import { createServer } from "node:http"
import { createLLMFirewall } from "llm-firewall-js"

const firewall = createLLMFirewall()

const server = createServer(async (req, res) => {
  firewall.setCors(req, res)

  if (req.method === "OPTIONS") {
    res.writeHead(204)
    res.end()
    return
  }

  if (req.url !== "/api/chat" || req.method !== "POST") {
    res.writeHead(404, { "Content-Type": "application/json" })
    res.end(JSON.stringify({ error: "Not found." }))
    return
  }

  const body = await readJson(req)
  const inputCheck = await firewall.inspectInput({
    request: req,
    body,
    text: body.question || body.prompt || "",
  })

  if (!inputCheck.ok) {
    firewall.reject(res, inputCheck)
    return
  }

  const modelData = await callYourLLMProvider(body)
  const outputCheck = firewall.inspectOutput(modelData)

  if (!outputCheck.ok) {
    firewall.reject(res, outputCheck)
    return
  }

  res.writeHead(200, { "Content-Type": "application/json" })
  res.end(JSON.stringify(outputCheck.data))
})

server.listen(3000, () => {
  console.log("Generic Node example running at http://localhost:3000")
})

async function readJson(req) {
  const chunks = []
  for await (const chunk of req) chunks.push(chunk)
  const raw = Buffer.concat(chunks).toString("utf8")
  return raw ? JSON.parse(raw) : {}
}

async function callYourLLMProvider(body) {
  return {
    message: `Replace this with your LLM provider call. User asked: ${body.question || body.prompt || ""}`,
  }
}