upstream-tldraw/templates/image-pipeline/worker/routes/images.ts

import { IRequest } from 'itty-router'

/**
 * POST /api/images/:imageId
 *
 * Upload a generated image to R2 for persistence.
 */
export async function handleImageUpload(request: IRequest, env: Env) {
	const { imageId } = request.params
	const contentType = request.headers.get('content-type') ?? 'image/png'

	if (!contentType.startsWith('image/')) {
		return new Response(JSON.stringify({ error: 'Invalid content type' }), {
			status: 400,
			headers: { 'Content-Type': 'application/json' },
		})
	}

	// Don't overwrite existing images.
	if (await env.IMAGE_BUCKET.head(imageId)) {
		return new Response(JSON.stringify({ ok: true }), {
			headers: { 'Content-Type': 'application/json' },
		})
	}

	await env.IMAGE_BUCKET.put(imageId, request.body, {
		httpMetadata: { contentType },
	})

	return new Response(JSON.stringify({ ok: true }), {
		headers: { 'Content-Type': 'application/json' },
	})
}

/**
 * GET /api/images/:imageId
 *
 * Download a generated image from R2 with caching.
 */
export async function handleImageDownload(request: IRequest, env: Env, ctx: ExecutionContext) {
	const { imageId } = request.params

	// Check edge cache first.
	// Use caches.open() to avoid DOM/Workers CacheStorage type conflict.
	const cache = await caches.open('images')
	const cacheKey = new Request(request.url, { headers: request.headers })
	const cachedResponse = await cache.match(cacheKey)
	if (cachedResponse) {
		return cachedResponse
	}

	const object = await env.IMAGE_BUCKET.get(imageId)
	if (!object) {
		return new Response('Not found', { status: 404 })
	}

	const headers = new Headers()
	headers.set('content-type', object.httpMetadata?.contentType ?? 'image/png')
	// Generated images are immutable — cache them aggressively.
	headers.set('cache-control', 'public, max-age=31536000, immutable')

	const response = new Response(object.body, { headers })

	// Cache in the edge for future requests.
	ctx.waitUntil(cache.put(cacheKey, response.clone()))

	return response
}