website/routes/_middleware.ts

import { FreshContext } from '$fresh/server.ts'
import { SessionStore } from ':src/session/mod.ts'
import { getCookies, setCookie } from '@std/http/cookie'

export async function handler(request: Request, ctx: FreshContext) {
	// Update fresh context state with session
	ctx.state = { ...ctx.state, session: SessionStore.getFromRequest(request) }

	// Allow service worker to serve root scope
	const response = await ctx.next()
	const url = new URL(request.url)
	if (url.pathname.endsWith('island-startserviceworker.js')) {
		response.headers.set('Service-Worker-Allowed', '/')
	}

	// Start session
	if (SessionStore.getFromRequest(request) === undefined) {
		// Clear outdated cookies
		for (const cookie in getCookies(request.headers)) {
			setCookie(response.headers, {
				name: cookie,
				value: '',
				path: '/',
				expires: 0,
			})
		}

		// Create new session
		const session = SessionStore.createSession()
		ctx.state = { ...ctx.state, session }

		// Set session cookie
		setCookie(response.headers, {
			name: '_SESSION',
			value: session.uuid,
			httpOnly: true,
			sameSite: 'Strict',
			secure: true,
			path: '/',
			expires: SessionStore.maxAge,
		})

		// Set csrf
		const csrf = crypto.randomUUID()
		session.set('_csrf', csrf)

		setCookie(response.headers, {
			name: '_CSRF',
			value: csrf,
			httpOnly: false,
			sameSite: 'Strict',
			secure: true,
			path: '/',
			expires: SessionStore.maxAge,
		})
	}

	return response
}