<?php
/**
 * Device, system and browser of a visitor.
 *
 * @package Dealroot
 */

namespace Dealroot;

defined( 'ABSPATH' ) || exit;

/**
 * Reads the kind of device, the operating system and the browser from the browser's user
 * agent. Only these three names are kept, never the user agent itself.
 */
class Devices {

	/**
	 * Browsers and in-app browsers, most specific first: pattern => name.
	 */
	const BROWSERS = array(
		'/Instagram/'                           => 'Instagram',
		'/FBAN|FBAV|FB_IAB/'                    => 'Facebook',
		'/musical_ly|BytedanceWebview|TikTok/i' => 'TikTok',
		'/LinkedInApp/'                         => 'LinkedIn',
		'/Snapchat/'                            => 'Snapchat',
		'/Pinterest/'                           => 'Pinterest',
		'/; wv\)|WebView/'                      => 'In-app browser',
		'/SamsungBrowser/'                      => 'Samsung Internet',
		'/EdgA?\/|EdgiOS\//'                    => 'Edge',
		'/OPR\/|Opera/'                         => 'Opera',
		'/YaBrowser/'                           => 'Yandex Browser',
		'/DuckDuckGo\//'                        => 'DuckDuckGo',
		'/Firefox\/|FxiOS\//'                   => 'Firefox',
		'/Chrome\/|CriOS\//'                    => 'Chrome',
		'/Safari\//'                            => 'Safari',
	);

	/**
	 * Operating systems, most specific first: pattern => name.
	 */
	const SYSTEMS = array(
		'/iPhone|iPad|iPod/'   => 'iOS',
		'/Android/'            => 'Android',
		'/CrOS/'               => 'ChromeOS',
		'/Windows/'            => 'Windows',
		'/Macintosh|Mac OS X/' => 'macOS',
		'/Linux/'              => 'Linux',
	);

	/**
	 * Device of the current request.
	 *
	 * @return array{type: string, os: string, browser: string}|null
	 */
	public static function from_request() {
		$agent = isset( $_SERVER['HTTP_USER_AGENT'] ) ? sanitize_text_field( wp_unslash( $_SERVER['HTTP_USER_AGENT'] ) ) : '';

		return self::from_user_agent( $agent );
	}

	/**
	 * Device of a user agent.
	 *
	 * @param string $agent User agent.
	 * @return array{type: string, os: string, browser: string}|null
	 */
	public static function from_user_agent( $agent ) {
		$agent = (string) $agent;

		if ( '' === $agent || Visits::is_bot( $agent ) ) {
			return null;
		}

		if ( preg_match( '/iPad|Tablet|PlayBook|Silk|Kindle/i', $agent ) || ( false !== strpos( $agent, 'Android' ) && false === strpos( $agent, 'Mobile' ) ) ) {
			$type = 'tablet';
		} elseif ( preg_match( '/Mobi|iPhone|iPod|Android|Windows Phone/i', $agent ) ) {
			$type = 'mobile';
		} else {
			$type = 'desktop';
		}

		return array(
			'type'    => $type,
			'os'      => self::first_match( self::SYSTEMS, $agent ),
			'browser' => self::first_match( self::BROWSERS, $agent ),
		);
	}

	/**
	 * A stored device, limited to the known names.
	 *
	 * @param mixed $device Stored value.
	 * @return array{type: string, os: string, browser: string}|null
	 */
	public static function sanitize( $device ) {
		if ( ! is_array( $device ) || ! in_array( $device['type'] ?? '', array( 'mobile', 'tablet', 'desktop' ), true ) ) {
			return null;
		}

		return array(
			'type'    => $device['type'],
			'os'      => in_array( $device['os'] ?? '', self::SYSTEMS, true ) ? $device['os'] : '',
			'browser' => in_array( $device['browser'] ?? '', self::BROWSERS, true ) ? $device['browser'] : '',
		);
	}

	/**
	 * Name of a kind of device.
	 *
	 * @param string $type mobile, tablet or desktop.
	 * @return string
	 */
	public static function type_label( $type ) {
		$labels = array(
			'mobile'  => __( 'Smartphone', 'dealroot' ),
			'tablet'  => __( 'Tablet', 'dealroot' ),
			'desktop' => __( 'Computer', 'dealroot' ),
		);

		return $labels[ $type ] ?? '';
	}

	/**
	 * Name of a browser for display.
	 *
	 * @param string $browser Stored name.
	 * @return string
	 */
	public static function browser_label( $browser ) {
		return 'In-app browser' === $browser ? __( 'In-app browser', 'dealroot' ) : (string) $browser;
	}

	/**
	 * Name of the first pattern that matches.
	 *
	 * @param array  $patterns Pattern => name.
	 * @param string $agent    User agent.
	 * @return string
	 */
	private static function first_match( array $patterns, $agent ) {
		foreach ( $patterns as $pattern => $name ) {
			if ( preg_match( $pattern, $agent ) ) {
				return $name;
			}
		}

		return '';
	}
}