"use strict"

async function readJsonBody(req, maxBytes = 1_000_000) {
  return new Promise((resolve, reject) => {
    const chunks = []
    let total = 0
    req.on("data", (chunk) => {
      total += chunk.length
      if (total > maxBytes) {
        req.destroy()
        reject(Object.assign(new Error("request body too large"), { status: 413 }))
        return
      }
      chunks.push(chunk)
    })
    req.on("end", () => {
      try {
        const raw = Buffer.concat(chunks).toString("utf-8")
        resolve(raw ? JSON.parse(raw) : {})
      } catch (err) {
        reject(Object.assign(err, { status: 400 }))
      }
    })
    req.on("error", reject)
  })
}

function sendJson(res, status, body, headers = {}) {
  const json = JSON.stringify(body)
  res.writeHead(status, {
    "Content-Type": "application/json; charset=utf-8",
    "Cache-Control": "no-store",
    ...headers
  })
  res.end(json)
}

function openAiError(res, status, message, code) {
  sendJson(res, status, { error: { message, type: code, code } })
}

module.exports = { readJsonBody, sendJson, openAiError }