Add blocks preprocessor

Currently, we need to wrap top-level non-column blocks into a single
column. This is done in the preprocessor.

[MAILPOET-5540]

mailpoet/lib/DI/ContainerConfigurator.php

@@ -319,6 +319,7 @@ class ContainerConfigurator implements IContainerConfigurator {
     $container->autowire(\MailPoet\EmailEditor\Engine\Renderer\BodyRenderer::class)->setPublic(true);
     $container->autowire(\MailPoet\EmailEditor\Engine\Renderer\BlocksRenderer::class)->setPublic(true);
     $container->autowire(\MailPoet\EmailEditor\Engine\Renderer\BlocksRegistry::class)->setPublic(true);
+    $container->autowire(\MailPoet\EmailEditor\Engine\Renderer\Preprocessor::class)->setPublic(true);
     $container->autowire(\MailPoet\EmailEditor\Integrations\Core\Initializer::class)->setPublic(true);
     $container->autowire(\MailPoet\EmailEditor\Integrations\MailPoet\EmailEditor::class)->setPublic(true);
     $container->autowire(\MailPoet\EmailEditor\Integrations\MailPoet\EmailApiController::class)->setPublic(true);

mailpoet/lib/EmailEditor/Engine/Renderer/BodyRenderer.php

@@ -13,10 +13,7 @@ class BodyRenderer {
     $this->blocksRenderer = $blocksRenderer;
   }
 
-  public function renderBody(string $postContent): string {
-    $parser = new \WP_Block_Parser();
-    $parsedBlocks = $parser->parse($postContent);
-    // @todo We need to wrap top level blocks which are not in columns into a column
+  public function renderBody(array $parsedBlocks): string {
     return $this->blocksRenderer->render($parsedBlocks);
   }
 }

mailpoet/lib/EmailEditor/Engine/Renderer/Preprocessor.php

@@ -0,0 +1,52 @@
+<?php declare(strict_types = 1);
+
+namespace MailPoet\EmailEditor\Engine\Renderer;
+
+class Preprocessor {
+
+  const SINGLE_COLUMN_TEMPLATE = [
+    'blockName' => 'core/columns',
+    'attrs' => [],
+    'innerBlocks' => [[
+      'blockName' => 'core/column',
+      'attrs' => [],
+      'innerBlocks' => [],
+    ]],
+  ];
+
+  public function preprocess(array $parsedBlocks): array {
+    return $this->addTopLevelColumns($parsedBlocks);
+  }
+
+  /**
+   * In the editor we allow putting content blocks directly into the root level of the email.
+   * But for rendering purposes it is more convenient to have them wrapped in a single column.
+   * This method walks through the first level of blocks and wraps non column blocks into a single column.
+   */
+  private function addTopLevelColumns(array $parsedBlocks): array {
+    $wrappedParsedBlocks = [];
+    $nonColumnsBlocksBuffer = [];
+    foreach ($parsedBlocks as $block) {
+      // The next block is columns so we can flush the buffer and add the columns block
+      if ($block['blockName'] === 'core/columns') {
+        if ($nonColumnsBlocksBuffer) {
+          $columnsBlock = self::SINGLE_COLUMN_TEMPLATE;
+          $columnsBlock['innerBlocks'][0]['innerBlocks'] = $nonColumnsBlocksBuffer;
+          $nonColumnsBlocksBuffer = [];
+          $wrappedParsedBlocks[] = $columnsBlock;
+        }
+        $wrappedParsedBlocks[] = $block;
+        continue;
+      }
+      // Non columns block so we add it to the buffer
+      $nonColumnsBlocksBuffer[] = $block;
+    }
+    // Flush the buffer if there are any blocks left
+    if ($nonColumnsBlocksBuffer) {
+      $columnsBlock = self::SINGLE_COLUMN_TEMPLATE;
+      $columnsBlock['innerBlocks'][0]['innerBlocks'] = $nonColumnsBlocksBuffer;
+      $wrappedParsedBlocks[] = $columnsBlock;
+    }
+    return $wrappedParsedBlocks;
+  }
+}

mailpoet/lib/EmailEditor/Engine/Renderer/Renderer.php

@@ -13,6 +13,9 @@ class Renderer {
   /** @var BodyRenderer */
   private $bodyRenderer;
 
+  /** @var Preprocessor */
+  private $preprocessor;
+
   const TEMPLATE_FILE = 'template.html';
   const STYLES_FILE = 'styles.css';
 
@@ -21,14 +24,21 @@ class Renderer {
    */
   public function __construct(
     \MailPoetVendor\CSS $cssInliner,
+    Preprocessor $preprocessor,
     BodyRenderer $bodyRenderer
   ) {
     $this->cssInliner = $cssInliner;
+    $this->preprocessor = $preprocessor;
     $this->bodyRenderer = $bodyRenderer;
   }
 
   public function render(\WP_Post $post, string $subject, string $preHeader, string $language, $metaRobots = ''): array {
-    $renderedBody = $this->bodyRenderer->renderBody($post->post_content); // phpcs:ignore Squiz.NamingConventions.ValidVariableName.MemberNotCamelCaps
+    $parser = new \WP_Block_Parser();
+    $parsedBlocks = $parser->parse($post->post_content); // phpcs:ignore Squiz.NamingConventions.ValidVariableName.MemberNotCamelCaps
+
+    $parsedBlocks = $this->preprocessor->preprocess($parsedBlocks);
+    $renderedBody = $this->bodyRenderer->renderBody($parsedBlocks);
+
     $styles = (string)file_get_contents(dirname(__FILE__) . '/' . self::STYLES_FILE);
     $styles = apply_filters('mailpoet_email_renderer_styles', $styles, $post);
 

mailpoet/tests/unit/EmailEditor/Engine/Renderer/PreprocessorTest.php

@@ -0,0 +1,63 @@
+<?php declare(strict_types = 1);
+
+namespace MailPoet\EmailEditor\Engine\Renderer;
+
+class PreprocessorTest extends \MailPoetUnitTest {
+
+  private $paragraphBlock = [
+    'blockName' => 'core/paragraph',
+    'attrs' => [],
+    'innerHTML' => 'Paragraph content',
+  ];
+
+  private $columnsBlock = [
+    'blockName' => 'core/columns',
+    'attrs' => [],
+    'innerBlocks' => [[
+      'blockName' => 'core/column',
+      'attrs' => [],
+      'innerBlocks' => [],
+    ]],
+  ];
+
+  /** @var Preprocessor */
+  private $preprocessor;
+
+  public function _before() {
+    parent::_before();
+    $this->preprocessor = new Preprocessor();
+  }
+
+  public function testItWrapsSingleTopLevelBlockIntoColumns() {
+    $parsedDocument = [$this->paragraphBlock];
+    $result = $this->preprocessor->preprocess($parsedDocument);
+    expect($result[0]['blockName'])->equals('core/columns');
+    expect($result[0]['innerBlocks'][0]['blockName'])->equals('core/column');
+    expect($result[0]['innerBlocks'][0]['innerBlocks'][0]['blockName'])->equals('core/paragraph');
+    expect($result[0]['innerBlocks'][0]['innerBlocks'][0]['innerHTML'])->equals('Paragraph content');
+  }
+
+  public function testItDoesntWrapColumns() {
+    $parsedDocumentWithMultipleColumns = [$this->columnsBlock, $this->columnsBlock];
+    $result = $this->preprocessor->preprocess($parsedDocumentWithMultipleColumns);
+    expect($result)->equals($parsedDocumentWithMultipleColumns);
+  }
+
+  public function testItWrapsTopLevelBlocksSpreadBetweenColumns() {
+    $parsedDocument = [$this->paragraphBlock, $this->columnsBlock, $this->paragraphBlock, $this->paragraphBlock];
+    // We expect to wrap top level paragraph blocks into columns so the result should three columns blocks
+    $result = $this->preprocessor->preprocess($parsedDocument);
+    expect($result)->count(3);
+    // First columns contain columns with one paragraph block
+    expect($result[0]['innerBlocks'][0]['blockName'])->equals('core/column');
+    expect($result[0]['innerBlocks'][0]['innerBlocks'][0]['blockName'])->equals('core/paragraph');
+    // Second columns remains empty
+    expect($result[1]['innerBlocks'][0]['blockName'])->equals('core/column');
+    expect($result[1]['innerBlocks'][0]['innerBlocks'])->isEmpty();
+    // Third columns contain columns with two paragraph blocks
+    expect($result[2]['innerBlocks'][0]['blockName'])->equals('core/column');
+    expect($result[2]['innerBlocks'][0]['innerBlocks'])->count(2);
+    expect($result[2]['innerBlocks'][0]['innerBlocks'][0]['blockName'])->equals('core/paragraph');
+    expect($result[2]['innerBlocks'][0]['innerBlocks'][1]['blockName'])->equals('core/paragraph');
+  }
+}