<?php
if (session_status() === PHP_SESSION_NONE) { session_start(); }

function current_user() {
    if (!empty($_SESSION["user_id"])) {
        $st = db()->prepare("SELECT * FROM users WHERE id=?");
        $st->execute([$_SESSION["user_id"]]);
        return $st->fetch();
    }
    return null;
}

function is_login() {
    return !empty($_SESSION["user_id"]);
}

function is_admin() {
    $u = current_user();
    return $u && $u["role"] === "admin";
}

function require_admin() {
    if (!is_admin()) {
        header("Location: " . SITE_URL . "login.php");
        exit;
    }
}

function attempt_login($username, $password) {
    $st = db()->prepare("SELECT * FROM users WHERE username=?");
    $st->execute([$username]);
    $user = $st->fetch();
    if ($user && password_verify($password, $user["password_hash"])) {
        $_SESSION["user_id"] = $user["id"];
        return true;
    }
    return false;
}

function logout() {
    unset($_SESSION["user_id"]);
}