1import { DurableObject } from 'cloudflare:workers'2import type { BrowserWorker } from '@cloudflare/puppeteer'3import { PuppeteerExecutor, type BrowserExecutor } from './executor'4import { errorResponse, FRAME_URLS, LIMITS, validateRenderRequest, type Engine, type RenderRequest } from './contracts'56export interface Env {7 BROWSER: BrowserWorker8 BROWSER_SESSIONS: DurableObjectNamespace<BrowserSession>9 INTERNAL_TOKEN?: string10}1112function json(value: unknown, init: ResponseInit = {}): Response {13 const headers = new Headers(init.headers)14 headers.set('Content-Type', 'application/json; charset=utf-8')15 headers.set('Cache-Control', 'no-store')16 return Response.json(value, { ...init, headers })17}1819function sessionName(engine: Engine): string { return `renderer:${engine}` }2021export function responseFromRenderResult(result: Awaited<ReturnType<BrowserExecutor['render']>>): Response {22 if (!result.ok) return json({ error: { code: 'frame_failed', message: result.error } }, { status: 422 })23 return json({ svg: result.svg, version: result.version, build: result.build, pipeline: result.pipeline })24}2526export class BrowserSession extends DurableObject<Env> {27 private executor?: BrowserExecutor28 private queue: Promise<unknown> = Promise.resolve()2930 private getExecutor(): BrowserExecutor {31 return this.executor ??= new PuppeteerExecutor(this.env.BROWSER)32 }3334 private enqueue<T>(operation: () => Promise<T>): Promise<T> {35 const next = this.queue.then(operation, operation)36 this.queue = next.then(() => undefined, () => undefined)37 return next38 }3940 async fetch(request: Request): Promise<Response> {41 if (request.method !== 'POST') return json({ error: { code: 'method_not_allowed', message: 'POST required.' } }, { status: 405 })42 let input: RenderRequest43 try { input = validateRenderRequest(await request.json()) } catch (error) { return errorResponse(error) }44 return this.enqueue(async () => {45 try {46 const result = await this.getExecutor().render(input)47 await this.ctx.storage.setAlarm(Date.now() + 60_000)48 return responseFromRenderResult(result)49 } catch (error) {50 await this.close()51 return errorResponse(error)52 }53 })54 }5556 async close(): Promise<void> {57 if (this.executor) await this.executor.close()58 this.executor = undefined59 }6061 async alarm(): Promise<void> { await this.close() }62}6364export default {65 async fetch(request: Request, env: Env): Promise<Response> {66 const url = new URL(request.url)67 if (url.pathname !== '/render') return json({ error: { code: 'not_found', message: 'Route not found.' } }, { status: 404 })68 if (request.method !== 'POST') return json({ error: { code: 'method_not_allowed', message: 'POST required.' } }, { status: 405 })69 if (env.INTERNAL_TOKEN && request.headers.get('Authorization') !== `Bearer ${env.INTERNAL_TOKEN}`) return json({ error: { code: 'unauthorized', message: 'Internal authorization required.' } }, { status: 401 })70 const contentLength = Number(request.headers.get('Content-Length') ?? 0)71 if (contentLength > LIMITS.source + 4_096) return json({ error: { code: 'request_too_large', message: 'Request exceeds the source limit.' } }, { status: 413 })72 let input: RenderRequest73 try {74 const body = await request.arrayBuffer()75 if (body.byteLength > LIMITS.source + 16_384) return json({ error: { code: 'request_too_large', message: 'Request exceeds the source limit.' } }, { status: 413 })76 input = validateRenderRequest(JSON.parse(new TextDecoder().decode(body)))77 } catch (error) { return errorResponse(error) }78 const stub = env.BROWSER_SESSIONS.getByName(sessionName(input.engine))79 return stub.fetch(new Request('https://browser-session.internal/render', { method: 'POST', headers: { 'Content-Type': 'application/json' }, body: JSON.stringify(input) }))80 },81}8283export { FRAME_URLS }