<?php

class Analytics
{
    private PDO $pdo;

    public function __construct(PDO $pdo)
    {
        $this->pdo = $pdo;
    }

    public function record(string $event, ?string $pasteId = null, array $extra = []): void
    {
        try {
            $stmt = $this->pdo->prepare(
                'INSERT INTO analytics (event, paste_id, ip, user_agent, referer, extra)
                 VALUES (?, ?, ?, ?, ?, ?)'
            );
            $stmt->execute([
                $event,
                $pasteId,
                $this->getClientIp(),
                substr($_SERVER['HTTP_USER_AGENT'] ?? '', 0, 512),
                substr($_SERVER['HTTP_REFERER']    ?? '', 0, 512),
                empty($extra) ? null : json_encode($extra, JSON_UNESCAPED_UNICODE),
            ]);
        } catch (PDOException $e) {
            // analytics failure must never break the app
        }
    }

    private function getClientIp(): string
    {
        foreach (['HTTP_X_FORWARDED_FOR', 'HTTP_X_REAL_IP', 'REMOTE_ADDR'] as $key) {
            if (!empty($_SERVER[$key])) {
                $ip = trim(explode(',', $_SERVER[$key])[0]);
                if (filter_var($ip, FILTER_VALIDATE_IP)) {
                    return $ip;
                }
            }
        }
        return '';
    }
}