import { Router } from 'express';
import {
  getInstances, getInstance, getDistinctStacks,
  createInstance, updateInstance, deleteInstance, importInstances,
} from './db.js';

export const router = Router();

// ── Validation ────────────────────────────────────────────────────────────────

const VALID_STATES  = ['deployed', 'testing', 'degraded'];
const VALID_STACKS  = ['production', 'development'];
const SERVICE_KEYS  = ['atlas', 'argus', 'semaphore', 'patchmon', 'tailscale', 'andromeda'];

function validate(body) {
  const errors = [];
  if (!body.name || typeof body.name !== 'string' || !body.name.trim())
    errors.push('name is required');
  if (!Number.isInteger(body.vmid) || body.vmid < 1)
    errors.push('vmid must be a positive integer');
  if (!VALID_STATES.includes(body.state))
    errors.push(`state must be one of: ${VALID_STATES.join(', ')}`);
  if (!VALID_STACKS.includes(body.stack))
    errors.push(`stack must be one of: ${VALID_STACKS.join(', ')}`);
  const ip = (body.tailscale_ip ?? '').trim();
  if (ip && !/^(\d{1,3}\.){3}\d{1,3}$/.test(ip))
    errors.push('tailscale_ip must be a valid IPv4 address or empty');
  return errors;
}

function normalise(body) {
  const row = {
    name:                  body.name.trim(),
    state:                 body.state,
    stack:                 body.stack,
    vmid:                  body.vmid,
    tailscale_ip:          (body.tailscale_ip ?? '').trim(),
    hardware_acceleration: body.hardware_acceleration ? 1 : 0,
  };
  for (const svc of SERVICE_KEYS) row[svc] = body[svc] ? 1 : 0;
  return row;
}

// ── Routes ────────────────────────────────────────────────────────────────────

// GET /api/instances/stacks — must be declared before /:vmid
router.get('/instances/stacks', (_req, res) => {
  res.json(getDistinctStacks());
});

// GET /api/instances
router.get('/instances', (req, res) => {
  const { search, state, stack } = req.query;
  res.json(getInstances({ search, state, stack }));
});

// GET /api/instances/:vmid
router.get('/instances/:vmid', (req, res) => {
  const vmid = parseInt(req.params.vmid, 10);
  if (!vmid) return res.status(400).json({ error: 'invalid vmid' });

  const instance = getInstance(vmid);
  if (!instance) return res.status(404).json({ error: 'instance not found' });

  res.json(instance);
});

// POST /api/instances
router.post('/instances', (req, res) => {
  const errors = validate(req.body);
  if (errors.length) return res.status(400).json({ errors });

  try {
    const data = normalise(req.body);
    createInstance(data);
    const created = getInstance(data.vmid);
    res.status(201).json(created);
  } catch (e) {
    if (e.message.includes('UNIQUE')) return res.status(409).json({ error: 'vmid already exists' });
    if (e.message.includes('CHECK'))  return res.status(400).json({ error: 'invalid field value' });
    console.error('POST /api/instances', e);
    res.status(500).json({ error: 'internal server error' });
  }
});

// PUT /api/instances/:vmid
router.put('/instances/:vmid', (req, res) => {
  const vmid = parseInt(req.params.vmid, 10);
  if (!vmid) return res.status(400).json({ error: 'invalid vmid' });
  if (!getInstance(vmid)) return res.status(404).json({ error: 'instance not found' });

  const errors = validate(req.body);
  if (errors.length) return res.status(400).json({ errors });

  try {
    const data = normalise(req.body);
    updateInstance(vmid, data);
    res.json(getInstance(data.vmid));
  } catch (e) {
    if (e.message.includes('UNIQUE')) return res.status(409).json({ error: 'vmid already exists' });
    if (e.message.includes('CHECK'))  return res.status(400).json({ error: 'invalid field value' });
    console.error('PUT /api/instances/:vmid', e);
    res.status(500).json({ error: 'internal server error' });
  }
});

// GET /api/export
router.get('/export', (_req, res) => {
  const instances = getInstances();
  const date = new Date().toISOString().slice(0, 10);
  res.setHeader('Content-Disposition', `attachment; filename="catalyst-backup-${date}.json"`);
  res.json({ version: 1, exported_at: new Date().toISOString(), instances });
});

// POST /api/import
router.post('/import', (req, res) => {
  const { instances } = req.body ?? {};
  if (!Array.isArray(instances)) {
    return res.status(400).json({ error: 'body must contain an instances array' });
  }
  const errors = [];
  for (const [i, row] of instances.entries()) {
    const errs = validate(normalise(row));
    if (errs.length) errors.push({ index: i, errors: errs });
  }
  if (errors.length) return res.status(400).json({ errors });
  try {
    importInstances(instances.map(normalise));
    res.json({ imported: instances.length });
  } catch (e) {
    console.error('POST /api/import', e);
    res.status(500).json({ error: 'internal server error' });
  }
});

// DELETE /api/instances/:vmid
router.delete('/instances/:vmid', (req, res) => {
  const vmid = parseInt(req.params.vmid, 10);
  if (!vmid) return res.status(400).json({ error: 'invalid vmid' });

  const instance = getInstance(vmid);
  if (!instance) return res.status(404).json({ error: 'instance not found' });
  if (instance.stack !== 'development')
    return res.status(422).json({ error: 'only development instances can be deleted' });

  try {
    deleteInstance(vmid);
    res.status(204).end();
  } catch (e) {
    console.error('DELETE /api/instances/:vmid', e);
    res.status(500).json({ error: 'internal server error' });
  }
});