exact' : $value['comparison'];
			$this->add_source( $value['pattern'], $value['comparison'], ! empty( $value['ignore'] ) ? 'case' : '' );
		}
	}

	/**
	 * Add source.
	 *
	 * @param string $pattern    Pattern to add.
	 * @param string $comparison Comparison for pattern.
	 * @param string $ignore     Ignore flag.
	 */
	public function add_source( $pattern, $comparison, $ignore = '' ) {
		$pattern = trim( $pattern );
		if ( empty( $pattern ) ) {
			return;
		}

		$pattern = $this->sanitize_source( wp_strip_all_tags( $pattern, true ), $comparison );
		if ( ! $pattern ) {
			return;
		}

		$this->data['sources'][] = [
			'ignore'     => $ignore,
			'pattern'    => $pattern,
			'comparison' => $comparison,
		];
	}

	/**
	 * Add and sanitize destination URL.
	 *
	 * @param string $url URL to process.
	 */
	public function add_destination( $url ) {
		$processed = trim( wp_strip_all_tags( $url, true ) );

		// If beginning looks like a domain but without protocol then let's add home_url().
		if ( ! empty( $processed ) && Url::is_relative( $processed ) ) {
			$processed = home_url( $processed );
		}

		$this->data['url_to'] = $processed;
	}

	/**
	 * Sanitize source.
	 *
	 * @param string $pattern    Pattern to sanitize.
	 * @param string $comparison Comparison of pattern.
	 *
	 * @return string
	 */
	private function sanitize_source( $pattern, $comparison ) {
		if ( 'exact' === $comparison ) {
			$pattern = $this->sanitize_source_url( $pattern );
			if ( $pattern && false === $this->nocache ) {
				$this->pre_redirection_cache( $pattern );
			}

			return $pattern;
		} elseif ( 'regex' === $comparison ) {
			return $this->sanitize_source_regex( $pattern );
		}

		// Other comparison types: "contains", "start", "end".
		return filter_var( $pattern, FILTER_SANITIZE_SPECIAL_CHARS, FILTER_FLAG_STRIP_LOW | FILTER_FLAG_STRIP_BACKTICK );
	}

	/**
	 * Sanitize redirection source URL.
	 *
	 * Following urls converted to URI:
	 *    '' => false
	 *    '/' => false
	 *    /URI => URI
	 *    #URI => #URI
	 *    https://website.com/#URI/ => #URI
	 *    https://website.com#URI/ => #URI
	 *    website.com => false
	 *    www.website.com => false
	 *    http://sub.website.com/URI => false
	 *    http://external.com/URI => false
	 *    website.com/URI => URI
	 *    website.com/URI/ => URI
	 *    http://website.com/URI => URI
	 *    http://website.com/URI/ => URI
	 *    https://website.com/URI => URI
	 *    https://website.com/URI/ => URI
	 *    www.website.com/URI => URI
	 *    www.website.com/URI/ => URI
	 *    http://www.website.com/URI => URI
	 *    http://www.website.com/URI/ => URI
	 *    https://www.website.com/URI => URI
	 *    https://www.website.com/URI/ => URI
	 *
	 * @param string $url User-input source URL.
	 *
	 * @return string|false
	 */
	private function sanitize_source_url( $url ) {
		if ( empty( $url ) || '/' === $url ) {
			return false;
		}

		if ( '#' === $url[0] || '/' === $url[0] ) {
			return ltrim( $url, '/' );
		}

		$original = $url;
		$domain   = $this->get_home_domain();
		$url      = trailingslashit( $url );
		$url      = str_replace( $domain . '#', $domain . '/#', $url );  // For website.com#URI link.
		$domain   = trailingslashit( $domain );
		$search   = [
			'http://' . $domain,
			'http://www.' . $domain,
			'https://' . $domain,
			'https://www.' . $domain,
			'www.' . $domain,
		];
		$url      = str_replace( $search, '', $url );
		$url      = preg_replace( '/^' . preg_quote( $domain, '/' ) . '/s', '', $url );

		// Empty url.
		// External domain.
		if ( empty( $url ) || 0 === strpos( $url, 'http://' ) || 0 === strpos( $url, 'https://' ) ) {
			return false;
		}

		// Remove trailing slash if original url doesn't have it.
		if ( '/' !== substr( $original, -1 ) ) {
			$url = untrailingslashit( $url );
		}

		return urldecode( self::strip_subdirectory( $url ) );
	}

	/**
	 * Sanitize redirection source for regex.
	 *
	 * @param  string $pattern Pattern to process.
	 * @return string
	 */
	private function sanitize_source_regex( $pattern ) {
		// No new lines.
		$pattern = preg_replace( "/[\r\n\t].*?$/s", '', $pattern );

		// Clean control codes.
		$pattern = preg_replace( '/[^\PC\s]/u', '', $pattern );

		// Check if it's a valid pattern.
		if ( @preg_match( '@' . $pattern . '@', '' ) === false ) { // phpcs:ignore
			/* translators: source pattern */
			Helper::add_notification( sprintf( __( 'Invalid regex pattern: %s', 'rank-math' ), $pattern ), [ 'type' => 'error' ] );
			return false;
		}

		return $pattern;
	}

	/**
	 * Maybe collect WordPress object to add redirection cache.
	 *
	 * @param string $slug Url to search for.
	 */
	private function pre_redirection_cache( $slug ) {
		global $wpdb;

		// Check for post.
		$post_id = url_to_postid( home_url( $slug ) );
		if ( $post_id ) {
			$this->cache[] = [
				'from_url'    => $slug,
				'object_id'   => $post_id,
				'object_type' => 'post',
			];
			return;
		}

		// Check for term.
		$terms = DB_Helper::get_results( $wpdb->prepare( "SELECT term_id FROM $wpdb->terms WHERE slug = %s", $slug ) );
		if ( $terms ) {
			foreach ( $terms as $term ) {
				$this->cache[] = [
					'from_url'    => $slug,
					'object_id'   => $term->term_id,
					'object_type' => 'term',
				];
			}
			return;
		}

		// Check for user.
		$user = get_user_by( 'slug', $slug );
		if ( $user ) {
			$this->cache[] = [
				'from_url'    => $slug,
				'object_id'   => $user->ID,
				'object_type' => 'user',
			];
			return;
		}
	}

	/**
	 * Save redirection caches.
	 */
	private function save_redirection_cache() {
		if ( ! $this->get_id() || empty( $this->cache ) ) {
			return;
		}

		foreach ( $this->cache as $item ) {
			$item['redirection_id'] = $this->get_id();
			Cache::add( $item );
		}
	}

	/**
	 * Get the domain, without www. and protocol.
	 *
	 * @return string
	 */
	private function get_home_domain() {
		if ( ! is_null( $this->domain ) ) {
			return $this->domain;
		}

		$this->domain = Url::get_host( home_url() );

		return $this->domain;
	}

	/**
	 * Strip home directory when WP is installed in subdirectory.
	 *
	 * @param string $url URL to strip from.
	 *
	 * @return string
	 */
	public static function strip_subdirectory( $url ) {
		$home_dir = ltrim( Helper::get_home_url( '', 'relative' ), '/' );

		return $home_dir ? str_replace( trailingslashit( $home_dir ), '', $url ) : $url;
	}

	/**
	 * Get the current URI.
	 *
	 * @return string
	 */
	public static function get_full_uri() {
		$uri = str_replace( home_url( '/' ), '', Param::server( 'REQUEST_URI' ) );
		$uri = urldecode( $uri );
		$uri = trim( self::strip_subdirectory( $uri ), '/' );

		return $uri;
	}
}