<?php
/**
 * Places of postcodes.
 *
 * @package Dealroot
 */

namespace Dealroot;

defined( 'ABSPATH' ) || exit;

/**
 * Where a postcode or a town lies, from the free postcode lists of GeoNames, one file per
 * country. An enquiry or an order that gives a postcode or a town is put on the map there,
 * which is far more exact than the place of an internet connection.
 *
 * The lists are downloaded only when cities are turned on: the one of the site's country right
 * away, others the first time an enquiry from that country arrives.
 */
class Postcodes {

	const STATE       = 'dealroot_postcodes';
	const UPDATE_HOOK = 'dealroot_postcodes_update';
	const SOURCE      = 'https://download.geonames.org/export/zip/%s.zip';

	/**
	 * Most countries kept.
	 */
	const MAX_COUNTRIES = 12;

	/**
	 * A list older than this is replaced.
	 */
	const MAX_AGE = 90 * DAY_IN_SECONDS;

	/**
	 * Lists read in this request.
	 *
	 * @var array<string, array|false>
	 */
	private static $lists = array();

	/**
	 * 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 );
	}

	/**
	 * Country of the site: the shop's country, else the one of the phone numbers.
	 *
	 * @return string
	 */
	public static function site_country() {
		if ( function_exists( 'WC' ) && WC()->countries ) {
			$country = Geo::code( (string) WC()->countries->get_base_country() );

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

		return Geo::code( (string) ( Settings::get( 'phone_country' ) ? Settings::get( 'phone_country' ) : Phone::default_country() ) );
	}

	/**
	 * Countries with a list, and how each one is doing.
	 *
	 * @return array<string, array{built: int, error: string}>
	 */
	public static function countries() {
		$state = get_option( self::STATE, array() );

		return is_array( $state ) ? $state : array();
	}

	/**
	 * Fetches the list of the site's country when cities were just turned on, removes all lists
	 * 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::request( self::site_country() );
		} elseif ( ! $now && $was ) {
			self::remove();
		}
	}

	/**
	 * Asks for the list of a country, downloaded in the background.
	 *
	 * @param string $country Country code.
	 */
	public static function request( $country ) {
		$country = Geo::code( $country );
		$known   = self::countries();

		if ( '' === $country || ! Settings::get( 'geo_cities' ) || isset( $known[ $country ] ) || count( $known ) >= self::MAX_COUNTRIES ) {
			return;
		}

		$known[ $country ] = array(
			'built' => 0,
			'error' => '',
		);
		update_option( self::STATE, $known, false );

		if ( ! wp_next_scheduled( self::UPDATE_HOOK ) ) {
			wp_schedule_single_event( time() + 10, self::UPDATE_HOOK );
		}
	}

	/**
	 * Replaces lists that are a few months old, and fetches the one of the site's country.
	 */
	public static function maybe_update() {
		if ( ! Settings::get( 'geo_cities' ) ) {
			return;
		}

		self::request( self::site_country() );

		foreach ( self::countries() as $state ) {
			if ( time() - (int) $state['built'] > self::MAX_AGE && ! wp_next_scheduled( self::UPDATE_HOOK ) ) {
				wp_schedule_single_event( time() + 10, self::UPDATE_HOOK );
			}
		}
	}

	/**
	 * Downloads the lists that are missing or old, then places the recent leads again.
	 */
	public static function update() {
		if ( ! Settings::get( 'geo_cities' ) || get_transient( 'dealroot_postcodes_lock' ) ) {
			return;
		}

		set_transient( 'dealroot_postcodes_lock', 1, 10 * MINUTE_IN_SECONDS );

		$fetched = array();
		foreach ( self::countries() as $country => $state ) {
			if ( ( ! self::ready( $country ) || time() - (int) $state['built'] > self::MAX_AGE ) && self::download( $country ) ) {
				$fetched[] = $country;
			}
		}

		delete_transient( 'dealroot_postcodes_lock' );

		if ( $fetched ) {
			Lead_Place::refine( $fetched );
		}
	}

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

		foreach ( array_keys( self::countries() ) as $country ) {
			$path = self::path( $country );
			if ( '' !== $path && file_exists( $path ) ) {
				wp_delete_file( $path );
			}
		}

		delete_option( self::STATE );
		self::$lists = array();
	}

	/**
	 * Whether the list of a country is there.
	 *
	 * @param string $country Country code.
	 * @return bool
	 */
	public static function ready( $country ) {
		$path = self::path( $country );

		return '' !== $path && is_readable( $path );
	}

	/**
	 * Place of a postcode, or of a town when the postcode is not known.
	 *
	 * @param string $country  Country code.
	 * @param string $postcode Postcode as typed, may be empty.
	 * @param string $town     Town as typed, may be empty.
	 * @return array{city: string, lat: float, lon: float}|null
	 */
	public static function find( $country, $postcode, $town = '' ) {
		$list = self::load( $country );

		if ( ! $list ) {
			return null;
		}

		foreach ( self::keys( $country, $postcode ) as $key ) {
			if ( isset( $list['p'][ $key ] ) ) {
				return self::place( $list['p'][ $key ] );
			}
		}

		$town = self::town_key( $town );

		if ( '' !== $town && isset( $list['n'][ $town ] ) ) {
			return self::place( $list['n'][ $town ] );
		}

		return null;
	}

	/**
	 * Ways a postcode may be written in the list, most exact first: "1011 AB" is listed as
	 * 1011 in the Netherlands, "SW1A 1AA" as SW1A in Britain, "1010" stays 1010 in Austria.
	 *
	 * @param string $country  Country code.
	 * @param string $postcode Postcode as typed.
	 * @return string[]
	 */
	private static function keys( $country, $postcode ) {
		$code = strtoupper( trim( (string) preg_replace( '/^[A-Z]{1,2}\s*-\s*(?=\d)/i', '', trim( (string) $postcode ) ) ) );

		if ( '' === $code ) {
			return array();
		}

		$keys = array( (string) preg_replace( '/\s+/', '', $code ) );

		if ( preg_match( '/^(\d{4})\s*[A-Z]{2}$/', $code, $match ) ) {
			$keys[] = $match[1];
		}

		if ( preg_match( '/^([A-Z]{1,2}\d[A-Z\d]?)\s*\d[A-Z]{2}$/', $code, $match ) ) {
			$keys[] = $match[1];
		}

		// A German postcode written with four digits, e.g. "1067" for 01067.
		if ( 'DE' === $country && preg_match( '/^\d{4}$/', $keys[0] ) ) {
			$keys[] = '0' . $keys[0];
		}

		return array_unique( $keys );
	}

	/**
	 * A town as a key of the list.
	 *
	 * @param string $town Town.
	 * @return string
	 */
	private static function town_key( $town ) {
		$town = trim( (string) preg_replace( '/\s*\(.*\)$/', '', (string) $town ) );

		return '' === $town ? '' : mb_strtolower( $town );
	}

	/**
	 * Place of a list entry.
	 *
	 * @param array $entry Latitude, longitude and name.
	 * @return array
	 */
	private static function place( array $entry ) {
		return array(
			'city' => (string) $entry[2],
			'lat'  => (float) $entry[0],
			'lon'  => (float) $entry[1],
		);
	}

	/**
	 * Reads the list of a country.
	 *
	 * @param string $country Country code.
	 * @return array|false
	 */
	private static function load( $country ) {
		$country = Geo::code( $country );

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

		if ( ! isset( self::$lists[ $country ] ) ) {
			$path = self::path( $country );
			$data = '' !== $path && is_readable( $path ) ? json_decode( (string) file_get_contents( $path ), true ) : null; // phpcs:ignore WordPress.WP.AlternativeFunctions.file_get_contents_file_get_contents -- A local file of the plugin.

			self::$lists[ $country ] = is_array( $data ) && isset( $data['p'], $data['n'] ) ? $data : false;
		}

		return self::$lists[ $country ];
	}

	/**
	 * Path of the list of a country.
	 *
	 * @param string $country Country code.
	 * @return string
	 */
	private static function path( $country ) {
		$uploads = wp_upload_dir( null, false );
		$country = Geo::code( $country );

		return empty( $uploads['basedir'] ) || '' === $country ? '' : trailingslashit( $uploads['basedir'] ) . 'dealroot/postcodes-' . strtolower( $country ) . '.json';
	}

	/**
	 * Downloads the list of a country and keeps, for each postcode and each town, the middle of
	 * its places.
	 *
	 * @param string $country Country code.
	 * @return bool
	 */
	private static function download( $country ) {
		require_once ABSPATH . 'wp-admin/includes/file.php';

		$path = self::path( $country );

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

		/**
		 * Filters the address of the postcode list of a country.
		 *
		 * @param string $url     Address of a ZIP file in the format of GeoNames.
		 * @param string $country Country code.
		 */
		$url      = (string) apply_filters( 'dealroot_postcodes_url', sprintf( self::SOURCE, $country ), $country );
		$download = download_url( $url, 120 );

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

		$text = self::unzip( $download, $country . '.txt' );
		wp_delete_file( $download );

		$sums = array(
			'p' => array(),
			'n' => array(),
		);

		foreach ( preg_split( '/\r?\n/', (string) $text ) as $line ) {
			$cols = explode( "\t", $line );

			if ( count( $cols ) < 11 || ! is_numeric( $cols[9] ) || ! is_numeric( $cols[10] ) ) {
				continue;
			}

			$name = trim( (string) preg_replace( '/\s*\(.*\)$/', '', $cols[2] ) );
			$keys = array(
				'p' => strtoupper( (string) preg_replace( '/\s+/', '', $cols[1] ) ),
				'n' => mb_strtolower( $name ),
			);

			foreach ( $keys as $kind => $key ) {
				if ( '' === $key ) {
					continue;
				}

				$lat = (float) $cols[9];
				$lon = (float) $cols[10];

				if ( ! isset( $sums[ $kind ][ $key ] ) ) {
					$sums[ $kind ][ $key ] = array( 0.0, 0.0, $name, 0, $lat, $lat, $lon, $lon );
				}

				$sums[ $kind ][ $key ][0] += $lat;
				$sums[ $kind ][ $key ][1] += $lon;
				++$sums[ $kind ][ $key ][3];
				$sums[ $kind ][ $key ][4] = min( $sums[ $kind ][ $key ][4], $lat );
				$sums[ $kind ][ $key ][5] = max( $sums[ $kind ][ $key ][5], $lat );
				$sums[ $kind ][ $key ][6] = min( $sums[ $kind ][ $key ][6], $lon );
				$sums[ $kind ][ $key ][7] = max( $sums[ $kind ][ $key ][7], $lon );
			}
		}

		if ( ! $sums['p'] ) {
			return self::failed( $country, __( 'The postcode list could not be read.', 'dealroot' ) );
		}

		$list = array(
			'p' => array(),
			'n' => array(),
		);
		foreach ( $sums as $kind => $entries ) {
			foreach ( $entries as $key => $sum ) {
				// A name that several towns far apart share, such as Neustadt, says nothing.
				if ( 'n' === $kind && ( $sum[5] - $sum[4] > 0.6 || $sum[7] - $sum[6] > 0.6 ) ) {
					continue;
				}

				$list[ $kind ][ $key ] = array( round( $sum[0] / $sum[3], 3 ), round( $sum[1] / $sum[3], 3 ), $sum[2] );
			}
		}

		$written = file_put_contents( $path, wp_json_encode( $list, JSON_UNESCAPED_UNICODE ) ); // phpcs:ignore WordPress.WP.AlternativeFunctions.file_system_operations_file_put_contents -- Written by cron, where WP_Filesystem may need credentials.

		if ( ! $written ) {
			return self::failed( $country, __( 'The postcode list could not be saved.', 'dealroot' ) );
		}

		$state             = self::countries();
		$state[ $country ] = array(
			'built' => time(),
			'error' => '',
		);
		update_option( self::STATE, $state, false );
		unset( self::$lists[ $country ] );

		return true;
	}

	/**
	 * One file of a ZIP archive.
	 *
	 * @param string $archive ZIP file.
	 * @param string $name    Name of the file inside.
	 * @return string
	 */
	private static function unzip( $archive, $name ) {
		if ( class_exists( '\ZipArchive' ) ) {
			$zip = new \ZipArchive();

			if ( true === $zip->open( $archive ) ) {
				$text = $zip->getFromName( $name );
				$zip->close();

				return false === $text ? '' : $text;
			}

			return '';
		}

		// Without the zip extension, WordPress unpacks the archive with its own library.
		global $wp_filesystem;

		$folder = get_temp_dir() . 'dealroot-postcodes-' . wp_generate_password( 8, false );

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

		$done = unzip_file( $archive, $folder );
		$text = ! is_wp_error( $done ) && $wp_filesystem->exists( $folder . '/' . $name ) ? (string) $wp_filesystem->get_contents( $folder . '/' . $name ) : '';
		$wp_filesystem->delete( $folder, true );

		return $text;
	}

	/**
	 * Keeps the reason a download failed.
	 *
	 * @param string $country Country code.
	 * @param string $message Reason.
	 * @return bool False.
	 */
	private static function failed( $country, $message ) {
		$state             = self::countries();
		$state[ $country ] = array(
			'built' => (int) ( $state[ $country ]['built'] ?? 0 ),
			'error' => $message,
		);
		update_option( self::STATE, $state, false );

		return false;
	}
}