<?php
/**
 * Renders the email preview.
 */

declare( strict_types=1 );

namespace Automattic\WooCommerce\Internal\Admin\EmailPreview;

use Automattic\WooCommerce\Internal\EmailEditor\WooContentProcessor;
use Automattic\WooCommerce\Enums\OrderStatus;
use Throwable;
use WC_Email;
use WC_Order;
use WC_Order_Item_Product;
use WC_Order_Item_Shipping;
use WC_Product;
use WC_Product_Variation;
use WP_User;

defined( 'ABSPATH' ) || exit;


/**
 * EmailPreview Class.
 */
class EmailPreview {
	const DEFAULT_EMAIL_TYPE = 'WC_Email_Customer_Processing_Order';
	const DEFAULT_EMAIL_ID   = 'customer_processing_order';
	const USER_OBJECT_EMAILS = array(
		'WC_Email_Customer_New_Account',
		'WC_Email_Customer_Reset_Password',
	);

	const TRANSIENT_PREVIEW_EMAIL_IMPROVEMENTS = 'woocommerce_preview_email_improvements';

	/**
	 * All fields IDs that can customize email styles in Settings.
	 *
	 * @var array
	 */
	private static array $email_style_setting_ids = array(
		'woocommerce_email_background_color',
		'woocommerce_email_base_color',
		'woocommerce_email_body_background_color',
		'woocommerce_email_font_family',
		'woocommerce_email_footer_text',
		'woocommerce_email_footer_text_color',
		'woocommerce_email_header_alignment',
		'woocommerce_email_header_image',
		'woocommerce_email_header_image_width',
		'woocommerce_email_text_color',
	);

	/**
	 * All fields IDs that can customize specific email content in Settings.
	 *
	 * @var array
	 */
	private static array $email_content_setting_ids = array();

	/**
	 * Whether the email setting IDs are initialized.
	 *
	 * @var bool
	 */
	private static bool $email_setting_ids_initialized = false;

	/**
	 * The email type to preview.
	 *
	 * @var string|null
	 */
	private ?string $email_type = null;

	/**
	 * The email object.
	 *
	 * @var WC_Email|null
	 */
	private ?WC_Email $email = null;

	/**
	 * The single instance of the class.
	 *
	 * @var object
	 */
	protected static $instance = null;

	/**
	 * Whether the locale has been switched when rendering the preview.
	 *
	 * @var bool
	 */
	private bool $locale_switched = false;

	/**
	 * Get class instance.
	 *
	 * @return object Instance.
	 */
	final public static function instance() {
		if ( null === static::$instance ) {
			static::$instance = new static();
		}
		return static::$instance;
	}

	/**
	 * Get all email setting IDs.
	 */
	public static function get_all_email_setting_ids() {
		if ( ! self::$email_setting_ids_initialized ) {
			self::$email_setting_ids_initialized = true;

			$emails = WC()->mailer()->get_emails();
			foreach ( $emails as $email ) {
				self::$email_content_setting_ids = array_merge(
					self::$email_content_setting_ids,
					self::get_email_content_setting_ids( $email->id )
				);
			}
			self::$email_content_setting_ids = array_unique( self::$email_content_setting_ids );
		}
		return array_merge(
			self::$email_style_setting_ids,
			self::$email_content_setting_ids,
		);
	}

	/**
	 * Get email style setting IDs.
	 */
	public static function get_email_style_setting_ids() {
		/**
		 * Filter the email style setting IDs. Email preview automatically refreshes when these settings are changed.
		 *
		 * @param array $setting_ids The email style setting IDs.
		 *
		 * @since 9.8.0
		 */
		return apply_filters( 'woocommerce_email_preview_email_style_setting_ids', self::$email_style_setting_ids );
	}

	/**
	 * Get email content setting IDs for specific email.
	 *
	 * @param string|null $email_id Email ID.
	 */
	public static function get_email_content_setting_ids( ?string $email_id ) {
		if ( ! $email_id ) {
			return array();
		}
		$setting_ids = array(
			"woocommerce_{$email_id}_subject",
			"woocommerce_{$email_id}_heading",
			"woocommerce_{$email_id}_additional_content",
			"woocommerce_{$email_id}_email_type",
		);

		/**
		 * Filter the email content setting IDs for specific email. Email preview automatically refreshes when these settings are changed.
		 *
		 * @param array  $setting_ids The email content setting IDs.
		 * @param string $email_id The email ID.
		 *
		 * @since 9.8.0
		 */
		return apply_filters( 'woocommerce_email_preview_email_content_setting_ids', $setting_ids, $email_id );
	}

	/**
	 * Set the email type to preview.
	 *
	 * @param string $email_type Email type.
	 *
	 * @throws \InvalidArgumentException When the email type is invalid.
	 */
	public function set_email_type( string $email_type ) {
		$this->switch_to_site_locale();

		$wc_emails = WC()->mailer()->get_emails();
		$emails    = array_combine(
			array_map( 'get_class', $wc_emails ),
			$wc_emails
		);
		if ( ! in_array( $email_type, array_keys( $emails ), true ) ) {
			throw new \InvalidArgumentException( 'Invalid email type' );
		}
		$this->email_type = $email_type;
		$this->email      = $emails[ $email_type ];
		$object           = null;

		if ( in_array( $email_type, self::USER_OBJECT_EMAILS, true ) ) {
			$object                  = new WP_User( 0 );
			$object->user_email      = 'user_preview@example.com';
			$object->user_login      = 'user_preview';
			$object->first_name      = 'John';
			$object->last_name       = 'Doe';
			$this->email->user_email = $object->user_email;
			$this->email->user_login = $object->user_login;

			if ( property_exists( $this->email, 'reset_key' ) ) {
				$this->email->reset_key = 'reset_key';
			}

			if ( property_exists( $this->email, 'set_password_url' ) ) {
				$this->email->set_password_url = 'https://example.com/set-password';
			}

			if ( property_exists( $this->email, 'user_id' ) ) {
				$this->email->user_id = 0;
			}

			$this->email->set_object( $object );
		} else {
			$object = $this->get_dummy_order();
			if ( 'WC_Email_Customer_Note' === $email_type ) {
				$this->email->customer_note = __( "This is an order note sent from the Admin to the customer during fulfillment when you add a new Order Note and choose to send it to the customer.\n\nIt can be multiple lines.", 'woocommerce' );
			}
			if ( 'WC_Email_Customer_Refunded_Order' === $email_type ) {
				$this->email->partial_refund = false;
			}
			$this->email->set_object( $object );
		}
		$this->email->placeholders = array_merge(
			$this->email->placeholders,
			$this->get_placeholders( $object )
		);

		/**
		 * Allow to modify the email object before rendering the preview to add additional data.
		 *
		 * @param WC_Email $email The email object.
		 *
		 * @since 9.6.0
		 */
		$this->email = apply_filters( 'woocommerce_prepare_email_for_preview', $this->email );

		$this->restore_locale();
	}

	/**
	 * Get the email object.
	 *
	 * @return WC_Email
	 */
	public function get_email() {
		return $this->email;
	}

	/**
	 * Get the preview email content.
	 *
	 * @return string
	 */
	public function render() {
		return $this->render_preview_email();
	}

	/**
	 * Ensure links open in new tab. User in WooCommerce Settings,
	 * so the links don't open inside the iframe.
	 *
	 * @param string $content Email content HTML.
	 * @return string
	 */
	public function ensure_links_open_in_new_tab( string $content ) {
		if ( empty( $content ) || strpos( $content, '<a' ) === false ) {
			return $content;
		}

		if ( ! class_exists( 'DOMDocument' ) ) {
			return $content;
		}

		// Suppress libxml errors to prevent them from being displayed.
		$previous_use_internal_errors = libxml_use_internal_errors( true );

		try {
			$dom = new \DOMDocument();

			// Add UTF-8 encoding and load with error suppression flags.
			$html_with_encoding = '<?xml encoding="UTF-8">' . $content;
			$dom->loadHTML(
				$html_with_encoding,
				LIBXML_HTML_NOIMPLIED | LIBXML_HTML_NODEFDTD | LIBXML_NOWARNING | LIBXML_NOERROR
			);

			$links = $dom->getElementsByTagName( 'a' );
			foreach ( $links as $link ) {
				$link->setAttribute( 'target', '_blank' );
				$link->setAttribute( 'rel', 'noopener' );
			}

			$result = $dom->saveHTML();

			// Remove the XML declaration we added earlier, it's not meant to be used in an HTML document.
			$result = preg_replace( '/<\?xml[^>]*>\s*/i', '', $result );

			return $result;
		} catch ( \Exception $e ) {
			return $content;
		} finally {
			libxml_use_internal_errors( $previous_use_internal_errors );
			libxml_clear_errors();
		}
	}

	/**
	 * Get the preview email content.
	 *
	 * @return string
	 */
	public function get_subject() {
		if ( ! $this->email ) {
			return '';
		}
		$this->set_up_filters();
		$subject = $this->email->get_subject();
		$this->clean_up_filters();
		return $subject;
	}

	/**
	 * Return a dummy product when the product is not set in email classes.
	 *
	 * @param WC_Product|null $product Order item product.
	 * @return WC_Product
	 */
	public function get_dummy_product_when_not_set( $product ) {
		if ( $product ) {
			return $product;
		}
		return $this->get_dummy_product();
	}

	/**
	 * Render HTML content of the preview email.
	 *
	 * @return string
	 */
	private function render_preview_email() {
		if ( ! $this->email_type ) {
			$this->set_email_type( self::DEFAULT_EMAIL_TYPE );
		}

		$this->set_up_filters();

		if ( 'plain' === $this->email->get_email_type() ) {
			$content  = '<pre style="word-wrap: break-word; white-space: pre-wrap; text-align: ' . ( is_rtl() ? 'right' : 'left' ) . ';">';
			$content .= $this->email->get_content_plain();
			$content .= '</pre>';
		} else {
			$content = $this->email->get_content_html();
		}
		$inlined = $this->email->style_inline( $content );

		$this->clean_up_filters();

		/** This filter is documented in src/Internal/Admin/EmailPreview/EmailPreview.php */
		return apply_filters( 'woocommerce_mail_content', $inlined ); // phpcs:ignore WooCommerce.Commenting.CommentHooks.MissingSinceComment
	}

	/**
	 * Get a dummy order object without the need to create in the database.
	 *
	 * @return WC_Order
	 */
	private function get_dummy_order() {
		$product              = $this->get_dummy_product();
		$variation            = $this->get_dummy_product_variation();
		$downloadable_product = $this->get_dummy_downloadable_product();

		// PreviewOrder keeps its id at 0 so it can never read from or write to a
		// real order. It surfaces a display number via get_order_number() instead.
		$order = new PreviewOrder();

		// Create and add product items manually without saving to database.
		// Use add_item() instead of add_product() to avoid immediate database writes.
		if ( $product ) {
			$item = new WC_Order_Item_Product();
			$item->set_props(
				array(
					'name'         => $product->get_name(),
					'tax_class'    => $product->get_tax_class(),
					'product_id'   => $product->get_id(),
					'variation_id' => 0,
					'quantity'     => 2,
					'subtotal'     => $product->get_price() * 2,
					'total'        => $product->get_price() * 2,
				)
			);
			$order->add_item( $item );
		}
		if ( $variation ) {
			$item = new WC_Order_Item_Product();
			$item->set_props(
				array(
					'name'         => $variation->get_name(),
					'tax_class'    => $variation->get_tax_class(),
					'product_id'   => $variation->get_parent_id(),
					'variation_id' => $variation->get_id(),
					'variation'    => $variation->get_attributes(),
					'quantity'     => 1,
					'subtotal'     => $variation->get_price(),
					'total'        => $variation->get_price(),
				)
			);
			$order->add_item( $item );
		}
		if ( $downloadable_product ) {
			$item = new WC_Order_Item_Product();
			$item->set_props(
				array(
					'name'         => $downloadable_product->get_name(),
					'tax_class'    => $downloadable_product->get_tax_class(),
					'product_id'   => $downloadable_product->get_id(),
					'variation_id' => 0,
					'quantity'     => 1,
					'subtotal'     => $downloadable_product->get_price(),
					'total'        => $downloadable_product->get_price(),
				)
			);
			$order->add_item( $item );
		}

		$order->set_date_created( time() );
		$order->set_currency( 'USD' );
		$order->set_discount_total( 10 );
		$order->set_shipping_total( 5 );
		$order->set_total( 80 );
		$order->set_payment_method_title( __( 'Direct bank transfer', 'woocommerce' ) );
		$order->set_transaction_id( '999999999' );
		$order->set_customer_note( __( "This is a customer note. Customers can add a note to their order on checkout.\n\nIt can be multiple lines. If there's no note, this section is hidden.", 'woocommerce' ) );

		$order = $this->apply_dummy_order_status( $order );

		// Add shipping method.
		$shipping_item = new WC_Order_Item_Shipping();
		$shipping_item->set_props(
			array(
				'method_title' => __( 'Flat rate', 'woocommerce' ),
				'method_id'    => 'flat_rate',
				'total'        => '5.00',
			)
		);
		$order->add_item( $shipping_item );

		$address = $this->get_dummy_address();
		$order->set_billing_address( $address );
		$order->set_shipping_address( $address );

		/**
		 * A dummy WC_Order used in email preview.
		 *
		 * @param WC_Order $order The dummy order object.
		 * @param string   $email_type The email type to preview.
		 *
		 * @since 9.6.0
		 */
		return apply_filters( 'woocommerce_email_preview_dummy_order', $order, $this->email_type );
	}

	/**
	 * Apply a contextual status to the dummy order based on the previewed email type.
	 *
	 * @param WC_Order $order Dummy order instance.
	 * @return WC_Order
	 */
	private function apply_dummy_order_status( WC_Order $order ): WC_Order {
		$email_type_status_map = array(
			'WC_Email_Customer_Completed_Order'  => OrderStatus::COMPLETED,
			'WC_Email_Customer_Processing_Order' => OrderStatus::PROCESSING,
			'WC_Email_Customer_On_Hold_Order'    => OrderStatus::ON_HOLD,
			'WC_Email_Customer_Failed_Order'     => OrderStatus::FAILED,
			'WC_Email_Customer_Cancelled_Order'  => OrderStatus::CANCELLED,
			'WC_Email_Customer_Refunded_Order'   => OrderStatus::REFUNDED,
			'WC_Email_New_Order'                 => OrderStatus::PROCESSING,
			'WC_Email_Cancelled_Order'           => OrderStatus::CANCELLED,
			'WC_Email_Failed_Order'              => OrderStatus::FAILED,
		);

		$status = $email_type_status_map[ $this->email_type ] ?? OrderStatus::PROCESSING;
		$order->set_status( $status );
		return $order;
	}

	/**
	 * Get a dummy product. Also used with `woocommerce_order_item_product` filter
	 * when email templates tries to get the product from the database.
	 *
	 * @return WC_Product
	 */
	private function get_dummy_product() {
		$product = new WC_Product();
		$product->set_name( __( 'Dummy Product', 'woocommerce' ) );
		$product->set_price( 25 );

		/**
		 * A dummy WC_Product used in email preview.
		 *
		 * @param WC_Product $product The dummy product object.
		 * @param string     $email_type The email type to preview.
		 *
		 * @since 9.6.0
		 */
		return apply_filters( 'woocommerce_email_preview_dummy_product', $product, $this->email_type );
	}

	/**
	 * Get a dummy product variation.
	 *
	 * @return WC_Product_Variation
	 */
	private function get_dummy_product_variation() {
		$variation = new WC_Product_Variation();
		$variation->set_name( __( 'Dummy Product Variation', 'woocommerce' ) );
		$variation->set_price( 20 );
		$variation->set_attributes(
			array(
				__( 'Color', 'woocommerce' ) => __( 'Red', 'woocommerce' ),
				__( 'Size', 'woocommerce' )  => __( 'Small', 'woocommerce' ),
			)
		);

		/**
		 * A dummy WC_Product_Variation used in email preview.
		 *
		 * @param WC_Product_Variation $variation The dummy product variation object.
		 * @param string               $email_type The email type to preview.
		 *
		 * @since 9.7.0
		 */
		return apply_filters( 'woocommerce_email_preview_dummy_product_variation', $variation, $this->email_type );
	}

	/**
	 * Get a dummy downloadable/virtual product.
	 *
	 * @return WC_Product
	 */
	private function get_dummy_downloadable_product() {
		$product = new WC_Product();
		$product->set_name( __( 'Dummy Downloadable Product', 'woocommerce' ) );
		$product->set_price( 15 );
		$product->set_virtual( true );
		$product->set_downloadable( true );

		/**
		 * A dummy downloadable WC_Product used in email preview.
		 *
		 * @param WC_Product $product The dummy downloadable product object.
		 * @param string     $email_type The email type to preview.
		 *
		 * @since 10.3.0
		 */
		return apply_filters( 'woocommerce_email_preview_dummy_downloadable_product', $product, $this->email_type );
	}

	/**
	 * Get a dummy address.
	 *
	 * @return array
	 */
	private function get_dummy_address() {
		$address = array(
			'first_name' => 'John',
			'last_name'  => 'Doe',
			'company'    => 'Company',
			'email'      => 'john@company.com',
			'phone'      => '555-555-5555',
			'address_1'  => '123 Fake Street',
			'city'       => 'Faketown',
			'postcode'   => '12345',
			'country'    => 'US',
			'state'      => 'CA',
		);

		/**
		 * A dummy address used in email preview as billing and shipping one.
		 *
		 * @param array  $address The dummy address.
		 * @param string $email_type The email type to preview.
		 *
		 * @since 9.6.0
		 */
		return apply_filters( 'woocommerce_email_preview_dummy_address', $address, $this->email_type );
	}

	/**
	 * Get the placeholders for the email preview.
	 *
	 * @param mixed $email_object The object to render email with. Can be WC_Order, WP_User, etc.
	 * @return array
	 */
	private function get_placeholders( $email_object ) {
		$placeholders = array();

		if ( is_a( $email_object, 'WC_Order' ) ) {
			$placeholders['{order_date}']              = wc_format_datetime( $email_object->get_date_created() );
			$placeholders['{order_number}']            = $email_object->get_order_number();
			$placeholders['{order_billing_full_name}'] = $email_object->get_formatted_billing_full_name();
		}

		/**
		 * Placeholders for email preview.
		 *
		 * @param array  $placeholders Placeholders for email subject.
		 * @param string $email_type   The email type to preview.
		 * @param mixed  $email_object The object to render email with. @since 9.9.0
		 *
		 * @since 9.6.0
		 */
		return apply_filters( 'woocommerce_email_preview_placeholders', $placeholders, $this->email_type, $email_object );
	}

	/**
	 * Set up filters for email preview.
	 */
	public function set_up_filters() {
		$this->switch_to_site_locale();
		// Always show shipping address in the preview email.
		add_filter( 'woocommerce_order_needs_shipping_address', array( $this, 'enable_shipping_address' ) );
		// Email templates fetch product from the database to show additional information, which are not
		// saved in WC_Order_Item_Product. This filter enables fetching that data also in email preview.
		add_filter( 'woocommerce_order_item_product', array( $this, 'get_dummy_product_when_not_set' ), 10, 1 );
		// Enable email preview mode - this way transient values are fetched for live preview.
		add_filter( 'woocommerce_is_email_preview', array( $this, 'enable_preview_mode' ) );
		// Use placeholder image included in WooCommerce files.
		add_filter( 'woocommerce_order_item_thumbnail', array( $this, 'get_placeholder_image' ) );
		// Make products in preview considered downloadable and provide dummy file so WC core shows downloads.
		add_filter( 'woocommerce_is_downloadable', array( $this, 'force_product_downloadable' ), 10, 1 );
		add_filter( 'woocommerce_product_file', array( $this, 'provide_dummy_product_file' ), 10, 1 );
		// Provide dummy downloadable items for email preview.
		add_filter( 'woocommerce_order_get_downloadable_items', array( $this, 'get_dummy_downloadable_items' ), 10, 1 );
	}

	/**
	 * Clean up filters after email preview.
	 */
	public function clean_up_filters() {
		remove_filter( 'woocommerce_order_needs_shipping_address', array( $this, 'enable_shipping_address' ) );
		remove_filter( 'woocommerce_order_item_product', array( $this, 'get_dummy_product_when_not_set' ), 10 );
		remove_filter( 'woocommerce_is_email_preview', array( $this, 'enable_preview_mode' ) );
		remove_filter( 'woocommerce_order_item_thumbnail', array( $this, 'get_placeholder_image' ) );
		remove_filter( 'woocommerce_is_downloadable', array( $this, 'force_product_downloadable' ), 10 );
		remove_filter( 'woocommerce_product_file', array( $this, 'provide_dummy_product_file' ), 10 );
		remove_filter( 'woocommerce_order_get_downloadable_items', array( $this, 'get_dummy_downloadable_items' ), 10 );
		$this->restore_locale();
	}

	/**
	 * Enable shipping address in the preview email. Not using __return_true so
	 * we don't accidentally remove the same filter used by other plugin or theme.
	 *
	 * @return true
	 */
	public function enable_shipping_address() {
		return true;
	}

	/**
	 * Enable preview mode to use transient values in email-styles.php. Not using __return_true
	 * so we don't accidentally remove the same filter used by other plugin or theme.
	 *
	 * @return true
	 */
	public function enable_preview_mode() {
		return true;
	}

	/**
	 * Get the placeholder image for the preview email.
	 *
	 * @return string
	 */
	public function get_placeholder_image() {
		return '<img src="' . WC()->plugin_url() . '/assets/images/placeholder.webp" width="48" height="48" alt="" />';
	}

	/**
	 * Force products in preview to be considered downloadable so core renders downloads section.
	 *
	 * @param bool $is_downloadable Current value.
	 * @return bool
	 */
	public function force_product_downloadable( $is_downloadable ) {
		/**
		 * Filters whether the current request is an email preview.
		 *
		 * When true, products should be considered downloadable so the downloads
		 * section renders in applicable emails during preview.
		 *
		 * @since 9.6.0
		 *
		 * @param bool $is_email_preview Whether preview mode is active.
		 */
		if ( apply_filters( 'woocommerce_is_email_preview', false ) ) {
			return true;
		}
		return $is_downloadable;
	}

	/**
	 * Provide a dummy product file so product->has_file() returns true in preview.
	 *
	 * @param array|null $file Current file array or null.
	 * @return array|null
	 */
	public function provide_dummy_product_file( $file ) {
		/**
		 * Filters whether the current request is an email preview.
		 *
		 * When true, provide a dummy product file array so downloadable template parts
		 * can render during preview.
		 *
		 * @since 9.6.0
		 *
		 * @param bool $is_email_preview Whether preview mode is active.
		 */
		if ( apply_filters( 'woocommerce_is_email_preview', false ) ) {
			return array(
				'name' => __( 'Sample Download File.pdf', 'woocommerce' ),
				'file' => 'sample-download.pdf',
			);
		}
		return $file;
	}

	/**
	 * Get dummy downloadable items for email preview.
	 *
	 * @param array $downloads Existing downloads.
	 * @return array
	 */
	public function get_dummy_downloadable_items( $downloads ) {
		$dummy_downloads = array(
			array(
				'product_name'   => $this->get_dummy_downloadable_product()->get_name(),
				'product_id'     => $this->get_dummy_downloadable_product()->get_id(),
				'download_url'   => 'https://example.com/download',
				'download_name'  => __( 'Sample Download File.pdf', 'woocommerce' ),
				'access_expires' => time() + ( 30 * DAY_IN_SECONDS ),
			),
		);

		return array_merge( $downloads, $dummy_downloads );
	}

	/**
	 * Generate placeholder content for a specific email type, typically used in the email editor.
	 *
	 * Encapsulates the logic for setting the email type, generating raw content, applying styles,
	 * ensuring links open in new tabs, and handling errors based on WP_DEBUG.
	 *
	 * @param string $email_type_class_name The class name of the WC_Email type (e.g., 'WC_Email_Customer_Processing_Order').
	 * @return string The generated and styled HTML content.
	 * @throws \RuntimeException If content generation fails. If rendering fails.
	 */
	public function generate_placeholder_content( string $email_type_class_name ): string {
		// Note: set_email_type can throw InvalidArgumentException.
		$this->set_email_type( $email_type_class_name );

		$woo_content_processor = wc_get_container()->get( WooContentProcessor::class );

		$generate_content_closure = function () use ( $woo_content_processor ) {
			// Note: If 'woocommerce_email_styles' filter was intentional and `prepare_css` isn't
			// the intended callback, adjust accordingly. This assumes `prepare_css` applies styles
			// needed for the Woo content block.
			add_filter( 'woocommerce_email_styles', array( $woo_content_processor, 'prepare_css' ), 10, 2 );
			$content = $woo_content_processor->get_woo_content( $this->get_email() );
			$content = $this->get_email()->style_inline( $content );
			$content = $this->ensure_links_open_in_new_tab( $content );
			return $content;
		};

		$this->set_up_filters();

		$message = '';
		try {
			if ( defined( 'WP_DEBUG' ) && WP_DEBUG ) {
				$message = $generate_content_closure();
			} else {
				// Use output buffering to prevent partial renders with PHP notices or warnings when WP_DEBUG is off.
				ob_start();
				try {
					$message = $generate_content_closure();
				} catch ( Throwable $e ) {
					ob_end_clean();
					// Let the caller handle the exception.
					throw new \RuntimeException( esc_html__( 'There was an error rendering the email editor placeholder content.', 'woocommerce' ), 0, $e );
				}
				ob_end_clean();
			}
		} finally {
			$this->clean_up_filters();
		}

		return $message;
	}

	/**
	 * Switch to the site locale. This is to ensure the email is displayed
	 * in the store's language, as the customer would see it, not the admin's language.
	 */
	private function switch_to_site_locale() {
		if ( ! $this->locale_switched ) {
			wc_switch_to_site_locale();
			$this->locale_switched = true;
		}
	}

	/**
	 * Restore the original locale.
	 */
	private function restore_locale() {
		if ( $this->locale_switched ) {
			wc_restore_locale();
			$this->locale_switched = false;
		}
	}
}
