<?php

session_start();

const SW_MANUAL_LOG_FILE = __DIR__ . '/logs/access.log';

function sw_load_users(): array {
    $cfgPath = __DIR__ . '/auth.config.php';
    if (!file_exists($cfgPath)) {
        return [];
    }
    $cfg = require $cfgPath;
    return $cfg['users'] ?? [];
}

function sw_verify_login(string $username, string $password): bool {
    $users = sw_load_users();
    if (!isset($users[$username])) {
        return false;
    }
    $expected = (string)$users[$username];
    return hash_equals($expected, $password);
}

function sw_current_user(): ?string {
    return $_SESSION['sw_manual_user'] ?? null;
}

function sw_require_login(): void {
    if (!sw_current_user()) {
        header('Location: login.php');
        exit;
    }
}

function sw_record_login(string $username): void {
    $dir = dirname(SW_MANUAL_LOG_FILE);
    if (!is_dir($dir)) {
        @mkdir($dir, 0775, true);
    }
    $ts   = (new DateTimeImmutable('now', new DateTimeZone('Europe/Berlin')))->format(DateTimeInterface::ATOM);
    $ip   = $_SERVER['REMOTE_ADDR'] ?? '-';
    $ua   = $_SERVER['HTTP_USER_AGENT'] ?? '-';
    $line = $ts . ';' . $username . ';' . $ip . ';' . str_replace("\n", ' ', $ua) . "\n";
    @file_put_contents(SW_MANUAL_LOG_FILE, $line, FILE_APPEND | LOCK_EX);
}

function sw_last_login_for_user(string $username): ?DateTimeImmutable {
    if (!file_exists(SW_MANUAL_LOG_FILE)) {
        return null;
    }

    $fh = @fopen(SW_MANUAL_LOG_FILE, 'r');
    if (!$fh) {
        return null;
    }

    $last = null;
    while (($line = fgets($fh)) !== false) {
        $parts = explode(';', trim($line));
        if (count($parts) < 2) {
            continue;
        }
        [$ts, $user] = $parts;
        if ($user !== $username) {
            continue;
        }
        try {
            $dt = new DateTimeImmutable($ts);
            if ($last === null || $dt > $last) {
                $last = $dt;
            }
        } catch (Exception $e) {
            continue;
        }
    }
    fclose($fh);

    return $last;
}

function sw_format_dt(?DateTimeImmutable $dt): string {
    if ($dt === null) {
        return '–';
    }
    return $dt->setTimezone(new DateTimeZone('Europe/Berlin'))->format('d.m.Y, H:i \U\h\r');
}