<?php
/**
 * api/nav.php —— 导航数据 JSON 接口
 * 用法：api/nav.php?cat=popular | red | blue
 * 返回：[{ "title": "...", "items": [{"label":"...","url":"...","note":"..."}] }]
 */
require_once dirname(__DIR__) . '/includes/db.php';

header('Content-Type: application/json; charset=utf-8');

$cat = (string)($_GET['cat'] ?? '');
if (!in_array($cat, ['popular', 'red', 'blue'], true)) {
    http_response_code(400);
    echo json_encode(['error' => 'cat 参数须为 popular/red/blue'], JSON_UNESCAPED_UNICODE);
    exit;
}

$pdo = db();
$st = $pdo->prepare('SELECT * FROM categories WHERE key = ? LIMIT 1');
$st->execute([$cat]);
$catRow = $st->fetch();
if (!$catRow) {
    http_response_code(404);
    echo json_encode(['error' => '分类不存在'], JSON_UNESCAPED_UNICODE);
    exit;
}

$out = [];
$st = $pdo->prepare('SELECT * FROM nav_blocks WHERE cat_id = ? ORDER BY sort ASC, id ASC');
$st->execute([(int)$catRow['id']]);
$blocks = $st->fetchAll();
$itemSt = $pdo->prepare('SELECT * FROM nav_items WHERE block_id = ? ORDER BY sort ASC, id ASC LIMIT 15');
foreach ($blocks as $b) {
    $itemSt->execute([(int)$b['id']]);
    $items = [];
    foreach ($itemSt->fetchAll() as $it) {
        $items[] = [
            'label' => (string)$it['label'],
            'url'   => (string)$it['url'],
            'note'  => (string)$it['note'],
        ];
    }
    $out[] = ['title' => (string)$b['title'], 'items' => $items];
}

echo json_encode($out, JSON_UNESCAPED_UNICODE);