<?php
/**
 * article/data.php —— 文章库 JSON 数据接口
 *   data.php?mode=list                文章元数据列表（按分区分组，含分区名）
 *   data.php?mode=content&id=N        单篇文章完整数据（含 markdown 正文）
 * 说明：仅返回前台可见（enabled=1）文章；隐文不对外。
 */
require_once dirname(__DIR__) . '/includes/db.php';

header('Content-Type: application/json; charset=utf-8');
header('Cache-Control: no-store');

$pdo = db();

function json_out(array $data): void
{
    echo json_encode($data, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES);
    exit;
}

$mode = (string)($_GET['mode'] ?? 'list');

if ($mode === 'content') {
    $id = (int)($_GET['id'] ?? 0);
    if ($id <= 0) {
        json_out(['ok' => false, 'msg' => '缺少文章 id']);
    }
    $st = $pdo->prepare('SELECT id, part, title, summary, markdown, pinned, created_at, updated_at
                         FROM articles WHERE id = ? AND enabled = 1 LIMIT 1');
    $st->execute([$id]);
    $row = $st->fetch();
    if (!$row) {
        json_out(['ok' => false, 'msg' => '文章不存在或已隐藏']);
    }
    json_out(['ok' => true, 'article' => $row]);
}

// ---- 默认：list 分组元数据（分区顺序取各分区首篇 id 序；分区内置顶 → sort → id） ----
$rows = $pdo->query('SELECT id, part, title, summary, pinned, sort, created_at, updated_at
                     FROM articles WHERE enabled = 1 ORDER BY id ASC')->fetchAll();
$parts = [];
if ($rows) {
    $partOrder = [];
    $byPart = [];
    foreach ($rows as $r) {
        $part = trim((string)$r['part']);
        if ($part === '') {
            $part = '未分类';
        }
        if (!isset($byPart[$part])) {
            $byPart[$part] = [];
            $partOrder[] = $part;
        }
        $byPart[$part][] = $r;
    }
    foreach ($partOrder as $part) {
        $items = $byPart[$part];
        usort($items, static function (array $a, array $b): int {
            if ((int)$a['pinned'] !== (int)$b['pinned']) {
                return (int)$b['pinned'] - (int)$a['pinned'];
            }
            if ((int)$a['sort'] !== (int)$b['sort']) {
                return (int)$a['sort'] <=> (int)$b['sort'];
            }
            return (int)$a['id'] <=> (int)$b['id'];
        });
        $parts[] = ['part' => $part, 'articles' => $items];
    }
}
json_out(['ok' => true, 'parts' => $parts]);