<?php
/**
 * URL handling.
 *
 * @package VyatkaShop
 */

if ( ! defined( 'ABSPATH' ) ) {
	exit;
}

/**
 * Build links against the host the visitor actually asked for.
 *
 * WordPress stores one canonical home URL, so a site reachable under more than
 * one name (a bare host and a proxied domain, say) would otherwise send people
 * back to the stored one mid-session. Only the request host is trusted here,
 * and only when it matches a host WordPress already knows about, so this cannot
 * be driven by a forged Host header.
 *
 * @param string $url Complete URL generated by WordPress.
 * @return string
 */
function vyatka_shop_request_host_url( string $url ): string {
	$request_host = vyatka_shop_request_host();
	if ( '' === $request_host || ! vyatka_shop_host_is_known( $request_host ) ) {
		return $url;
	}

	$parts = wp_parse_url( $url );
	if ( ! is_array( $parts ) ) {
		return $url;
	}

	$forwarded_proto = isset( $_SERVER['HTTP_X_FORWARDED_PROTO'] )
		? strtolower( trim( explode( ',', sanitize_text_field( wp_unslash( $_SERVER['HTTP_X_FORWARDED_PROTO'] ) ) )[0] ) )
		: '';
	$scheme          = 'https' === $forwarded_proto || is_ssl() ? 'https' : 'http';

	$rewritten  = $scheme . '://' . $request_host;
	$rewritten .= $parts['path'] ?? '';
	$rewritten .= isset( $parts['query'] ) ? '?' . $parts['query'] : '';
	$rewritten .= isset( $parts['fragment'] ) ? '#' . $parts['fragment'] : '';
	return $rewritten;
}
add_filter( 'home_url', 'vyatka_shop_request_host_url' );
add_filter( 'site_url', 'vyatka_shop_request_host_url' );

/**
 * The host from the current request, without its port.
 */
function vyatka_shop_request_host(): string {
	if ( ! isset( $_SERVER['HTTP_HOST'] ) ) {
		return '';
	}

	return strtolower( preg_replace( '/:\d+$/', '', sanitize_text_field( wp_unslash( $_SERVER['HTTP_HOST'] ) ) ) );
}

/**
 * Hosts this installation answers to: whatever is stored in the options, plus
 * anything a site owner adds through the filter.
 *
 * @return array<int,string>
 */
function vyatka_shop_known_hosts(): array {
	$hosts = array();

	foreach ( array( 'home', 'siteurl' ) as $option_name ) {
		$host = wp_parse_url( (string) get_option( $option_name ), PHP_URL_HOST );
		if ( is_string( $host ) && '' !== $host ) {
			$hosts[] = strtolower( $host );
		}
	}

	// Sites behind a proxy answer to a name the stored options do not know.
	// Declare those in wp-config.php:
	//   define( 'VYATKA_SHOP_HOSTS', 'shop.example.com, www.example.com' );
	if ( defined( 'VYATKA_SHOP_HOSTS' ) ) {
		foreach ( explode( ',', (string) VYATKA_SHOP_HOSTS ) as $host ) {
			$host = strtolower( trim( $host ) );
			if ( '' !== $host ) {
				$hosts[] = $host;
			}
		}
	}

	/**
	 * Additional hosts the site is served under.
	 *
	 * @param array<int,string> $hosts Known hostnames.
	 */
	return array_values( array_unique( (array) apply_filters( 'vyatka_shop_known_hosts', $hosts ) ) );
}

/**
 * @param string $host Hostname to test.
 */
function vyatka_shop_host_is_known( string $host ): bool {
	return in_array( strtolower( $host ), vyatka_shop_known_hosts(), true );
}

/**
 * Strip the origin from internal links in the finished HTML.
 *
 * Rewriting only the rendered document leaves redirects, REST responses and
 * WP-CLI output fully qualified, while the markup a browser receives stays
 * usable under whichever host served it.
 *
 * @param string $html Completed response body.
 * @return string
 */
function vyatka_shop_relative_frontend_urls( string $html ): string {
	foreach ( headers_list() as $header ) {
		if ( 0 === stripos( $header, 'Content-Type:' ) && false === stripos( $header, 'text/html' ) ) {
			return $html;
		}
	}

	$hosts        = vyatka_shop_known_hosts();
	$request_host = vyatka_shop_request_host();
	if ( '' !== $request_host ) {
		$hosts[] = $request_host;
	}

	$absolute_bases = array();
	foreach ( array_unique( $hosts ) as $host ) {
		$absolute_bases[] = 'https://' . $host;
		$absolute_bases[] = 'http://' . $host;
		$absolute_bases[] = '//' . $host;
	}
	// Longest first, so "//host" never truncates "https://host".
	usort( $absolute_bases, static fn( string $left, string $right ): int => strlen( $right ) <=> strlen( $left ) );

	return str_replace( $absolute_bases, '', $html );
}

/**
 * Buffer ordinary frontend documents so their internal links can be made
 * relative without changing the site's canonical configuration.
 */
function vyatka_shop_start_relative_url_buffer(): void {
	if ( is_admin() || wp_doing_ajax() || wp_is_json_request() || is_feed() ) {
		return;
	}

	ob_start( 'vyatka_shop_relative_frontend_urls' );
}
add_action( 'template_redirect', 'vyatka_shop_start_relative_url_buffer', 0 );

/**
 * Recover stale filtered category URLs when the selected page no longer exists.
 *
 * Filter forms always target page one, but bookmarked or cached /page/N/ URLs
 * can still reach WordPress directly and become a 404 after the result set is
 * narrowed. Preserve their query string and retry the category from page one.
 */
function vyatka_shop_redirect_stale_filtered_category_page(): void {
	if ( ! is_404() || empty( $_GET ) ) {
		return;
	}

	$filter_keys = array(
		'filter_min_price',
		'filter_max_price',
		'feature',
		'collection',
		'per_page',
		'orderby',
	);

	if ( ! array_intersect( $filter_keys, array_keys( $_GET ) ) ) {
		return;
	}

	$request_uri  = isset( $_SERVER['REQUEST_URI'] ) ? wp_unslash( $_SERVER['REQUEST_URI'] ) : '';
	$request_path = wp_parse_url( $request_uri, PHP_URL_PATH );
	if ( ! is_string( $request_path ) || ! preg_match( '#^(.*/product-category/[^/]+)/page/[1-9][0-9]*/?$#u', $request_path, $matches ) ) {
		return;
	}

	$target = add_query_arg( wp_unslash( $_GET ), trailingslashit( $matches[1] ) );
	wp_safe_redirect( $target, 302, 'Vyatka Shop' );
	exit;
}
add_action( 'template_redirect', 'vyatka_shop_redirect_stale_filtered_category_page', -10 );