class-edit-post-preview.php

<?php
/**
 * Edit Post Preview class.
 *
 * @package WordPress
 * @subpackage Customize
 */

/**
 * Class Edit_Post_Preview
 */
class Edit_Post_Preview {

	const PREVIEW_POST_NONCE_ACTION = 'customize_preview_post';
	const PREVIEW_POST_NONCE_QUERY_VAR = 'customize_preview_post_nonce';
	const UPDATE_CHANGESET_NONCE_ACTION = 'customize_posts_update_changeset';
	const UPDATE_CHANGESET_NONCE = 'customize_posts_update_changeset_nonce';

	/**
	 * Plugin instance.
	 *
	 * @access public
	 * @var Customize_Posts_Plugin
	 */
	public $plugin;

	/**
	 * Constructor.
	 *
	 * @access public
	 *
	 * @param Customize_Posts_Plugin $plugin Plugin instance.
	 */
	public function __construct( Customize_Posts_Plugin $plugin ) {
		$this->plugin = $plugin;
		add_action( 'admin_enqueue_scripts', array( $this, 'enqueue_admin_scripts' ) );
		add_filter( 'customize_loaded_components', array( $this, 'filter_customize_loaded_component' ) );
		add_action( 'customize_controls_init', array( $this, 'remove_static_controls_and_sections' ), 100 );
		add_action( 'customize_controls_enqueue_scripts', array( $this, 'enqueue_customize_scripts' ) );
		add_action( 'customize_preview_init', array( $this, 'make_auto_draft_status_previewable' ) );
		add_action( 'wp_ajax_' . self::UPDATE_CHANGESET_NONCE_ACTION, array( $this, 'update_post_changeset' ) );
	}

	/**
	 * Return whether the Customizer post preview should load.
	 *
	 * There must be a query var for the previewed_post and a valid nonce must be present.
	 */
	public function can_load_customize_post_preview() {
		return isset( $_GET['previewed_post'] ) && check_ajax_referer( self::PREVIEW_POST_NONCE_ACTION, self::PREVIEW_POST_NONCE_QUERY_VAR, false );
	}

	/**
	 * Remove widgets and nav_menus from loaded components if opening in post preview.
	 *
	 * Since all panels and sections are hidden aside from the post type panel and
	 * the section specific to this post, we can save load time by turning off these
	 * components.
	 *
	 * @param array $components Components.
	 * @return array Components.
	 */
	public function filter_customize_loaded_component( $components ) {
		if ( $this->can_load_customize_post_preview() ) {
			foreach ( array( 'widgets', 'nav_menus' ) as $component ) {
				$i = array_search( $component, $components, true );
				if ( false !== $i ) {
					unset( $components[ $i ] );
				}
			}
		}
		return $components;
	}

	/**
	 * Get previewed post.
	 *
	 * @return WP_Post|null
	 */
	public function get_previewed_post() {
		if ( function_exists( 'get_current_screen' ) && get_current_screen() && 'post' === get_current_screen()->base ) {
			$post = get_post();
		} elseif ( is_preview() ) {
			$post = get_post();
		} elseif ( isset( $_GET['previewed_post'] ) && preg_match( '/^\d+$/', wp_unslash( $_GET['previewed_post'] ) ) ) {
			$post = get_post( intval( $_GET['previewed_post'] ) );
		}
		if ( empty( $post ) ) {
			return null;
		}
		$post_type_obj = get_post_type_object( $post->post_type );
		if ( ! $post_type_obj || ! current_user_can( $post_type_obj->cap->edit_post, $post->ID ) ) {
			return null;
		}

		return $post;
	}

	/**
	 * Generate a preview permalink for a post/page.
	 *
	 * @access public
	 *
	 * @param WP_Post $post The post in question.
	 * @return string Edit post link.
	 */
	public static function get_preview_post_link( $post ) {
		$permalink = '';

		if ( $post instanceof WP_Post && post_type_exists( $post->post_type ) ) {
			$id_param = ( 'page' === $post->post_type ) ? 'page_id' : 'p';
			$args = array();
			$args['preview'] = true;
			$args[ $id_param ] = $post->ID;
			if ( 'page_id' !== $id_param && 'post' !== $post->post_type ) {
				$args['post_type'] = $post->post_type;
			}
			$permalink = get_preview_post_link( $post, $args, home_url( '/' ) );
		}

		return $permalink;
	}

	/**
	 * Enqueue scripts for post edit screen.
	 */
	public function enqueue_admin_scripts() {
		if ( ! function_exists( 'get_current_screen' ) || ! get_current_screen() || 'post' !== get_current_screen()->base || ! current_user_can( 'customize' ) ) {
			return;
		}
		wp_enqueue_script( 'edit-post-preview-admin' );
		wp_enqueue_style( 'edit-post-preview-admin' );
		$post = $this->get_previewed_post();

		$customize_url = add_query_arg(
			array(
				'previewed_post' => $post->ID,
				'autofocus[section]' => sprintf( 'post[%s][%d]', $post->post_type, $post->ID ),
				self::PREVIEW_POST_NONCE_QUERY_VAR => wp_create_nonce( self::PREVIEW_POST_NONCE_ACTION ),
			),
			wp_customize_url()
		);

		$data = array(
			'customize_url' => $customize_url,
			self::UPDATE_CHANGESET_NONCE => wp_create_nonce( self::UPDATE_CHANGESET_NONCE_ACTION ),
			'previewed_post' => $post->ID,
		);

		wp_scripts()->add_data( 'edit-post-preview-admin', 'data', sprintf( 'var _editPostPreviewAdminExports = %s;', wp_json_encode( $data ) ) );
		wp_enqueue_script( 'customize-loader' );
		wp_add_inline_script( 'edit-post-preview-admin', 'jQuery( function() { EditPostPreviewAdmin.init(); } );', 'after' );
	}

	/**
	 * Remove all statically-registered sections and controls.
	 *
	 * The post sections and the controls inside of them will be created dynamically.
	 * Anything construct other than the previewed post's panel should be removed.
	 */
	public function remove_static_controls_and_sections() {
		if ( ! $this->can_load_customize_post_preview() ) {
			return;
		}

		global $wp_customize;
		if ( empty( $wp_customize ) ) {
			return;
		}
		foreach ( $wp_customize->controls() as $control ) {
			$wp_customize->remove_control( $control->id );
		}
		foreach ( $wp_customize->sections() as $section ) {
			$wp_customize->remove_section( $section->id );
		}
	}

	/**
	 * Enqueue scripts for Customizer opened from post edit screen.
	 */
	public function enqueue_customize_scripts() {
		if ( ! $this->can_load_customize_post_preview() ) {
			return;
		}
		$post = $this->get_previewed_post();
		if ( ! $post ) {
			return;
		}
		wp_enqueue_script( 'edit-post-preview-customize' );
		wp_enqueue_style( 'edit-post-preview-customize' );
		$data = array(
			'previewed_post' => $post->to_array(),
		);
		wp_scripts()->add_data( 'edit-post-preview-customize', 'data', sprintf( 'var _editPostPreviewCustomizeExports = %s;', wp_json_encode( $data ) ) );
		wp_add_inline_script( 'edit-post-preview-customize', 'EditPostPreviewCustomize.init();', 'after' );
	}

	/**
	 * Make the auto-draft status protected so that it can be queried. Props iseulde.
	 *
	 * @link https://github.com/iseulde/wp-front-end-editor/blob/bc65aff6a9197aec3a91135e98b033279853ad98/src/class-fee.php#L39-L42
	 */
	public function make_auto_draft_status_previewable() {
		global $wp_post_statuses;
		$wp_post_statuses['auto-draft']->protected = true;
	}

	/**
	 * Updates changeset via ajax when preview button is clicked.
	 *
	 * @global WP_Customize_Manager $wp_customize
	 */
	public function update_post_changeset() {
		global $wp_customize;

		if ( ! check_ajax_referer( self::UPDATE_CHANGESET_NONCE_ACTION, self::UPDATE_CHANGESET_NONCE, false ) ) {
			status_header( 400 );
			wp_send_json_error( 'bad_nonce' );
		} elseif ( ! current_user_can( 'customize' ) ) {
			status_header( 403 );
			wp_send_json_error( 'customize_not_allowed' );
		} elseif ( ! isset( $_POST['previewed_post'] ) ) {
			status_header( 400 );
			wp_send_json_error( 'missing_previewed_post' );
		} elseif ( empty( $_POST['input_data'] ) || ! is_array( $_POST['input_data'] ) ) {
			status_header( 400 );
			wp_send_json_error( 'missing_input_data' );
		}

		$previewed_post_id = intval( wp_unslash( $_POST['previewed_post'] ) );
		if ( empty( $previewed_post_id ) || ! get_post( $previewed_post_id ) ) {
			status_header( 404 );
			wp_send_json_error( 'post_not_found' );
		} elseif ( ! current_user_can( 'edit_post', $previewed_post_id ) ) {
			status_header( 403 );
			wp_send_json_error( 'missing_previewed_post' );
		}

		$changeset_uuid = get_post_meta( $previewed_post_id, '_preview_changeset_uuid', true );

		if ( empty( $wp_customize ) || ! ( $wp_customize instanceof WP_Customize_Manager ) ) {
			require_once ABSPATH . WPINC . '/class-wp-customize-manager.php';
			require_once dirname( __FILE__ ) . '/class-wp-customize-posts.php';
		}

		if ( $changeset_uuid ) {
			$wp_customize = new WP_Customize_Manager( array(
				'changeset_uuid' => $changeset_uuid,
			) ); // WPCS: override ok.
			$changeset_post_id = $wp_customize->changeset_post_id();

			if ( $changeset_post_id ) {
				if ( 'publish' === get_post_status( $changeset_post_id ) ) {
					status_header( 400 );
					wp_send_json_error( 'changeset_already_published' );
				}

				if ( ! current_user_can( get_post_type_object( 'customize_changeset' )->cap->edit_post, $changeset_post_id ) ) {
					status_header( 403 );
					wp_send_json_error( 'cannot_edit_changeset_post' );
				}
			}
		}

		if ( empty( $changeset_post_id ) ) {
			if ( ! current_user_can( get_post_type_object( 'customize_changeset' )->cap->create_posts ) ) {
				status_header( 403 );
				wp_send_json_error( 'cannot_create_changeset_post' );
			}
			$wp_customize = new WP_Customize_Manager(); // WPCS: override ok.
			$changeset_uuid = $wp_customize->changeset_uuid();
			update_post_meta( $previewed_post_id, '_preview_changeset_uuid', $changeset_uuid );
		}

		if ( ! isset( $wp_customize->posts ) || ! ( $wp_customize->posts instanceof WP_Customize_Posts ) ) {
			wp_send_json_error( 'missing_posts_component' );
		}

		/**
		 * Posts component.
		 *
		 * @var WP_Customize_Posts $wp_customize_posts
		 */
		$wp_customize_posts = $wp_customize->posts;

		$settings = $wp_customize_posts->get_settings( array( $previewed_post_id ) );
		$setting = array_shift( $settings );

		if ( ! $setting ) {
			status_header( 404 );
			wp_send_json_error( 'setting_not_found' );
			return;
		} elseif ( ! $setting->check_capabilities() ) {
			status_header( 403 );
			wp_send_json_error( 'changeset_already_published' );
			return;
		}
		$setting->preview();

		// Note that save_changeset_post() will handle validation and sanitization.
		$wp_customize->set_post_value( $setting->id, wp_array_slice_assoc(
			array_merge( $setting->value(), wp_unslash( $_POST['input_data'] ) ),
			array_keys( $setting->default )
		) );
		$response = $wp_customize->save_changeset_post();
		if ( is_wp_error( $response ) ) {
			wp_send_json_error( $response->get_error_code() );
		}

		wp_send_json_success( compact( 'changeset_uuid', 'response' ) );
	}
}