From 0fc0addf47a34b0a4e8c80a9c7ecd2a9d68cac94 Mon Sep 17 00:00:00 2001
From: Martin Slachta <martin.slachta@outlook.com>
Date: Sun, 14 Jun 2026 11:07:14 +0200
Subject: [PATCH] #6 - Output elements

---
 PLAN.md                                       | 181 ++++++++++++++++++
 .../Handlers/RsvOutputTextElementHandler.php  |  21 ++
 includes/Views/RsvFormsPage.php               |  18 +-
 reservair.php                                 |   1 +
 4 files changed, 220 insertions(+), 1 deletion(-)
 create mode 100644 PLAN.md
 create mode 100644 includes/Services/Forms/Handlers/RsvOutputTextElementHandler.php

diff --git a/PLAN.md b/PLAN.md
new file mode 100644
index 0000000..a8a83b7
--- /dev/null
+++ b/PLAN.md
@@ -0,0 +1,181 @@
+# Implementation Brief: Live form preview in the form editor
+
+## Goal
+Add a real-time form preview pane beside the elements editor on the form **edit** page. Reuse the existing PHP renderer (`RsvFormHtmlRenderer`) via a new admin REST endpoint — do **not** build a JS renderer.
+
+## Context you need (don't re-derive)
+- **Editor**: `includes/Views/RsvFormsPage.php`. `show_edit()` renders the edit page; `elements_table_script()` emits the inline `<script>` that drives the elements table. Elements live in an in-memory JS object `rsv_elements_source`; `rsv_elements_source.get_all()` returns the elements array (without internal `id`). Nothing is persisted until the form is saved (PUT).
+- **Renderer**: `includes/Services/Forms/RsvFormHtmlRenderer.php`. `draw(RsvFormDefinition $form): bool` **echoes** the real `<form>` HTML; returns `false` and echoes nothing when the form has no elements. This is the same renderer the frontend uses (`src/render.php`).
+- **Definition object**: `new RsvFormDefinition(string $id, array $definition)` where `$definition` has keys `elements` (array), `email_key`, `success_message`.
+- **Assets**: admin already enqueues the `rsv-client` bundle (`rsv_enqueue_admin_assets` in `includes/RsvAssetsDefinition.php`). It defines the custom elements (`<rsv-reservation-selector>`, `<rsv-reservation-summary>`) and bundles the form CSS (`RsvFormStyles.css` -> confirmed in `build/client.css`). **So form HTML injected via `innerHTML` into the admin page is styled and auto-upgrades its custom elements — no extra assets needed.**
+- `ReservairServiceAPI.nonce` and `ReservairServiceAPI.restUrl` are available globally in admin (localized onto `rsv-client`).
+- The registries `$rsv_form_registry` / `$rsv_template_registry` are populated on `plugins_loaded` (`rsv_bootstrap`), which runs for REST requests too.
+- REST errors are handled globally by the `rest_dispatch_request` filter in `includes/RsvRestApiDefinition.php` (any `Throwable` -> 500 JSON `{error}`), so the endpoint needs no try/catch.
+- `RsvColumnLayout::split('3:2')->column(fn)->column(fn)->output()` (`modules/Layout/RsvColumnLayout.php`) renders side-by-side columns; each callable just echoes. CSS for `.rsv-cols`/`.rsv-col` already exists (used on the list page).
+
+## The plan is JS-inline only — no webpack rebuild
+All new editor JS goes inside the existing inline `<script>` in `elements_table_script()`. Do **not** add CSS to `assets/css/*` (that would require a webpack rebuild); use inline `style=""`/a `<style>` block in the PHP if you want the sticky preview.
+
+---
+
+## Task 1 — Preview endpoint
+**File:** `includes/Controllers/RsvFormDefinitionController.php`
+
+In `register_routes()`, add a standalone route (the `\d+` id route won't match the non-numeric `preview`, so order is safe):
+
+```php
+register_rest_route($this->namespace, '/' . $this->resource_name . '/preview', [
+    'methods'             => 'POST',
+    'callback'            => [$this, 'preview'],
+    'permission_callback' => [RsvRestPolicy::class, 'admin'],
+]);
+```
+
+Add the method:
+
+```php
+/** Renders an unsaved definition to HTML for the editor's live preview. */
+function preview(WP_REST_Request $request): WP_REST_Response {
+    $definition = $request->get_json_params()['definition'] ?? [];
+    if (!is_array($definition)) {
+        $definition = [];
+    }
+
+    ob_start();
+    (new RsvFormHtmlRenderer())->draw(new RsvFormDefinition('preview', $definition));
+    $html = ob_get_clean();
+
+    return new WP_REST_Response(['html' => $html], 200);
+}
+```
+
+Notes: no-elements case -> `$html` is `''` (handled client-side). A malformed element payload would throw, but the global filter turns it into a 500 the client catch handles gracefully.
+
+---
+
+## Task 2 — Editor layout (two columns + preview pane)
+**File:** `includes/Views/RsvFormsPage.php`, `show_edit()`.
+
+Replace the current Form Elements block (the `<h2>Form Elements</h2>` heading, `#form_elements_table`, the add button, and the submit button — currently around lines 133–142) with a split layout. **Keep the existing IDs `form_elements_table` and `rsv_add_element_btn`.** `RsvColumnLayout` is already imported at the top of the file.
+
+```php
+        <hr>
+        <h2>Form Elements</h2>
+        <p>Define the fields that will appear in this form.</p>
+        <?php
+        RsvColumnLayout::split('3:2')
+            ->column(function (): void { ?>
+                <div id="form_elements_table"></div>
+                <p>
+                    <button type="button" class="button" id="rsv_add_element_btn">+ Add Element</button>
+                </p>
+                <p class="submit">
+                    <button type="submit" form="edit_form_definition" class="button button-primary">Update Form Definition</button>
+                </p>
+            <?php })
+            ->column(function (): void { ?>
+                <h3>Live preview</h3>
+                <div id="rsv_form_preview" class="rsv-form-preview" style="position: sticky; top: 40px;"></div>
+            <?php })
+            ->output();
+        ?>
+```
+
+The container is `rsv-form-preview` (a plain wrapper) — **not** `reservair-form`; the injected HTML brings its own `<form class="reservair-form ...">`.
+
+---
+
+## Task 3 — Editor wiring (inline JS in `elements_table_script()`)
+
+### 3a. Shared definition collector + preview functions
+Add at the top level of the script (right after the `rsv_elements_source` IIFE). `<?= $form_id ?>` is the meta form's id (`edit_form_definition` on the edit page):
+
+```js
+function rsv_collect_definition() {
+    const form = document.getElementById('<?= $form_id ?>');
+    const get  = (n) => form?.querySelector(`[name="${n}"]`)?.value ?? '';
+    return {
+        name: get('name'),
+        definition: {
+            email_key:       get('definition.email_key'),
+            success_message: get('definition.success_message'),
+            elements:        rsv_elements_source.get_all(),
+        },
+    };
+}
+
+const rsv_preview_el = document.getElementById('rsv_form_preview');
+let rsv_preview_timer = null;
+
+function rsv_schedule_preview() {
+    if (!rsv_preview_el) return;
+    clearTimeout(rsv_preview_timer);
+    rsv_preview_timer = setTimeout(rsv_render_preview, 300);
+}
+
+function rsv_render_preview() {
+    if (!rsv_preview_el) return;
+    fetch('<?= get_rest_url(null, 'reservations/v1/form-definition/preview') ?>', {
+        method: 'POST',
+        credentials: 'same-origin',
+        headers: {
+            'Content-Type': 'application/json',
+            'Accept': 'application/json',
+            'X-WP-Nonce': ReservairServiceAPI.nonce,
+        },
+        body: JSON.stringify(rsv_collect_definition()),
+    })
+    .then(r => r.ok ? r.json() : r.json().then(e => { throw new Error(e.error || 'Preview failed'); }))
+    .then(data => {
+        rsv_preview_el.innerHTML = data.html || '<p class="rsv-preview-empty">No fields to preview yet.</p>';
+    })
+    .catch(() => { rsv_preview_el.innerHTML = '<p class="rsv-preview-empty">Preview unavailable.</p>'; });
+}
+
+// The preview form is inert: block submission (capture so it works after re-render).
+rsv_preview_el?.addEventListener('submit', (e) => e.preventDefault(), true);
+```
+
+### 3b. Trigger preview on every mutation
+- **Inline edit** (`rsv_render_element_inline_form`, the `builder.build({...})` options): change the two callbacks to also schedule a preview:
+  ```js
+  on_success: () => { elements_dt.refresh(); rsv_schedule_preview(); },
+  on_cancel:  () => { elements_dt.refresh(); rsv_schedule_preview(); },
+  ```
+- **Move Up / Move Down / Remove** `func_action`s and the **`rsv_add_element_btn` onclick**: add `rsv_schedule_preview();` right after each `dt.refresh()` / `elements_dt.refresh()`.
+- **Meta fields**: after the existing `rsv_email_key_select` block, add:
+  ```js
+  const rsv_meta_form = document.getElementById('<?= $form_id ?>');
+  ['name', 'definition.email_key', 'definition.success_message'].forEach((n) => {
+      const el = rsv_meta_form?.querySelector(`[name="${n}"]`);
+      el?.addEventListener('input', rsv_schedule_preview);
+      el?.addEventListener('change', rsv_schedule_preview);
+  });
+  ```
+
+### 3c. Reuse the collector for saving
+Simplify the existing `RsvAdminForm.bind(...)` `transform` to reuse the collector (keeps preview == saved shape):
+```js
+transform: () => rsv_collect_definition(),
+```
+
+### 3d. Initial render
+At the end of the script add:
+```js
+rsv_render_preview();
+```
+(`rsv_render_preview` no-ops when `#rsv_form_preview` is absent, e.g. the create page, so the shared script stays safe there.)
+
+---
+
+## Edge cases / constraints
+- A freshly-added element defaults to `type: 'text'`, which has no registered handler -> silently skipped in the preview until a real type is chosen. Expected.
+- The `<rsv-reservation-selector>` in the preview will fetch availability read-only by `timetable-id` — fine, makes the preview realistic.
+- Use form id `'preview'` (already in the endpoint) so it never collides with a real numeric form id.
+- Don't touch `RsvFormHtmlRenderer` — submission is neutralized client-side.
+
+## Verification
+- `php -l includes/Controllers/RsvFormDefinitionController.php includes/Views/RsvFormsPage.php`
+- `composer lint` (runs phpcs, phpstan, psalm) — must pass.
+- No JS build needed (all editor JS is inline).
+- Manual: open a form's edit page -> edit/add/reorder elements and change the meta fields -> preview updates within ~300 ms and matches the frontend form.
diff --git a/includes/Services/Forms/Handlers/RsvOutputTextElementHandler.php b/includes/Services/Forms/Handlers/RsvOutputTextElementHandler.php
new file mode 100644
index 0000000..4b99c7e
--- /dev/null
+++ b/includes/Services/Forms/Handlers/RsvOutputTextElementHandler.php
@@ -0,0 +1,21 @@
+<?php
+
+
+class RsvOutputTextElementHandler implements RsvFormElementHandler {
+
+    private const ALLOWED_TAGS = ['p', 'h1', 'h2', 'h3', 'h4', 'h5', 'h6'];
+
+    public function draw(RsvFormElementDefinition $def): void {
+        $raw = $def->getAttr('tag', 'p');
+        $tag = in_array($raw, self::ALLOWED_TAGS, true) ? $raw : 'p';
+        echo '<' . $tag . ' class="rsv-form-output-text">' . esc_html($def->getLabel()) . '</' . $tag . '>';
+    }
+
+    public function submit(RsvFormElementDefinition $def, int $submit_id, array $data, RsvFormSubmitResult $result): bool {
+        return true;
+    }
+
+    public function rollback(RsvFormElementDefinition $def, int $submit_id, array $data, RsvFormSubmitResult $result): void {
+        // No side effects to undo.
+    }
+}
diff --git a/includes/Views/RsvFormsPage.php b/includes/Views/RsvFormsPage.php
index 82fd820..f17b350 100644
--- a/includes/Views/RsvFormsPage.php
+++ b/includes/Views/RsvFormsPage.php
@@ -176,7 +176,7 @@ class RsvFormsPage extends RsvAdminPage {
                     if (idx === -1) return Promise.reject(new Error('Element not found'));
                     // Destructure reservation-specific fields so they don't bleed into extra_attrs.
                     const { id: _id, name: _n, label: _l, type: _t, desc: _d, required: _r,
-                            price_per_block: _p, email_templates: _et, timetable_id: _ti, ...extra_attrs } = items[idx];
+                            price_per_block: _p, email_templates: _et, timetable_id: _ti, tag: _tag, ...extra_attrs } = items[idx];
                     items[idx] = {
                         ...extra_attrs,
                         id,
@@ -190,6 +190,9 @@ class RsvFormsPage extends RsvAdminPage {
                             pattern:         data.pattern ?? '',
                             pattern_message: data.pattern_message ?? '',
                         } : {}),
+                        ...(data.type === 'output-text' ? {
+                            tag: data.tag ?? 'p',
+                        } : {}),
                         ...(data.type === 'reservation' ? {
                             timetable_id:    data.timetable_id ? parseInt(data.timetable_id) : null,
                             price_per_block: parseFloat(data.price_per_block ?? '0') || 0,
@@ -262,6 +265,19 @@ class RsvFormsPage extends RsvAdminPage {
                         .input_textarea('email_refused_body', 'Body', refused.body ?? RSV_EMAIL_DEFAULTS.refused_body);
             }
 
+            if ((data?.type ?? rsv_element_types[0]) === 'output-text') {
+                builder
+                    .input_select('tag', 'Tag', [
+                        { value: 'p',  label: 'Paragraph (p)' },
+                        { value: 'h1', label: 'Heading 1 (h1)' },
+                        { value: 'h2', label: 'Heading 2 (h2)' },
+                        { value: 'h3', label: 'Heading 3 (h3)' },
+                        { value: 'h4', label: 'Heading 4 (h4)' },
+                        { value: 'h5', label: 'Heading 5 (h5)' },
+                        { value: 'h6', label: 'Heading 6 (h6)' },
+                    ], data?.tag ?? 'p');
+            }
+
             if ((data?.type ?? rsv_element_types[0]) === 'input-text') {
                 builder
                     .input_select('validation', 'Validation', [
diff --git a/reservair.php b/reservair.php
index 8124d11..4a3ed55 100644
--- a/reservair.php
+++ b/reservair.php
@@ -51,6 +51,7 @@ function rsv_bootstrap(): void {
 	$rsv_form_registry->register( 'button',                     new RsvButtonElementHandler() );
 	$rsv_form_registry->register( 'reservation',                new RsvFormReservationElementHandler() );
 	$rsv_form_registry->register( 'output-reservation-summary', new RsvReservationSummaryElementHandler() );
+	$rsv_form_registry->register( 'output-text',                new RsvOutputTextElementHandler() );
 
 	// Template custom-element registry. Extensions register via the action.
 	add_action( 'rsv-template-register-custom-elements', function ( \Reservair\Templating\RsvTemplateRegistry $reg ): void {