/**
 * KHAELOR
 * File: website/server.mjs
 * Description: Zero-dependency static server for www.khaelor.sh — serves public/, the install tarball, and /health.
 *
 * Author: Simon-Pierre Boucher
 * Contact: contact@spboucher.ai
 *
 * Run:   node server.mjs            (PORT env var, default 8790; binds 0.0.0.0)
 * Serves:
 *   /                → public/index.html
 *   /docs/...        → public/docs/...
 *   /install.sh      → public/install.sh          (no-cache)
 *   /khaelor.tgz     → artifacts/khaelor.tgz       (no-cache; 503 if absent)
 *   /health          → {"ok":true,"version":...}
 */

import { createServer } from "node:http";
import { createReadStream, existsSync, statSync } from "node:fs";
import { extname, join, normalize, resolve, sep } from "node:path";
import { fileURLToPath } from "node:url";

const VERSION = "1.0.0";
const PORT = Number.parseInt(process.env.PORT ?? "8790", 10);
const HOST = "0.0.0.0";

const ROOT = fileURLToPath(new URL(".", import.meta.url));
const PUBLIC_DIR = resolve(ROOT, "public");
const TARBALL_PATH = resolve(ROOT, "artifacts", "khaelor.tgz");

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

/** Assets get a day of caching; the installer and tarball must always be fresh. */
function cacheHeaderFor(urlPath) {
  if (urlPath === "/install.sh" || urlPath === "/khaelor.tgz" || urlPath === "/health") {
    return "no-cache, no-store, must-revalidate";
  }
  if (urlPath.endsWith(".html") || urlPath === "/" || extname(urlPath) === "") {
    return "no-cache"; // revalidate pages so doc updates show up immediately
  }
  return "public, max-age=86400"; // css/js/images
}

function log(req, status, extra = "") {
  const now = new Date().toISOString();
  const ip =
    req.headers["x-forwarded-for"]?.split(",")[0]?.trim() ??
    req.socket.remoteAddress ??
    "-";
  console.log(`${now} ${ip} ${req.method} ${req.url} ${status}${extra ? " " + extra : ""}`);
}

function sendText(req, res, status, body, headers = {}) {
  res.writeHead(status, {
    "Content-Type": "text/plain; charset=utf-8",
    "Content-Length": Buffer.byteLength(body),
    "Cache-Control": "no-cache, no-store, must-revalidate",
    ...headers,
  });
  res.end(req.method === "HEAD" ? undefined : body);
  log(req, status);
}

function sendFile(req, res, filePath, urlPath) {
  let st;
  try {
    st = statSync(filePath);
  } catch {
    return sendText(req, res, 404, "404 — not found\n");
  }
  if (!st.isFile()) return sendText(req, res, 404, "404 — not found\n");

  const type = MIME[extname(filePath).toLowerCase()] ?? "application/octet-stream";
  res.writeHead(200, {
    "Content-Type": type,
    "Content-Length": st.size,
    "Cache-Control": cacheHeaderFor(urlPath),
    "X-Content-Type-Options": "nosniff",
  });
  if (req.method === "HEAD") {
    res.end();
    log(req, 200);
    return;
  }
  const stream = createReadStream(filePath);
  stream.on("error", () => {
    if (!res.headersSent) sendText(req, res, 500, "500 — read error\n");
    else res.destroy();
  });
  stream.pipe(res);
  log(req, 200, `${st.size}b`);
}

const server = createServer((req, res) => {
  if (req.method !== "GET" && req.method !== "HEAD") {
    return sendText(req, res, 405, "405 — method not allowed\n", { Allow: "GET, HEAD" });
  }

  let urlPath;
  try {
    urlPath = decodeURIComponent(new URL(req.url, "http://localhost").pathname);
  } catch {
    return sendText(req, res, 400, "400 — bad request\n");
  }

  // ── health ──────────────────────────────────────────────────────────
  if (urlPath === "/health") {
    const body = JSON.stringify({ ok: true, version: VERSION });
    res.writeHead(200, {
      "Content-Type": "application/json; charset=utf-8",
      "Content-Length": Buffer.byteLength(body),
      "Cache-Control": "no-cache, no-store, must-revalidate",
    });
    res.end(req.method === "HEAD" ? undefined : body);
    return log(req, 200);
  }

  // ── install tarball (dropped into artifacts/ at deploy time) ───────
  if (urlPath === "/khaelor.tgz") {
    if (!existsSync(TARBALL_PATH)) {
      return sendText(
        req,
        res,
        503,
        "The khaelor package tarball is not available on this server yet.\n" +
          "Try again shortly, or contact contact@spboucher.ai.\n",
        { "Retry-After": "3600" },
      );
    }
    return sendFile(req, res, TARBALL_PATH, urlPath);
  }

  // ── static files from public/ ───────────────────────────────────────
  if (urlPath === "/") urlPath = "/index.html";
  // directory-style URLs: /docs → /docs/index.html would 404; leave as-is.

  const resolved = resolve(PUBLIC_DIR, "." + normalize("/" + urlPath));
  if (resolved !== PUBLIC_DIR && !resolved.startsWith(PUBLIC_DIR + sep)) {
    return sendText(req, res, 403, "403 — forbidden\n");
  }

  let target = resolved;
  if (existsSync(target) && statSync(target).isDirectory()) {
    target = join(target, "index.html");
  }
  if (!existsSync(target) && extname(target) === "" && existsSync(target + ".html")) {
    target = target + ".html"; // /docs/usage → /docs/usage.html
  }

  return sendFile(req, res, target, urlPath);
});

server.listen(PORT, HOST, () => {
  console.log(
    `${new Date().toISOString()} khaelor-website v${VERSION} listening on http://${HOST}:${PORT} (public: ${PUBLIC_DIR})`,
  );
});

for (const sig of ["SIGINT", "SIGTERM"]) {
  process.on(sig, () => {
    console.log(`${new Date().toISOString()} ${sig} received — shutting down`);
    server.close(() => process.exit(0));
    setTimeout(() => process.exit(0), 2000).unref();
  });
}