// Requires Node.js 24 or newer. Uses only Node.js built-ins and the global fetch API; no third-party packages are required.
import {createHash} from 'node:crypto'
import {access,readFile} from 'node:fs/promises'
import http from 'node:http'
import vm from 'node:vm'
import {fileURLToPath} from 'node:url'

const sha256=value=>createHash('sha256').update(value).digest('hex')
const siblingFixtureURL=new URL('./web-acquisition-fixture.html.txt',import.meta.url)
const repositoryFixtureURL=new URL('../content/labs/web-acquisition-fixture.html.txt',import.meta.url)
async function fixtureURL(){try{await access(siblingFixtureURL);return siblingFixtureURL}catch{return repositoryFixtureURL}}

function extract(html){
  const jsonText=/<script type="application\/ld\+json">([\s\S]*?)<\/script>/.exec(html)?.[1]
  const heading=/<main>[\s\S]*?<h1>([^<]+)<\/h1>/.exec(html)?.[1]
  const summary=/<p id="summary">([^<]+)<\/p>/.exec(html)?.[1]
  if(!jsonText||!heading||!summary)throw new Error('Fixture extraction contract changed')
  const product=JSON.parse(jsonText)
  return {heading,summary,product:{name:product.name,sku:product.sku,price:product.offers?.price,currency:product.offers?.priceCurrency,availability:product.offers?.availability??null},warnings:product.offers?.availability?[]:['optional field missing: availability']}
}

function simulateDeclaredMutation(html){
  const script=/<script>(setTimeout[\s\S]*?)<\/script>/.exec(html)?.[1]
  const initial=/<span id="price"[^>]*>([^<]+)<\/span>/.exec(html)?.[1]
  if(!script||!initial)throw new Error('Fixture render contract changed')
  const price={textContent:initial};let requestedDelay
  vm.runInNewContext(script,{document:{querySelector:selector=>{if(selector!=='#price')throw new Error('Unexpected selector');return price}},setTimeout:(callback,delay)=>{requestedDelay=delay;callback()}})
  return {adapter:'fixture-simulated-dom/v1',browserEngine:null,initialPrice:initial,renderedPrice:price.textContent,declaredDelayMs:requestedDelay,warning:'Simulated DOM adapter; no browser engine was executed.'}
}

function handler(bytes){return(request,response)=>{
    if(request.url==='/redirect'){response.writeHead(302,{location:'/fixture'});return response.end()}
    if(request.url==='/fixture'){response.writeHead(200,{'content-type':'text/html; charset=utf-8'});return response.end(bytes)}
    response.writeHead(404,{'content-type':'text/plain; charset=utf-8'});response.end('Synthetic fixture route not found')
  }}

async function fixtureBytes(){return readFile(await fixtureURL())}

export async function serveFixture({port=4179}={}){
  const bytes=await fixtureBytes(),server=http.createServer(handler(bytes))
  await new Promise((resolve,reject)=>{server.once('error',reject);server.listen(port,'127.0.0.1',resolve)})
  const actualPort=server.address().port
  return {server,url:`http://127.0.0.1:${actualPort}/fixture`,expectedSelector:'#price',expectedText:'$24.00'}
}

export async function runFixtureLab(){
  const bytes=await fixtureBytes(),html=bytes.toString('utf8'),server=http.createServer(handler(bytes))
  await new Promise((resolve,reject)=>{server.once('error',reject);server.listen(0,'127.0.0.1',resolve)})
  try{
    const base=`http://127.0.0.1:${server.address().port}`
    const redirect=await fetch(`${base}/redirect`,{redirect:'manual'}),followed=await fetch(`${base}/redirect`),missing=await fetch(`${base}/missing`),body=Buffer.from(await followed.arrayBuffer()),extracted=extract(html),rendered=simulateDeclaredMutation(html)
    return {schema:'martybytes-web-acquisition-lab/v1',fixture:{kind:'synthetic',containsPersonalData:false,bodyBytes:body.length,bodySha256:sha256(body)},fetch:{requestedPath:'/redirect',redirectStatus:redirect.status,redirectLocation:redirect.headers.get('location'),finalPath:new URL(followed.url).pathname,targetStatus:followed.status,contentType:followed.headers.get('content-type'),missingPathStatus:missing.status},rendered,extracted,extractedSha256:sha256(Buffer.from(JSON.stringify(extracted)))}
  }finally{await new Promise(resolve=>server.close(resolve))}
}

if(process.argv[1]===fileURLToPath(import.meta.url)){
  if(process.argv[2]==='--serve'&&process.argv.length===3){const running=await serveFixture();console.log(JSON.stringify({ok:true,url:running.url,expectedSelector:running.expectedSelector,expectedText:running.expectedText,stop:'Ctrl+C'}))}
  else if(process.argv.length===2)console.log(JSON.stringify(await runFixtureLab(),null,2))
  else{console.error('Usage: node web-acquisition-fixture.mjs [--serve]');process.exitCode=1}
}