<?php
declare(strict_types=1);

function e($value): string
{
    return htmlspecialchars((string)($value ?? ''), ENT_QUOTES, 'UTF-8');
}

/**
 * 读取 config.php（每个请求只读一次）
 * 页面里的第三方 Key 一律从这里取，避免同一个值散落在多个文件里
 */
function app_config(): array
{
    static $config = null;
    if ($config === null) {
        $config = require dirname(__DIR__) . '/config.php';
    }
    return $config;
}

function url(string $route, array $params = []): string
{
    $params = array_merge(['r' => $route], $params);
    return '/index.php?' . http_build_query($params);
}

function redirect(string $route, array $params = [], string $anchor = ''): void
{
    $location = url($route, $params);
    if ($anchor !== '') {
        $location .= '#' . ltrim($anchor, '#');
    }
    header('Location: ' . $location);
    exit;
}

function view(string $template, array $data = []): void
{
    extract($data, EXTR_SKIP);
    $basePath = dirname(__DIR__);
    $content  = $basePath . '/templates/' . $template . '.php';
    if (!file_exists($content)) {
        throw new \RuntimeException("模板不存在: $template");
    }
    require $basePath . '/templates/layout.php';
}

function flash(string $key, ?string $value = null): ?string
{
    if ($value !== null) {
        $_SESSION['_flash'][$key] = $value;
        return null;
    }
    $v = $_SESSION['_flash'][$key] ?? null;
    unset($_SESSION['_flash'][$key]);
    return $v;
}

function csrf_token(): string
{
    if (empty($_SESSION['_csrf'])) {
        $_SESSION['_csrf'] = bin2hex(random_bytes(16));
    }
    return $_SESSION['_csrf'];
}

function csrf_check(): void
{
    $token = $_POST['_csrf'] ?? '';
    if (!hash_equals($_SESSION['_csrf'] ?? '', $token)) {
        http_response_code(419);
        exit('CSRF token 校验失败');
    }
}

function json_decode_field($json, $default = [])
{
    if (empty($json)) return $default;
    if (is_array($json)) return $json;
    $decoded = json_decode($json, true);
    return $decoded ?? $default;
}