// The client sites' server: static files, an SPA fallback, and env-config.js from the
// environment. Node built-ins only — the runtime base already carries node for the API, so a
// second web server (and the shell its startup script needed) would be two more moving parts to
// serve files the first one serves fine.
//
// What the nginx arrangement this replaces did, it does: every unknown path without an extension
// falls back to index.html (client-side routing), nothing is cached (the site is tiny and a stale
// index.html after a deploy is the only caching bug this app has ever had), and env-config.js is
// regenerated from the container's environment at start — which is how one built image serves
// under any API URL.
import { createServer } from "node:http";
import { readFileSync, writeFileSync, createReadStream, statSync } from "node:fs";
import { join, resolve, extname } from "node:path";

const root = resolve(process.env.HTML_ROOT ?? "/site");
const port = Number(process.env.PORT ?? 80);

// .env names the variables the site reads; the environment overrides their values. Written once
// at start, exactly as the env.sh this replaces did.
const pairs = [];
for (const line of readFileSync(join(root, ".env"), "utf8").split("\n")) {
  const at = line.indexOf("=");
  if (at < 1) continue;
  const name = line.slice(0, at).trim();
  pairs.push(`  ${name}: ${JSON.stringify(process.env[name] ?? line.slice(at + 1).trim())},`);
}
writeFileSync(join(root, "env-config.js"), `window._env_ = {\n${pairs.join("\n")}\n}\n`);

const types = {
  ".html": "text/html; charset=utf-8",
  ".js": "application/javascript",
  ".mjs": "application/javascript",
  ".css": "text/css",
  ".json": "application/json",
  ".map": "application/json",
  ".svg": "image/svg+xml",
  ".png": "image/png",
  ".jpg": "image/jpeg",
  ".jpeg": "image/jpeg",
  ".gif": "image/gif",
  ".webp": "image/webp",
  ".ico": "image/x-icon",
  ".txt": "text/plain; charset=utf-8",
  ".woff": "font/woff",
  ".woff2": "font/woff2",
  ".ttf": "font/ttf",
};

createServer((request, response) => {
  const asked = decodeURIComponent(new URL(request.url, "http://x").pathname);
  // resolve() collapses any ".." before the prefix check, so a path cannot escape the root.
  let path = resolve(join(root, asked));
  if (!path.startsWith(root)) {
    response.writeHead(403).end();
    return;
  }
  let served;
  try {
    served = statSync(path);
    if (served.isDirectory()) {
      path = join(path, "index.html");
      served = statSync(path);
    }
  } catch {
    // Not a file: a client-side route, answered by the app itself — unless it asked for a file
    // by extension, where index.html would be a wrong answer dressed as a right one.
    if (extname(asked) !== "") {
      response.writeHead(404, { "Content-Type": "text/plain" }).end("not found\n");
      return;
    }
    path = join(root, "index.html");
    served = statSync(path);
  }
  response.writeHead(200, {
    "Content-Type": types[extname(path)] ?? "application/octet-stream",
    "Content-Length": served.size,
    "Cache-Control": "no-cache",
  });
  createReadStream(path).pipe(response);
}).listen(port, () => console.log(`serving ${root} on :${port}`));