<?php

/**

 * Administration: Community Events class.

 *

 * @package WordPress

 * @subpackage Administration

 * @since 4.8.0

 */

/**

 * Class WP_Community_Events.

 *

 * A client for api.wordpress.org/events.

 *

 * @since 4.8.0

 */

class WP_Community_Events {

	/**

	 * ID for a WordPress user account.

	 *

	 * @since 4.8.0

	 *

	 * @var int

	 */

	protected $user_id = 0;

	/**

	 * Stores location data for the user.

	 *

	 * @since 4.8.0

	 *

	 */

	protected $user_location = false;

	/**

	 * Constructor for WP_Community_Events.

	 *

	 * @since 4.8.0

	 *

	 * @param int        $user_id       WP user ID.

	 *     @type string $description The name of the location

	 *     @type string $latitude    The latitude in decimal degrees notation, without the degree

	 *                               symbol. e.g.: 47.615200.

	 *     @type string $longitude   The longitude in decimal degrees notation, without the degree

	 *                               symbol. e.g.: -122.341100.

	 *     @type string $country     The ISO 3166-1 alpha-2 country code. e.g.: BR

	 * }

	 */

	public function __construct( $user_id, $user_location = false ) {

		$this->user_id       = absint( $user_id );

		$this->user_location = $user_location;

	}

	/**

	 * Gets data about events near a particular location.

	 *

	 * Cached events will be immediately returned if the `user_location` property

	 * is set for the current user, and cached events exist for that location.

	 *

	 * Otherwise, this method sends a request to the w.org Events API with location

	 * data. The API will send back a recognized location based on the data, along

	 * with nearby events.

	 *

	 * The browser's request for events is proxied with this method, rather

	 * than having the browser make the request directly to api.wordpress.org,

	 * because it allows results to be cached server-side and shared with other

	 * users and sites in the network. This makes the process more efficient,

	 * since increasing the number of visits that get cached data means users

	 * don't have to wait as often; if the user's browser made the request

	 * directly, it would also need to make a second request to WP in order to

	 * pass the data for caching. Having WP make the request also introduces

	 * the opportunity to anonymize the IP before sending it to w.org, which

	 * mitigates possible privacy concerns.

	 *

	 * @since 4.8.0

	 *

	 * @param string $location_search Optional. City name to help determine the location.

	 *                                e.g., "Seattle". Default empty string.

	 * @param string $timezone        Optional. Timezone to help determine the location.

	 *                                Default empty string.

	 * @return array|WP_Error A WP_Error on failure; an array with location and events on

	 *                        success.

	 */

	public function get_events( $location_search = '', $timezone = '' ) {

		$cached_events = $this->get_cached_events();

		if ( ! $location_search && $cached_events ) {

			return $cached_events;

		}

		// Include an unmodified $wp_version.

		require ABSPATH . WPINC . '/version.php';

		$api_url                    = 'http://api.wordpress.org/events/1.0/';

		$request_args               = $this->get_request_args( $location_search, $timezone );

		$request_args['user-agent'] = 'WordPress/' . $wp_version . '; ' . home_url( '/' );

		if ( wp_http_supports( array( 'ssl' ) ) ) {

			$api_url = set_url_scheme( $api_url, 'https' );

		}

		$response       = wp_remote_get( $api_url, $request_args );

		$response_code  = wp_remote_retrieve_response_code( $response );

		$response_body  = json_decode( wp_remote_retrieve_body( $response ), true );

		$response_error = null;

		if ( is_wp_error( $response ) ) {

			$response_error = $response;

		} elseif ( 200 !== $response_code ) {

			$response_error = new WP_Error(

				'api-error',

				/* translators: %d: Numeric HTTP status code, e.g. 400, 403, 500, 504, etc. */

				sprintf( __( 'Invalid API response code (%d).' ), $response_code )

			);

		} elseif ( ! isset( $response_body['location'], $response_body['events'] ) ) {

			$response_error = new WP_Error(

				'api-invalid-response',

				isset( $response_body['error'] ) ? $response_body['error'] : __( 'Unknown API error.' )

			);

		}

		if ( is_wp_error( $response_error ) ) {

			return $response_error;

		} else {

			$expiration = false;

			if ( isset( $response_body['ttl'] ) ) {

				$expiration = $response_body['ttl'];

				unset( $response_body['ttl'] );

			}

			/*

			 * The IP in the response is usually the same as the one that was sent

			 * in the request, but in some cases it is different. In those cases,

			 * it's important to reset it back to the IP from the request.

			 *

			 * For example, if the IP sent in the request is private (e.g., 192.168.1.100),

			 * then the API will ignore that and use the corresponding public IP instead,

			 * and the public IP will get returned. If the public IP were saved, though,

			 * then get_cached_events() would always return `false`, because the transient

			 * would be generated based on the public IP when saving the cache, but generated

			 * based on the private IP when retrieving the cache.

			 */

			if ( ! empty( $response_body['location']['ip'] ) ) {

				$response_body['location']['ip'] = $request_args['body']['ip'];

			}

			/*

			 * The API doesn't return a description for latitude/longitude requests,

			 * but the description is already saved in the user location, so that

			 * one can be used instead.

			 */

			if ( $this->coordinates_match( $request_args['body'], $response_body['location'] ) && empty( $response_body['location']['description'] ) ) {

				$response_body['location']['description'] = $this->user_location['description'];

			}

			$this->cache_events( $response_body, $expiration );

			return $response_body;

		}

	}

	/**

	 * Builds an array of args to use in an HTTP request to the w.org Events API.

	 *

	 * @since 4.8.0

	 *

	 * @param string $search   Optional. City search string. Default empty string.

	 * @param string $timezone Optional. Timezone string. Default empty string.

	 * @return array The request args.

	 */

	protected function get_request_args( $search = '', $timezone = '' ) {

		$args = array(

			'number' => 5, // Get more than three in case some get trimmed out.

			'ip'     => self::get_unsafe_client_ip(),

		);

		/*

		 * Include the minimal set of necessary arguments, in order to increase the

		 * chances of a cache-hit on the API side.

		 */

		if ( empty( $search ) && isset( $this->user_location['latitude'], $this->user_location['longitude'] ) ) {

			$args['latitude']  = $this->user_location['latitude'];

			$args['longitude'] = $this->user_location['longitude'];

		} else {

			$args['locale'] = get_user_locale( $this->user_id );

			if ( $timezone ) {

				$args['timezone'] = $timezone;

			}

			if ( $search ) {

				$args['location'] = $search;

			}

		}

		// Wrap the args in an array compatible with the second parameter of `wp_remote_get()`.

		return array(

			'body' => $args,

		);

	}

	/**

	 * Determines the user's actual IP address and attempts to partially

	 * anonymize an IP address by converting it to a network ID.

	 *

	 * Geolocating the network ID usually returns a similar location as the

	 * actual IP, but provides some privacy for the user.

	 *

	 * $_SERVER['REMOTE_ADDR'] cannot be used in all cases, such as when the user

	 * is making their request through a proxy, or when the web server is behind

	 * a proxy. In those cases, $_SERVER['REMOTE_ADDR'] is set to the proxy address rather

	 * than the user's actual address.

	 *

	 * Modified from https://stackoverflow.com/a/2031935/450127, MIT license.

	 * Modified from https://github.com/geertw/php-ip-anonymizer, MIT license.

	 *

	 * SECURITY WARNING: This function is _NOT_ intended to be used in

	 * circumstances where the authenticity of the IP address matters. This does

	 * _NOT_ guarantee that the returned address is valid or accurate, and it can

	 * be easily spoofed.

	 *

	 * @since 4.8.0

	 *

	 * @return string|false The anonymized address on success; the given address

	 *                      or false on failure.

	 */

	public static function get_unsafe_client_ip() {

		$client_ip = false;

		// In order of preference, with the best ones for this purpose first.

		$address_headers = array(

			'HTTP_CLIENT_IP',

			'HTTP_X_FORWARDED_FOR',

			'HTTP_X_FORWARDED',

			'HTTP_X_CLUSTER_CLIENT_IP',

			'HTTP_FORWARDED_FOR',

			'HTTP_FORWARDED',

			'REMOTE_ADDR',

		);

		foreach ( $address_headers as $header ) {

			if ( array_key_exists( $header, $_SERVER ) ) {

				/*

				 * HTTP_X_FORWARDED_FOR can contain a chain of comma-separated

				 * addresses. The first one is the original client. It can't be

				 * trusted for authenticity, but we don't need to for this purpose.

				 */

				$address_chain = explode( ',', $_SERVER[ $header ] );

				$client_ip     = trim( $address_chain[0] );

				break;

			}

		}

		if ( ! $client_ip ) {

			return false;

		}

		$anon_ip = wp_privacy_anonymize_ip( $client_ip, true );

		if ( '0.0.0.0' === $anon_ip || '::' === $anon_ip ) {

			return false;

		}

		return $anon_ip;

	}

	/**

	 * Test if two pairs of latitude/longitude coordinates match each other.

	 *

	 * @since 4.8.0

	 *

	 * @param array $a The first pair, with indexes 'latitude' and 'longitude'.

	 * @param array $b The second pair, with indexes 'latitude' and 'longitude'.

	 * @return bool True if they match, false if they don't.

	 */

	protected function coordinates_match( $a, $b ) {

		if ( ! isset( $a['latitude'], $a['longitude'], $b['latitude'], $b['longitude'] ) ) {

			return false;

		}

		return $a['latitude'] === $b['latitude'] && $a['longitude'] === $b['longitude'];

	}

	/**

	 * Generates a transient key based on user location.

	 *

	 * This could be reduced to a one-liner in the calling functions, but it's

	 * intentionally a separate function because it's called from multiple

	 * functions, and having it abstracted keeps the logic consistent and DRY,

	 * which is less prone to errors.

	 *

	 * @since 4.8.0

	 *

	 * @param array $location Should contain 'latitude' and 'longitude' indexes.

	 */

	protected function get_events_transient_key( $location ) {

		$key = false;

		if ( isset( $location['ip'] ) ) {

			$key = 'community-events-' . md5( $location['ip'] );

		} elseif ( isset( $location['latitude'], $location['longitude'] ) ) {

			$key = 'community-events-' . md5( $location['latitude'] . $location['longitude'] );

		}

		return $key;

	}

	/**

	 * Caches an array of events data from the Events API.

	 *

	 * @since 4.8.0

	 *

	 * @return bool true if events were cached; false if not.

	 */

	protected function cache_events( $events, $expiration = false ) {

		$set              = false;

		$transient_key    = $this->get_events_transient_key( $events['location'] );

		$cache_expiration = $expiration ? absint( $expiration ) : HOUR_IN_SECONDS * 12;

		if ( $transient_key ) {

			$set = set_site_transient( $transient_key, $events, $cache_expiration );

		}

		return $set;

	}

	/**

	 * Gets cached events.

	 *

	 * @since 4.8.0

	 *

	 * @return array|false An array containing `location` and `events` items

	 *                     on success, false on failure.

	 */

	public function get_cached_events() {

		$cached_response = get_site_transient( $this->get_events_transient_key( $this->user_location ) );

	}

	/**

	 * Adds formatted date and time items for each event in an API response.

	 *

	 * This has to be called after the data is pulled from the cache, because

	 * the cached events are shared by all users. If it was called before storing

	 * the cache, then all users would see the events in the localized data/time

	 * of the user who triggered the cache refresh, rather than their own.

	 *

	 * @since 4.8.0

	 *

	 * @param array $response_body The response which contains the events.

	 * @return array The response with dates and times formatted.

	 */

	protected function format_event_data_time( $response_body ) {

		if ( isset( $response_body['events'] ) ) {

			foreach ( $response_body['events'] as $key => $event ) {

				$timestamp = strtotime( $event['date'] );

				/*

				 * The `date_format` option is not used because it's important

				 * in this context to keep the day of the week in the formatted date,

				 * so that users can tell at a glance if the event is on a day they

				 * are available, without having to open the link.

				 */

				$formatted_date = date_i18n( __( 'l, M j, Y' ), $timestamp );

				$formatted_time = date_i18n( get_option( 'time_format' ), $timestamp );

				if ( isset( $event['end_date'] ) ) {

					$end_timestamp      = strtotime( $event['end_date'] );

					$formatted_end_date = date_i18n( __( 'l, M j, Y' ), $end_timestamp );

					if ( 'meetup' !== $event['type'] && $formatted_end_date !== $formatted_date ) {

						$start_month = date_i18n( _x( 'F', 'upcoming events month format' ), $timestamp );

						$end_month   = date_i18n( _x( 'F', 'upcoming events month format' ), $end_timestamp );

						if ( $start_month === $end_month ) {

							$formatted_date = sprintf(

								/* translators: Date string for upcoming events. 1: Month, 2: Starting day, 3: Ending day, 4: Year. */

								__( '%1$s %2$d–%3$d, %4$d' ),

								$start_month,

								date_i18n( _x( 'j', 'upcoming events day format' ), $timestamp ),

								date_i18n( _x( 'j', 'upcoming events day format' ), $end_timestamp ),

								date_i18n( _x( 'Y', 'upcoming events year format' ), $timestamp )

							);

						} else {

							$formatted_date = sprintf(

								/* translators: Date string for upcoming events. 1: Starting month, 2: Starting day, 3: Ending month, 4: Ending day, 5: Year. */

								__( '%1$s %2$d – %3$s %4$d, %5$d' ),

								$start_month,

								date_i18n( _x( 'j', 'upcoming events day format' ), $timestamp ),

								$end_month,

								date_i18n( _x( 'j', 'upcoming events day format' ), $end_timestamp ),

								date_i18n( _x( 'Y', 'upcoming events year format' ), $timestamp )

							);

						}

						$formatted_date = wp_maybe_decline_date( $formatted_date, 'F j, Y' );

					}

				}