const test = require('node:test');
const assert = require('node:assert/strict');
const EventEmitter = require('events');

const { bindStateEvents, isOperationalState, OPERATIONAL_STATES } =
  require('../../src/state/stateBindings');

function makeFakeState() {
  const emitter = new EventEmitter();
  let current = 'idle';
  return {
    emitter,
    setState(s) { current = s; },
    getCurrentState() { return current; },
  };
}

test('bindStateEvents attaches both listeners and they fire on emit', () => {
  const state = makeFakeState();
  let posCalls = 0;
  let stateCalls = 0;
  let lastStateArg = null;

  bindStateEvents({
    state,
    onPositionChange: () => { posCalls++; },
    onStateChange: (newState) => { stateCalls++; lastStateArg = newState; },
  });

  assert.equal(state.emitter.listenerCount('positionChange'), 1);
  assert.equal(state.emitter.listenerCount('stateChange'), 1);

  state.emitter.emit('positionChange', 42);
  state.emitter.emit('stateChange', 'operational');

  assert.equal(posCalls, 1);
  assert.equal(stateCalls, 1);
  assert.equal(lastStateArg, 'operational');
});

test('bindStateEvents teardown removes both listeners and is idempotent', () => {
  const state = makeFakeState();
  const teardown = bindStateEvents({
    state,
    onPositionChange: () => {},
    onStateChange: () => {},
  });

  assert.equal(state.emitter.listenerCount('positionChange'), 1);
  assert.equal(state.emitter.listenerCount('stateChange'), 1);

  teardown();
  assert.equal(state.emitter.listenerCount('positionChange'), 0);
  assert.equal(state.emitter.listenerCount('stateChange'), 0);

  teardown();
  assert.equal(state.emitter.listenerCount('positionChange'), 0);
});

test('bindStateEvents validates context shape', () => {
  assert.throws(() => bindStateEvents(null), /ctx\.state\.emitter is required/);
  assert.throws(
    () => bindStateEvents({ state: makeFakeState() }),
    /handlers are required/,
  );
});

test('isOperationalState returns true for operational/accelerating/decelerating/warmingup', () => {
  const state = makeFakeState();
  for (const s of ['operational', 'accelerating', 'decelerating', 'warmingup']) {
    state.setState(s);
    assert.equal(isOperationalState(state), true, `expected ${s} to be operational`);
  }
});

test('isOperationalState returns false for non-operational states and bad input', () => {
  const state = makeFakeState();
  for (const s of ['idle', 'starting', 'stopping', 'coolingdown', 'emergencystopped']) {
    state.setState(s);
    assert.equal(isOperationalState(state), false, `expected ${s} not to be operational`);
  }
  assert.equal(isOperationalState(null), false);
  assert.equal(isOperationalState({}), false);
});

test('OPERATIONAL_STATES list is exported and frozen-ish (no extras beyond contract)', () => {
  assert.deepEqual(
    [...OPERATIONAL_STATES].sort(),
    ['accelerating', 'decelerating', 'operational', 'warmingup'],
  );
});