<?php
/**
 * Issue fingerprints.
 *
 * @package A11yMate
 */

namespace A11yMate\Support;

defined( 'ABSPATH' ) || exit;

/**
 * The same problem on the same template element hashes to the same value on every page,
 * which is what lets the results group "on 48 pages" into one row.
 */
class Fingerprint {

	/**
	 * Build a fingerprint.
	 *
	 * @param string $rule     Rule id.
	 * @param string $selector Selector.
	 * @param string $snippet  Snippet.
	 * @return string 40 hex characters.
	 */
	public static function make( $rule, $selector, $snippet ) {
		return sha1( $rule . '|' . self::selector( $selector ) . '|' . self::signature( $snippet ) );
	}

	/**
	 * Selector without positional indices, so the same slot in a list or template matches.
	 *
	 * @param string $selector Selector.
	 * @return string
	 */
	public static function selector( $selector ) {
		$selector = Html::normalise( $selector );
		$selector = preg_replace( '/:nth-of-type\(\d+\)/', '', $selector );
		return $selector;
	}

	/**
	 * The identity of an element from its snippet: tag plus class, role, type and name.
	 * Text, links and image sources are left out so repeated cards collapse into one row.
	 *
	 * @param string $snippet Snippet.
	 * @return string
	 */
	public static function signature( $snippet ) {
		if ( ! preg_match( '/^<([a-z0-9-]+)([^>]*)>/i', (string) $snippet, $m ) ) {
			return Html::normalise( $snippet );
		}
		$sig = strtolower( $m[1] );
		foreach ( array( 'class', 'role', 'type', 'name', 'for', 'target' ) as $attr ) {
			if ( preg_match( '/\s' . $attr . '="([^"]*)"/i', $m[2], $a ) ) {
				$sig .= '|' . $attr . '=' . Html::normalise( $a[1] );
			}
		}
		return $sig;
	}
}