/**
 * End-to-end server verification: WebSocket streaming, the control API, and the
 * copilot (including its offline fallback).
 *
 * Start the server first, then:  node scripts/apicheck.mjs
 */

import WebSocket from 'ws';

const BASE = process.env.BASE || 'http://localhost:8787';
let failures = 0;

function check(name, ok, detail = '') {
  if (!ok) failures++;
  console.log(`  [${ok ? 'PASS' : 'FAIL'}] ${name}${detail ? '  ' + detail : ''}`);
}

async function post(path, body) {
  const res = await fetch(`${BASE}${path}`, {
    method: 'POST',
    headers: { 'Content-Type': 'application/json' },
    body: JSON.stringify(body || {}),
  });
  return { status: res.status, json: await res.json().catch(() => null) };
}

async function get(path) {
  const res = await fetch(`${BASE}${path}`);
  return { status: res.status, json: await res.json().catch(() => null) };
}

/** Collect n frames from the websocket. */
function collectFrames(n, timeoutMs = 15000) {
  return new Promise((resolve, reject) => {
    const ws = new WebSocket(`${BASE.replace('http', 'ws')}/ws`);
    const frames = [];
    const timer = setTimeout(() => { ws.close(); reject(new Error(`timed out after ${frames.length} frames`)); }, timeoutMs);
    ws.on('message', (raw) => {
      const msg = JSON.parse(raw.toString());
      if (msg.type === 'frame') frames.push(msg.frame);
      if (frames.length >= n) { clearTimeout(timer); ws.close(); resolve(frames); }
    });
    ws.on('error', (err) => { clearTimeout(timer); reject(err); });
  });
}

/** Read an SSE copilot response to completion. */
async function askCopilot(question, timeoutMs = 120000) {
  const ctl = new AbortController();
  const timer = setTimeout(() => ctl.abort(), timeoutMs);
  try {
    const res = await fetch(`${BASE}/api/copilot/chat`, {
      method: 'POST',
      signal: ctl.signal,
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({ question, history: [] }),
    });
    let text = '';
    let meta = null;
    let notes = [];
    let buf = '';
    const dec = new TextDecoder();
    for await (const chunk of res.body) {
      buf += dec.decode(chunk, { stream: true });
      let i;
      while ((i = buf.indexOf('\n\n')) >= 0) {
        const line = buf.slice(0, i).trim();
        buf = buf.slice(i + 2);
        if (!line.startsWith('data:')) continue;
        const obj = JSON.parse(line.slice(5).trim());
        if (obj.type === 'token') text += obj.text;
        if (obj.type === 'meta') meta = obj;
        if (obj.type === 'note') notes.push(obj.text);
      }
    }
    return { text, meta, notes };
  } finally {
    clearTimeout(timer);
  }
}

console.log(`\n=== A. Metadata and health (${BASE}) ===`);
const meta = await get('/api/meta');
check('GET /api/meta returns 200', meta.status === 200);
check('five stations described', meta.json?.stations?.length === 5, (meta.json?.stations || []).map((s) => s.id).join(','));
check('four fault profiles offered', meta.json?.faults?.length === 4);
check('source reports its capabilities', Boolean(meta.json?.source?.capabilities?.faultInjection));
console.log(`  copilot: ${meta.json?.copilot?.label} (${meta.json?.copilot?.detail})`);

const health = await get('/api/health');
check('GET /api/health ok', health.status === 200 && health.json.ok === true);

console.log('\n=== B. WebSocket streaming ===');
{
  await post('/api/control/speed', { speed: 1 });
  const frames = await collectFrames(3);
  check('received 3 frames', frames.length === 3);
  const f = frames[frames.length - 1];
  check('frame has stations, kpi, analytics', Boolean(f.stations && f.kpi && f.analytics));
  check('frame carries analytics arrays',
    Array.isArray(f.analytics.alarms) && Array.isArray(f.analytics.predictions));
  check('simulated time advances between frames', frames[2].t > frames[0].t,
    `${frames[0].t.toFixed(1)}s -> ${frames[2].t.toFixed(1)}s`);
  check('every station reports a state', f.stations.every((s) => typeof s.state === 'string'));
  check('sim block reports speed and tick', f.sim.tickMs > 0 && typeof f.sim.speed === 'number');
}

console.log('\n=== C. Control API ===');
{
  const sp = await post('/api/control/setpoint', { value: 325 });
  check('POST setpoint accepted', sp.status === 200 && sp.json.result === 325, JSON.stringify(sp.json));

  const clamp = await post('/api/control/setpoint', { value: 9999 });
  check('setpoint is clamped, not rejected', clamp.json.result === 360, `got ${clamp.json.result}`);

  const ls = await post('/api/control/line-speed', { value: 115 });
  check('POST line-speed accepted', ls.json.result === 115);

  const speed = await post('/api/control/speed', { speed: 60 });
  check('POST speed 60x accepted', speed.json.result === 60);

  const badSpeed = await post('/api/control/speed', { speed: 999 });
  check('invalid speed rejected with 400', badSpeed.status === 400, badSpeed.json?.error);

  const badFault = await post('/api/control/fault', { id: 'nope', action: 'inject' });
  check('unknown fault rejected with 400', badFault.status === 400, badFault.json?.error);

  await post('/api/control/setpoint', { value: 305 });
  await post('/api/control/line-speed', { value: 100 });
}

console.log('\n=== D. Fault injection propagates to the stream ===');
{
  await post('/api/control/speed', { speed: 60 });
  await post('/api/control/fault', { id: 'packer-jam', action: 'inject' });
  const frames = await collectFrames(8);
  const last = frames[frames.length - 1];
  const pkg = last.stations.find((s) => s.id === 'PKG-05');
  check('packer shows fault state in the stream', pkg.state === 'fault', pkg.state);
  check('a critical alarm is raised',
    last.analytics.alarms.some((a) => a.severity === 'critical'),
    last.analytics.alarms.map((a) => `${a.severity}:${a.station}`).join(', '));
  check('fault is listed on the frame', last.faults.some((f) => f.id === 'packer-jam'));

  await post('/api/control/fault', { id: 'packer-jam', action: 'clear' });
  const after = await collectFrames(6);
  const pkg2 = after[after.length - 1].stations.find((s) => s.id === 'PKG-05');
  check('packer recovers after the fault is cleared', pkg2.state !== 'fault', pkg2.state);
}

console.log('\n=== E. Copilot ===');
{
  // Build up a real condition so the answers have something to work with.
  await post('/api/control/fault', { id: 'bearing-degradation', action: 'inject' });
  await post('/api/control/speed', { speed: 60 });
  await new Promise((r) => setTimeout(r, 12000));
  await post('/api/control/speed', { speed: 1 });

  const state = await get('/api/state');
  const vib = state.json.stations.find((s) => s.id === 'CNC-02').signals.vibration;
  console.log(`  CNC-02 vibration is now ${vib.toFixed(2)} mm/s; alarms: ${state.json.analytics.alarms.length}; predictions: ${state.json.analytics.predictions.length}`);

  const qs = [
    'What is wrong with CNC-02?',
    'Why is OEE down?',
    'Draft a maintenance work order.',
    'What happens if I raise line speed by 10%?',
  ];
  for (const q of qs) {
    const ans = await askCopilot(q);
    const ok = ans.text.trim().length > 40;
    check(`answered: "${q}"`, ok, ok ? `${ans.text.trim().length} chars via ${ans.meta?.provider}` : JSON.stringify(ans).slice(0, 200));
    if (ans.notes.length) console.log(`     note: ${ans.notes[0]}`);
    console.log(`     -> ${ans.text.trim().split('\n')[0].slice(0, 160)}`);
  }

  // The answer must be grounded in real telemetry, not generic prose.
  const diag = await askCopilot('What is wrong with CNC-02?');
  check('answer cites the actual station', /CNC-02/i.test(diag.text));
  check('answer cites a real measurement', /\d+\.\d+/.test(diag.text));

  await post('/api/control/fault', { id: 'bearing-degradation', action: 'clear' });
  await post('/api/control/reset', {});
}

console.log(`\n${failures === 0 ? 'ALL API CHECKS PASSED' : failures + ' CHECK(S) FAILED'}\n`);
process.exit(failures === 0 ? 0 : 1);