// Late-subscriber replay: a measurement child that already holds a value when
// the pumpingStation registers it (e.g. a once-only inject that fired during
// startup before the parent subscribed) must still surface on Port 0. The
// emitter only delivers future updates, so _subscribeMeasurement seeds from the
// child's current sample.

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

const PumpingStation = require('../../src/specificClass');
const { MeasurementContainer, configManager } = require('generalFunctions');

function makePsConfig() {
  const cm = new configManager();
  return cm.buildConfig('pumpingStation', { name: 'PS' }, 'ps-replay', {
    basin: { volume: 50, height: 5, inflowLevel: 3, outflowLevel: 0.2, overflowLevel: 4.5 },
    hydraulics: { minHeightBasedOn: 'outlet' },
    control: {
      mode: 'levelbased',
      allowedModes: new Set(['levelbased']),
      levelbased: { minLevel: 1, startLevel: 2, maxLevel: 4, curveType: 'linear' },
    },
    safety: {},
  });
}

function makeFlowMeasurementChild(id = 'meas-replay') {
  const measurements = new MeasurementContainer({ autoConvert: true, preferredUnits: { flow: 'm3/s' } });
  assert.ok(typeof measurements.emitter?.on === 'function');
  return {
    id,
    source: {
      config: {
        general: { id, name: id },
        functionality: { softwareType: 'measurement', positionVsParent: 'upstream' },
        asset: { type: 'flow' },
      },
      measurements,
    },
  };
}

test('value written BEFORE registration is replayed on subscribe (once-inject timing)', () => {
  const ps = new PumpingStation(makePsConfig());
  const child = makeFlowMeasurementChild();

  // Child already holds a value — emitted into the void before the parent existed.
  child.source.measurements
    .type('flow').variant('measured').position('upstream')
    .value(50, Date.now(), 'm3/h');

  // Parent registers AFTER the value is present. Without replay it would only
  // catch future emits and surface nothing.
  ps.childRegistrationUtils.registerChild(child.source, 'upstream');

  const out = ps.getOutput();
  const upstreamKeys = Object.keys(out).filter((k) => k.startsWith('flow.measured.upstream'));
  assert.ok(upstreamKeys.length > 0, 'parent must surface flow.measured.upstream.* after late subscribe');
});

test('no stored value → nothing replayed, no crash', () => {
  const ps = new PumpingStation(makePsConfig());
  const child = makeFlowMeasurementChild('empty-child');
  // Register with an empty child container; replay must be a safe no-op.
  assert.doesNotThrow(() => ps.childRegistrationUtils.registerChild(child.source, 'upstream'));
  const out = ps.getOutput();
  const upstreamKeys = Object.keys(out).filter((k) => k.startsWith('flow.measured.upstream'));
  assert.equal(upstreamKeys.length, 0, 'no upstream key when child has no value');
});

test('future emits still delivered after subscribe (listener intact)', () => {
  const ps = new PumpingStation(makePsConfig());
  const child = makeFlowMeasurementChild('streaming-child');
  ps.childRegistrationUtils.registerChild(child.source, 'upstream');
  // Emit AFTER registration — the normal streaming-sensor path.
  child.source.measurements.type('flow').variant('measured').position('upstream').value(30, Date.now(), 'm3/h');
  const out = ps.getOutput();
  const upstreamKeys = Object.keys(out).filter((k) => k.startsWith('flow.measured.upstream'));
  assert.ok(upstreamKeys.length > 0, 'normal post-subscribe emit still surfaces');
});