<?php
/**
 * 附件上传接口
 * ------------------------------------------------------------------
 * 两种存储方式由后台设置决定（attachment.storage）：
 *
 *  ① oss（阿里云 OSS 直传，原行为）
 *     POST upload.php kind=&ext=&size=&mime=&csrf=
 *     → 返回 host / key / policy / signature…，浏览器把文件直接 POST 到 OSS，
 *       文件不经过本服务器。凭证来自 ECS 实例 RAM 角色的临时凭证（或静态 AK）。
 *
 *  ② local（存本机磁盘）
 *     第一步同上，只是返回的 host 指向本文件的 ?action=put；
 *     第二步浏览器把文件 multipart POST 到 upload.php?action=put，
 *       服务端校验后落到 uploads/YYYY/MM/ 下。
 *
 * 两种方式共用同一套校验：扩展名 / MIME 白名单、单文件大小、每 IP 频率、全站总量上限。
 */
require __DIR__ . '/lib/bootstrap.php';

/** 统一 JSON 输出 */
function fb_up_json($data, $code = 200) {
    http_response_code($code);
    header('Content-Type: application/json; charset=utf-8');
    header('Cache-Control: no-store');
    header('X-Content-Type-Options: nosniff');
    echo json_encode($data, JSON_UNESCAPED_UNICODE | JSON_UNESCAPED_SLASHES);
    exit;
}

if (strtoupper(isset($_SERVER['REQUEST_METHOD']) ? $_SERVER['REQUEST_METHOD'] : 'GET') !== 'POST') {
    fb_up_json(['ok' => false, 'error' => 'method not allowed'], 405);
}

$mode  = fb_store_mode();
$putAt = (isset($_GET['action']) && (string)$_GET['action'] === 'put');

if ($mode === 'off') {
    fb_up_json(['ok' => false, 'error' => '附件上传未启用。'], 403);
}
if ($mode === 'oss' && !fb_oss_enabled()) {
    fb_up_json(['ok' => false, 'error' => '对象存储未配置完整，请到后台「站点设置」补齐桶信息。'], 403);
}
if ($mode === 'local' && !fb_local_writable()) {
    $ld = fb_local_diag();
    fb_up_json(['ok' => false, 'error' => '本机附件目录不可写（uploads/）。' . ($ld['tip'] !== '' ? ' ' . $ld['tip'] : '')], 403);
}
if (!fb_csrf_ok(isset($_POST['csrf']) ? $_POST['csrf'] : '')) {
    fb_up_json(['ok' => false, 'error' => '会话已过期，请刷新页面后重试。'], 400);
}

/* ==================================================================
 * 本机存储：接收文件本体
 * ================================================================== */
if ($putAt) {
    if ($mode !== 'local') { fb_up_json(['ok' => false, 'error' => '当前存储方式不支持本机上传。'], 400); }

    $kind = strtolower(trim(isset($_POST['kind']) ? (string)$_POST['kind'] : ''));
    $key  = trim(isset($_POST['key']) ? (string)$_POST['key'] : '');

    if ($kind !== 'image' && $kind !== 'video') { fb_up_json(['ok' => false, 'error' => '不支持的附件类型。'], 400); }
    if (!fb_upload_kind_on($kind))              { fb_up_json(['ok' => false, 'error' => '该类型附件未开放上传。'], 403); }
    if (!fb_attach_is_local($key) || !fb_upload_key_ok($key)) {
        fb_up_json(['ok' => false, 'error' => '附件地址不合法，请重新上传。'], 400);
    }

    $ext = fb_upload_key_ext($key);
    if (!fb_upload_ext_ok($kind, $ext)) { fb_up_json(['ok' => false, 'error' => '不支持的文件格式。'], 400); }

    if (empty($_FILES['file']) || !is_array($_FILES['file'])) {
        fb_up_json(['ok' => false, 'error' => '没有收到文件。'], 400);
    }
    $f = $_FILES['file'];
    if (!isset($f['error']) || (int)$f['error'] !== UPLOAD_ERR_OK) {
        fb_up_json(['ok' => false, 'error' => '文件上传失败（错误码 ' . (int)(isset($f['error']) ? $f['error'] : -1) . '）。'], 400);
    }
    if (!is_uploaded_file((string)$f['tmp_name'])) {
        fb_up_json(['ok' => false, 'error' => '文件上传失败。'], 400);
    }

    $size = (int)@filesize($f['tmp_name']);
    $maxB = (int)fb_upload_cfg($kind . '_max_bytes', 0);
    if ($size <= 0) { fb_up_json(['ok' => false, 'error' => '文件为空。'], 400); }
    if ($maxB > 0 && $size > $maxB) {
        fb_up_json(['ok' => false, 'error' => '文件超过大小限制（' . fb_size_h($maxB) . '）。'], 400);
    }

    $mime = strtolower(trim(isset($_POST['mime']) ? (string)$_POST['mime'] : ''));
    if ($mime === '') { $mime = fb_upload_mime_of_ext($ext); }
    if (!fb_upload_mime_ok($kind, $mime)) { fb_up_json(['ok' => false, 'error' => '不支持的文件类型。'], 400); }

    // 二次确认总量上限（防止并发绕过）
    $pdo = fb_db();
    $cap = (int)fb_upload_cfg('total_cap_bytes', 0);
    if ($cap > 0 && (fb_attach_total_bytes($pdo) + $size) > $cap) {
        fb_up_json(['ok' => false, 'error' => '附件存储空间已满，暂时无法上传。'], 507);
    }

    $path = fb_local_path_of($key);
    $dir  = dirname($path);
    if (!is_dir($dir)) { @mkdir($dir, 0755, true); }
    if (!is_dir($dir) || !@move_uploaded_file((string)$f['tmp_name'], $path)) {
        fb_up_json(['ok' => false, 'error' => '保存文件失败，请稍后重试。'], 500);
    }
    @chmod($path, 0644);

    fb_up_json([
        'ok'   => true,
        'key'  => $key,
        'url'  => fb_attach_url($key),
        'size' => $size,
        'mime' => $mime,
    ]);
}

/* ==================================================================
 * 领取上传凭证
 * ================================================================== */
$kind = strtolower(trim(isset($_POST['kind']) ? (string)$_POST['kind'] : ''));
if ($kind !== 'image' && $kind !== 'video') {
    fb_up_json(['ok' => false, 'error' => '不支持的附件类型。'], 400);
}
if (!fb_upload_kind_on($kind)) {
    fb_up_json(['ok' => false, 'error' => '该类型附件未开放上传。'], 403);
}

$ext  = fb_upload_norm_ext(isset($_POST['ext']) ? (string)$_POST['ext'] : '');
$size = (int)(isset($_POST['size']) ? $_POST['size'] : 0);
$mime = strtolower(trim(isset($_POST['mime']) ? (string)$_POST['mime'] : ''));
if ($mime === '') { $mime = fb_upload_mime_of_ext($ext); }

$maxBytes = (int)fb_upload_cfg($kind . '_max_bytes', 0);

if ($ext === '' || !fb_upload_ext_ok($kind, $ext)) {
    fb_up_json(['ok' => false, 'error' => '不支持的文件格式。'], 400);
}
if (!fb_upload_mime_ok($kind, $mime)) {
    fb_up_json(['ok' => false, 'error' => '不支持的文件类型。'], 400);
}
if ($size <= 0) {
    fb_up_json(['ok' => false, 'error' => '文件为空。'], 400);
}
if ($maxBytes > 0 && $size > $maxBytes) {
    fb_up_json(['ok' => false, 'error' => '文件超过大小限制（' . fb_size_h($maxBytes) . '）。'], 400);
}

$limit = (int)fb_upload_cfg('upload_per_hour', 60);
if (!fb_rate_check('upload', $limit)) {
    fb_up_json(['ok' => false, 'error' => '上传过于频繁，请稍后再试。'], 429);
}

// 全站总量上限：达到后不再发放凭证
$pdo = fb_db();
$cap = (int)fb_upload_cfg('total_cap_bytes', 0);
if ($cap > 0 && (fb_attach_total_bytes($pdo) + $size) > $cap) {
    fb_up_json(['ok' => false, 'error' => '附件存储空间已满，暂时无法上传，请稍后再试。'], 507);
}

/* ---------- 本机存储：返回一个指向本文件的上传地址 ---------- */
if ($mode === 'local') {
    $key = fb_local_make_key($ext);
    fb_rate_hit('upload');
    fb_up_json([
        'ok'         => true,
        'credential' => [
            'host' => 'upload.php?action=put',
            'key'  => $key,
            'url'  => fb_attach_url($key),
        ],
        'fields'     => [
            'csrf' => fb_csrf_token(),
            'key'  => $key,
            'kind' => $kind,
            'mime' => $mime,
        ],
        'mime'       => $mime,
        'kind'       => $kind,
    ]);
}

/* ---------- OSS 直传 ---------- */
$key  = fb_oss_make_key($ext);
$cred = fb_oss_upload_credential($key, $maxBytes, $kind . '/');

fb_rate_hit('upload');

// extra_fields 是除固定项外需要浏览器一并提交的表单域：使用实例 RAM 角色的
// 临时凭证时，就是 x-oss-security-token（OSS 靠它识别这份临时身份）。
$fields = [
    'key'                   => $cred['key'],
    'policy'                => $cred['policy'],
    'OSSAccessKeyId'        => $cred['access_key_id'],
    'signature'             => $cred['signature'],
    'success_action_status' => '200',
    'Content-Type'          => $mime,
];
if (!empty($cred['extra_fields']) && is_array($cred['extra_fields'])) {
    foreach ($cred['extra_fields'] as $k => $v) { $fields[$k] = $v; }
}

fb_up_json([
    'ok'         => true,
    'credential' => $cred,
    'fields'     => $fields,
    'mime'       => $mime,
    'kind'       => $kind,
]);