<?php

if (!defined('ABSPATH')) {
    exit;
}

class AdGhost_IVT_Session {

    const COOKIE = 'adghost_sid';
    const TTL    = 30 * MINUTE_IN_SECONDS;

    private static $id = null;

    public static function id() {
        if (self::$id !== null) {
            return self::$id;
        }

        $existing = isset($_COOKIE[self::COOKIE]) ? sanitize_key(wp_unslash($_COOKIE[self::COOKIE])) : '';
        if (preg_match('/^[a-f0-9]{32}$/', $existing)) {
            self::$id = $existing;
            return self::$id;
        }

        self::$id = md5(wp_generate_password(32, true, true) . microtime(true));

        if (!headers_sent()) {
            setcookie(self::COOKIE, self::$id, [
                'expires'  => time() + self::TTL,
                'path'     => COOKIEPATH ? COOKIEPATH : '/',
                'domain'   => COOKIE_DOMAIN,
                'secure'   => is_ssl(),
                'httponly' => true,
                'samesite' => 'Lax',
            ]);
        }

        return self::$id;
    }

    public static function is_returning() {
        $existing = isset($_COOKIE[self::COOKIE]) ? sanitize_key(wp_unslash($_COOKIE[self::COOKIE])) : '';
        return (bool) preg_match('/^[a-f0-9]{32}$/', $existing);
    }

    public static function store(array $verdict) {
        set_transient(self::key(self::id()), $verdict, self::TTL);
    }

    public static function verdict() {
        if (!self::is_returning()) {
            return null;
        }
        $stored = get_transient(self::key(self::id()));
        return is_array($stored) ? $stored : null;
    }

    public static function hash_ip($ip = null) {
        $ip = $ip ?? (isset($_SERVER['REMOTE_ADDR']) ? sanitize_text_field(wp_unslash($_SERVER['REMOTE_ADDR'])) : '');
        return hash_hmac('sha256', $ip, self::daily_salt());
    }

    private static function daily_salt() {
        $today  = gmdate('Y-m-d');
        $stored = get_option('adghost_ivt_salt', []);

        if (is_array($stored) && ($stored['date'] ?? '') === $today && !empty($stored['salt'])) {
            return $stored['salt'];
        }

        $salt = wp_generate_password(64, true, true);
        update_option('adghost_ivt_salt', ['date' => $today, 'salt' => $salt], false);
        return $salt;
    }

    private static function key($id) {
        return 'adghost_ivt_' . $id;
    }

    public static function forget() {
        if (self::is_returning()) {
            delete_transient(self::key(self::id()));
        }
    }
}