From 2019eaecdaa572fdc0bcf2ad06de2b1757498547 Mon Sep 17 00:00:00 2001
From: Elliot Mitchum <elliot.mitchum@ellioseven.com>
Date: Sun, 24 Jul 2016 20:15:24 +1000
Subject: [PATCH] Integrate Context Layout submodule port

---
 .../context_layout/context_layout.info.yml    |   8 +
 .../context_layout.links.menu.yml             |   5 +
 .../context_layout.links.task.yml             |   5 +
 .../context_layout/context_layout.routing.yml |  53 ++
 .../context_layout.services.yml               |   9 +
 .../LayoutPageDisplayVariantSubscriber.php    |  67 +++
 .../context_layout/src/Form/SettingsForm.php  | 100 ++++
 .../ContextLayout/ContextLayoutManager.php    | 109 ++++
 .../src/Plugin/ContextReaction/Layouts.php    | 560 ++++++++++++++++++
 .../ContextLayoutPageVariant.php              | 120 ++++
 .../ContextReactionLayoutsController.php      | 179 ++++++
 .../Layouts/Form/LayoutBlockAddForm.php       |  31 +
 .../Layouts/Form/LayoutBlockDeleteForm.php    |  50 ++
 .../Layouts/Form/LayoutBlockEditForm.php      |  31 +
 .../Layouts/Form/LayoutBlockFormBase.php      | 141 +++++
 15 files changed, 1468 insertions(+)
 create mode 100644 modules/context_layout/context_layout.info.yml
 create mode 100644 modules/context_layout/context_layout.links.menu.yml
 create mode 100644 modules/context_layout/context_layout.links.task.yml
 create mode 100644 modules/context_layout/context_layout.routing.yml
 create mode 100644 modules/context_layout/context_layout.services.yml
 create mode 100644 modules/context_layout/src/EventSubscriber/LayoutPageDisplayVariantSubscriber.php
 create mode 100644 modules/context_layout/src/Form/SettingsForm.php
 create mode 100644 modules/context_layout/src/Plugin/ContextLayout/ContextLayoutManager.php
 create mode 100644 modules/context_layout/src/Plugin/ContextReaction/Layouts.php
 create mode 100644 modules/context_layout/src/Plugin/DisplayVariant/ContextLayoutPageVariant.php
 create mode 100644 modules/context_layout/src/Reaction/Layouts/Controller/ContextReactionLayoutsController.php
 create mode 100644 modules/context_layout/src/Reaction/Layouts/Form/LayoutBlockAddForm.php
 create mode 100644 modules/context_layout/src/Reaction/Layouts/Form/LayoutBlockDeleteForm.php
 create mode 100644 modules/context_layout/src/Reaction/Layouts/Form/LayoutBlockEditForm.php
 create mode 100644 modules/context_layout/src/Reaction/Layouts/Form/LayoutBlockFormBase.php

diff --git a/modules/context_layout/context_layout.info.yml b/modules/context_layout/context_layout.info.yml
new file mode 100644
index 0000000..66c3242
--- /dev/null
+++ b/modules/context_layout/context_layout.info.yml
@@ -0,0 +1,8 @@
+name: Context Layout
+type: module
+description: 'Block Page Reaction (with Layout plugin integration)'
+core: 8.x
+package: Context
+dependencies:
+  - context
+  - layout_plugin
\ No newline at end of file
diff --git a/modules/context_layout/context_layout.links.menu.yml b/modules/context_layout/context_layout.links.menu.yml
new file mode 100644
index 0000000..c927363
--- /dev/null
+++ b/modules/context_layout/context_layout.links.menu.yml
@@ -0,0 +1,5 @@
+context_layout.admin_settings:
+  title: 'Context Layout settings'
+  description: 'Configure context layout reactions.'
+  route_name: context_layout.admin_settings
+  parent: 'system.admin_config_development'
\ No newline at end of file
diff --git a/modules/context_layout/context_layout.links.task.yml b/modules/context_layout/context_layout.links.task.yml
new file mode 100644
index 0000000..e866bf6
--- /dev/null
+++ b/modules/context_layout/context_layout.links.task.yml
@@ -0,0 +1,5 @@
+context_layout.admin_settings:
+  title: 'Settings'
+  route_name: context_layout.admin_settings
+  base_route: context_layout.admin_settings
+  weight: 0
\ No newline at end of file
diff --git a/modules/context_layout/context_layout.routing.yml b/modules/context_layout/context_layout.routing.yml
new file mode 100644
index 0000000..81c4c8a
--- /dev/null
+++ b/modules/context_layout/context_layout.routing.yml
@@ -0,0 +1,53 @@
+context_layout.admin_settings:
+  path: '/admin/config/development/context_layout'
+  defaults:
+    _form: '\Drupal\context_layout\Form\SettingsForm'
+    _title: 'Context Layout'
+  requirements:
+    _permission: 'administer site configuration'
+
+context.reaction.layouts.theme_select:
+  path: '/admin/structure/context/{context}/reaction/layouts/theme'
+  defaults:
+    _controller: '\Drupal\context_layout\Reaction\Layouts\Controller\ContextReactionLayoutsController::themeSelect'
+  requirements:
+    _entity_access: 'context.update'
+
+context.reaction.layouts.layout_select:
+  path: '/admin/structure/context/{context}/reaction/layouts/layout'
+  defaults:
+    _controller: '\Drupal\context_layout\Reaction\Layouts\Controller\ContextReactionLayoutsController::layoutSelect'
+  requirements:
+    _permission: 'administer contexts'
+
+context.reaction.layouts.library:
+  path: '/admin/structure/context/{context}/reaction/layouts/{reaction_id}/library'
+  defaults:
+    _title: 'Add block'
+    _controller: '\Drupal\context_layout\Reaction\Layouts\Controller\ContextReactionLayoutsController::blocksLibrary'
+  requirements:
+    _entity_access: 'context.update'
+
+context.reaction.layouts.block_delete:
+  path: '/admin/structure/context/{context}/reaction/layouts/delete/{block_id}'
+  defaults:
+    _form: '\Drupal\context_layout\Reaction\Layouts\Form\LayoutBlockDeleteForm'
+    _title: 'Delete block'
+  requirements:
+    _entity_access: 'context.update'
+
+context.reaction.layouts.block_add:
+  path: '/admin/structure/context/{context}/reaction/layouts/{reaction_id}/add/{block_id}'
+  defaults:
+    _form: '\Drupal\context_layout\Reaction\Layouts\Form\LayoutBlockAddForm'
+    _title: 'Add block'
+  requirements:
+    _entity_access: 'context.update'
+
+context.reaction.layouts.block_edit:
+  path: '/admin/structure/context/{context}/reaction/layouts/{reaction_id}/edit/{block_id}'
+  defaults:
+    _form: '\Drupal\context_layout\Reaction\Layouts\Form\LayoutBlockEditForm'
+    _title: 'Edit block'
+  requirements:
+    _entity_access: 'context.update'
\ No newline at end of file
diff --git a/modules/context_layout/context_layout.services.yml b/modules/context_layout/context_layout.services.yml
new file mode 100644
index 0000000..a46843f
--- /dev/null
+++ b/modules/context_layout/context_layout.services.yml
@@ -0,0 +1,9 @@
+services:
+  context_layout.layout_page_display_variant_subscriber:
+    class: Drupal\context_layout\EventSubscriber\LayoutPageDisplayVariantSubscriber
+    arguments: ['@context.manager']
+    tags:
+      - { name: event_subscriber }
+  plugin.manager.context_layout:
+    class: Drupal\context_layout\Plugin\ContextLayout\ContextLayoutManager
+    arguments: ['@container.namespaces', '@cache.discovery', '@module_handler', '@theme_handler']
\ No newline at end of file
diff --git a/modules/context_layout/src/EventSubscriber/LayoutPageDisplayVariantSubscriber.php b/modules/context_layout/src/EventSubscriber/LayoutPageDisplayVariantSubscriber.php
new file mode 100644
index 0000000..39c6170
--- /dev/null
+++ b/modules/context_layout/src/EventSubscriber/LayoutPageDisplayVariantSubscriber.php
@@ -0,0 +1,67 @@
+<?php
+
+namespace Drupal\context_layout\EventSubscriber;
+
+use Drupal\context\ContextManager;
+use Drupal\context_layout\Plugin\ContextReaction\Layouts;
+use Drupal\Core\Render\RenderEvents;
+use Drupal\Core\Render\PageDisplayVariantSelectionEvent;
+use Symfony\Component\EventDispatcher\EventSubscriberInterface;
+
+/**
+ * Selects the layout page display variant.
+ *
+ * @see \Drupal\block\Plugin\DisplayVariant\BlockPageVariant
+ */
+class LayoutPageDisplayVariantSubscriber implements EventSubscriberInterface {
+
+  /**
+   * Context Manager.
+   *
+   * @var \Drupal\context\ContextManager
+   */
+  private $contextManager;
+
+  /**
+   * Constructs a LayoutPageDisplayVariantSubscriber object.
+   *
+   * @param \Drupal\context\ContextManager $contextManager
+   *    Context manager service.
+   */
+  public function __construct(ContextManager $contextManager) {
+    $this->contextManager = $contextManager;
+  }
+
+  /**
+   * Selects the context layout page display variant.
+   *
+   * @param \Drupal\Core\Render\PageDisplayVariantSelectionEvent $event
+   *   The event to process.
+   */
+  public function onSelectPageDisplayVariant(PageDisplayVariantSelectionEvent $event) {
+    // Exit if on admin route and context_layout.settings.admin_allow is true.
+    $admin = \Drupal::service('router.admin_context')->isAdminRoute();
+    $allow = \Drupal::config('context_layout.settings')
+      ->get('admin_allow');
+    if ($admin && !$allow) {
+      return;
+    }
+    // Activate the context block page display variant if any of the reactions
+    // is a blocks reaction.
+    foreach ($this->contextManager->getActiveReactions() as $reaction) {
+      if ($reaction instanceof Layouts) {
+        $event->setPluginId('context_layout_page');
+        break;
+      }
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function getSubscribedEvents() {
+    $events[RenderEvents::SELECT_PAGE_DISPLAY_VARIANT][] = array('onSelectPageDisplayVariant');
+    return $events;
+  }
+
+}
diff --git a/modules/context_layout/src/Form/SettingsForm.php b/modules/context_layout/src/Form/SettingsForm.php
new file mode 100644
index 0000000..599aa53
--- /dev/null
+++ b/modules/context_layout/src/Form/SettingsForm.php
@@ -0,0 +1,100 @@
+<?php
+
+namespace Drupal\context_layout\Form;
+
+use Drupal\Core\Config\ConfigFactoryInterface;
+use Drupal\Core\Form\ConfigFormBase;
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\layout_plugin\Plugin\Layout\LayoutPluginManagerInterface;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * Manage module configuration form.
+ */
+class SettingsForm extends ConfigFormBase {
+
+  /**
+   * Constructs SettingsForm object.
+   *
+   * @param \Drupal\layout_plugin\Plugin\Layout\LayoutPluginManagerInterface $contextLayoutManager
+   *    Context layout manager service.
+   * @param \Drupal\Core\Config\ConfigFactoryInterface $config_factory
+   *    Config factory service.
+   */
+  public function __construct(LayoutPluginManagerInterface $contextLayoutManager, ConfigFactoryInterface $config_factory) {
+    $this->contextLayoutManager = $contextLayoutManager;
+    parent::__construct($config_factory);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormId() {
+    return 'context_layout_settings';
+  }
+
+  /**
+   * Inject dependencies to constructor.
+   *
+   * @param \Symfony\Component\DependencyInjection\ContainerInterface $container
+   *    The current service container.
+   *
+   * @return static
+   *    Dependencies for injection.
+   */
+  public static function create(ContainerInterface $container) {
+    return new static(
+      $container->get('plugin.manager.context_layout'),
+      $container->get('config.factory')
+    );
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildForm(array $form, FormStateInterface $form_state) {
+    // Module settings.
+    $config = $this->config('context_layout.settings');
+
+    // Default layout for layout reactions.
+    $form['default_layout'] = [
+      '#title' => t('Default Layout'),
+      '#description' => t('Select a default layout for layout reactions'),
+      '#type' => 'select',
+      '#options' => [0 => '---'] + $this->contextLayoutManager->getLayoutOptions(
+          ['group_by_category' => TRUE]
+        ),
+      '#default_value' => $config->get('default_layout'),
+    ];
+
+    // Exclude layout displays on admin routes.
+    $form['admin_allow'] = [
+      '#title' => t('Allow Admin Routes'),
+      '#description' => t('Check to allow Context Layout reactions on admin routes, eg: admin/structure.'),
+      '#type' => 'checkbox',
+      '#default_value' => $config->get('admin_allow'),
+    ];
+
+    return parent::buildForm($form, $form_state);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitForm(array &$form, FormStateInterface $form_state) {
+    $values = $form_state->getValues();
+    $this->config('context_layout.settings')
+      ->set('default_layout', $values['default_layout'])
+      ->set('admin_allow', $values['admin_allow'])
+      ->save();
+    parent::submitForm($form, $form_state);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function getEditableConfigNames() {
+    return ['context_layout.settings'];
+  }
+
+}
diff --git a/modules/context_layout/src/Plugin/ContextLayout/ContextLayoutManager.php b/modules/context_layout/src/Plugin/ContextLayout/ContextLayoutManager.php
new file mode 100644
index 0000000..a83bbdd
--- /dev/null
+++ b/modules/context_layout/src/Plugin/ContextLayout/ContextLayoutManager.php
@@ -0,0 +1,109 @@
+<?php
+
+namespace Drupal\context_layout\Plugin\ContextLayout;
+
+use Drupal\Core\Cache\CacheBackendInterface;
+use Drupal\Core\Extension\ModuleHandlerInterface;
+use Drupal\Core\Extension\ThemeHandlerInterface;
+use Drupal\layout_plugin\Plugin\Layout\LayoutPluginManager;
+
+/**
+ * Provides an interface for the discovery and instantiation of context layouts.
+ */
+class ContextLayoutManager extends LayoutPluginManager {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getLayoutOptions(array $params = []) {
+    $type = 'full';
+    $group_by_category = !empty($params['group_by_category']);
+    $plugins = $this->getDefinitions();
+    $options = array();
+    // Sort the plugins first by category, then by label.
+    foreach ($plugins as $id => $plugin) {
+      // Only layouts of type 'full' are allowed.
+      if ($type != $plugin['type']) {
+        continue;
+      }
+      if ($group_by_category) {
+        $category = isset($plugin['category']) ? (string) $plugin['category'] : 'default';
+        if (!isset($options[$category])) {
+          $options[$category] = array();
+        }
+        $options[$category][$id] = $plugin['label'];
+      }
+      else {
+        $options[$id] = $plugin['label'];
+      }
+    }
+    return $options;
+  }
+
+  /**
+   * Returns a Drupal\layout_plugin\Layout instance.
+   *
+   * @param string $layout
+   *    Layout ID (machine name).
+   * @param bool|false $fallback
+   *    Whether to return a fallback layout if default doesn't exist.
+   *
+   * @return object
+   *    Drupal\layout_plugin\Layout instance.
+   */
+  public function loadLayout($layout, $fallback = FALSE) {
+    // We want to return the correct layout if 'default' is passed.
+    if ('default' == $layout) {
+      $layout = $this->createInstance($this->getDefaultLayout($fallback));
+    }
+    else {
+      $layout = $this->createInstance($layout);
+    }
+    return $layout;
+  }
+
+  /**
+   * Returns default Drupal\layout_plugin\Layout instance.
+   *
+   * @param bool|false $fallback
+   *    Whether to return a fallback layout if default doesn't exist.
+   *
+   * @return string
+   *    Layout ID (machine name).
+   */
+  public function getDefaultLayout($fallback = FALSE) {
+    $layout = \Drupal::config('context_layout.settings')
+      ->get('default_layout');
+    if ($fallback && !$layout) {
+      // Get the first available layout.
+      $layout = array_keys(
+        $this->getLayoutOptions()
+      )[0];
+    }
+    return $layout;
+  }
+
+  /**
+   * Return available layout regions.
+   *
+   * @param array $regions
+   *    Region ID's.
+   * @param string $layout_id
+   *    Layout ID (machine name).
+   *
+   * @return array
+   *    Available layout region ID's.
+   */
+  public function filterLayoutRegions($regions, $layout_id) {
+    $layout = \Drupal::service('plugin.manager.context_layout')
+      ->loadLayout($layout_id);
+    $layout_regions = array_keys($layout->getRegionDefinitions());
+    foreach ($regions as $region_id => $region) {
+      if (!in_array($region_id, $layout_regions)) {
+        unset($regions[$region_id]);
+      }
+    }
+    return $regions;
+  }
+
+}
diff --git a/modules/context_layout/src/Plugin/ContextReaction/Layouts.php b/modules/context_layout/src/Plugin/ContextReaction/Layouts.php
new file mode 100644
index 0000000..2551c69
--- /dev/null
+++ b/modules/context_layout/src/Plugin/ContextReaction/Layouts.php
@@ -0,0 +1,560 @@
+<?php
+
+namespace Drupal\context_layout\Plugin\ContextReaction;
+
+use Drupal\context\ContextReactionManager;
+use Drupal\Core\Link;
+use Drupal\Core\Url;
+use Drupal\context\ContextInterface;
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\Core\Theme\ThemeManagerInterface;
+use Drupal\context\ContextReactionPluginBase;
+use Drupal\Core\Extension\ThemeHandlerInterface;
+use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
+use Drupal\Core\Plugin\Context\ContextHandlerInterface;
+use Drupal\Core\Plugin\Context\ContextRepositoryInterface;
+use Drupal\layout_plugin\Plugin\Layout\LayoutPluginManagerInterface;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * Provides a content reaction that will let you place blocks in the current
+ * layout's regions.
+ *
+ * @ContextReaction(
+ *   id = "layouts",
+ *   label = @Translation("Layouts")
+ * )
+ */
+class Layouts extends ContextReactionPluginBase implements ContainerFactoryPluginInterface {
+
+  /**
+   * Manages the list of available themes.
+   *
+   * @var \Drupal\Core\Extension\ThemeHandlerInterface
+   */
+  protected $themeHandler;
+
+  /**
+   * Offers a global context repository.
+   *
+   * @var \Drupal\Core\Plugin\Context\ContextRepositoryInterface
+   */
+  protected $contextRepository;
+
+  /**
+   * Provides an interface for handling sets of contexts.
+   *
+   * @var \Drupal\Core\Plugin\Context\ContextHandlerInterface
+   */
+  protected $contextHandler;
+
+  /**
+   * Provides a high level access to the active theme and methods to use it.
+   *
+   * @var \Drupal\Core\Theme\ThemeManagerInterface
+   */
+  protected $themeManager;
+
+  /**
+   * Provides an interface for the discovery and instantiation of layout plugins.
+   *
+   * @var \Drupal\layout_plugin\Plugin\Layout\LayoutPluginManagerInterface
+   */
+  protected $contextLayoutManager;
+
+  /**
+   * Base class for context plugin manager.
+   *
+   * @var \Drupal\context\ContextReactionManager
+   */
+  protected $contextReactionManager;
+
+  /**
+   * Layout ID (machine name).
+   *
+   * @var string|null
+   */
+  protected $layout = NULL;
+
+  /**
+   * Drupal\context\Plugin\ContextReaction\Blocks instance.
+   *
+   * @var object
+   */
+  protected $blocks;
+
+  /**
+   * {@inheritdoc}
+   */
+  public function __construct(
+    array $configuration,
+    $pluginId,
+    $pluginDefinition,
+    ThemeHandlerInterface $themeHandler,
+    ThemeManagerInterface $themeManager,
+    ContextRepositoryInterface $contextRepository,
+    ContextHandlerInterface $contextHandler,
+    LayoutPluginManagerInterface $contextLayoutManager,
+    ContextReactionManager $contextReactionManager
+  ) {
+    $this->themeHandler = $themeHandler;
+    $this->contextRepository = $contextRepository;
+    $this->contextHandler = $contextHandler;
+    $this->themeManager = $themeManager;
+    $this->contextLayoutManager = $contextLayoutManager;
+    $this->contextReactionManager = $contextReactionManager;
+    // Create a Drupal\context\Plugin\ContextReaction\Blocks instance.
+    $this->blocks = $contextReactionManager->createInstance('blocks');
+    parent::__construct($configuration, $pluginId, $pluginDefinition);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container, array $configuration, $pluginId, $pluginDefinition) {
+    return new static(
+      $configuration,
+      $pluginId,
+      $pluginDefinition,
+      $container->get('theme_handler'),
+      $container->get('theme.manager'),
+      $container->get('context.repository'),
+      $container->get('context.handler'),
+      $container->get('plugin.manager.context_layout'),
+      $container->get('plugin.manager.context_reaction')
+    );
+  }
+
+  /**
+   * Executes the plugin.
+   *
+   * @param array $build
+   *   The current build of the page.
+   *
+   * @param string|null $title
+   *   The page title.
+   *
+   * @param string|null $main_content
+   *   The main page content.
+   *
+   * @return array
+   */
+  public function execute(array $build = array(), $title = NULL, $main_content = NULL) {
+    // Check for an existing context layout from page build.
+    if (isset($build['#layout'])) {
+      $layout = $build['#layout']['id'];
+      $layout_regions = $this->contextLayoutManager
+        ->loadLayout($build['#layout']['id'])
+        ->getRegionDefinitions();
+    }
+    else {
+      $layout = $this->layout;
+      $layout_regions = $this->contextLayoutManager
+        ->loadLayout($this->layout)
+        ->getRegionDefinitions($this->layout);
+    }
+    $layout_regions = array_keys($layout_regions);
+
+    // Use the currently active theme to fetch blocks.
+    $theme = $this->themeManager->getActiveTheme()->getName();
+    $theme_regions = array_keys(system_region_list($theme));
+
+    // Get Blocks context reaction build array.
+    $build = $this->blocks->execute($build, $title, $main_content);
+
+    // Remove blocks that are not available in layout's regions.
+    foreach ($build as $key => $value) {
+      $in_theme = in_array($key, $theme_regions);
+      $in_layout = in_array($key, $layout_regions);
+      if ($in_theme && !$in_layout) {
+        unset($build[$key]);
+      }
+    }
+
+    /** @var $layout \Drupal\layout_plugin\Layout */
+    $layout = $this->contextLayoutManager->loadLayout($layout);
+    return $layout->build($build);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function summary() {
+    return $this->t('Lets you select a layout and blocks.');
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildConfigurationForm(array $form, FormStateInterface $form_state, ContextInterface $context = NULL) {
+    // Check for available layouts and display appropriate form.
+    $options = $this->getLayoutOptions();
+    if (!$options) {
+      return $this->invalidConfigurationForm($form);
+    }
+    else {
+      return $this->validConfigurationForm($form, $form_state, $context);
+    }
+  }
+
+  /**
+   * Display invalid build form.
+   *
+   * @param array $form
+   *   An associative array containing the structure of the form.
+   *
+   * @return array
+   *   Modified $form.
+   */
+  private function invalidConfigurationForm(array $form) {
+    $form['no_layouts'] = [
+      '#type' => 'item',
+      '#title' => t('No Defined Layouts'),
+      '#description' => t('You have no defined \'full\' type layouts. You
+      must register layouts with the type of \'full\' within your theme. ') .
+        Link::fromTextAndUrl(
+          'See Layout Plugin documentation',
+          Url::fromUri('https://www.drupal.org/node/2578731'))->toString()
+    ];
+    return $form;
+  }
+
+  /**
+   * Display valid configuration build form.
+   *
+   * @param array $form
+   *    An associative array containing the structure of the form.
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
+   *    The current state of the form.
+   * @param \Drupal\context\ContextInterface|null $context
+   *    Current context.
+   *
+   * @return array
+   *   Modified $form.
+   */
+  private function validConfigurationForm(array $form, FormStateInterface $form_state, ContextInterface $context = NULL) {
+    $layout = $form_state->getValue('layout', $this->getLayout());
+
+    // The layout to use for the context reaction.
+    $form['layout'] = [
+      '#type' => 'select',
+      '#title' => t('Layout'),
+      '#options' => $this->getLayoutOptions([
+        'group_by_category' => TRUE,
+        'default' => TRUE,
+      ]),
+      '#default_value' => $layout,
+      '#ajax' => [
+        'url' => Url::fromRoute('context.reaction.layouts.layout_select', [
+          'context' => $context->id(),
+        ]),
+      ],
+    ];
+
+    // Build blocks reaction build configuration form.
+    $form += $this->blocks->buildConfigurationForm($form, $form_state, $context);
+
+    // Filter the blocks reaction build configuration form.
+    $this->filterForm($form, $form_state, $context);
+
+    return $form;
+  }
+
+  /**
+   * Get layout regions from collection of blocks.
+   *
+   * @param string $theme
+   *   The theme to get blocks for.
+   * @param string $layout
+   *    Layout ID (machine name).
+   *
+   * @return array
+   *    Region ID's.
+   */
+  private function getUsedLayoutRegions($theme, $layout) {
+    $layout_regions  = [];
+    $regions = $this->blocks->getBlocks()->getAllByRegion($theme);
+    foreach ($regions as $region_id => $region) {
+      foreach ($region as $theme_block) {
+        if ($layout == $theme_block->configuration['layout']) {
+          $layout_regions[] = $region_id;
+        }
+      }
+    }
+    return $layout_regions;
+  }
+
+  /**
+   * Filter blocks reaction build configuration form.
+   *
+   * @param array $form
+   *    An associative array containing the structure of the form.
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
+   *    The current state of the form.
+   * @param \Drupal\context\ContextInterface|null $context
+   *    Current context.
+   *
+   * @return array
+   *   Modified $form.
+   */
+  private function filterForm(array &$form, FormStateInterface &$form_state, ContextInterface $context) {
+    $layout = $form_state->getValue('layout', $this->getLayout());
+    $default_theme = $this->themeHandler->getDefault();
+    $theme = $form_state->getValue('theme', $default_theme);
+    $system_regions = system_region_list($theme);
+
+    /** @var \Drupal\Core\Block\BlockPluginInterface $blocks */
+    $blocks = $this->blocks->getBlocks()->getAllByRegion($theme);
+
+    // Get layout region ID's.
+    $layout_regions = array_keys(
+      $this->contextLayoutManager->loadLayout($layout)
+        ->getRegionDefinitions()
+    );
+
+    $used_layout_regions = $this->getUsedLayoutRegions($theme, $layout);
+
+    // Filter theme selection route.
+    $form['theme']['#ajax']['url'] = Url::fromRoute(
+      'context.reaction.layouts.theme_select', [
+        'context' => $context->id(),
+      ]
+    );
+
+    // Filter block library route.
+    $form['blocks']['block_add']['#url'] = Url::fromRoute(
+      'context.reaction.layouts.library', [
+        'context' => $context->id(),
+        'reaction_id' => $this->getPluginId(),
+      ], [
+        'query' => [
+          'theme' => $theme,
+          'layout' => $layout,
+        ],
+      ]
+    );
+
+    // Tabledrag row count.
+    $table_count = 0;
+    foreach ($system_regions as $region => $title) {
+
+      // Remove regions unavailable to layout.
+      $region_id = 'region-' . $region;
+      $region_message_id = $region_id . '-message';
+      $layout_has_region = in_array($region, $layout_regions);
+      $layout_used_region = in_array($region, $used_layout_regions);
+
+      if (!$layout_has_region) {
+        unset($form['blocks']['blocks'][$region_message_id]);
+        unset($form['blocks']['blocks'][$region_id]);
+      }
+
+      // Apply empty classes to tabledrag rows that may now be empty.
+      if ($layout_has_region && !$layout_used_region) {
+        if (isset($form['blocks']['blocks'][$region_message_id])) {
+          foreach ($form['blocks']['blocks'][$region_message_id]['#attributes']['class'] as $i => $class) {
+            if ('region-populated' == $class) {
+              unset($form['blocks']['blocks'][$region_message_id]['#attributes']['class'][$i]);
+              $form['blocks']['blocks'][$region_message_id]['#attributes']['class'][] = 'region-empty';
+            }
+          }
+        }
+      }
+
+      // Remove tabledrag rows unavailable to layout.
+      if (!in_array($region, $layout_regions)) {
+        unset($form['blocks']['blocks']['#tabledrag'][$table_count]);
+        unset($form['blocks']['blocks']['#tabledrag'][$table_count + 1]);
+      }
+
+      // Tabledrag has 2 rows per region.
+      $table_count += 2;
+
+      if (isset($blocks[$region])) {
+
+        // Loop through blocks within the current region.
+        foreach ($blocks[$region] as $block_id => $block) {
+
+          // Route args for block's operations.
+          $url_args = [
+            'context' => $context->id(),
+            'reaction_id' => $this->getPluginId(),
+            'block_id' => $block_id,
+          ];
+
+          // Filter block edit route.
+          $form['blocks']['blocks'][$block_id]['operations']['#links']['edit']['url'] = Url::fromRoute(
+            'context.reaction.layouts.block_edit',
+            $url_args
+          );
+
+          // Filter block delete route.
+          $form['blocks']['blocks'][$block_id]['operations']['#links']['delete']['url'] = Url::fromRoute(
+            'context.reaction.layouts.block_delete',
+            $url_args
+          );
+
+          // Remove blocks that are in a region unavailable to layout.
+          if (!in_array($region, $layout_regions)) {
+            unset($form['blocks']['blocks'][$block_id]);
+          }
+        }
+      }
+    }
+
+    // Remove block instances that are not in the current layout.
+    foreach ($blocks as $region_id => $region_blocks) {
+      foreach ($region_blocks as $block_id => $block) {
+        if ($layout != $block->configuration['layout']) {
+          unset($form['blocks']['blocks'][$block_id]);
+        }
+      }
+    }
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function defaultConfiguration() {
+    $configuration = parent::defaultConfiguration();
+    $configuration += $this->blocks->defaultConfiguration();
+    $configuration['layout'] = NULL;
+    return $configuration;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setConfiguration(array $configuration) {
+    $this->blocks->setConfiguration($configuration);
+    $this->configuration = $configuration + $this->defaultConfiguration();
+    if (isset($configuration['layout'])) {
+      $this->layout = $configuration['layout'];
+    }
+    return $this;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getConfiguration() {
+    $configuration = $this->blocks->getConfiguration();
+    // Restore ID to configuration.
+    $configuration['id'] = 'layouts';
+    $configuration['layout'] = $this->configuration['layout'];
+    $configuration += parent::getConfiguration();
+    return $configuration;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function submitConfigurationForm(array &$form, FormStateInterface $form_state) {
+    $this->blocks->submitConfigurationForm($form, $form_state);
+    $this->configuration['layout'] = $form_state->getValue('layout');
+  }
+
+  /**
+   * Get most appropriate layout.
+   *
+   * @return string
+   *    Layout ID (machine name).
+   */
+  protected function getLayout() {
+    // Current layout.
+    if ($this->layout) {
+      return $this->layout;
+    }
+    // Default layout.
+    elseif ($this->contextLayoutManager->getDefaultLayout()) {
+      return 'default';
+    }
+    // Fallback layout.
+    else {
+      $fallback = TRUE;
+      return $this->contextLayoutManager->getDefaultLayout($fallback);
+    }
+  }
+
+  /**
+   * Return formatted layout region options.
+   *
+   * @param array $params
+   *   (optional) An associative array with the following keys:
+   *   - group_by_category: (bool) If set to TRUE, return an array of arrays
+   *   grouped by the category name; otherwise, return a single-level
+   *   associative array.
+   *
+   * @return array
+   *   Layout options, as array.
+   */
+  protected function getLayoutOptions(array $params = []) {
+    $default = !empty($params['default']);
+    $layouts = $this->contextLayoutManager->getLayoutOptions($params);
+    // Prepend default layout option.
+    if ($default && $this->contextLayoutManager->getDefaultLayout()) {
+      $default_layout = $this->contextLayoutManager->createInstance(
+        $this->contextLayoutManager->getDefaultLayout()
+      );
+      $label = $default_layout->getPluginDefinition()['label'] . ' (' . t('Default') . ')';
+      $layouts = ['default' => $label] + $layouts;
+    }
+    return $layouts;
+  }
+
+  /**
+   * Add a new block.
+   *
+   * @param array $configuration
+   *    Reaction configuration.
+   *
+   * @return string
+   *    Generated UUID.
+   */
+  public function addBlock(array $configuration) {
+    return $this->blocks->addBlock($configuration);
+  }
+
+  /**
+   * Update an existing blocks configuration.
+   *
+   * @param string $blockId
+   *    The ID of the block to update.
+   *
+   * @param $configuration
+   *    The updated configuration for the block.
+   *
+   * @return object
+   *    $this.
+   */
+  public function updateBlock($blockId, array $configuration) {
+    return $this->blocks->updateBlock($blockId, $configuration);
+  }
+
+  /**
+   * Remove a block from block instances.
+   *
+   * @param string $blockId
+   *    The ID of the block to get.
+   *
+   * @return object
+   *    $this.
+   */
+  public function removeBlock($blockId) {
+    return $this->blocks->removeBlock($blockId);
+  }
+
+  /**
+   * Get a block by id.
+   *
+   * @param string $blockId
+   *    The ID of the block to get.
+   *
+   * @return object
+   *    BlockPluginInterface instance.
+   */
+  public function getBlock($blockId) {
+    return $this->blocks->getBlock($blockId);
+  }
+
+}
diff --git a/modules/context_layout/src/Plugin/DisplayVariant/ContextLayoutPageVariant.php b/modules/context_layout/src/Plugin/DisplayVariant/ContextLayoutPageVariant.php
new file mode 100644
index 0000000..a3aeb12
--- /dev/null
+++ b/modules/context_layout/src/Plugin/DisplayVariant/ContextLayoutPageVariant.php
@@ -0,0 +1,120 @@
+<?php
+
+namespace Drupal\context_layout\Plugin\DisplayVariant;
+
+use Drupal\context\ContextManager;
+use Drupal\Core\Display\VariantBase;
+use Drupal\Core\Display\PageVariantInterface;
+use Drupal\Core\Plugin\ContainerFactoryPluginInterface;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * Provides a page variant that simply contains blocks.
+ *
+ * @see \Drupal\Core\Block\MainContentBlockPluginInterface
+ * @see \Drupal\Core\Block\MessagesBlockPluginInterface
+ *
+ * @PageDisplayVariant(
+ *   id = "context_layout_page",
+ *   admin_label = @Translation("Page with blocks and layout integration")
+ * )
+ */
+class ContextLayoutPageVariant extends VariantBase implements PageVariantInterface, ContainerFactoryPluginInterface {
+
+  /**
+   * Context manager service.
+   *
+   * @var \Drupal\context\ContextManager
+   */
+  protected $contextManager;
+
+  /**
+   * The render array representing the main page content.
+   *
+   * @var array
+   */
+  protected $mainContent = [];
+
+  /**
+   * The page title: a string (plain title) or a render array (formatted title).
+   *
+   * @var string|array
+   */
+  protected $title = '';
+
+  /**
+   * Constructs a new ContextLayoutPageVariant.
+   *
+   * @param array $configuration
+   *    A configuration array containing information about the plugin instance.
+   *
+   * @param string $plugin_id
+   *    The plugin ID for the plugin instance.
+   *
+   * @param mixed $plugin_definition
+   *    The plugin implementation definition.
+   *
+   * @param ContextManager $contextManager
+   *    The context module manager.
+   */
+  public function __construct(array $configuration, $plugin_id, $plugin_definition, ContextManager $contextManager) {
+    parent::__construct($configuration, $plugin_id, $plugin_definition);
+    $this->contextManager = $contextManager;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
+    return new static(
+      $configuration,
+      $plugin_id,
+      $plugin_definition,
+      $container->get('context.manager')
+    );
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setMainContent(array $main_content) {
+    $this->mainContent = $main_content;
+    return $this;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function setTitle($title) {
+    $this->title = $title;
+    return $this;
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function build() {
+    $build = [
+      '#cache' => [
+        'tags' => ['context_layout_page', $this->getPluginId()],
+      ],
+    ];
+
+    // Place main content and messages blocks, these will be removed by the
+    // reactions if a message or content block has been manually placed.
+    $build['content']['system_main'] = $this->mainContent;
+
+    $build['content']['messages'] = [
+      '#weight' => -1000,
+      '#type' => 'status_messages',
+    ];
+
+    // Execute each block reaction and let them modify the page build.
+    foreach ($this->contextManager->getActiveReactions('layouts') as $reaction) {
+      $build = $reaction->execute($build, $this->title, $this->mainContent);
+    }
+
+    return $build;
+  }
+
+}
diff --git a/modules/context_layout/src/Reaction/Layouts/Controller/ContextReactionLayoutsController.php b/modules/context_layout/src/Reaction/Layouts/Controller/ContextReactionLayoutsController.php
new file mode 100644
index 0000000..fb5269a
--- /dev/null
+++ b/modules/context_layout/src/Reaction/Layouts/Controller/ContextReactionLayoutsController.php
@@ -0,0 +1,179 @@
+<?php
+
+namespace Drupal\context_layout\Reaction\Layouts\Controller;
+
+use Drupal\context\ContextManager;
+use Drupal\context\Reaction\Blocks\Controller\ContextReactionBlocksController;
+use Drupal\Core\Ajax\AjaxResponse;
+use Drupal\Core\Ajax\ReplaceCommand;
+use Drupal\context\ContextInterface;
+use Drupal\Core\Block\BlockManagerInterface;
+use Drupal\Core\Extension\ThemeHandlerInterface;
+use Drupal\Core\Plugin\Context\ContextRepositoryInterface;
+use Drupal\Core\Url;
+use Drupal\layout_plugin\Plugin\Layout\LayoutPluginManagerInterface;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+use Symfony\Component\HttpFoundation\Request;
+
+/**
+ * Controller for context layout reaction routes.
+ */
+class ContextReactionLayoutsController extends ContextReactionBlocksController {
+
+  /**
+   * Provides an interface for the discovery and instantiation of context layouts.
+   *
+   * @var \Drupal\layout_plugin\Plugin\Layout\LayoutPluginManagerInterface
+   */
+  protected $contextLayoutManager;
+
+  /**
+   * Constructs a ContextReactionLayoutsController object.
+   *
+   * @param \Drupal\Core\Block\BlockManagerInterface $blockManager
+   *   Provides an interface for the discovery and instantiation of block plugins.
+   * @param \Drupal\Core\Plugin\Context\ContextRepositoryInterface $contextRepository
+   *   Offers a global context repository.
+   * @param \Drupal\Core\Extension\ThemeHandlerInterface $themeHandler
+   *   Manages the list of available themes.
+   * @param \Drupal\context\ContextManager $contextManager
+   *   Context manager service.
+   * @param \Drupal\layout_plugin\Plugin\Layout\LayoutPluginManagerInterface $contextLayoutManager
+   *   Provides an interface for the discovery and instantiation of layout plugins.
+   */
+  public function __construct(
+    BlockManagerInterface $blockManager,
+    ContextRepositoryInterface $contextRepository,
+    ThemeHandlerInterface $themeHandler,
+    ContextManager $contextManager,
+    LayoutPluginManagerInterface $contextLayoutManager
+  ) {
+    $this->contextLayoutManager = $contextLayoutManager;
+    return parent::__construct($blockManager, $contextRepository, $themeHandler, $contextManager);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container) {
+    return new static(
+      $container->get('plugin.manager.block'),
+      $container->get('context.repository'),
+      $container->get('theme_handler'),
+      $container->get('context.manager'),
+      $container->get('plugin.manager.context_layout')
+    );
+  }
+
+  /**
+   * Display a library of blocks that can be added to the context reaction.
+   *
+   * @param \Symfony\Component\HttpFoundation\Request $request
+   *    The request object.
+   *
+   * @param \Drupal\context\ContextInterface $context
+   *    The context the blocks reaction belongs to.
+   *
+   * @param string $reaction_id
+   *    The ID of the blocks reaction that the selected block
+   *    should be added to.
+   *
+   * @return array
+   *    Build array of block library.
+   */
+  public function blocksLibrary(Request $request, ContextInterface $context, $reaction_id) {
+    // If a theme has been defined in the query string then use this for
+    // the add block link, default back to the default theme.
+    $theme = $request->query->get('theme');
+
+    // If a layout has been defined in the query string then use this for
+    // the add block link, default back to the default layout.
+    $fallback = TRUE;
+    $layout = $request->query->get('layout', $this->contextLayoutManager->getDefaultLayout($fallback));
+
+    // Build ContextReactionBlocksController block library.
+    $build = parent::blocksLibrary($request, $context, $reaction_id);
+
+    foreach ($build['blocks']['#rows'] as &$row) {
+      // Filter block operation routes.
+      $url = $row['operations']['data']['#links']['add']['url'];
+      $params = $url->getRouteParameters();
+      // Filter block add route.
+      $new_url = Url::fromRoute('context.reaction.layouts.block_add', [
+        'context' => $params['context'],
+        'reaction_id' => $params['reaction_id'],
+        'block_id' => $params['block_id'],
+      ], [
+        'query' => [
+          'theme' => $theme,
+          'layout' => $layout,
+        ],
+      ]
+      );
+      $row['operations']['data']['#links']['add']['url'] = $new_url;
+    }
+
+    return $build;
+  }
+
+  /**
+   * Callback for the theme select list on the Context layouts reaction form.
+   *
+   * @param Request $request
+   *    The current request.
+   *
+   * @param ContextInterface $context
+   *    The context the block reaction is located on.
+   *
+   * @return \Drupal\Core\Ajax\AjaxResponse
+   *    AJAX Response instance.
+   */
+  public function themeSelect(Request $request, ContextInterface $context) {
+    // Get the context form and supply it with the layouts theme value.
+    $theme = $request->request->get('reactions[layouts][theme]', '', TRUE);
+    // Get the context form and supply it with the layouts layout value.
+    $layout = $request->request->get('reactions[layouts][layout]', '', TRUE);
+    $form = $this->contextManager->getForm($context, 'edit', [
+      'reactions' => [
+        'layouts' => [
+          'theme' => $theme,
+          'layout' => $layout,
+        ],
+      ],
+    ]);
+    $response = new AjaxResponse();
+    $response->addCommand(new ReplaceCommand('#context-reactions', $form['reactions']));
+    return $response;
+  }
+
+  /**
+   * Callback for the theme select list on the Context layouts reaction form.
+   *
+   * @param Request $request
+   *    The current request.
+   *
+   * @param ContextInterface $context
+   *    The context the block reaction is located on.
+   *
+   * @return \Drupal\Core\Ajax\AjaxResponse
+   *    AJAX Response instance.
+   */
+  public function layoutSelect(Request $request, ContextInterface $context) {
+    // Get the context form and supply it with the layouts theme value.
+    $theme = $request->request->get('reactions[layouts][theme]', '', TRUE);
+    // Get the context form and supply it with the layouts layout value.
+    $layout = $request->request->get('reactions[layouts][layout]', '', TRUE);
+    $form = $this->contextManager->getForm($context, 'edit', [
+      'reactions' => [
+        'layouts' => [
+          'layout' => $layout,
+          'theme' => $theme,
+        ],
+      ],
+    ]);
+    $response = new AjaxResponse();
+    $response->addCommand(new ReplaceCommand('#context-reactions', $form['reactions']));
+    return $response;
+  }
+
+}
diff --git a/modules/context_layout/src/Reaction/Layouts/Form/LayoutBlockAddForm.php b/modules/context_layout/src/Reaction/Layouts/Form/LayoutBlockAddForm.php
new file mode 100644
index 0000000..6de88a5
--- /dev/null
+++ b/modules/context_layout/src/Reaction/Layouts/Form/LayoutBlockAddForm.php
@@ -0,0 +1,31 @@
+<?php
+
+namespace Drupal\context_layout\Reaction\Layouts\Form;
+
+/**
+ * Manage layout block add form.
+ */
+class LayoutBlockAddForm extends LayoutBlockFormBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormId() {
+    return 'context_reaction_layouts_add_block_form';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function getSubmitValue() {
+    return $this->t('Add block');
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function prepareBlock($block_id) {
+    return $this->blockManager->createInstance($block_id);
+  }
+
+}
diff --git a/modules/context_layout/src/Reaction/Layouts/Form/LayoutBlockDeleteForm.php b/modules/context_layout/src/Reaction/Layouts/Form/LayoutBlockDeleteForm.php
new file mode 100644
index 0000000..9c76323
--- /dev/null
+++ b/modules/context_layout/src/Reaction/Layouts/Form/LayoutBlockDeleteForm.php
@@ -0,0 +1,50 @@
+<?php
+
+namespace Drupal\context_layout\Reaction\Layouts\Form;
+
+use Drupal\context\Reaction\Blocks\Form\BlockDeleteForm;
+use Drupal\context\ContextInterface;
+use Drupal\Core\Form\ConfirmFormBase;
+use Drupal\Core\Form\FormStateInterface;
+
+/**
+ * Manage layout block delete form.
+ *
+ * @package Drupal\context_layout\Reaction\Layouts\Form
+ */
+class LayoutBlockDeleteForm extends BlockDeleteForm {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormId() {
+    return 'context_reaction_layouts_delete_block_form';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public function buildForm(array $form, FormStateInterface $form_state, ContextInterface $context = NULL, $block_id = NULL) {
+    $this->context = $context;
+    $this->reaction = $this->context->getReaction('layouts');
+    $this->block = $this->reaction->getBlock($block_id);
+
+    // Build Drupal\Core\Form\ConfirmFormBase form.
+    $form = ConfirmFormBase::buildForm($form, $form_state);
+
+    // Remove the cancel button if this is an AJAX request since Drupals built
+    // in modal dialogues does not handle buttons that are not a primary
+    // button very well.
+    if ($this->getRequest()->isXmlHttpRequest()) {
+      unset($form['actions']['cancel']);
+    }
+
+    // Submit the form with AJAX if possible.
+    $form['actions']['submit']['#ajax'] = [
+      'callback' => '::submitFormAjax',
+    ];
+
+    return $form;
+  }
+
+}
diff --git a/modules/context_layout/src/Reaction/Layouts/Form/LayoutBlockEditForm.php b/modules/context_layout/src/Reaction/Layouts/Form/LayoutBlockEditForm.php
new file mode 100644
index 0000000..ecbee7f
--- /dev/null
+++ b/modules/context_layout/src/Reaction/Layouts/Form/LayoutBlockEditForm.php
@@ -0,0 +1,31 @@
+<?php
+
+namespace Drupal\context_layout\Reaction\Layouts\Form;
+
+/**
+ * Manage layout block edit form.
+ */
+class LayoutBlockEditForm extends LayoutBlockFormBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function getFormId() {
+    return 'context_reaction_layouts_edit_block_form';
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function getSubmitValue() {
+    return $this->t('Update block');
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function prepareBlock($block_id) {
+    return $this->reaction->getBlock($block_id);
+  }
+
+}
diff --git a/modules/context_layout/src/Reaction/Layouts/Form/LayoutBlockFormBase.php b/modules/context_layout/src/Reaction/Layouts/Form/LayoutBlockFormBase.php
new file mode 100644
index 0000000..12558cc
--- /dev/null
+++ b/modules/context_layout/src/Reaction/Layouts/Form/LayoutBlockFormBase.php
@@ -0,0 +1,141 @@
+<?php
+
+namespace Drupal\context_layout\Reaction\Layouts\Form;
+
+use Drupal\context\ContextManager;
+use Drupal\context\ContextReactionManager;
+use Drupal\context\Reaction\Blocks\Form\BlockFormBase;
+use Drupal\Core\Extension\ThemeHandlerInterface;
+use Drupal\Core\Form\FormBuilderInterface;
+use Drupal\context\ContextInterface;
+use Drupal\Core\Form\FormStateInterface;
+use Drupal\Component\Plugin\PluginManagerInterface;
+use Drupal\Core\Plugin\Context\ContextRepositoryInterface;
+use Drupal\layout_plugin\Plugin\Layout\LayoutPluginManagerInterface;
+use Symfony\Component\DependencyInjection\ContainerInterface;
+
+/**
+ * Base form for layout block management.
+ *
+ * @package Drupal\context_layout\Reaction\Layouts\Form
+ */
+abstract class LayoutBlockFormBase extends BlockFormBase {
+
+  /**
+   * Provides an interface for the discovery and instantiation of context layouts.
+   *
+   * @var \Drupal\layout_plugin\Plugin\Layout\LayoutPluginManagerInterface
+   */
+  protected $contextLayoutManager;
+
+  /**
+   * {@inheritdoc}
+   */
+  public function __construct(
+    PluginManagerInterface $block_manager,
+    ContextRepositoryInterface $contextRepository,
+    ThemeHandlerInterface $themeHandler,
+    FormBuilderInterface $formBuilder,
+    ContextReactionManager $contextReactionManager,
+    ContextManager $contextManager,
+    LayoutPluginManagerInterface $contextLayoutManager
+  ) {
+    $this->contextLayoutManager = $contextLayoutManager;
+    parent::__construct($block_manager, $contextRepository, $themeHandler, $formBuilder, $contextReactionManager, $contextManager);
+  }
+
+  /**
+   * {@inheritdoc}
+   */
+  public static function create(ContainerInterface $container) {
+    return new static(
+      $container->get('plugin.manager.block'),
+      $container->get('context.repository'),
+      $container->get('theme_handler'),
+      $container->get('form_builder'),
+      $container->get('plugin.manager.context_reaction'),
+      $container->get('context.manager'),
+      $container->get('plugin.manager.context_layout')
+    );
+  }
+
+  /**
+   * Form constructor.
+   *
+   * @param array $form
+   *    An associative array containing the structure of the form.
+   *
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
+   *    The current state of the form.
+   *
+   * @param ContextInterface $context
+   *    The context the reaction belongs to.
+   *
+   * @param string|null $reaction_id
+   *    The ID of the blocks reaction the block should be added to.
+   *
+   * @param string|null $block_id
+   *    The ID of the block to show a configuration form for.
+   *
+   * @return array
+   *   Build form structure.
+   */
+  public function buildForm(array $form, FormStateInterface $form_state, ContextInterface $context = NULL, $reaction_id = NULL, $block_id = NULL) {
+    // Submit BlockFormBase build form.
+    $form = parent::buildForm($form, $form_state, $context, $reaction_id, $block_id);
+
+    // If a theme was defined in the query use this theme for the block
+    // otherwise use the default theme.
+    $theme = $this->getRequest()->query->get('theme', $this->themeHandler->getDefault());
+
+    $configuration = $this->block->getConfiguration();
+    $regions = $this->getThemeRegionOptions($theme);
+
+    // Get layout from either request or configuration.
+    if ($this->getRequest()->query->get('layout') || $configuration['layout']) {
+      $layout = $configuration['layout'];
+      // Layout from request takes precedence.
+      if ($this->getRequest()->query->get('layout')) {
+        $layout = $this->getRequest()->query->get('layout');
+      }
+      $regions = $this->contextLayoutManager->filterLayoutRegions(
+        $this->getThemeRegionOptions($theme),
+        $layout
+      );
+    }
+    else {
+      $fallback = TRUE;
+      $layout = $this->contextLayoutManager->getDefaultLayout($fallback);
+    }
+
+    // Remove regions unavailable to layout.
+    $form['region']['#options'] = $regions;
+
+    $form['layout'] = [
+      '#type' => 'value',
+      '#value' => $layout,
+    ];
+
+    return $form;
+  }
+
+  /**
+   * Form submission handler.
+   *
+   * @param array $form
+   *    An associative array containing the structure of the form.
+   *
+   * @param \Drupal\Core\Form\FormStateInterface $form_state
+   *    The current state of the form.
+   */
+  public function submitForm(array &$form, FormStateInterface $form_state) {
+    $configuration = array_merge($this->block->getConfiguration(), [
+      'layout' => $form_state->getValue('layout'),
+    ]);
+    // Set layout value in block configuration.
+    $this->block->setConfiguration($configuration);
+    // Let BlockFormBase do the rest.
+    parent::submitForm($form, $form_state);
+  }
+
+}