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

const PORT = process.env.LAYOUT_SERVER_PORT || 4001;
const LAYOUT_PATH = path.join(__dirname, "..", "config", "layout.json");

function sendJson(res, status, data) {
  res.writeHead(status, {
    "Content-Type": "application/json",
    "Access-Control-Allow-Origin": "*",
  });
  res.end(JSON.stringify(data, null, 2));
}

function sendText(res, status, text) {
  res.writeHead(status, {
    "Content-Type": "text/plain",
    "Access-Control-Allow-Origin": "*",
  });
  res.end(text);
}

const server = http.createServer(async (req, res) => {
  if (req.method === "OPTIONS") {
    res.writeHead(204, {
      "Access-Control-Allow-Origin": "*",
      "Access-Control-Allow-Methods": "GET, POST, OPTIONS",
      "Access-Control-Allow-Headers": "Content-Type",
    });
    res.end();
    return;
  }

  if (req.url === "/layout" && req.method === "GET") {
    try {
      const contents = await fs.promises.readFile(LAYOUT_PATH, "utf-8");
      const json = JSON.parse(contents);
      sendJson(res, 200, json);
    } catch (err) {
      sendJson(res, 500, { error: "Failed to read layout", detail: err.message });
    }
    return;
  }

  if (req.url === "/layout" && req.method === "POST") {
    let body = "";
    req.on("data", (chunk) => {
      body += chunk.toString();
      if (body.length > 1_000_000) {
        req.destroy();
      }
    });
    req.on("end", async () => {
      try {
        const json = JSON.parse(body);
        await fs.promises.writeFile(LAYOUT_PATH, JSON.stringify(json, null, 2));
        sendJson(res, 200, { ok: true });
      } catch (err) {
        sendJson(res, 400, { error: "Invalid JSON", detail: err.message });
      }
    });
    return;
  }

  sendText(res, 404, "Not found");
});

server.listen(PORT, () => {
  console.log(`Layout config server listening on http://localhost:${PORT}`);
});