import { createServer } from "node:http";
import { readFile } from "node:fs/promises";
import { extname, resolve, sep } from "node:path";
import { fileURLToPath } from "node:url";
import { probeTls } from "../src/tls-probe.js";

const trustlabRoot = resolve(fileURLToPath(new URL("..", import.meta.url)));
const host = "127.0.0.1";
const port = Number.parseInt(process.env.TRUSTLAB_PORT ?? "4173", 10);
const contentTypes = {
  ".css": "text/css; charset=utf-8",
  ".html": "text/html; charset=utf-8",
  ".js": "text/javascript; charset=utf-8",
  ".json": "application/json; charset=utf-8",
};

const server = createServer(async (request, response) => {
  try {
    const url = new URL(request.url ?? "/", `http://${host}:${port}`);
    if (url.pathname === "/api/probe") {
      await handleProbe(request, response);
      return;
    }
    const relativePath = url.pathname === "/" ? "ui/index.html" : url.pathname.slice(1);
    const requestedPath = resolve(trustlabRoot, relativePath);
    if (!requestedPath.startsWith(`${trustlabRoot}${sep}`)) {
      respond(response, 403, "Forbidden");
      return;
    }

    const body = await readFile(requestedPath);
    response.writeHead(200, {
      "Content-Type": contentTypes[extname(requestedPath)] ?? "application/octet-stream",
      "Cache-Control": "no-store",
      "X-Content-Type-Options": "nosniff",
      "Content-Security-Policy": "default-src 'self'; style-src 'self'; script-src 'self'; object-src 'none'; frame-ancestors 'none'",
    });
    response.end(body);
  } catch (error) {
    if (error?.code === "ENOENT" || error?.code === "EISDIR") {
      respond(response, 404, "Not found");
      return;
    }
    respond(response, 500, "Internal server error");
  }
});

server.listen(port, host, () => {
  console.log(`TrustLab UI: http://${host}:${port}`);
});

function respond(response, status, message) {
  response.writeHead(status, {
    "Content-Type": "text/plain; charset=utf-8",
    "Cache-Control": "no-store",
  });
  response.end(message);
}

async function handleProbe(request, response) {
  if (request.method !== "POST") {
    respond(response, 405, "Method not allowed");
    return;
  }
  const expectedOrigin = `http://${host}:${port}`;
  if (request.headers.origin && request.headers.origin !== expectedOrigin) {
    respond(response, 403, "Origin not allowed");
    return;
  }
  if (!request.headers["content-type"]?.startsWith("application/json")) {
    respond(response, 415, "Expected application/json");
    return;
  }
  try {
    const chunks = [];
    let size = 0;
    for await (const chunk of request) {
      size += chunk.length;
      if (size > 4096) throw new RangeError("Request body is too large");
      chunks.push(chunk);
    }
    const input = JSON.parse(Buffer.concat(chunks).toString("utf8"));
    const report = await probeTls(input.target, { timeoutMs: 10_000 });
    respondJson(response, 200, report);
  } catch (error) {
    respondJson(response, error instanceof RangeError ? 413 : 400, {
      error: error.message,
    });
  }
}

function respondJson(response, status, value) {
  response.writeHead(status, {
    "Content-Type": "application/json; charset=utf-8",
    "Cache-Control": "no-store",
    "X-Content-Type-Options": "nosniff",
  });
  response.end(JSON.stringify(value));
}