<?php
/**
 * Code-level fixes for common theme, plugin and content barriers.
 *
 * @package AriAccess
 */

defined( 'ABSPATH' ) || exit;

/**
 * Fixes.
 */
class AriAccess_Fixes {

	/**
	 * Hook in.
	 */
	public static function init() {
		if ( is_admin() ) {
			return;
		}
		$f = AriAccess_Settings::get( 'fixes' );
		add_action( 'wp_enqueue_scripts', array( __CLASS__, 'enqueue' ) );
		if ( $f['skip_link'] ) {
			add_action( 'wp_body_open', array( __CLASS__, 'skip_link' ), 1 );
		}
		if ( $f['media_alt'] ) {
			add_filter( 'the_content', array( __CLASS__, 'fill_media_alt' ), 13 );
		}
		if ( $f['strip_titles'] ) {
			add_filter( 'the_content', array( __CLASS__, 'strip_titles' ), 14 );
			add_filter( 'wp_generate_tag_cloud_data', array( __CLASS__, 'tag_cloud' ) );
		}
		if ( 'remove' === $f['new_window'] ) {
			add_filter( 'the_content', array( __CLASS__, 'remove_targets' ), 15 );
		}
		if ( $f['read_more'] ) {
			add_filter( 'the_content_more_link', array( __CLASS__, 'more_link' ), 20 );
			add_filter( 'excerpt_more', array( __CLASS__, 'excerpt_more' ), 20 );
		}
		if ( $f['form_labels'] ) {
			add_filter( 'get_search_form', array( __CLASS__, 'search_form' ), 20 );
		}
	}

	/**
	 * Which JS fixes are on.
	 *
	 * @return array
	 */
	private static function js_config() {
		$f = AriAccess_Settings::get( 'fixes' );
		return array(
			'skip'        => (bool) $f['skip_link'],
			'skipTarget'  => (string) $f['skip_target'],
			'labels'      => (bool) $f['form_labels'],
			'zoom'        => (bool) $f['zoom'],
			'newWindow'   => (string) $f['new_window'],
			'tabindex'    => (bool) $f['tabindex'],
			'lang'        => $f['lang_dir'] ? str_replace( '_', '-', get_bloginfo( 'language' ) ) : '',
			'dir'         => $f['lang_dir'] ? ( is_rtl() ? 'rtl' : 'ltr' ) : '',
			'emptySearch' => (bool) $f['empty_search'],
			'i18n'        => array(
				'skip'        => __( 'Skip to content', 'ariaccess' ),
				'newTab'      => __( '(opens in a new tab)', 'ariaccess' ),
				'search'      => __( 'Search', 'ariaccess' ),
				'emptySearch' => __( 'Please type something to search for.', 'ariaccess' ),
			),
		);
	}

	/**
	 * Enqueue the fixes CSS and script.
	 */
	public static function enqueue() {
		$f   = AriAccess_Settings::get( 'fixes' );
		$css = '.ariaccess-sr{position:absolute!important;width:1px!important;height:1px!important;padding:0!important;margin:-1px!important;overflow:hidden!important;clip:rect(0,0,0,0)!important;white-space:nowrap!important;border:0!important}';
		if ( $f['skip_link'] ) {
			$css .= '.ariaccess-skip{position:absolute;left:12px;top:-200px;z-index:2147483647;padding:12px 18px;background:#fff;color:#111;font:600 16px/1.2 system-ui,sans-serif;border:3px solid #111;border-radius:6px;text-decoration:underline}.ariaccess-skip:focus{top:12px;outline:3px solid ' . esc_attr( $f['focus_color'] ) . ';outline-offset:2px}';
		}
		if ( $f['focus_outline'] ) {
			$css .= ':where(a,button,input,select,textarea,summary,[tabindex],[contenteditable]):focus-visible{outline:3px solid ' . esc_attr( $f['focus_color'] ) . '!important;outline-offset:2px!important;box-shadow:0 0 0 5px #fff!important}';
		}
		if ( $f['underline_links'] ) {
			$css .= ':where(.entry-content,.wp-block-post-content,.post-content,article) p a,:where(.entry-content,.wp-block-post-content,.post-content,article) li a{text-decoration:underline!important;text-underline-offset:.15em}';
		}
		if ( $f['reduced_motion'] ) {
			$css .= '@media (prefers-reduced-motion:reduce){*,*::before,*::after{animation-duration:.001ms!important;animation-iteration-count:1!important;transition-duration:.001ms!important;scroll-behavior:auto!important}}';
		}
		if ( $f['empty_search'] ) {
			$css .= '.ariaccess-search-error{display:block;margin:.4em 0;padding:.4em .6em;background:#fff;color:#b00020;border-left:4px solid #b00020;font-weight:600}';
		}
		wp_register_style( 'ariaccess-fixes', false, array(), ARIACCESS_VERSION );
		wp_enqueue_style( 'ariaccess-fixes' );
		wp_add_inline_style( 'ariaccess-fixes', $css );

		$needs_js = $f['skip_link'] || $f['form_labels'] || $f['zoom'] || 'off' !== $f['new_window'] || $f['tabindex'] || $f['lang_dir'] || $f['empty_search'];
		if ( $needs_js ) {
			wp_enqueue_script( 'ariaccess-fixes', ARIACCESS_URL . 'assets/js/fixes.js', array(), ARIACCESS_VERSION, array( 'strategy' => 'defer', 'in_footer' => true ) );
			wp_add_inline_script( 'ariaccess-fixes', 'window.ariaccessFixes=' . wp_json_encode( self::js_config() ) . ';', 'before' );
		}
	}

	/**
	 * Print the skip link at the top of the body.
	 */
	public static function skip_link() {
		$target = (string) AriAccess_Settings::get( 'fixes', 'skip_target' );
		$href   = ( '' !== $target && '#' === $target[0] && preg_match( '/^#[\w-]+$/', $target ) ) ? $target : '#main';
		printf( '<a class="ariaccess-skip" href="%s" data-ariaccess-skip>%s</a>', esc_attr( $href ), esc_html__( 'Skip to content', 'ariaccess' ) );
	}

	/**
	 * Fill missing or empty alt text on library images from the Media Library.
	 *
	 * The block editor copies alt text into the post when an image is inserted, so alt text
	 * added to the Media Library later never reaches older posts. This fills the gap.
	 *
	 * @param string $html Content.
	 * @return string
	 */
	public static function fill_media_alt( $html ) {
		if ( false === strpos( (string) $html, 'wp-image-' ) ) {
			return $html;
		}
		return preg_replace_callback(
			'/<img\b[^>]*>/i',
			function ( $m ) {
				$tag = $m[0];
				if ( ! preg_match( '/\bwp-image-(\d+)\b/', $tag, $id ) ) {
					return $tag;
				}
				if ( preg_match( '/\brole=["\'](presentation|none)["\']|\baria-hidden=["\']true["\']/i', $tag ) ) {
					return $tag;
				}
				$has_alt = preg_match( '/\salt=(["\'])(.*?)\1/is', $tag, $alt );
				if ( $has_alt && '' !== trim( $alt[2] ) ) {
					return $tag;
				}
				$library = trim( (string) get_post_meta( (int) $id[1], '_wp_attachment_image_alt', true ) );
				if ( '' === $library ) {
					return $tag;
				}
				$attr = 'alt="' . esc_attr( $library ) . '"';
				if ( $has_alt ) {
					return preg_replace( '/\salt=(["\'])(.*?)\1/is', $attr, $tag, 1 );
				}
				return preg_replace( '/^<img\b/i', '<img ' . $attr, $tag );
			},
			$html
		);
	}

	/**
	 * Remove title attributes from images, and from links whose title repeats the link text.
	 *
	 * @param string $html Content.
	 * @return string
	 */
	public static function strip_titles( $html ) {
		$html = preg_replace( '/(<img\b[^>]*?)\s+title=(["\']).*?\2/i', '$1', (string) $html );
		return preg_replace_callback(
			'/<a\b([^>]*?)\s+title=(["\'])(.*?)\2([^>]*)>(.*?)<\/a>/is',
			function ( $m ) {
				$title = trim( wp_strip_all_tags( html_entity_decode( $m[3], ENT_QUOTES, 'UTF-8' ) ) );
				$text  = trim( wp_strip_all_tags( html_entity_decode( $m[5], ENT_QUOTES, 'UTF-8' ) ) );
				if ( '' !== $text && 0 === strcasecmp( $title, $text ) ) {
					return '<a' . $m[1] . $m[4] . '>' . $m[5] . '</a>';
				}
				return $m[0];
			},
			$html
		);
	}

	/**
	 * Tag clouds: the count tooltip duplicates the aria-label.
	 *
	 * @param array $tags Tag data.
	 * @return array
	 */
	public static function tag_cloud( $tags ) {
		foreach ( $tags as &$tag ) {
			$tag['title'] = '';
		}
		return $tags;
	}

	/**
	 * Remove target="_blank" from content links.
	 *
	 * @param string $html Content.
	 * @return string
	 */
	public static function remove_targets( $html ) {
		return preg_replace( '/(<a\b[^>]*?)\s+target=(["\'])_blank\2/i', '$1', (string) $html );
	}

	/**
	 * "Read more" link with the post title for screen readers.
	 *
	 * @param string $link Link HTML.
	 * @return string
	 */
	public static function more_link( $link ) {
		if ( AriAccess_Checker::$rendering || false !== strpos( $link, 'ariaccess-sr' ) || false !== strpos( $link, 'screen-reader-text' ) ) {
			return $link;
		}
		$title = get_the_title();
		if ( '' === $title ) {
			return $link;
		}
		return preg_replace( '/<\/a>/', '<span class="ariaccess-sr">: ' . esc_html( wp_strip_all_tags( $title ) ) . '</span></a>', $link, 1 );
	}

	/**
	 * Excerpt "more" links with context.
	 *
	 * @param string $more More text/link.
	 * @return string
	 */
	public static function excerpt_more( $more ) {
		if ( false === strpos( (string) $more, '</a>' ) ) {
			return $more;
		}
		return self::more_link( $more );
	}

	/**
	 * Search forms without a label get one.
	 *
	 * @param string $form Form HTML.
	 * @return string
	 */
	public static function search_form( $form ) {
		if ( false !== stripos( $form, '<label' ) || false !== stripos( $form, 'aria-label' ) ) {
			return $form;
		}
		return preg_replace( '/<input\b(?=[^>]*\bname=(["\'])s\1)/i', '<input aria-label="' . esc_attr__( 'Search', 'ariaccess' ) . '"', $form, 1 );
	}
}