<?php

namespace Glovario\Locale;

use Glovario\Cache\PageCachePurger;

defined( 'ABSPATH' ) || exit;

/**
 * Lets full-page caches keep one copy per standalone language.
 *
 * In standalone mode the glovario_locale cookie switches the complete WordPress
 * locale on the same URL. Caches that can store a copy per cookie value are
 * told about the cookie (WP Super Cache, LiteSpeed Cache, and W3 Total Cache
 * through a cookie group), so pages in the second language are cached too and
 * purged with the others. Only when no such cache is active is a page in the
 * second language marked as not cacheable, so that no other cache can serve
 * it to a visitor in the default language.
 */
final class PageCacheCompatibility {
	const NOCACHE_REASON = 'Glovario standalone locale cookie';

	/**
	 * LiteSpeed Cache version and switcher state for which its rewrite rules
	 * were last regenerated with the language cookie.
	 */
	const LITESPEED_OPTION = 'glovario_litespeed_vary';
	/** When Glovario last had LiteSpeed Cache rewrite its rule (OpenLiteSpeed needs a restart after each). */
	const LITESPEED_CHANGED = 'glovario_litespeed_vary_changed';

	private $locales;

	public function __construct( StandaloneLocale $locales ) {
		$this->locales = $locales;
	}

	public function register() {
		// LiteSpeed Cache keeps one cached copy per cookie value.
		add_filter( 'litespeed_vary_cookies', array( $this, 'cache_cookies' ) );
		add_filter( 'litespeed_vary_curr_cookies', array( $this, 'cache_cookies' ) );
		add_action( 'admin_init', array( $this, 'register_super_cache_cookie' ) );
		add_action( 'template_redirect', array( $this, 'prevent_storing_cookie_variant' ), 2 );
		add_action( 'add_option_' . LocaleManager::OPTION, array( $this, 'settings_added' ), 10, 2 );
		add_action( 'update_option_' . LocaleManager::OPTION, array( $this, 'settings_updated' ), 10, 2 );
	}

	public function cache_cookies( $cookies ) {
		$cookies = is_array( $cookies ) ? $cookies : array();
		if ( $this->locales->standalone_available() && ! in_array( StandaloneLocale::COOKIE, $cookies, true ) ) {
			$cookies[] = StandaloneLocale::COOKIE;
		}
		return $cookies;
	}

	/**
	 * WP Super Cache stores a separate copy per cookie value once told about it.
	 * Re-adding is a no-op, and it restores the cookie after a cache config reset.
	 */
	public function register_super_cache_cookie() {
		if ( $this->locales->standalone_available() ) {
			do_action( 'wpsc_add_cookie', StandaloneLocale::COOKIE ); // phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedHooknameFound -- WP Super Cache's documented API action.
		}
		$this->sync_w3tc_cookie( $this->locales->standalone_available() );
		$this->sync_litespeed_vary( $this->locales->standalone_available() );
	}

	/**
	 * LiteSpeed Cache adds the cookies from litespeed_vary_cookies to its
	 * .htaccess "Cache-Vary" rule only when it regenerates its rules, normally
	 * when its own settings are saved. Until then the server keeps one copy per
	 * URL and serves the default-language page to every visitor. Saving its
	 * settings through its public API regenerates the rule; this runs once per
	 * switcher change and LiteSpeed Cache version.
	 *
	 * @param bool $enabled Whether the standalone switcher is active.
	 */
	public function sync_litespeed_vary( $enabled ) {
		if ( ! defined( 'LSCWP_V' ) ) {
			return;
		}
		$state = LSCWP_V . '|' . ( $enabled ? '1' : '0' );
		if ( get_option( self::LITESPEED_OPTION ) === $state ) {
			return;
		}
		do_action( 'litespeed_save_conf' ); // phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedHooknameFound -- LiteSpeed Cache's documented API action.
		update_option( self::LITESPEED_OPTION, $state, false );
		update_option( self::LITESPEED_CHANGED, (string) microtime( true ), false );
	}

	/**
	 * Removes the language cookie from the page caches when Glovario is deactivated.
	 */
	public static function deactivate() {
		do_action( 'wpsc_delete_cookie', StandaloneLocale::COOKIE ); // phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedHooknameFound -- WP Super Cache's documented API action.
		$compat = new self( new StandaloneLocale( new LocaleManager( new \Glovario\Repository\RuleRepository() ) ) );
		$compat->sync_w3tc_cookie( false );
		if ( defined( 'LSCWP_V' ) ) {
			add_filter(
				'litespeed_vary_cookies',
				static function ( $cookies ) {
					return array_values( array_diff( (array) $cookies, array( StandaloneLocale::COOKIE ) ) );
				},
				PHP_INT_MAX
			);
			do_action( 'litespeed_save_conf' ); // phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedHooknameFound -- LiteSpeed Cache's documented API action.
		}
		delete_option( self::LITESPEED_OPTION );
		delete_option( self::LITESPEED_CHANGED );
	}

	/**
	 * W3 Total Cache serves cached pages before plugins load and keys them by
	 * URL. A cookie group per second language ("glovario_it_it" matching
	 * glovario_locale=it_IT) makes it keep a separate, cached copy for that language.
	 *
	 * @param bool $enabled Whether the standalone switcher is active.
	 */
	public function sync_w3tc_cookie( $enabled ) {
		if ( ! function_exists( 'w3tc_config' ) ) {
			return;
		}
		try {
			$config  = w3tc_config();
			$groups  = (array) $config->get_array( 'pgcache.cookiegroups.groups' );
			$wanted  = array();
			$second  = $this->locales->manager()->settings()['second_locale'];
			if ( $enabled && '' !== $second ) {
				$wanted[ self::w3tc_group( $second ) ] = array(
					'enabled' => true,
					'cache'   => true,
					'cookies' => array( StandaloneLocale::COOKIE . '=' . $second ),
				);
			}
			$updated = array_merge(
				array_filter(
					$groups,
					static function ( $name ) {
						return 0 !== strpos( (string) $name, 'glovario_' );
					},
					ARRAY_FILTER_USE_KEY
				),
				$wanted
			);
			// Disk: Enhanced serves cached files from rewrite rules that ignore cookie
			// groups, so the cookie is rejected there instead: visitors who chose the
			// second language skip the static files and get pages from WordPress.
			$enhanced = self::w3tc_enhanced( $config );
			$rejected = (array) $config->get_array( 'pgcache.reject.cookie' );
			$kept     = array_values( array_diff( $rejected, array( StandaloneLocale::COOKIE ) ) );
			if ( $wanted && $enhanced ) {
				$kept[] = StandaloneLocale::COOKIE;
			}
			if ( $updated === $groups && $kept === $rejected && ( ! $wanted || $config->get_boolean( 'pgcache.cookiegroups.enabled' ) ) ) {
				return;
			}
			$config->set( 'pgcache.cookiegroups.groups', $updated );
			$config->set( 'pgcache.reject.cookie', $kept );
			if ( $wanted ) {
				$config->set( 'pgcache.cookiegroups.enabled', true );
			}
			$config->save();
			if ( $kept !== $rejected && $enhanced && class_exists( '\W3TC\Dispatcher' ) ) {
				// Rewrite its .htaccess rules with the new list, as its fix_environment command does.
				\W3TC\Dispatcher::component( 'PgCache_Environment' )->fix_on_wpadmin_request( $config, true );
			}
		} catch ( \Exception $exception ) {
			do_action( 'glovario_multilingual_integration_error', 'w3-total-cache', $exception );
		}
	}

	/**
	 * The caching proxy or CDN in front of the site, recognised from the
	 * headers it adds to the current (admin) request; no network request.
	 *
	 * @return string Its name, or an empty string.
	 */
	public static function proxy_in_front() {
		$header = static function ( $name ) {
			return isset( $_SERVER[ $name ] ) ? sanitize_text_field( wp_unslash( $_SERVER[ $name ] ) ) : '';
		};
		$proxy  = '';
		if ( '' !== $header( 'HTTP_CF_RAY' ) ) {
			$proxy = 'Cloudflare';
		} elseif ( '' !== $header( 'HTTP_FASTLY_CLIENT_IP' ) || false !== stripos( $header( 'HTTP_CDN_LOOP' ), 'fastly' ) ) {
			$proxy = 'Fastly';
		} elseif ( '' !== $header( 'HTTP_X_VARNISH' ) || false !== stripos( $header( 'HTTP_VIA' ), 'varnish' ) ) {
			$proxy = 'Varnish';
		}
		/**
		 * Filters the caching proxy or CDN reported in front of the site; Locale
		 * Settings tells Standalone-mode sites how to keep it from serving one
		 * language's cached page to visitors who chose the other.
		 *
		 * @param string $proxy Name, or an empty string when none is recognised.
		 */
		return (string) apply_filters( 'glovario_proxy_cache_in_front', $proxy );
	}

	private static function w3tc_enhanced( $config ) {
		return $config->get_boolean( 'pgcache.enabled' ) && 'file_generic' === $config->get_string( 'pgcache.engine' );
	}

	private static function w3tc_group( $locale ) {
		return 'glovario_' . strtolower( sanitize_key( $locale ) );
	}

	/**
	 * Whether an active page cache keeps a separate copy for this language.
	 *
	 * @param string $locale Locale selected by the cookie.
	 * @return bool
	 */
	public function cache_keeps_language_copies( $locale ) {
		$keeps = false;
		if ( defined( 'LSCWP_V' ) && get_option( self::LITESPEED_OPTION ) === LSCWP_V . '|1' ) {
			$keeps = true; // Its vary rule includes the cookie (see sync_litespeed_vary).
		}
		if ( ! empty( $GLOBALS['wpsc_cookies'] ) && in_array( StandaloneLocale::COOKIE, (array) $GLOBALS['wpsc_cookies'], true ) ) {
			$keeps = true;
		}
		if ( function_exists( 'w3tc_config' ) ) {
			try {
				$config = w3tc_config();
				$groups = (array) $config->get_array( 'pgcache.cookiegroups.groups' );
				// Disk: Enhanced rejects the cookie (see sync_w3tc_cookie), so no copy is kept there.
				$keeps  = $keeps || ( ! self::w3tc_enhanced( $config ) && $config->get_boolean( 'pgcache.cookiegroups.enabled' ) && ! empty( $groups[ self::w3tc_group( $locale ) ]['enabled'] ) );
			} catch ( \Exception $exception ) {
				do_action( 'glovario_multilingual_integration_error', 'w3-total-cache', $exception );
			}
		}
		/**
		 * Filters whether the active page cache stores one copy per language
		 * cookie value. Return true for a cache configured to vary on glovario_locale,
		 * so pages in the second language are cached instead of rebuilt.
		 *
		 * @param bool   $keeps  Whether a known cache keeps language copies.
		 * @param string $locale Locale selected by the cookie.
		 */
		return (bool) apply_filters( 'glovario_cache_varies_by_language_cookie', $keeps, $locale );
	}

	public function prevent_storing_cookie_variant() {
		$locale = $this->locales->cookie_variant_locale();
		if ( is_admin() || wp_doing_ajax() || ( defined( 'REST_REQUEST' ) && REST_REQUEST ) || '' === $locale || $this->cache_keeps_language_copies( $locale ) ) {
			return;
		}
		if ( ! defined( 'DONOTCACHEPAGE' ) ) {
			define( 'DONOTCACHEPAGE', true ); // phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedConstantFound -- The shared page-cache constant that cache plugins read.
		}
		if ( ! headers_sent() ) {
			nocache_headers();
		}
		do_action( 'litespeed_control_set_nocache', self::NOCACHE_REASON ); // phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedHooknameFound -- LiteSpeed Cache's documented API action.
	}

	public function settings_added( $option, $settings ) {
		$this->settings_updated( array(), $settings );
	}

	public function settings_updated( $previous, $settings ) {
		// The site-wide flag is part of the cached HTML, so switching it on or off purges too.
		$fields   = array( 'mode', 'default_locale', 'second_locale', 'global_switcher' );
		$previous = array_intersect_key( is_array( $previous ) ? $previous : array(), array_flip( $fields ) );
		$settings = array_intersect_key( is_array( $settings ) ? $settings : array(), array_flip( $fields ) );
		if ( $previous === $settings ) {
			return;
		}

		if ( $this->locales->standalone_available() ) {
			do_action( 'wpsc_add_cookie', StandaloneLocale::COOKIE ); // phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedHooknameFound -- WP Super Cache's documented API action.
		} else {
			do_action( 'wpsc_delete_cookie', StandaloneLocale::COOKIE ); // phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedHooknameFound -- WP Super Cache's documented API action.
		}
		$this->sync_w3tc_cookie( $this->locales->standalone_available() );
		$this->sync_litespeed_vary( $this->locales->standalone_available() );

		// Pages cached under the previous locale configuration may show the wrong language or flag.
		PageCachePurger::purge(
			'locale_settings',
			array(
				'settings' => $settings,
				'previous' => $previous,
			)
		);
	}
}