'use strict';

const express = require('express');
const config = require('../config');
const { invites, clients, audit } = require('../db');
const { uuid, randomToken, sha256 } = require('../crypto');
const { requireAuth, requireAdmin } = require('../auth');

const router = express.Router();

const { baseUrl } = config;

function inviteLink(req, kind, token) {
  return `${baseUrl(req)}/${kind === 'enroll' ? 'enroll' : 's'}/${token}`;
}

function publicInvite(i) {
  return {
    id: i.id,
    kind: i.kind,
    clientId: i.client_id,
    clientName: i.client_name,
    label: i.label,
    role: i.role,
    maxUses: i.max_uses,
    uses: i.uses,
    expiresAt: i.expires_at,
    revokedAt: i.revoked_at,
    lastUsedAt: i.last_used_at,
    createdBy: i.created_by,
    createdAt: i.created_at,
    status: i.revoked_at
      ? 'revoked'
      : i.expires_at && i.expires_at < Date.now()
        ? 'expired'
        : i.max_uses > 0 && i.uses >= i.max_uses
          ? 'used up'
          : 'active',
  };
}

router.use(requireAuth, requireAdmin);

router.get('/', (req, res) => {
  res.json({ invites: invites.list().map(publicInvite) });
});

/**
 * Two kinds of invite:
 *  - enroll:  hand to a *machine*. Redeeming it registers a new client.
 *  - session: hand to a *person*. Redeeming it grants time-boxed access to one client.
 */
router.post('/', (req, res) => {
  const body = req.body || {};
  const kind = body.kind === 'enroll' ? 'enroll' : 'session';

  let clientId = null;
  let role = null;
  let prefill = null;

  if (kind === 'session') {
    if (!config.allowSessionInvites) {
      return res.status(403).json({ error: 'session invites are disabled on this server' });
    }
    const client = clients.get(String(body.clientId || ''));
    if (!client) return res.status(400).json({ error: 'a valid clientId is required for a session invite' });
    clientId = client.id;
    role = body.role === 'operator' ? 'operator' : 'viewer';
  } else {
    // Defaults applied to whatever machine redeems this enrollment link.
    prefill = JSON.stringify({
      name: body.name ? String(body.name).trim() : null,
      tags: body.tags ? String(body.tags) : '',
      requireConsent: body.requireConsent ? 1 : 0,
    });
    if (body.clientId) {
      // Re-enrolling an existing client (replace a machine, rotate its key).
      const client = clients.get(String(body.clientId));
      if (!client) return res.status(400).json({ error: 'no such client' });
      clientId = client.id;
    }
  }

  const ttlMs = Number(body.ttlMs) > 0 ? Number(body.ttlMs) : config.inviteDefaultTtlMs;
  // An enrollment link is meant for exactly one machine. A support link should
  // survive a dropped connection, so it defaults to unlimited uses until it expires.
  const defaultMaxUses = kind === 'enroll' ? 1 : 0;
  const maxUses = body.maxUses === undefined || body.maxUses === null || body.maxUses === ''
    ? defaultMaxUses
    : Math.max(0, Number.parseInt(body.maxUses, 10) || 0);

  const token = randomToken(32);
  const invite = invites.create({
    id: uuid(),
    token_hash: sha256(token),
    kind,
    client_id: clientId,
    label: body.label ? String(body.label).slice(0, 200) : null,
    role,
    prefill,
    max_uses: maxUses,
    expires_at: Date.now() + ttlMs,
    created_by: req.username,
  });

  audit(req.username, 'invite.create', invite.id, { kind, clientId, role, maxUses, ttlMs });

  // The token itself is shown exactly once; only its hash is persisted.
  res.status(201).json({
    invite: publicInvite({ ...invite, client_name: clientId ? clients.get(clientId)?.name : null }),
    url: inviteLink(req, kind, token),
    token,
  });
});

router.post('/:id/revoke', (req, res) => {
  const invite = invites.get(req.params.id);
  if (!invite) return res.status(404).json({ error: 'no such invite' });
  invites.revoke(invite.id);
  audit(req.username, 'invite.revoke', invite.id, null);
  res.json({ ok: true });
});

router.delete('/:id', (req, res) => {
  const invite = invites.get(req.params.id);
  if (!invite) return res.status(404).json({ error: 'no such invite' });
  invites.remove(invite.id);
  audit(req.username, 'invite.delete', invite.id, null);
  res.json({ ok: true });
});

module.exports = { router, baseUrl, publicInvite };