<?php
/**
 * Where the service lives.
 *
 * The live hosts are fixed here. wp-config.php may point them elsewhere for a local stand-in of the service
 * (`SRANYWHERE_API_URL`, `SRANYWHERE_DELIVERY_URL`, `SRANYWHERE_START_URL`); nothing else can (decision 0006).
 *
 * @package SRAnywhere
 */

namespace SRAnywhere;

defined( 'ABSPATH' ) || exit;

/**
 * The service's addresses.
 */
final class Config {

	const API      = 'https://anywhere.sliderrevolution.com';
	const DELIVERY = 'https://embed.sliderrevolution.com';
	const PORTAL   = 'https://anywhere.sliderrevolution.com/portal/';

	/**
	 * The connector API's base, for the server's calls.
	 *
	 * @return string
	 */
	public static function api_url() {
		return self::constant_url( 'SRANYWHERE_API_URL', self::API );
	}

	/**
	 * The delivery's public base: every URL a visitor's browser loads comes from here.
	 *
	 * @return string
	 */
	public static function delivery_url() {
		return self::constant_url( 'SRANYWHERE_DELIVERY_URL', self::DELIVERY );
	}

	/**
	 * Where the server fetches a module's start from. The public delivery unless a stand-in is set.
	 *
	 * @return string
	 */
	public static function start_url() {
		return self::constant_url( 'SRANYWHERE_START_URL', self::delivery_url() );
	}

	/**
	 * The portal, for links that open in a new tab.
	 *
	 * @return string
	 */
	public static function portal_url() {
		return self::PORTAL;
	}

	/**
	 * Whether a URL may be loaded by a visitor's browser: the delivery's scheme, host and port, no user info, nothing a
	 * browser and PHP could read differently (backslashes, whitespace, control characters).
	 *
	 * @param string $url A URL from the service.
	 * @return bool
	 */
	public static function is_delivery_url( $url ) {
		return self::same_origin( $url, self::delivery_url() );
	}

	/**
	 * Whether a link may be offered to the person: https on the portal's host (the service's own pages), for links that
	 * come from the API (preview, publish, edit, plans …).
	 *
	 * @param string $url A URL from the service.
	 * @return bool
	 */
	public static function is_portal_url( $url ) {
		$portal = wp_parse_url( self::portal_url() );
		$got    = self::clean_parts( $url );
		return null !== $got && ! empty( $portal['host'] ) && 'https' === $got['scheme'] && strtolower( $portal['host'] ) === $got['host'];
	}

	/**
	 * How long the API's answers are cached, in seconds; `SRANYWHERE_CACHE_TTL` shortens it for tests.
	 *
	 * @param int $seconds The normal time.
	 * @return int
	 */
	public static function cache_ttl( $seconds ) {
		return defined( 'SRANYWHERE_CACHE_TTL' ) && is_numeric( SRANYWHERE_CACHE_TTL ) ? max( 1, (int) SRANYWHERE_CACHE_TTL ) : (int) $seconds;
	}

	/**
	 * Whether a URL has exactly the scheme, host and port of another.
	 *
	 * @param string $url  The URL to check.
	 * @param string $base The allowed origin.
	 * @return bool
	 */
	private static function same_origin( $url, $base ) {
		$want = wp_parse_url( $base );
		$got  = self::clean_parts( $url );
		if ( null === $got || empty( $want['host'] ) || empty( $want['scheme'] ) ) {
			return false;
		}
		return $got['host'] === strtolower( $want['host'] ) && $got['scheme'] === $want['scheme'] && $got['port'] === ( $want['port'] ?? null );
	}

	/**
	 * A URL's scheme, host and port, or null when it is not a plain absolute http(s) URL.
	 *
	 * @param mixed $url The URL.
	 * @return array{scheme:string,host:string,port:int|null}|null
	 */
	private static function clean_parts( $url ) {
		if ( ! is_string( $url ) || '' === $url || preg_match( '/[\x5c\s\x00-\x1f\x7f]/', $url ) ) {
			return null;
		}
		$parts = wp_parse_url( $url );
		if ( ! is_array( $parts ) || empty( $parts['host'] ) || empty( $parts['scheme'] ) || isset( $parts['user'] ) || isset( $parts['pass'] ) ) {
			return null;
		}
		$scheme = strtolower( $parts['scheme'] );
		if ( 'https' !== $scheme && 'http' !== $scheme ) {
			return null;
		}
		return array(
			'scheme' => $scheme,
			'host'   => strtolower( $parts['host'] ),
			'port'   => isset( $parts['port'] ) ? (int) $parts['port'] : null,
		);
	}

	/**
	 * A constant from wp-config.php, or the default.
	 *
	 * @param string $name     The constant's name.
	 * @param string $fallback The live value.
	 * @return string
	 */
	private static function constant_url( $name, $fallback ) {
		if ( defined( $name ) && is_string( constant( $name ) ) && '' !== constant( $name ) ) {
			return untrailingslashit( esc_url_raw( constant( $name ) ) );
		}
		return $fallback;
	}
}