="field-error" role="alert"><?= e($errors['form']) ?></p>
+    <?php endif; ?>
     <form method="post" action="index.php?route=register" class="form">
         <?= csrf_field() ?>
         <label for="name">Name</label>
-        <input id="name" name="name" type="text" autocomplete="name" required>
+        <input
+            id="name"
+            name="name"
+            type="text"
+            maxlength="100"
+            autocomplete="name"
+            value="<?= e($values['name'] ?? '') ?>"
+            class="<?= !empty($errors['name']) ? 'input-error' : '' ?>"
+            <?= !empty($errors['name']) ? 'aria-invalid="true" aria-describedby="name-error"' : '' ?>
+            required
+        >
+        <?php if (!empty($errors['name'])): ?>
+            <small id="name-error" class="field-error"><?= e($errors['name']) ?></small>
+        <?php endif; ?>
 
         <label for="email">E-Mail</label>
-        <input id="email" name="email" type="email" autocomplete="email" required>
+        <input
+            id="email"
+            name="email"
+            type="email"
+            maxlength="190"
+            autocomplete="email"
+            value="<?= e($values['email'] ?? '') ?>"
+            class="<?= !empty($errors['email']) ? 'input-error' : '' ?>"
+            <?= !empty($errors['email']) ? 'aria-invalid="true" aria-describedby="email-error"' : '' ?>
+            required
+        >
+        <?php if (!empty($errors['email'])): ?>
+            <small id="email-error" class="field-error"><?= e($errors['email']) ?></small>
+        <?php endif; ?>
 
         <label for="password">Passwort</label>
-        <input id="password" name="password" type="password" minlength="8" autocomplete="new-password" required>
-        <small>Mindestens 8 Zeichen.</small>
+        <input
+            id="password"
+            name="password"
+            type="password"
+            minlength="8"
+            autocomplete="new-password"
+            class="<?= !empty($errors['password']) ? 'input-error' : '' ?>"
+            <?= !empty($errors['password']) ? 'aria-invalid="true" aria-describedby="password-error password-help"' : 'aria-describedby="password-help"' ?>
+            required
+        >
+        <small id="password-help">Mindestens 8 Zeichen.</small>
+        <?php if (!empty($errors['password'])): ?>
+            <small id="password-error" class="field-error"><?= e($errors['password']) ?></small>
+        <?php endif; ?>
 
         <button type="submit">Konto erstellen</button>
     </form>