<?php
require_once __DIR__ . '/../config/db.php';

// 产品切换
if (isset($_GET['set_product'])) {
    $pid = (int)$_GET['set_product'];
    if ($pid > 0) {
        if (isAdmin()) {
            $stmt = $pdo->prepare('SELECT id FROM products WHERE id = ? AND status = 1');
            $stmt->execute([$pid]);
        } else if (isset($_SESSION['user_id'])) {
            $stmt = $pdo->prepare('SELECT p.id FROM products p INNER JOIN user_products up ON p.id = up.product_id WHERE p.id = ? AND p.status = 1 AND up.user_id = ?');
            $stmt->execute([$pid, $_SESSION['user_id']]);
        }
        if ($stmt && $stmt->fetch()) {
            $_SESSION['current_product_id'] = $pid;
        }
    }
    $url = strtok($_SERVER['REQUEST_URI'], '?');
    $params = $_GET;
    unset($params['set_product']);
    if ($params) {
        $url .= '?' . http_build_query($params);
    }
    header("Location: $url");
    exit;
}

function isLoggedIn(): bool {
    return isset($_SESSION['user_id']);
}

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

function isAdmin(): bool {
    return isset($_SESSION['role']) && $_SESSION['role'] === 'admin';
}

function requireAdmin(): void {
    requireLogin();
    if (!isAdmin()) {
        header('Location: index.php');
        exit;
    }
}

function getCurrentUserId(): ?int {
    return $_SESSION['user_id'] ?? null;
}

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

function getCurrentProductId(): ?int {
    $pid = $_SESSION['current_product_id'] ?? null;
    if ($pid) {
        $products = getEnabledProducts();
        $ids = array_column($products, 'id');
        if (!in_array($pid, $ids)) {
            unset($_SESSION['current_product_id']);
            $pid = null;
        }
    }
    if (!$pid) {
        $products = getEnabledProducts();
        if (!empty($products)) {
            $_SESSION['current_product_id'] = (int)$products[0]['id'];
            $pid = (int)$products[0]['id'];
        }
    }
    return $pid;
}

function getEnabledProducts(): array {
    global $pdo;
    if (isAdmin()) {
        $stmt = $pdo->query('SELECT id, name FROM products WHERE status = 1 ORDER BY id ASC');
    } else {
        $stmt = $pdo->prepare('SELECT p.id, p.name FROM products p INNER JOIN user_products up ON p.id = up.product_id WHERE up.user_id = ? AND p.status = 1 ORDER BY p.id ASC');
        $stmt->execute([getCurrentUserId()]);
    }
    return $stmt->fetchAll();
}