_worker.js for pages api

_worker.js

/* eslint-disable */

/**
 * Add _worker.js to your public directory to enable /api/* proxying
 *
 * env.API_ROUTER_URL
 *  Requests to /api/* is proxied to this url
 *
 * env.API_ROUTER_STRIP_PREFIX
 *  Remove this part from the beginning of pathname before proxying
 *  Useful if you need to hide /api/ from the backend. (GET /api/test -> GET /test)
 *
 * env.ROBOTS_TXT
 *   Set to 'allow' to return User-agent: * Allow: /
 *
 * env.ROBOTS_TXT_OVERRIDE
 *   Return this text for /robots.txt
*
 * env.FIREBASE_AUTH_PROJECT
 *  Set to Google Identity Platform / Firebase Auth project id.
 *  This is useful for signInWithRedirect (authDomain=origin)
 *
 * wget https://gist.githubusercontent.com/moander/6f4fb4c1ca89a144794d6e46a3e85874/raw/_worker.js
 */
export default {
  async fetch(request, env) {
    const url = new URL(request.url)
    if (url.pathname.startsWith('/api/')) {
      if (!env.API_ROUTER_URL) {
        return new Response('env.API_ROUTER_URL is required', { status: 500 })
      }
      let pathname = url.pathname
      if (env.API_ROUTER_STRIP_PREFIX && pathname.startsWith(env.API_ROUTER_STRIP_PREFIX)) {
        pathname = pathname.substring(env.API_ROUTER_STRIP_PREFIX.length)
      }
      const proxyToUrl = env.API_ROUTER_URL + pathname + url.search + url.hash
      return await proxyTo(proxyToUrl, request)
    }
    else if (url.pathname.startsWith('/robots.txt')) {
      let output = 'User-agent: *\nDisallow: /\n'
      if (env.ROBOTS_TXT === 'allow') {
        output = 'User-agent: *\nAllow: /\n'
      }
      if (env.ROBOTS_TXT_OVERRIDE) {
        output = env.ROBOTS_TXT_OVERRIDE?.toString().replaceAll('\\n', '\n').trim() || output
      }
      return new Response(output, {
        headers: { 'Content-Type': 'text/plain' },
      })
    }
    else if (url.pathname.startsWith('/__/auth/')) {
      if (!env.FIREBASE_AUTH_PROJECT) {
        return new Response('env.FIREBASE_AUTH_PROJECT is required', { status: 500 })
      }

      const proxyToUrl = `https://${env.FIREBASE_AUTH_PROJECT}.firebaseapp.com` + url.pathname + url.search + url.hash

      return await proxyTo(proxyToUrl, request)
    }
    return env.ASSETS.fetch(request)
  },
}

async function proxyTo(proxyToUrl, request) {
  return await fetch(proxyToUrl, {
    method: request.method,
    headers: request.headers,
    body: request.body,
  }).catch(err => {
    console.error('proxyError', JSON.stringify({ message: err.message, proxyToUrl }))
    return Response.json({ message: `API proxy error: ${err.message}` }, {
      status: 502,
    })
  })
}