// Minimal local simulator for testing SAN01 replacement only.
// - Serves the exported "out" folder.
// - For text files (.html, .js, .json, .css, .txt) replaces <%=SAN01%> -> "ismail" on the fly.
// - Supports mapping /CPL?/path to /path in the export.

import http from "http";
import fs from "fs";
import path from "path";

const PORT = process.env.PORT ? Number(process.env.PORT) : 3030;
const ROOT = path.join(process.cwd(), "out");

function exists(p) {
  try {
    fs.accessSync(p, fs.constants.F_OK);
    return true;
  } catch {
    return false;
  }
}

function contentTypeByExt(ext) {
  switch (ext) {
    case ".html":
      return "text/html; charset=utf-8";
    case ".js":
      return "application/javascript; charset=utf-8";
    case ".json":
      return "application/json; charset=utf-8";
    case ".css":
      return "text/css; charset=utf-8";
    case ".txt":
      return "text/plain; charset=utf-8";
    case ".svg":
      return "image/svg+xml";
    case ".png":
      return "image/png";
    case ".jpg":
    case ".jpeg":
      return "image/jpeg";
    case ".ico":
      return "image/x-icon";
    default:
      return "application/octet-stream";
  }
}

function isTextExt(ext) {
  return [".html", ".js", ".json", ".css", ".txt", ".svg"].includes(ext);
}

function sendFileWithSAN01Replace(res, filePath) {
  const ext = path.extname(filePath).toLowerCase();
  const type = contentTypeByExt(ext);
  if (isTextExt(ext)) {
    try {
      let content = fs.readFileSync(filePath, "utf8");
      content = content.replace(/<%=SAN01%>/g, "ismail");
      res.writeHead(200, { "Content-Type": type });
      res.end(content);
      return;
    } catch {
      // fall through to stream as binary if read fails
    }
  }
  res.writeHead(200, { "Content-Type": type });
  fs.createReadStream(filePath).pipe(res);
}

function notFound(res) {
  res.writeHead(404, { "Content-Type": "text/plain; charset=utf-8" });
  res.end("Not Found");
}

const server = http.createServer((req, res) => {
  try {
    const url = new URL(req.url, `http://localhost:${PORT}`);
    const pathname = decodeURIComponent(url.pathname);
    const rawQuery = req.url.includes("?") ? req.url.split("?")[1] : "";

    // Minimal CPL? mapping: /CPL?/CPL/... -> /CPL/...
    if (pathname === "/CPL" && rawQuery) {
      const q = decodeURIComponent(rawQuery);
      if (q.startsWith("/")) {
        const rel = q.replace(/^\/+/, "");
        const target = path.join(ROOT, rel);
        if (exists(target) && fs.statSync(target).isFile()) {
          return sendFileWithSAN01Replace(res, target);
        }
        if (exists(target) && fs.statSync(target).isDirectory()) {
          const indexFile = path.join(target, "index.html");
          if (exists(indexFile))
            return sendFileWithSAN01Replace(res, indexFile);
        }
        return notFound(res);
      }
      // Non-file commands: just 200 OK
      res.writeHead(200, { "Content-Type": "text/plain; charset=utf-8" });
      res.end("OK");
      return;
    }

    // Static serving from export
    let filePath = path.join(ROOT, pathname);

    if (pathname.endsWith("/")) {
      filePath = path.join(filePath, "index.html");
      if (exists(filePath)) return sendFileWithSAN01Replace(res, filePath);
    }

    if (exists(filePath) && fs.statSync(filePath).isFile()) {
      return sendFileWithSAN01Replace(res, filePath);
    }

    const htmlVariant = filePath + ".html";
    if (exists(htmlVariant)) {
      return sendFileWithSAN01Replace(res, htmlVariant);
    }

    // Fallback: out/index.html
    const fallback = path.join(ROOT, "index.html");
    if (exists(fallback)) return sendFileWithSAN01Replace(res, fallback);

    return notFound(res);
  } catch (err) {
    res.writeHead(500, { "Content-Type": "text/plain; charset=utf-8" });
    res.end(
      "Internal Server Error\n" + (err && err.stack ? err.stack : String(err))
    );
  }
});

server.listen(PORT, () => {
  console.log(`Local CPL simulator running on http://localhost:${PORT}`);
  console.log(`Serving from: ${ROOT}`);
  console.log("Replacing <%=SAN01%> -> ismail in text responses");
});