<?php
/**
 * Country and city of a visitor.
 *
 * @package Dealroot
 */

namespace Dealroot;

defined( 'ABSPATH' ) || exit;

/**
 * Finds where a visitor is, from the most exact source there is:
 *
 * 1. The free DB-IP Lite database, when the site owner turned on cities of visitors. It is
 *    downloaded once a month and looked up on the server, so IP addresses go nowhere. When the
 *    owner also entered a MaxMind license key, MaxMind GeoLite2 City is asked first.
 *    Leads that give a postcode or a town are placed from that instead, see Lead_Place.
 * 2. The country that a CDN such as Cloudflare passes to the site, and its city where it does.
 * 3. The country of the time zone the visitor's browser is set to.
 *
 * Only the country code and the city name are kept, never the IP address.
 */
class Geo {

	const FILE        = 'dbip-city-lite.mmdb';
	const STATE       = 'dealroot_geo_database';
	const UPDATE_HOOK = 'dealroot_geo_update';
	const SOURCE      = 'https://download.db-ip.com/free/dbip-city-lite-%s.mmdb.gz';

	/**
	 * A database older than this is replaced.
	 */
	const MAX_AGE = 35 * DAY_IN_SECONDS;

	/**
	 * Open database, false when there is none.
	 *
	 * @var Mmdb_Reader|false|null
	 */
	private static $reader = null;

	/**
	 * Hooks.
	 */
	public function register() {
		add_action( self::UPDATE_HOOK, array( __CLASS__, 'update' ) );
		add_action( Installer::CLEANUP_HOOK, array( __CLASS__, 'maybe_update' ) );
		add_action( 'update_option_' . Settings::OPTION, array( __CLASS__, 'settings_saved' ), 10, 2 );
		add_action( 'admin_post_dealroot_geo_download', array( __CLASS__, 'handle_download' ) );
	}

	/**
	 * Location of the current visitor.
	 *
	 * @param string $time_zone Time zone of the visitor's browser, e.g. "Europe/Berlin".
	 * @return array{country: string, city: string, lat: float|null, lon: float|null, source: string}
	 */
	public static function locate( $time_zone = '' ) {
		$found = array(
			'country' => '',
			'city'    => '',
			'lat'     => null,
			'lon'     => null,
			'source'  => '',
		);

		$record = self::record( self::visitor_ip() );
		if ( $record ) {
			$found['source']  = 'ip';
			$found['country'] = self::code( $record['country']['iso_code'] ?? '' );
			$found['city']    = self::city_name( $record['city']['names'] ?? array() );

			if ( '' !== $found['city'] ) {
				list( $found['lat'], $found['lon'] ) = self::point( $record['location']['latitude'] ?? null, $record['location']['longitude'] ?? null );
			}
		}

		if ( '' === $found['country'] ) {
			$found['country'] = self::code( self::header( array( 'HTTP_CF_IPCOUNTRY', 'HTTP_CLOUDFRONT_VIEWER_COUNTRY', 'HTTP_X_VERCEL_IP_COUNTRY', 'HTTP_X_COUNTRY_CODE', 'GEOIP_COUNTRY_CODE' ) ) );

			if ( '' !== $found['country'] ) {
				$found['city'] = self::clean_city( rawurldecode( self::header( array( 'HTTP_CF_IPCITY', 'HTTP_X_VERCEL_IP_CITY', 'GEOIP_CITY' ) ) ) );

				if ( '' !== $found['city'] ) {
					list( $found['lat'], $found['lon'] ) = self::point( self::header( array( 'HTTP_CF_IPLATITUDE', 'HTTP_X_VERCEL_IP_LATITUDE', 'GEOIP_LATITUDE' ) ), self::header( array( 'HTTP_CF_IPLONGITUDE', 'HTTP_X_VERCEL_IP_LONGITUDE', 'GEOIP_LONGITUDE' ) ) );
				}

				$found['source'] = 'cdn';
			}
		}

		if ( '' === $found['country'] && '' !== (string) $time_zone ) {
			$found['country'] = self::country_of_time_zone( (string) $time_zone );
			$found['source']  = '' !== $found['country'] ? 'tz' : '';
		}

		return $found;
	}

	/**
	 * Name of a country in the language of the admin.
	 *
	 * @param string $code Country code, e.g. "DE".
	 * @return string
	 */
	public static function country_label( $code ) {
		$code = self::code( $code );

		return '' === $code ? __( '(not set)', 'dealroot' ) : self::country_name( $code );
	}

	/**
	 * Name of a country in the language of the admin, the code where PHP has no names.
	 *
	 * @param string $code Country code.
	 * @return string
	 */
	public static function country_name( $code ) {
		$code = self::code( $code );

		if ( '' !== $code && class_exists( '\\Locale' ) ) {
			$name = \Locale::getDisplayRegion( 'und-' . $code, determine_locale() );

			if ( is_string( $name ) && '' !== $name && $name !== $code ) {
				return $name;
			}
		}

		return $code;
	}

	/**
	 * City and country, e.g. "Hannover, Germany".
	 *
	 * @param string $country Country code.
	 * @param string $city    City.
	 * @return string
	 */
	public static function place( $country, $city ) {
		$country = self::code( $country );
		$city    = (string) $city;

		if ( '' === $country ) {
			return $city;
		}

		return ( '' !== $city ? $city . ', ' : '' ) . self::country_name( $country );
	}

	/**
	 * Valid two-letter country code, '' otherwise. "XX" and "T1" (Tor) of Cloudflare are unknown.
	 *
	 * @param mixed $code Raw code.
	 * @return string
	 */
	public static function code( $code ) {
		$code = strtoupper( trim( (string) $code ) );

		return preg_match( '/^[A-Z]{2}$/', $code ) && ! in_array( $code, array( 'XX', 'ZZ', 'EU', 'AP' ), true ) ? $code : '';
	}

	/**
	 * Place of a city on the map, to two decimals: about a kilometre, the centre of the city
	 * rather than where the visitor is.
	 *
	 * @param mixed $lat Latitude.
	 * @param mixed $lon Longitude.
	 * @return array{0: float|null, 1: float|null}
	 */
	public static function point( $lat, $lon ) {
		if ( ! is_numeric( $lat ) || ! is_numeric( $lon ) || abs( (float) $lat ) > 90 || abs( (float) $lon ) > 180 || ( 0.0 === (float) $lat && 0.0 === (float) $lon ) ) {
			return array( null, null );
		}

		return array( round( (float) $lat, 2 ), round( (float) $lon, 2 ) );
	}

	/**
	 * City name as stored: without the district DB-IP adds in brackets.
	 *
	 * @param string $city Raw name.
	 * @return string
	 */
	public static function clean_city( $city ) {
		$city = trim( (string) preg_replace( '/\s*\([^)]*\)\s*$/u', '', sanitize_text_field( (string) $city ) ) );

		return mb_substr( $city, 0, 100 );
	}

	/**
	 * Whether cities are looked up, and how the database is doing.
	 *
	 * @return array{enabled: bool, ready: bool, built: int, size: int, error: string, updating: bool}
	 */
	public static function status() {
		$state = get_option( self::STATE, array() );
		$state = is_array( $state ) ? $state : array();
		$path  = self::path();

		return array(
			'enabled'  => (bool) Settings::get( 'geo_cities' ),
			'ready'    => '' !== $path && is_readable( $path ),
			'built'    => (int) ( $state['built'] ?? 0 ),
			'size'     => '' !== $path && is_readable( $path ) ? (int) filesize( $path ) : 0,
			'error'    => (string) ( $state['error'] ?? '' ),
			'updating' => (bool) wp_next_scheduled( self::UPDATE_HOOK ),
		);
	}

	/**
	 * Downloads the database when cities were just turned on, removes it when they were turned off.
	 *
	 * @param mixed $old_value Settings before.
	 * @param mixed $value     Settings after.
	 */
	public static function settings_saved( $old_value, $value ) {
		$was = ! empty( $old_value['geo_cities'] );
		$now = ! empty( $value['geo_cities'] );

		if ( $now && ( ! $was || ! self::status()['ready'] ) ) {
			self::schedule();
		} elseif ( ! $now && $was ) {
			self::remove();
		}
	}

	/**
	 * Downloads the database right away, from the button in the settings.
	 */
	public static function handle_download() {
		check_admin_referer( 'dealroot_geo_download' );

		if ( ! current_user_can( 'manage_options' ) ) {
			wp_die( esc_html__( 'You are not allowed to change these settings.', 'dealroot' ), 403 );
		}

		wp_clear_scheduled_hook( self::UPDATE_HOOK );
		delete_transient( 'dealroot_geo_lock' );
		self::update();

		wp_safe_redirect( admin_url( 'admin.php?page=' . Admin\Admin::SETTINGS_PAGE . '#dealroot-section-tracking' ) );
		exit;
	}

	/**
	 * Replaces a database that is a month old.
	 */
	public static function maybe_update() {
		if ( ! Settings::get( 'geo_cities' ) ) {
			return;
		}

		$status = self::status();

		if ( ! $status['ready'] || time() - $status['built'] > self::MAX_AGE ) {
			self::schedule();
		}
	}

	/**
	 * Downloads the database in the background, a few seconds from now.
	 */
	public static function schedule() {
		if ( ! wp_next_scheduled( self::UPDATE_HOOK ) ) {
			wp_schedule_single_event( time() + 5, self::UPDATE_HOOK );
		}
	}

	/**
	 * Downloads this month's database, or last month's while this month's is not out yet.
	 *
	 * @return bool
	 */
	public static function update() {
		if ( ! Settings::get( 'geo_cities' ) ) {
			return false;
		}

		// One download at a time, e.g. when the scheduled one and a manual one meet.
		if ( get_transient( 'dealroot_geo_lock' ) ) {
			return false;
		}
		set_transient( 'dealroot_geo_lock', 1, 15 * MINUTE_IN_SECONDS );

		$done = self::download();

		delete_transient( 'dealroot_geo_lock' );

		return $done;
	}

	/**
	 * Downloads, unpacks and checks the database, then puts it in place of the old one.
	 *
	 * @return bool
	 */
	private static function download() {
		require_once ABSPATH . 'wp-admin/includes/file.php';

		if ( function_exists( 'set_time_limit' ) ) {
			set_time_limit( 900 ); // phpcs:ignore Squiz.PHP.DiscouragedFunctions.Discouraged -- About 60 MB are downloaded and unpacked.
		}

		$folder = self::folder();
		if ( '' === $folder || ! wp_mkdir_p( $folder ) ) {
			return self::failed( __( 'The folder for the database could not be created in the uploads folder.', 'dealroot' ) );
		}

		self::protect( $folder );

		$download = null;
		foreach ( array( gmdate( 'Y-m' ), gmdate( 'Y-m', strtotime( 'first day of last month' ) ) ) as $month ) {
			/**
			 * Filters the address of the location database, e.g. to load it from a mirror.
			 *
			 * @param string $url   Address of a gzip-packed MaxMind DB file.
			 * @param string $month Month of the database, e.g. "2026-10".
			 */
			$url      = (string) apply_filters( 'dealroot_geo_database_url', sprintf( self::SOURCE, $month ), $month );
			$download = download_url( $url, 900 );
			if ( ! is_wp_error( $download ) ) {
				break;
			}
		}

		if ( is_wp_error( $download ) ) {
			/* translators: %s: error message */
			return self::failed( sprintf( __( 'The database could not be downloaded: %s', 'dealroot' ), $download->get_error_message() ) );
		}

		$target   = $folder . '/' . self::FILE;
		$unpacked = $target . '.' . wp_generate_password( 8, false ) . '.new';
		$ok       = self::gunzip( $download, $unpacked );

		wp_delete_file( $download );

		try {
			$reader = $ok ? new Mmdb_Reader( $unpacked ) : null;
			$ok     = $reader && $reader->get( '8.8.8.8' );
			$built  = $reader ? (int) ( $reader->metadata()['build_epoch'] ?? time() ) : 0;
			unset( $reader );
		} catch ( \RuntimeException $e ) {
			$ok = false;
		}

		if ( ! $ok || ! rename( $unpacked, $target ) ) { // phpcs:ignore WordPress.WP.AlternativeFunctions.rename_rename -- Replaces the database in one step.
			wp_delete_file( $unpacked );
			return self::failed( __( 'The downloaded database could not be read.', 'dealroot' ) );
		}

		self::$reader = null;
		update_option(
			self::STATE,
			array(
				'built' => $built,
				'error' => '',
			),
			false
		);

		return true;
	}

	/**
	 * Removes the database.
	 */
	public static function remove() {
		wp_clear_scheduled_hook( self::UPDATE_HOOK );

		$path = self::path();
		if ( '' !== $path && file_exists( $path ) ) {
			wp_delete_file( $path );
		}

		delete_option( self::STATE );
		self::$reader = null;
	}

	/**
	 * Record of an IP address in the most exact database there is: MaxMind when its place is
	 * close enough, else DB-IP, else whatever MaxMind knows.
	 *
	 * @param string $ip IP address.
	 * @return array|null
	 */
	private static function record( $ip ) {
		if ( '' === $ip || ! Settings::get( 'geo_cities' ) || ! self::is_public( $ip ) ) {
			return null;
		}

		$maxmind = Geo_Maxmind::lookup( $ip );

		if ( Geo_Maxmind::exact( $maxmind ) ) {
			return $maxmind;
		}

		$dbip = self::lookup( $ip );

		return $dbip && ( ! empty( $dbip['city']['names'] ) || ! $maxmind ) ? $dbip : ( $maxmind ? $maxmind : $dbip );
	}

	/**
	 * Record of an IP address in the DB-IP database.
	 *
	 * @param string $ip IP address.
	 * @return array|null
	 */
	private static function lookup( $ip ) {
		if ( '' === $ip || ! Settings::get( 'geo_cities' ) || ! filter_var( $ip, FILTER_VALIDATE_IP, FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE ) ) {
			return null;
		}

		if ( null === self::$reader ) {
			$path = self::path();

			try {
				self::$reader = '' !== $path && is_readable( $path ) ? new Mmdb_Reader( $path ) : false;
			} catch ( \RuntimeException $e ) {
				self::$reader = false;
			}
		}

		if ( ! self::$reader ) {
			return null;
		}

		try {
			return self::$reader->get( $ip );
		} catch ( \RuntimeException $e ) {
			return null;
		}
	}

	/**
	 * City name in the language of the site, else in English.
	 *
	 * @param array $names Language => name.
	 * @return string
	 */
	private static function city_name( $names ) {
		if ( ! is_array( $names ) || ! $names ) {
			return '';
		}

		$language = substr( get_locale(), 0, 2 );

		return self::clean_city( (string) ( $names[ $language ] ?? $names['en'] ?? reset( $names ) ) );
	}

	/**
	 * Country of a time zone, e.g. DE for Europe/Berlin.
	 *
	 * @param string $time_zone Time zone.
	 * @return string
	 */
	private static function country_of_time_zone( $time_zone ) {
		if ( ! preg_match( '#^[A-Za-z]+(?:/[A-Za-z0-9_+\-]+){1,2}$#', $time_zone ) || ! in_array( $time_zone, timezone_identifiers_list(), true ) ) {
			return '';
		}

		$location = ( new \DateTimeZone( $time_zone ) )->getLocation();

		return is_array( $location ) ? self::code( $location['country_code'] ?? '' ) : '';
	}

	/**
	 * First request header that is set.
	 *
	 * @param string[] $names Server variable names.
	 * @return string
	 */
	private static function header( array $names ) {
		foreach ( $names as $name ) {
			if ( ! empty( $_SERVER[ $name ] ) ) {
				return sanitize_text_field( wp_unslash( $_SERVER[ $name ] ) );
			}
		}

		return '';
	}

	/**
	 * IP address of the visitor; behind Cloudflare the one it passes on.
	 *
	 * @return string
	 */
	private static function visitor_ip() {
		$ip = isset( $_SERVER['REMOTE_ADDR'] ) ? sanitize_text_field( wp_unslash( $_SERVER['REMOTE_ADDR'] ) ) : '';

		if ( ! empty( $_SERVER['HTTP_CF_CONNECTING_IP'] ) && ! empty( $_SERVER['HTTP_CF_RAY'] ) ) {
			$forwarded = sanitize_text_field( wp_unslash( $_SERVER['HTTP_CF_CONNECTING_IP'] ) );
			$ip        = filter_var( $forwarded, FILTER_VALIDATE_IP ) ? $forwarded : $ip;
		} elseif ( ! self::is_public( $ip ) ) {
			// The site sits behind a proxy of the host, e.g. a load balancer or a cache: the
			// visitor is the first public address it passes on.
			foreach ( array( 'HTTP_X_FORWARDED_FOR', 'HTTP_X_REAL_IP', 'HTTP_TRUE_CLIENT_IP', 'HTTP_X_CLIENT_IP' ) as $header ) {
				foreach ( explode( ',', self::header( array( $header ) ) ) as $candidate ) {
					$candidate = trim( $candidate );

					if ( self::is_public( $candidate ) ) {
						$ip = $candidate;
						break 2;
					}
				}
			}
		}

		/**
		 * Filters the IP address used to find the city of a visitor, e.g. behind a proxy that
		 * passes it in a header of its own. It is never stored.
		 *
		 * @param string $ip IP address.
		 */
		return (string) apply_filters( 'dealroot_visitor_ip', $ip );
	}

	/**
	 * Whether an address is one of the internet, not of a private network.
	 *
	 * @param string $ip IP address.
	 * @return bool
	 */
	private static function is_public( $ip ) {
		return (bool) filter_var( $ip, FILTER_VALIDATE_IP, FILTER_FLAG_NO_PRIV_RANGE | FILTER_FLAG_NO_RES_RANGE );
	}

	/**
	 * What the lookup finds for the admin looking at the settings, to show that it works, or
	 * why it does not.
	 *
	 * @return array{ip: string, city: string, country: string, reason: string, databases: array}
	 */
	public static function check() {
		$ip     = self::visitor_ip();
		$record = self::record( $ip );
		$reason = '';

		// What each database says, so the owner can compare them.
		$databases = array();
		if ( Geo_Maxmind::configured() && self::is_public( $ip ) ) {
			foreach ( array(
				'MaxMind' => Geo_Maxmind::lookup( $ip ),
				'DB-IP'   => self::lookup( $ip ),
			) as $name => $found ) {
				$databases[ $name ] = array(
					'place'  => $found ? self::place( self::code( $found['country']['iso_code'] ?? '' ), self::city_name( $found['city']['names'] ?? array() ) ) : '',
					'radius' => $found ? (int) ( $found['location']['accuracy_radius'] ?? 0 ) : 0,
					'used'   => $found && $found === $record,
				);
			}
		}

		if ( ! self::status()['ready'] && ! Geo_Maxmind::status()['ready'] ) {
			$reason = 'database';
		} elseif ( ! self::is_public( $ip ) ) {
			$reason = 'private';
		} elseif ( ! $record || empty( $record['city']['names'] ) ) {
			$reason = 'unknown';
		}

		return array(
			// The last part of the address is left out on the screen as well.
			'ip'        => (string) preg_replace( '/[.:][^.:]+$/', '.…', $ip ),
			'city'      => $record ? self::city_name( $record['city']['names'] ?? array() ) : '',
			'country'   => $record ? self::code( $record['country']['iso_code'] ?? '' ) : '',
			'reason'    => $reason,
			'databases' => $databases,
		);
	}

	/**
	 * Folder of the database in the uploads folder.
	 *
	 * @return string
	 */
	private static function folder() {
		$uploads = wp_upload_dir( null, false );

		return empty( $uploads['basedir'] ) ? '' : trailingslashit( $uploads['basedir'] ) . 'dealroot';
	}

	/**
	 * Path of the database.
	 *
	 * @return string
	 */
	private static function path() {
		$folder = self::folder();

		return '' === $folder ? '' : $folder . '/' . self::FILE;
	}

	/**
	 * Keeps the folder from being listed or downloaded.
	 *
	 * @param string $folder Folder.
	 */
	private static function protect( $folder ) {
		global $wp_filesystem;

		if ( ! $wp_filesystem && ! WP_Filesystem() ) {
			return;
		}

		foreach ( array(
			'index.php' => "<?php\n// Silence is golden.\n",
			'.htaccess' => "Require all denied\n",
		) as $name => $content ) {
			if ( ! file_exists( $folder . '/' . $name ) ) {
				$wp_filesystem->put_contents( $folder . '/' . $name, $content, FS_CHMOD_FILE );
			}
		}
	}

	/**
	 * Unpacks a .gz file chunk by chunk.
	 *
	 * @param string $source Packed file.
	 * @param string $target Unpacked file.
	 * @return bool
	 */
	private static function gunzip( $source, $target ) {
		// phpcs:disable WordPress.WP.AlternativeFunctions -- Streams about 130 MB, which WP_Filesystem would load into memory.
		$in  = function_exists( 'gzopen' ) ? gzopen( $source, 'rb' ) : false;
		$out = $in ? fopen( $target, 'wb' ) : false;

		if ( ! $in || ! $out ) {
			if ( $in ) {
				gzclose( $in );
			}
			return false;
		}

		$ok = true;
		while ( $ok && ! gzeof( $in ) ) {
			$chunk = gzread( $in, 1048576 );
			$ok    = false !== $chunk && false !== fwrite( $out, $chunk );
		}

		gzclose( $in );
		fclose( $out );
		// phpcs:enable

		return $ok;
	}

	/**
	 * Keeps the reason a download failed for the settings screen.
	 *
	 * @param string $message Reason.
	 * @return bool False.
	 */
	private static function failed( $message ) {
		$state          = get_option( self::STATE, array() );
		$state          = is_array( $state ) ? $state : array();
		$state['error'] = $message;

		update_option( self::STATE, $state, false );

		return false;
	}
}