/**
 * @file devices.js
 * @description The hub's enrolled remote-client machines (server mode only;
 * docs/plans/remote-clients/README.md). A user enrolls a machine running
 * AgentHub LOCAL with their hub password (`POST /api/remote/device/login`,
 * throttled like a login — `auth.checkLogin`) and gets ONE device token,
 * `ahdev_<32 random bytes>`, shown once; the hub keeps only its SHA-256.
 *
 * A token is good for `TOKEN_DAYS` (90) and until it is revoked — by its own
 * machine (logout), by its user, or by an admin (both behind the step-up
 * password, written to `audit_log`) — or its user is disabled. It is the only
 * thing a client holds: it opens the device routes and the gateway, never a
 * cookie route, and never carries a pool credential.
 * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
 */

const crypto = require("node:crypto");

const sql = (q) => require("../db").db.prepare(q);
const sha256 = (s) => crypto.createHash("sha256").update(s).digest("hex");

const TOKEN_DAYS = Number(process.env.AGENTHUB_DEVICE_TOKEN_DAYS) || 90;
const TOKEN_RE = /^ahdev_[A-Za-z0-9_-]{43}$/;
const MAX_NAME = 80;
/** last_seen_at is rewritten at most this often per device (every gateway call reads it). */
const SEEN_EVERY_MS = 60_000;

/** A device name as shown: printable, trimmed, capped; "" → "device". */
function cleanName(name) {
  const s = String(name || "")
    .replace(/[\u0000-\u001f\u007f]/g, "")
    .trim()
    .slice(0, MAX_NAME);
  return s || "device";
}

/** Mint a device for `userId`: `{token, device}` — the token exists only in this answer. */
function createDevice(userId, name) {
  const token = `ahdev_${crypto.randomBytes(32).toString("base64url")}`;
  const expires = new Date(Date.now() + TOKEN_DAYS * 864e5).toISOString();
  const r = sql(
    "INSERT INTO devices (user_id, name, token_hash, expires_at) VALUES (?, ?, ?, ?)"
  ).run(userId, cleanName(name), sha256(token), expires);
  return { token, device: getDevice(Number(r.lastInsertRowid)) };
}

/** A device row as the API shows it — never the hash. */
function shape(row) {
  if (!row) return null;
  const now = Date.now();
  return {
    id: row.id,
    userId: row.user_id,
    name: row.name,
    createdAt: row.created_at,
    expiresAt: row.expires_at,
    lastSeenAt: row.last_seen_at,
    lastIp: row.last_ip,
    revokedAt: row.revoked_at,
    active: !row.revoked_at && Date.parse(row.expires_at) > now,
  };
}

function getDevice(id) {
  return shape(sql("SELECT * FROM devices WHERE id = ?").get(Number(id)));
}

/** Every device of `userId` (null = every user's), newest first. */
function listDevices(userId = null) {
  const rows =
    userId == null
      ? sql("SELECT * FROM devices ORDER BY id DESC").all()
      : sql("SELECT * FROM devices WHERE user_id = ? ORDER BY id DESC").all(Number(userId));
  return rows.map(shape);
}

/** Revoke one device (idempotent); false when there is no such device. */
function revokeDevice(id) {
  const r = sql(
    "UPDATE devices SET revoked_at = COALESCE(revoked_at, strftime('%Y-%m-%dT%H:%M:%fZ','now')) WHERE id = ?"
  ).run(Number(id));
  return r.changes > 0;
}

/** The bearer token of a request (Authorization: Bearer, else x-api-key). */
function bearerOf(req) {
  const h = String(req.headers.authorization || "");
  const m = /^Bearer\s+(\S+)$/i.exec(h);
  if (m) return m[1];
  const k = req.headers["x-api-key"];
  return typeof k === "string" ? k : "";
}

/**
 * `{device, user}` for a request carrying a live device token of an enabled
 * user, else null. A malformed token is not even hashed against the table.
 */
function deviceFromRequest(req) {
  const token = bearerOf(req);
  if (!TOKEN_RE.test(token)) return null;
  const row = sql(
    `SELECT d.*, u.username, u.role, u.disabled
       FROM devices d JOIN users u ON u.id = d.user_id
      WHERE d.token_hash = ?`
  ).get(sha256(token));
  if (!row || row.revoked_at || row.disabled) return null;
  if (!(Date.parse(row.expires_at) > Date.now())) return null;
  const seen = row.last_seen_at ? Date.parse(row.last_seen_at) : 0;
  const ip = req.socket?.remoteAddress || null;
  if (Date.now() - seen > SEEN_EVERY_MS || ip !== row.last_ip) {
    sql("UPDATE devices SET last_seen_at = ?, last_ip = ? WHERE id = ?").run(
      new Date().toISOString(),
      ip,
      row.id
    );
  }
  return {
    device: shape(row),
    user: { id: row.user_id, username: row.username, role: row.role },
  };
}

module.exports = {
  TOKEN_DAYS,
  TOKEN_RE,
  cleanName,
  createDevice,
  getDevice,
  listDevices,
  revokeDevice,
  deviceFromRequest,
  bearerOf,
  __sha256: sha256,
};