const http = require("http");
const fs = require("fs");
const path = require("path");

const PORT = process.env.PORT || 3000;

function body(req) {
  return new Promise((resolve) => {
    let s = "";
    req.on("data", (c) => (s += c));
    req.on("end", () => {
      try { resolve(JSON.parse(s || "{}")); } catch (_) { resolve({}); }
    });
  });
}

async function createAlemSession() {
  const url = process.env.ALEM_BASE_URL + "/api/v1/open-api/conversation";
  const resp = await fetch(url, {
    method: "POST",
    headers: { "Content-Type": "application/json", "Authorization": "Bearer " + process.env.ALEM_API_KEY },
    body: JSON.stringify({ template_id: process.env.ALEM_TEMPLATE_ID, title: "Vibe42", user_id: "vibe42_user" })
  });
  if (!resp.ok) throw new Error("Alem create " + resp.status + ": " + (await resp.text()));
  const body = await resp.json();
  const sid = body && body.data && body.data.session_id;
  if (!sid) throw new Error("Alem не вернул session_id");
  return sid;
}

async function askAlem(sessionId, message) {
  const url = process.env.ALEM_BASE_URL + "/api/v1/open-api/conversation/" + sessionId + "/send";
  const resp = await fetch(url, {
    method: "POST",
    headers: { "Content-Type": "application/json", "Authorization": "Bearer " + process.env.ALEM_API_KEY },
    body: JSON.stringify({ content: message, user_id: "vibe42_user", model_api_key: process.env.ALEM_API_KEY })
  });
  if (!resp.ok) throw new Error("Alem " + resp.status + ": " + (await resp.text()));
  const raw = await resp.text();
  let answer = null;
  for (const line of raw.split("\n")) {
    const s = line.trim();
    if (!s.startsWith("data:")) continue;
    const payload = s.slice(5).trim();
    if (!payload || payload === "[DONE]") continue;
    try {
      const ev = JSON.parse(payload);
      if (ev && ev.detail && typeof ev.detail.full_content === "string" && ev.detail.full_content) {
        answer = ev.detail.full_content;
      }
    } catch (e) {}
  }
  return answer || "Нет ответа";
}

http.createServer(async (req, res) => {
  res.setHeader("Access-Control-Allow-Origin", "*");
  res.setHeader("Access-Control-Allow-Methods", "GET, POST, OPTIONS");
  res.setHeader("Access-Control-Allow-Headers", "Content-Type");

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

  if (req.method === "POST" && req.url === "/api/session") {
    try {
      const sessionId = await createAlemSession();
      res.writeHead(200, { "Content-Type": "application/json" });
      return res.end(JSON.stringify({ ok: true, sessionId }));
    } catch (err) {
      res.writeHead(500, { "Content-Type": "application/json" });
      return res.end(JSON.stringify({ ok: false, error: err.message }));
    }
  }

  if (req.method === "POST" && req.url === "/api/ask") {
    const data = await body(req);
    const { question, sessionId } = data;
    try {
      const answer = await askAlem(sessionId, question);
      res.writeHead(200, { "Content-Type": "application/json" });
      return res.end(JSON.stringify({ ok: true, answer }));
    } catch (err) {
      res.writeHead(500, { "Content-Type": "application/json" });
      return res.end(JSON.stringify({ ok: false, error: err.message }));
    }
  }

  let file = req.url === "/" ? "/index.html" : req.url.split("?")[0];
  const full = path.join(__dirname, file);
  if (full.startsWith(__dirname) && fs.existsSync(full) && fs.statSync(full).isFile()) {
    const ext = path.extname(full);
    const type = ext === ".css" ? "text/css" : ext === ".js" ? "application/javascript" : "text/html";
    res.writeHead(200, { "Content-Type": type + "; charset=utf-8" });
    return res.end(fs.readFileSync(full));
  }

  res.writeHead(404);
  res.end("Not found");
}).listen(PORT, () => console.log("Сервер запущен на порту " + PORT));