heretek-control-core/includes/class-child-theme-builder.php

<?php
/**
 * Scaffolds and activates a child theme of the active parent theme.
 *
 * This is the framework-agnostic enabler for agent-driven theme file edits: it
 * creates `style.css` + a minimal `functions.php` inside a fresh child theme
 * directory and switches to it. The agent then performs file writes through the
 * existing Filesystem tools (ABSPATH-confined, `edit_files`-gated, backed up,
 * audit-logged) targeting the returned child directory.
 *
 * Deliberately conservative: it only ever creates a child of the CURRENT active
 * parent, refuses when the active theme is already a child (no grandchildren),
 * never touches the parent or any other theme, and is idempotent (an existing
 * child is activated, never overwritten).
 *
 * @package EMCP_Tools
 * @since   3.4.0
 */

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/**
 * Child theme scaffolder.
 */
class EMCP_Tools_Child_Theme_Builder {

	/**
	 * Whether the active theme is itself a child (stylesheet != template).
	 *
	 * @return bool
	 */
	public static function is_active_a_child(): bool {
		return get_stylesheet() !== get_template();
	}

	/**
	 * The active parent (template) slug.
	 *
	 * @return string
	 */
	public static function parent_slug(): string {
		return (string) get_template();
	}

	/**
	 * The child theme slug (`<parent>-child`).
	 *
	 * @return string
	 */
	public static function child_slug(): string {
		return self::parent_slug() . '-child';
	}

	/**
	 * The child theme directory path.
	 *
	 * @return string
	 */
	public static function child_dir(): string {
		return trailingslashit( get_theme_root() ) . self::child_slug();
	}

	/**
	 * Whether the child theme directory already exists on disk.
	 *
	 * @return bool
	 */
	public static function child_exists(): bool {
		return is_dir( self::child_dir() );
	}

	/**
	 * Create (if needed) and activate the child theme.
	 *
	 * @return array|WP_Error { child, parent, directory, activated, created } or error.
	 */
	public static function create() {
		if ( self::is_active_a_child() ) {
			return new WP_Error(
				'is_child',
				__( 'The active theme is already a child theme; refusing to create a grandchild.', 'emcp-tools' )
			);
		}

		$parent  = self::parent_slug();
		$slug    = self::child_slug();
		$dir     = self::child_dir();
		$existed = self::child_exists();

		if ( ! $existed ) {
			if ( ! wp_mkdir_p( $dir ) ) {
				return new WP_Error( 'mkdir_failed', __( 'Could not create the child theme directory.', 'emcp-tools' ) );
			}
			$parent_theme = wp_get_theme( $parent );
			$parent_name  = ( $parent_theme && '' !== (string) $parent_theme->get( 'Name' ) )
				? (string) $parent_theme->get( 'Name' )
				: ucfirst( $parent );

			$wrote_style = self::write_file( $dir . '/style.css', self::style_css( $parent, $parent_name ) );
			$wrote_funcs = self::write_file( $dir . '/functions.php', self::functions_php( $parent_name ) );
			if ( false === $wrote_style || false === $wrote_funcs ) {
				return new WP_Error( 'write_failed', __( 'Could not write the child theme files.', 'emcp-tools' ) );
			}
		}

		switch_theme( $slug );

		return array(
			'child'     => $slug,
			'parent'    => $parent,
			'directory' => $dir,
			'activated' => true,
			'created'   => ! $existed,
		);
	}

	/**
	 * Write a file, preferring WP_Filesystem when initialized, else direct
	 * (matching the Filesystem tools' direct-FS posture). The target is always
	 * inside wp-content/themes/<child>/.
	 *
	 * @param string $path     Absolute path.
	 * @param string $contents File contents.
	 * @return int|false Bytes written, or false on failure.
	 */
	private static function write_file( string $path, string $contents ) {
		global $wp_filesystem;
		if ( $wp_filesystem && is_object( $wp_filesystem ) && method_exists( $wp_filesystem, 'put_contents' ) ) {
			return $wp_filesystem->put_contents( $path, $contents ) ? strlen( $contents ) : false;
		}
		return file_put_contents( $path, $contents );
	}

	/**
	 * @param string $parent      Parent template slug.
	 * @param string $parent_name Parent display name.
	 * @return string
	 */
	private static function style_css( string $parent, string $parent_name ): string {
		return "/*\n"
			. 'Theme Name: ' . $parent_name . " Child\n"
			. 'Template: ' . $parent . "\n"
			. "Version: 1.0.0\n"
			. 'Description: Child theme of ' . $parent_name . ", generated by EMCP Tools.\n"
			. "*/\n";
	}

	/**
	 * @param string $parent_name Parent display name.
	 * @return string
	 */
	private static function functions_php( string $parent_name ): string {
		return "<?php\n"
			. '// ' . $parent_name . " child theme, generated by EMCP Tools.\n"
			. "if ( ! defined( 'ABSPATH' ) ) { exit; }\n\n"
			. "add_action( 'wp_enqueue_scripts', function () {\n"
			. "\twp_enqueue_style( 'emcp-parent-style', get_template_directory_uri() . '/style.css' );\n"
			. "} );\n";
	}
}