<?php
/**
 * Visitors on the site right now.
 *
 * @package Dealroot
 */

namespace Dealroot;

defined( 'ABSPATH' ) || exit;

/**
 * While a page is open, the tracker tells the site which page it is and which form the visitor
 * is filling in: once a minute while the page lies idle, at most every 20 seconds while it is
 * read, and every five seconds while someone watches the live screen. So open pages cost few
 * requests when nobody looks. One row per browser tab is kept, with where the
 * visitor came from, the device and the city, and removed ten minutes after the last sign.
 * A random key tells the tabs apart; nothing identifies the person.
 *
 * phpcs:disable WordPress.DB.DirectDatabaseQuery.DirectQuery, WordPress.DB.DirectDatabaseQuery.NoCaching
 */
class Live {

	/**
	 * A visitor counts as on the site this long after the last sign of the page, which comes once a
	 * minute while nobody watches.
	 */
	const ACTIVE = 90;

	/**
	 * Rows are removed this long after the last sign.
	 */
	const KEEP = 600;

	/**
	 * States of the form on the page.
	 */
	const STATES = array( '', 'filling', 'sent' );

	/**
	 * Table name.
	 *
	 * @return string
	 */
	public static function table() {
		global $wpdb;

		return $wpdb->prefix . 'dealroot_live';
	}

	/**
	 * Whether the tracker reports open pages.
	 *
	 * @return bool
	 */
	public static function enabled() {
		return (bool) Settings::get( 'live_view' );
	}

	/**
	 * Notes a sign of an open page.
	 *
	 * @param string $key  Random key of the browser tab.
	 * @param array  $sign Page, title, form, state ("", "filling" or "sent"), and the nudge the
	 *                     visitor saw with nudge_state ("shown" or "clicked").
	 * @return array{ok: bool, push: string, fast: bool} Push: a message to show the visitor,
	 *               sent from the live screen; fast: someone watches the live screen.
	 */
	public static function record( $key, array $sign ) {
		global $wpdb;

		$answer = array(
			'ok'   => false,
			'push' => '',
			'fast' => self::watched(),
		);

		if ( ! preg_match( '/^[a-f0-9]{32}$/', (string) $key ) ) {
			return $answer;
		}

		$table  = self::table();
		$now    = current_time( 'mysql', true );
		$state  = in_array( $sign['state'] ?? '', self::STATES, true ) ? $sign['state'] : '';
		$nudged = in_array( $sign['nudge_state'] ?? '', array( 'shown', 'clicked' ), true ) ? $sign['nudge_state'] : '';
		$row    = array(
			'updated' => $now,
			'page'    => mb_substr( (string) strtok( sanitize_text_field( (string) ( $sign['page'] ?? '' ) ), '?#' ), 0, 191 ),
			'title'   => mb_substr( sanitize_text_field( (string) ( $sign['title'] ?? '' ) ), 0, 191 ),
			'form'    => '' === $state ? '' : mb_substr( sanitize_text_field( (string) ( $sign['form'] ?? '' ) ), 0, 191 ),
			'state'   => $state,
		);

		if ( '' !== $nudged ) {
			$row['nudge']       = mb_substr( sanitize_text_field( (string) ( $sign['nudge'] ?? '' ) ), 0, 100 );
			$row['nudge_state'] = $nudged;
		}

		$known = $wpdb->get_row( $wpdb->prepare( 'SELECT page, pages, city, push FROM %i WHERE id = %s', $table, $key ) );

		if ( $known ) {
			$row['pages'] = min( 999, (int) $known->pages + ( $known->page !== $row['page'] ? 1 : 0 ) );

			// A message from the live screen is handed over once.
			if ( '' !== (string) $known->push ) {
				$answer['push'] = (string) $known->push;
				$row['push']    = '';
			}

			// The city of a visitor who arrived before the location database was ready.
			if ( '' === $known->city && Settings::get( 'geo_cities' ) ) {
				$attribution = Attribution::from_request();
				$place       = Geo::locate( (string) ( $attribution['tz'] ?? '' ) );

				if ( '' !== $place['city'] ) {
					$row = array_merge(
						$row,
						$place,
						array(
							'lat' => (float) $place['lat'],
							'lon' => (float) $place['lon'],
						)
					);
				}
			}

			$answer['ok'] = false !== $wpdb->update( $table, $row, array( 'id' => $key ) );

			return $answer;
		}

		$wpdb->query( $wpdb->prepare( 'DELETE FROM %i WHERE updated < %s', $table, gmdate( 'Y-m-d H:i:s', time() - self::KEEP ) ) );

		$attribution = Attribution::from_request();
		$touch       = $attribution['last'] ?? array();
		$visitor     = Visitor::columns( (string) ( $attribution['tz'] ?? '' ) );

		$answer['ok'] = (bool) $wpdb->insert(
			$table,
			array_merge(
				$row,
				array(
					'id'      => $key,
					'ref'     => strtolower( wp_generate_password( 12, false ) ),
					'started' => $now,
					'pages'   => 1,
					'channel' => $touch ? Attribution::channel( $touch ) : 'direct',
					'source'  => $touch ? mb_substr( Sources::key( Sources::paid_key( Attribution::source( $touch ), Attribution::channel( $touch ) ) ), 0, 191 ) : '(direct)',
					'device'  => $visitor['device'],
					'browser' => $visitor['browser'],
					'country' => $visitor['country'],
					'city'    => $visitor['city'],
					'lat'     => $visitor['lat'],
					'lon'     => $visitor['lon'],
				)
			)
		);

		return $answer;
	}

	/**
	 * Messages the live screen can send to a visitor, e.g. the nudges of Dealroot Pro.
	 *
	 * @return array<int, array{id: string, label: string}>
	 */
	public static function pushes() {
		/**
		 * Filters the messages that can be sent to a visitor from the live screen. The tracker
		 * passes the ID to the page as the "dealroot:push" event, for a script that shows it.
		 *
		 * @param array $pushes ID (letters and digits, up to 20) and label of each message.
		 */
		$pushes = (array) apply_filters( 'dealroot_live_pushes', array() );

		return array_values(
			array_filter(
				array_map(
					static function ( $push ) {
						$id = (string) ( $push['id'] ?? '' );

						return preg_match( '/^[a-z0-9]{1,20}$/', $id ) ? array(
							'id'    => $id,
							'label' => mb_substr( (string) ( $push['label'] ?? $id ), 0, 80 ),
						) : null;
					},
					$pushes
				)
			)
		);
	}

	/**
	 * Hands a message to a visitor on their next sign.
	 *
	 * @param string $ref  Public key of the visitor on the live screen.
	 * @param string $push Message ID, one of pushes().
	 * @return bool
	 */
	public static function push( $ref, $push ) {
		global $wpdb;

		if ( ! preg_match( '/^[a-z0-9]{12}$/', (string) $ref ) || ! in_array( $push, wp_list_pluck( self::pushes(), 'id' ), true ) ) {
			return false;
		}

		return (bool) $wpdb->update( self::table(), array( 'push' => $push ), array( 'ref' => $ref ) );
	}

	/**
	 * Notes that someone watches the live screen, so pages report every few seconds.
	 */
	public static function watch() {
		set_transient( 'dealroot_live_watched', 1, 30 );
	}

	/**
	 * Whether someone watches the live screen.
	 *
	 * @return bool
	 */
	public static function watched() {
		return (bool) get_transient( 'dealroot_live_watched' );
	}

	/**
	 * Visitors with a page open now, the most recent arrivals first.
	 *
	 * @return object[]
	 */
	public static function current() {
		global $wpdb;

		return (array) $wpdb->get_results(
			$wpdb->prepare(
				'SELECT * FROM %i WHERE updated >= %s ORDER BY started DESC LIMIT 200',
				self::table(),
				gmdate( 'Y-m-d H:i:s', time() - self::ACTIVE )
			)
		);
	}

	/**
	 * Number of visitors on the site now.
	 *
	 * @return int
	 */
	public static function count() {
		global $wpdb;

		if ( ! self::enabled() ) {
			return 0;
		}

		return (int) $wpdb->get_var( $wpdb->prepare( 'SELECT COUNT(*) FROM %i WHERE updated >= %s', self::table(), gmdate( 'Y-m-d H:i:s', time() - self::ACTIVE ) ) );
	}

	/**
	 * Removes every row, e.g. when the setting is turned off.
	 */
	public static function clear() {
		global $wpdb;

		$wpdb->query( $wpdb->prepare( 'DELETE FROM %i', self::table() ) );
	}
}