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

const Machine = require('../../src/specificClass');
const { makeMachineConfig, makeStateConfig } = require('../helpers/factories');

function makePressurizedOperationalMachine() {
  const machine = new Machine(makeMachineConfig(), makeStateConfig({ state: { current: 'operational' } }));
  machine.updateMeasuredPressure(800, 'upstream', { timestamp: Date.now(), unit: 'mbar', childName: 'pt-up' });
  machine.updateMeasuredPressure(1200, 'downstream', { timestamp: Date.now(), unit: 'mbar', childName: 'pt-down' });
  return machine;
}

test('calcCog returns valid peak efficiency and index', () => {
  const machine = makePressurizedOperationalMachine();

  const result = machine.calcCog();

  assert.ok(Number.isFinite(result.cog), 'cog should be finite');
  assert.ok(result.cog > 0, 'peak efficiency should be positive');
  assert.ok(Number.isFinite(result.cogIndex), 'cogIndex should be finite');
  assert.ok(result.cogIndex >= 0, 'cogIndex should be non-negative');
  assert.ok(Number.isFinite(result.NCog), 'NCog should be finite');
  assert.ok(result.NCog >= 0 && result.NCog <= 1, 'NCog should be between 0 and 1');
  assert.ok(Number.isFinite(result.minEfficiency), 'minEfficiency should be finite');
  assert.ok(result.minEfficiency >= 0, 'minEfficiency should be non-negative');
});

test('calcCog peak is always >= minEfficiency', () => {
  const machine = makePressurizedOperationalMachine();

  const result = machine.calcCog();
  assert.ok(result.cog >= result.minEfficiency, 'Peak must be >= min');
});

test('calcEfficiencyCurve produces correct specific flow ratio', () => {
  const machine = makePressurizedOperationalMachine();
  const { powerCurve, flowCurve } = machine.getCurrentCurves();

  const { efficiencyCurve, peak, peakIndex, minEfficiency } = machine.calcEfficiencyCurve(powerCurve, flowCurve);

  assert.ok(efficiencyCurve.length > 0, 'Efficiency curve should not be empty');
  assert.equal(efficiencyCurve.length, powerCurve.y.length, 'Should match curve length');

  // Verify each point: efficiency = flow / power (unrounded, canonical units)
  for (let i = 0; i < efficiencyCurve.length; i++) {
    const power = powerCurve.y[i];
    const flow = flowCurve.y[i];
    if (power > 0 && flow >= 0) {
      const expected = flow / power;
      assert.ok(Math.abs(efficiencyCurve[i] - expected) < 1e-12, `Mismatch at index ${i}`);
    }
  }

  // Peak should be the max
  const actualMax = Math.max(...efficiencyCurve);
  assert.equal(peak, actualMax, 'Peak should match max of efficiency curve');
  assert.equal(efficiencyCurve[peakIndex], peak, 'peakIndex should point to peak value');
  assert.equal(minEfficiency, Math.min(...efficiencyCurve), 'minEfficiency should match min');
});

test('calcEfficiencyCurve handles empty curves gracefully', () => {
  const machine = new Machine(makeMachineConfig(), makeStateConfig({ state: { current: 'operational' } }));

  const result = machine.calcEfficiencyCurve({ x: [], y: [] }, { x: [], y: [] });

  assert.deepEqual(result.efficiencyCurve, []);
  assert.equal(result.peak, 0);
  assert.equal(result.peakIndex, 0);
  assert.equal(result.minEfficiency, 0);
});

test('calcDistanceBEP returns absolute and relative distances', () => {
  const machine = makePressurizedOperationalMachine();

  const efficiency = 5;
  const maxEfficiency = 10;
  const minEfficiency = 2;

  const result = machine.calcDistanceBEP(efficiency, maxEfficiency, minEfficiency);

  assert.ok(Number.isFinite(result.absDistFromPeak), 'abs distance should be finite');
  assert.equal(result.absDistFromPeak, Math.abs(efficiency - maxEfficiency));
  assert.ok(Number.isFinite(result.relDistFromPeak), 'rel distance should be finite');
});

test('calcRelativeDistanceFromPeak returns 1 when maxEfficiency equals minEfficiency', () => {
  const machine = makePressurizedOperationalMachine();

  const result = machine.calcRelativeDistanceFromPeak(5, 5, 5);
  assert.equal(result, 1, 'Should return default distance when max==min (division by zero guard)');
});

test('showCoG returns structured data with curve guards', () => {
  const machine = makePressurizedOperationalMachine();

  const result = machine.showCoG();

  assert.ok('cog' in result);
  assert.ok('cogIndex' in result);
  assert.ok('NCog' in result);
  assert.ok('NCogPercent' in result);
  assert.ok('minEfficiency' in result);
  assert.ok('currentEfficiencyCurve' in result);
  assert.ok(result.cog > 0);
  assert.equal(result.NCogPercent, Math.round(result.NCog * 100 * 100) / 100);
});

test('showCoG returns safe fallback when no curve is available', () => {
  const machine = new Machine(
    makeMachineConfig({ asset: { model: null } }),
    makeStateConfig()
  );

  const result = machine.showCoG();
  assert.equal(result.cog, 0);
  assert.ok('error' in result);
});

test('showWorkingCurves returns safe fallback when no curve is available', () => {
  const machine = new Machine(
    makeMachineConfig({ asset: { model: null } }),
    makeStateConfig()
  );

  const result = machine.showWorkingCurves();
  assert.ok('error' in result);
});

test('efficiency output fields are present in getOutput', () => {
  const machine = makePressurizedOperationalMachine();

  // Move to a position so predictions produce values
  machine.state.transitionToState('operational');
  machine.updatePosition();

  const output = machine.getOutput();

  assert.ok('cog' in output);
  assert.ok('NCog' in output);
  assert.ok('NCogPercent' in output);
  assert.ok('effDistFromPeak' in output);
  assert.ok('effRelDistFromPeak' in output);
  assert.ok('predictionQuality' in output);
  assert.ok('predictionConfidence' in output);
  assert.ok('predictionPressureSource' in output);
});