Add custom command for exporting body content

Add a custom Drush command that exports the body field values for node
and block body fields into a file.

This file can then be included within Tailwind's `purge` settings to
prevent classes used within the body fields from being purged.

References #55

.gitignore

@@ -15,4 +15,5 @@
 !/web/themes/custom/**
 /.idea/workspace.xml
 /vendor/
+/web/themes/custom/*/body-field-values.txt
 /web/themes/custom/*/dist/

web/modules/custom/custom/drush.services.yml

@@ -0,0 +1,6 @@
+services:
+  Drupal\custom\Command\ExportBodyValuesForThemePurgingCommand:
+    arguments: ['@database']
+    autowire: true
+    tags:
+      - { name: drush.command }

web/modules/custom/custom/src/Command/ExportBodyValuesForThemePurgingCommand.php

@@ -0,0 +1,49 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Drupal\custom\Command;
+
+use Drupal\Core\Database\Connection;
+use Illuminate\Support\Collection;
+
+final class ExportBodyValuesForThemePurgingCommand {
+
+  private static array $tableNames = [
+    'block_content__body',
+    'node__body',
+  ];
+
+  private string $filename = 'body-field-values.txt';
+
+  private Connection $database;
+
+  public function __construct(Connection $database) {
+    $this->database = $database;
+  }
+
+  /**
+   * Drush command to export body field values into a file.
+   *
+   * @command opdavies:export-body-values-for-theme-purging
+   */
+  public function handle() {
+    $values = Collection::make(self::$tableNames)
+      ->flatMap(fn(string $tableName) => $this->getValuesFromTable($tableName))
+      ->implode(PHP_EOL);
+
+    file_put_contents($this->getFilePath(), $values);
+  }
+
+  private function getFilePath(): string {
+    return drupal_get_path('theme', 'opdavies') . DIRECTORY_SEPARATOR . $this->filename;
+  }
+
+  private function getValuesFromTable(string $tableName): array {
+    return $this->database->select($tableName)
+      ->fields($tableName, ['body_value'])
+      ->execute()
+      ->fetchCol();
+  }
+
+}