woocommerce/plugins/woocommerce-blocks/src/BlockTemplatesController.php

<?php
namespace Automattic\WooCommerce\Blocks;

use Automattic\WooCommerce\Blocks\Utils\BlockTemplateUtils;

/**
 * BlockTypesController class.
 *
 * @internal
 */
class BlockTemplatesController {

	/**
	 * Holds the path for the directory where the block templates will be kept.
	 *
	 * @var string
	 */
	private $templates_directory;

	/**
	 * Directory name of the block template directory.
	 *
	 * @var string
	 */
	const TEMPLATES_DIR_NAME = 'block-templates';

	/**
	 * Constructor.
	 */
	public function __construct() {
		$this->templates_directory = plugin_dir_path( __DIR__ ) . 'templates/' . self::TEMPLATES_DIR_NAME;
		$this->init();
	}

	/**
	 * Initialization method.
	 */
	protected function init() {
		add_filter( 'get_block_templates', array( $this, 'add_block_templates' ), 10, 3 );
	}

	/**
	 * Add the block template objects to be used.
	 *
	 * @param array $query_result Array of template objects.
	 * @param array $query Optional. Arguments to retrieve templates.
	 * @param array $template_type wp_template or wp_template_part.
	 * @return array
	 */
	public function add_block_templates( $query_result, $query, $template_type ) {
		if ( ! gutenberg_supports_block_templates() || 'wp_template' !== $template_type ) {
			return $query_result;
		}

		$template_files = $this->get_block_templates();

		foreach ( $template_files as $template_file ) {
			$query_result[] = BlockTemplateUtils::gutenberg_build_template_result_from_file( $template_file, 'wp_template' );
		}

		return $query_result;
	}

	/**
	 * Get and build the block template objects from the block template files.
	 *
	 * @return array
	 */
	public function get_block_templates() {
		$template_files = BlockTemplateUtils::gutenberg_get_template_paths( $this->templates_directory );
		$templates      = array();

		foreach ( $template_files as $template_file ) {
			$template_slug = substr(
				$template_file,
				strpos( $template_file, self::TEMPLATES_DIR_NAME . DIRECTORY_SEPARATOR ) + 1 + strlen( self::TEMPLATES_DIR_NAME ),
				-5
			);

			// If the theme already has a template then there is no need to load ours in.
			if ( $this->theme_has_template( $template_slug ) ) {
				continue;
			}

			$new_template_item = array(
				'title' => ucwords( str_replace( '-', ' ', $template_slug ) ),
				'slug'  => $template_slug,
				'path'  => $template_file,
				'theme' => get_template_directory(),
				'type'  => 'wp_template',
			);
			$templates[]       = $new_template_item;
		}

		return $templates;
	}

	/**
	 * Check if the theme has a template. So we know if to load our own in or not.
	 *
	 * @param string $template_name name of the template file without .html extension e.g. 'single-product'.
	 * @return boolean
	 */
	public function theme_has_template( $template_name ) {
		return is_readable( get_template_directory() . '/block-templates/' . $template_name . '.html' ) ||
			is_readable( get_stylesheet_directory() . '/block-templates/' . $template_name . '.html' );
	}
}