// hd-commerce — Session-Auth (stateless signiertes Cookie), Rollen-Gate, Rate-Limit.
import { createHmac, timingSafeEqual } from 'node:crypto';
import { getUserById } from './store.js';

const SECRET = process.env.SESSION_SECRET || 'hd-commerce-dev-secret-change-me';
export const COOKIE_NAME = 'hdc_session';

// --- konfigurierbarer Admin-Pfad ---
function rawAdminPath() {
  let p = (process.env.ADMIN_PATH || 'admin').trim().replace(/^\/+|\/+$/g, '');
  if (!p) p = 'admin';
  return p;
}
export const adminBase = () => '/' + rawAdminPath();          // z.B. "/login" oder "/admin"
export const adminPathSegment = () => rawAdminPath();          // "login"
export const isCustomAdminPath = () => rawAdminPath() !== 'admin';
// Hilfsfunktion für Links in Astro-Seiten:
export const ab = (suffix = '') => adminBase() + (suffix || '');

// --- Cookie-Signatur ---
function b64url(buf) { return Buffer.from(buf).toString('base64').replace(/\+/g, '-').replace(/\//g, '_').replace(/=+$/, ''); }
function b64urlDecode(str) { return Buffer.from(str.replace(/-/g, '+').replace(/_/g, '/'), 'base64'); }

export function signSession(uid, maxAgeSeconds) {
  const exp = Math.floor(Date.now() / 1000) + (maxAgeSeconds || 60 * 60 * 12);
  const payload = b64url(JSON.stringify({ uid: Number(uid), exp }));
  const sig = b64url(createHmac('sha256', SECRET).update(payload).digest());
  return payload + '.' + sig;
}

export function verifySession(token) {
  if (!token || typeof token !== 'string' || !token.includes('.')) return null;
  const [payload, sig] = token.split('.');
  if (!payload || !sig) return null;
  const expected = b64url(createHmac('sha256', SECRET).update(payload).digest());
  try {
    const a = Buffer.from(sig), b = Buffer.from(expected);
    if (a.length !== b.length || !timingSafeEqual(a, b)) return null;
  } catch { return null; }
  let data;
  try { data = JSON.parse(b64urlDecode(payload).toString('utf8')); } catch { return null; }
  if (!data || !data.uid || !data.exp) return null;
  if (data.exp < Math.floor(Date.now() / 1000)) return null;
  return data;
}

export function buildCookie(token, remember) {
  const parts = [`${COOKIE_NAME}=${token}`, 'Path=/', 'HttpOnly', 'SameSite=Lax'];
  if (remember) parts.push('Max-Age=' + (60 * 60 * 24 * 30));
  return parts.join('; ');
}
export function clearCookie() {
  return `${COOKIE_NAME}=; Path=/; HttpOnly; SameSite=Lax; Max-Age=0`;
}

export function parseCookies(request) {
  const h = request.headers.get('cookie') || '';
  const out = {};
  h.split(';').forEach(p => {
    const i = p.indexOf('=');
    if (i > -1) out[p.slice(0, i).trim()] = decodeURIComponent(p.slice(i + 1).trim());
  });
  return out;
}

export function currentUser(request) {
  const token = parseCookies(request)[COOKIE_NAME];
  const sess = verifySession(token);
  if (!sess) return null;
  const u = getUserById(sess.uid);
  if (!u || !u.active) return null;
  return u;
}

// --- Rollen-Gate ---
// owner: alles · redaktion: Produkte/Inhalte/Marketing · versand: nur Bestellungen
const ROLE_SECTIONS = {
  owner: ['dashboard', 'bestellungen', 'produkte', 'kunden', 'analytics', 'marketing', 'rabatte', 'inhalte', 'versandzonen', 'einstellungen', 'nutzer', 'audit'],
  redaktion: ['dashboard', 'produkte', 'inhalte', 'marketing', 'rabatte', 'analytics', 'versandzonen'],
  versand: ['bestellungen'],
};
export function canAccess(role, section) {
  const allowed = ROLE_SECTIONS[role] || ROLE_SECTIONS.redaktion;
  return allowed.includes(section);
}
export function allowedSections(role) {
  return ROLE_SECTIONS[role] || ROLE_SECTIONS.redaktion;
}
export function landingFor(role) {
  if (role === 'versand') return adminBase() + '/bestellungen';
  return adminBase();
}

// --- Login-Rate-Limit (In-Memory) ---
const attempts = new Map(); // ip -> { count, until }
export function rateLimited(ip) {
  const r = attempts.get(ip);
  if (r && r.until && Date.now() < r.until) return true;
  return false;
}
export function registerFail(ip) {
  const r = attempts.get(ip) || { count: 0, until: 0 };
  r.count += 1;
  if (r.count >= 5) { r.until = Date.now() + 60 * 1000; r.count = 0; }
  attempts.set(ip, r);
}
export function clearFails(ip) { attempts.delete(ip); }

export function clientIp(request) {
  return (request.headers.get('x-forwarded-for') || request.headers.get('x-real-ip') || 'local').split(',')[0].trim();
}