92 lines
3.4 KiB
TypeScript
92 lines
3.4 KiB
TypeScript
import { loadSettings } from '../../../utils/appconfig'
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import { withSwarm } from '../../../utils/swarm'
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const IMAGE_TYPES: Record<string, string> = {
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jpg: 'image/jpeg',
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jpeg: 'image/jpeg',
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png: 'image/png',
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gif: 'image/gif',
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webp: 'image/webp',
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bmp: 'image/bmp',
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avif: 'image/avif'
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}
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/** 超过这个大小就不做在线预览了，从 swarm 拉一张大图的代价太高 */
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const MAX_PREVIEW_BYTES = 12 * 1024 * 1024
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/** 单张图片的下载时间上限 */
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const DOWNLOAD_TIMEOUT_MS = 25_000
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function normPath(value: string): string {
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return value.replace(/\\/g, '/').replace(/^\.\//, '')
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}
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/**
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* 从 swarm 里只把某一张图片的字节拉下来用于预览。
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* 只下载该文件覆盖到的分片，不落库、不长期占用磁盘。
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*/
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export default defineEventHandler(async (event) => {
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const infoHash = String(getRouterParam(event, 'infohash') || '').toLowerCase()
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if (!/^[a-f0-9]{40}$/.test(infoHash)) {
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throw createError({ statusCode: 400, statusMessage: 'infoHash 格式不正确' })
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}
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const query = getQuery(event)
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const magnet = String(query.magnet || '')
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const filePath = String(query.path || '')
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if (!/^magnet:\?/i.test(magnet)) {
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throw createError({ statusCode: 400, statusMessage: '缺少可用的磁力链，无法定位做种节点' })
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}
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if (!filePath) {
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throw createError({ statusCode: 400, statusMessage: '缺少 path 参数' })
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}
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const ext = filePath.slice(filePath.lastIndexOf('.') + 1).toLowerCase()
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const mime = IMAGE_TYPES[ext]
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if (!mime) {
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throw createError({ statusCode: 400, statusMessage: '只支持预览图片文件（jpg / png / gif / webp / bmp / avif）' })
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}
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const settings = await loadSettings()
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try {
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const bytes = await withSwarm(infoHash, magnet, settings.metadataTimeout, async (torrent) => {
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const target = (torrent.files || []).find(
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(f: any) => normPath(String(f.path || f.name || '')) === normPath(filePath)
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)
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if (!target) {
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throw createError({ statusCode: 404, statusMessage: '这个种子里没有该文件，文件清单可能已过期' })
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}
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if (target.length > MAX_PREVIEW_BYTES) {
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throw createError({
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statusCode: 413,
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statusMessage: `这张图 ${Math.round(target.length / 1024 / 1024)} MB，超过在线预览上限 ${MAX_PREVIEW_BYTES / 1024 / 1024} MB`
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})
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}
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return Promise.race<ArrayBuffer>([
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target.arrayBuffer(),
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new Promise<never>((_, reject) => {
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setTimeout(
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() => reject(new Error('下载图片超时：暂时没有可用的做种节点，稍后再试')),
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DOWNLOAD_TIMEOUT_MS
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)
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})
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])
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})
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setHeader(event, 'content-type', mime)
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setHeader(event, 'content-length', String(bytes.byteLength))
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setHeader(
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event,
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'content-disposition',
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`inline; filename="${encodeURIComponent(filePath.slice(filePath.lastIndexOf('/') + 1))}"`
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)
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setHeader(event, 'cache-control', 'private, max-age=3600')
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return Buffer.from(bytes)
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} catch (err) {
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// 把 withSwarm 抛出的原始错误（如 webtorrent 无法加载）转成可读的 HTTP 错误，
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// 避免前端看到 Nitro 的通用 Server Error 页面。
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if (err && typeof err === 'object' && 'statusCode' in err) throw err
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const message = err instanceof Error ? err.message : '从做种节点获取图片失败'
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throw createError({ statusCode: 503, statusMessage: message })
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}
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})
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