import { createServer } from "node:http";
import { readFile, writeFile, mkdir, stat, rename } from "node:fs/promises";
import { extname, join, normalize } from "node:path";
import { fileURLToPath } from "node:url";
import crypto from "node:crypto";

const __dirname = fileURLToPath(new URL(".", import.meta.url));
const PORT = Number(process.env.PORT || 8080);
const WEBHOOK_TOKEN = process.env.WEBHOOK_TOKEN || "";
const DATA_DIR = join(__dirname, "data");
const DATA_FILE = join(DATA_DIR, "links.json");
const PUBLIC_DIR = join(__dirname, "public");
const DEFAULT_SETTINGS = {
  browserTitle: "家中服务导航",
  brand: "STUN NAV",
  title: "家中服务",
  subtitle: "聚合 Lucky STUN 最新入口，一处打开所有家中应用"
};

const contentTypes = {
  ".html": "text/html; charset=utf-8",
  ".css": "text/css; charset=utf-8",
  ".js": "text/javascript; charset=utf-8",
  ".json": "application/json; charset=utf-8",
  ".svg": "image/svg+xml; charset=utf-8"
};

async function ensureDataFile() {
  await mkdir(DATA_DIR, { recursive: true });
  try {
    await stat(DATA_FILE);
  } catch {
    await writeFile(DATA_FILE, JSON.stringify({ settings: DEFAULT_SETTINGS, services: [] }, null, 2));
  }
}

async function readStore() {
  await ensureDataFile();
  const raw = await readFile(DATA_FILE, "utf8");
  const data = JSON.parse(raw || "{}");
  return {
    settings: sanitizeSettings(data.settings || {}),
    services: Array.isArray(data.services) ? data.services : []
  };
}

async function writeStore(data) {
  await ensureDataFile();
  const tempFile = `${DATA_FILE}.${process.pid}.${Date.now()}.tmp`;
  await writeFile(tempFile, JSON.stringify(data, null, 2));
  await rename(tempFile, DATA_FILE);
}

function sendJson(res, status, payload) {
  res.writeHead(status, {
    "content-type": "application/json; charset=utf-8",
    "cache-control": "no-store"
  });
  res.end(JSON.stringify(payload));
}

function sendText(res, status, text) {
  res.writeHead(status, { "content-type": "text/plain; charset=utf-8" });
  res.end(text);
}

function unauthorized(res) {
  sendJson(res, 401, { ok: false, error: "invalid webhook token" });
}

function getToken(req, url) {
  const auth = req.headers.authorization || "";
  if (auth.toLowerCase().startsWith("bearer ")) {
    return auth.slice(7).trim();
  }
  return req.headers["x-webhook-token"] || url.searchParams.get("token") || "";
}

function isWebhookAuthorized(req, url) {
  if (!WEBHOOK_TOKEN) return true;
  const actual = crypto.createHash("sha256").update(String(getToken(req, url))).digest();
  const expected = crypto.createHash("sha256").update(WEBHOOK_TOKEN).digest();
  return crypto.timingSafeEqual(
    actual,
    expected
  );
}

async function readBody(req) {
  const chunks = [];
  for await (const chunk of req) {
    chunks.push(chunk);
    if (Buffer.concat(chunks).length > 1024 * 1024) {
      throw new Error("request body too large");
    }
  }

  const raw = Buffer.concat(chunks).toString("utf8").trim();
  if (!raw) return {};

  const contentType = req.headers["content-type"] || "";
  if (contentType.includes("application/json")) {
    return JSON.parse(raw);
  }

  if (contentType.includes("application/x-www-form-urlencoded")) {
    return Object.fromEntries(new URLSearchParams(raw));
  }

  try {
    return JSON.parse(raw);
  } catch {
    return { url: raw };
  }
}

function slugify(value) {
  return String(value || "")
    .trim()
    .toLowerCase()
    .replace(/[^a-z0-9\u4e00-\u9fa5_-]+/gi, "-")
    .replace(/^-+|-+$/g, "")
    .slice(0, 80);
}

function firstValue(...values) {
  return values.find((value) => value !== undefined && value !== null && String(value).trim() !== "");
}

function trimText(value, fallback, maxLength = 80) {
  const text = String(firstValue(value, fallback)).trim();
  return text.slice(0, maxLength);
}

function sanitizeSettings(input = {}) {
  return {
    browserTitle: trimText(input.browserTitle, DEFAULT_SETTINGS.browserTitle, 80),
    brand: trimText(input.brand, DEFAULT_SETTINGS.brand, 40),
    title: trimText(input.title, DEFAULT_SETTINGS.title, 80),
    subtitle: trimText(input.subtitle, DEFAULT_SETTINGS.subtitle, 140)
  };
}

function buildUrl(input) {
  const directUrl = firstValue(input.url, input.href, input.link, input.target);
  if (directUrl) return normalizeUrl(String(directUrl));

  const addr = firstValue(input.addr, input.address, input.external, input.stun_addr);
  if (addr) {
    return normalizeUrl(`${input.scheme || input.protocol || "http"}://${addr}`);
  }

  const host = firstValue(input.host, input.ip, input.stun_ip);
  const port = firstValue(input.port, input.stun_port);
  if (!host || !port) return "";

  const path = firstValue(input.path, input.pathname) || "";
  return normalizeUrl(`${input.scheme || input.protocol || "http"}://${host}:${port}${path}`);
}

function normalizeUrl(value) {
  const raw = String(value || "").trim();
  if (!raw) return "";
  if (/^https?:\/\//i.test(raw)) return raw;
  return `http://${raw}`;
}

function serviceFromWebhook(idFromPath, query, body) {
  const merged = { ...query, ...body };
  const name = firstValue(merged.name, merged.service, merged.title, idFromPath);
  const id = slugify(firstValue(merged.id, merged.key, idFromPath, name));
  const url = buildUrl(merged);
  const protocol = firstValue(merged.protocol, merged.scheme, "http");

  if (!id) {
    return { error: "missing service id or name" };
  }

  if (!url) {
    return { error: "missing service url, addr, or host+port" };
  }

  return {
    service: {
      id,
      name: String(name || id),
      url,
      group: String(firstValue(merged.group, merged.category, "默认")),
      protocol: String(protocol).replace(/:$/, ""),
      note: String(firstValue(merged.note, merged.description) || ""),
      updatedAt: new Date().toISOString()
    }
  };
}

async function handleWebhook(req, res, url, idFromPath) {
  if (!isWebhookAuthorized(req, url)) {
    unauthorized(res);
    return;
  }

  let body = {};
  if (req.method !== "GET") {
    body = await readBody(req);
  }

  const query = Object.fromEntries(url.searchParams);
  const result = serviceFromWebhook(idFromPath, query, body);
  if (result.error) {
    sendJson(res, 400, { ok: false, error: result.error });
    return;
  }

  const data = await readStore();
  const index = data.services.findIndex((item) => item.id === result.service.id);
  if (index >= 0) {
    data.services[index] = { ...data.services[index], ...result.service };
  } else {
    data.services.push({ createdAt: result.service.updatedAt, ...result.service });
  }

  data.services.sort((a, b) => `${a.group}${a.name}`.localeCompare(`${b.group}${b.name}`, "zh-Hans-CN"));
  await writeStore(data);
  sendJson(res, 200, { ok: true, service: result.service });
}

async function handleList(res) {
  const data = await readStore();
  sendJson(res, 200, {
    ok: true,
    settings: data.settings,
    services: data.services.map((item) => ({
      id: item.id,
      name: item.name,
      url: item.url,
      group: item.group || "默认",
      note: item.note || "",
      updatedAt: item.updatedAt || item.createdAt || ""
    }))
  });
}

async function handleUpdateSettings(req, res, url) {
  if (!isWebhookAuthorized(req, url)) {
    unauthorized(res);
    return;
  }

  const body = await readBody(req);
  const data = await readStore();
  data.settings = sanitizeSettings({ ...data.settings, ...body });
  await writeStore(data);
  sendJson(res, 200, { ok: true, settings: data.settings });
}

async function handleDelete(req, res, url, idFromPath) {
  if (!isWebhookAuthorized(req, url)) {
    unauthorized(res);
    return;
  }

  const id = slugify(idFromPath);
  if (!id) {
    sendJson(res, 400, { ok: false, error: "missing service id" });
    return;
  }

  const data = await readStore();
  const before = data.services.length;
  data.services = data.services.filter((item) => item.id !== id);
  await writeStore(data);

  sendJson(res, 200, {
    ok: true,
    deleted: before !== data.services.length,
    id
  });
}

async function serveStatic(req, res, url) {
  let pathname = decodeURIComponent(url.pathname);
  if (pathname === "/") pathname = "/index.html";
  if (pathname === "/admin") pathname = "/admin.html";

  const filePath = normalize(join(PUBLIC_DIR, pathname));
  if (!filePath.startsWith(PUBLIC_DIR)) {
    sendText(res, 403, "Forbidden");
    return;
  }

  try {
    const content = await readFile(filePath);
    res.writeHead(200, {
      "content-type": contentTypes[extname(filePath)] || "application/octet-stream",
      "cache-control": "no-cache"
    });
    res.end(content);
  } catch {
    sendText(res, 404, "Not found");
  }
}

const server = createServer(async (req, res) => {
  try {
    const url = new URL(req.url || "/", `http://${req.headers.host || "localhost"}`);
    const webhookMatch = url.pathname.match(/^\/api\/webhook(?:\/([^/]+))?\/?$/);

    if (webhookMatch && ["GET", "POST", "PUT", "PATCH"].includes(req.method || "")) {
      await handleWebhook(req, res, url, webhookMatch[1] ? decodeURIComponent(webhookMatch[1]) : "");
      return;
    }

    if (url.pathname === "/api/services" && req.method === "GET") {
      await handleList(res);
      return;
    }

    if (url.pathname === "/api/settings" && ["POST", "PUT", "PATCH"].includes(req.method || "")) {
      await handleUpdateSettings(req, res, url);
      return;
    }

    const deleteMatch = url.pathname.match(/^\/api\/services\/([^/]+)\/?$/);
    if (deleteMatch && req.method === "DELETE") {
      await handleDelete(req, res, url, decodeURIComponent(deleteMatch[1]));
      return;
    }

    await serveStatic(req, res, url);
  } catch (error) {
    sendJson(res, 500, { ok: false, error: error.message || "server error" });
  }
});

server.listen(PORT, () => {
  console.log(`STUN navigation is running at http://localhost:${PORT}`);
  if (!WEBHOOK_TOKEN) {
    console.log("WEBHOOK_TOKEN is not set. Set it before exposing this service.");
  }
});