<?php
/**
 * Optional front-end marking of broken links (off by default).
 *
 * Front-end page views only read the plugin's tables when one of the two marking options is
 * on and checking was started. They never write, schedule or request anything.
 *
 * @package LinkTender
 */

defined( 'ABSPATH' ) || exit;

/**
 * Front-end output.
 */
class LinkTender_Frontend {

	/**
	 * Registers hooks when marking is enabled.
	 *
	 * @return void
	 */
	public function hooks() {
		if ( is_admin() || ! LinkTender_Install::is_installed() || ! LinkTender_Install::checking_started() ) {
			return;
		}
		add_action(
			'wp',
			function () {
				if ( LinkTender_Settings::get( 'mark_broken' ) || LinkTender_Settings::get( 'nofollow_broken' ) ) {
					add_filter( 'the_content', array( $this, 'filter_content' ), 20 );
					add_action( 'wp_enqueue_scripts', array( $this, 'styles' ) );
				}
			}
		);
	}

	/**
	 * Adds the strike-through style.
	 *
	 * @return void
	 */
	public function styles() {
		if ( ! LinkTender_Settings::get( 'mark_broken' ) ) {
			return;
		}
		wp_register_style( 'linktender-front', false, array(), LINKTENDER_VERSION );
		wp_enqueue_style( 'linktender-front' );
		wp_add_inline_style( 'linktender-front', 'a.linktender-broken{text-decoration:line-through;}' );
	}

	/**
	 * Marks broken links in post content.
	 *
	 * @param string $content Content.
	 * @return string
	 */
	public function filter_content( $content ) {
		$post_id = get_the_ID();
		if ( ! $post_id || false === stripos( $content, '<a' ) ) {
			return $content;
		}
		$broken = linktender()->links->broken_raw_urls_in_post( $post_id );
		if ( empty( $broken ) ) {
			return $content;
		}
		$broken    = array_flip( $broken );
		$mark      = LinkTender_Settings::get( 'mark_broken' );
		$nofollow  = LinkTender_Settings::get( 'nofollow_broken' );
		$processor = new WP_HTML_Tag_Processor( $content );
		while ( $processor->next_tag( 'a' ) ) {
			$href = $processor->get_attribute( 'href' );
			if ( ! is_string( $href ) || ! isset( $broken[ $href ] ) ) {
				continue;
			}
			if ( $mark ) {
				$processor->add_class( 'linktender-broken' );
			}
			if ( $nofollow ) {
				$rel = (string) $processor->get_attribute( 'rel' );
				if ( false === strpos( $rel, 'nofollow' ) ) {
					$processor->set_attribute( 'rel', trim( $rel . ' nofollow' ) );
				}
			}
		}
		return $processor->get_updated_html();
	}
}