image_cdn.ts

import * as functions from "firebase-functions"
import express from "express"
import * as admin from "firebase-admin"
import sharp from "sharp"

const MAX_WIDTH = 1080
const MAX_HEIGHT = 1080

interface Size {
	width: number
	height: number
}

const app = express()
const router = express.Router()
const cacheControl = "public, max-age=3600, s-maxage=36000"

const parseSize = (size: string): Size => {
	let width, height;
	if (size.indexOf(",") !== -1) {
		[width, height] = size.split(",");
	} else if (size.indexOf("x") !== -1) {
		[width, height] = size.split("x");
	} else {
		throw new Error(`height and width are not delimited by a "," or a "x"`);
	}
	width = parseInt(width, 10) || MAX_WIDTH
	height = parseInt(height, 10) || MAX_HEIGHT
	width = Math.min(width, MAX_WIDTH)
	height = Math.min(height, MAX_HEIGHT)
	return { width, height }
}

router.get("/w/:width/*", async (req, res, next) => {
	res.set("Cache-Control", cacheControl)
	const { width } = req.params
	let sizeWidth = parseInt(width, 10) || MAX_WIDTH
	let sizeHeight = parseInt(width, 10) || MAX_WIDTH

	sizeWidth = Math.min(sizeWidth, MAX_WIDTH)
	sizeHeight = Math.min(sizeHeight, MAX_WIDTH)

	const targetSize = {
		width: sizeWidth,
		height: sizeHeight
	}
	const path = req.params[0]
	if (path.includes(".jpg") || path.includes(".jpeg") || path.includes(".png")) {
		const bucket = admin.storage().bucket()
		try {
			const response = await bucket.file(path).download()
			const originalImage = response[0]
			if (path.includes(".jpg") || path.includes(".jpeg")) res.type("jpg")
			if (path.includes(".png")) res.type("png")
			const resizedImage = await sharp(originalImage)
				.resize(targetSize.width, targetSize.height)
				.toBuffer()
			res.status(200).send(resizedImage)
		} catch (error) {
			next(error)
		}
	}
})

router.get("/s/:size/*", async (req, res, next) => {
	res.set("Cache-Control", cacheControl)
	const { size } = req.params
	const targetSize = parseSize(size)
	const path = req.params[0]
	if (path.includes(".jpg") || path.includes(".jpeg") || path.includes(".png")) {
		const bucket = admin.storage().bucket()
		try {
			const response = await bucket.file(path).download()
			const originalImage = response[0]
			if (path.includes(".jpg") || path.includes(".jpeg")) res.type("jpg")
			if (path.includes(".png")) res.type("png")
			const resizedImage = await sharp(originalImage)
				.resize(targetSize.width, targetSize.height)
				.toBuffer()
			res.status(200).send(resizedImage)
		} catch (error) {
			next(error)
		}
	}
})

router.get("*", async (req, res, next) => {
	res.set("Cache-Control", cacheControl)
	const path = req.path.slice(1)
	if (path.includes(".jpg") || path.includes(".jpeg") || path.includes(".png")) {
		const bucket = admin.storage().bucket()
		try {
			const response = await bucket.file(path).download()
			if (path.includes(".jpg") || path.includes(".jpeg")) res.type("jpg")
			if (path.includes(".png")) res.type("png")
			res.status(200).send(response[0])
		} catch (error) {
			next(error)
		}
	}
})

router.use((req, res, next) => {
	const err = new Error("Not Found")
	next(err)
})

// error handler
router.use((req, res, next) => {
	res.status(400).send("Bad Request")
})

app.use("/cdn", router)

export const cdn = functions
	.runWith({
		memory: "2GB"
	})
	.https.onRequest(app)