'use strict';

const test = require('node:test');
const assert = require('node:assert');
const Calibrator = require('../../src/calibration/calibrator.js');

// Tiny logger spy so we can assert on warn() without pulling in the real
// generalFunctions logger.
function makeLogger() {
  const calls = { warn: [], info: [], debug: [], error: [] };
  return {
    calls,
    warn: (m) => calls.warn.push(m),
    info: (m) => calls.info.push(m),
    debug: (m) => calls.debug.push(m),
    error: (m) => calls.error.push(m),
  };
}

function makeCalibrator(values, config) {
  const logger = makeLogger();
  const cal = new Calibrator({
    storedValuesRef: () => values,
    configRef: () => config,
    logger,
  });
  return { cal, logger };
}

test('isStable: constant array → stable with stdDev=0', () => {
  const { cal } = makeCalibrator([5, 5, 5, 5], {});
  const r = cal.isStable();
  assert.strictEqual(r.isStable, true);
  assert.strictEqual(r.stdDev, 0);
});

test('isStable: high-variance array → original threshold is tautological (preserved)', () => {
  // BUG-PRESERVED: original check is `stdDev < stdDev*marginFactor`, which is
  // always true for stdDev>0. Length>=2 ⇒ isStable=true regardless of spread.
  // See calibrator stdDev-threshold note. We pin the behaviour here so the
  // refactor stays byte-equivalent; a separate behavioural PR can fix the rule.
  const { cal } = makeCalibrator([0, 100, 0, 100], {});
  const r = cal.isStable();
  assert.strictEqual(r.isStable, true);
  assert.ok(r.stdDev > 0);
});

test('isStable: < 2 values → unstable', () => {
  const { cal } = makeCalibrator([42], {});
  const r = cal.isStable();
  assert.strictEqual(r.isStable, false);
  assert.strictEqual(r.stdDev, 0);
});

test('calibrate: scaling enabled → offset = inputMin - currentOutputAbs', () => {
  const cfg = { scaling: { enabled: true, inputMin: 4, absMin: 0 } };
  const { cal } = makeCalibrator([10, 10, 10], cfg);
  const r = cal.calibrate(10);
  assert.deepStrictEqual(r, { offset: -6 });
});

test('calibrate: scaling disabled → offset = absMin - currentOutputAbs', () => {
  const cfg = { scaling: { enabled: false, inputMin: 4, absMin: 1 } };
  const { cal } = makeCalibrator([7, 7, 7], cfg);
  const r = cal.calibrate(7);
  assert.deepStrictEqual(r, { offset: -6 });
});

test('calibrate: not stable (length<2) → returns null and logs warn', () => {
  // Original rule has a tautological threshold, so "unstable" only triggers
  // when the rolling window has < 2 samples.
  const cfg = { scaling: { enabled: true, inputMin: 0, absMin: 0 } };
  const { cal, logger } = makeCalibrator([], cfg);
  const r = cal.calibrate(50);
  assert.strictEqual(r, null);
  assert.strictEqual(logger.calls.warn.length, 1);
  assert.match(logger.calls.warn[0], /Calibration aborted/);
});

test('evaluateRepeatability: smoothing=none → null', () => {
  const cfg = { smoothing: { smoothMethod: 'none' } };
  const { cal, logger } = makeCalibrator([5, 5, 5], cfg);
  const r = cal.evaluateRepeatability();
  assert.strictEqual(r.repeatability, null);
  assert.strictEqual(r.reason, 'smoothing-disabled');
  assert.match(logger.calls.warn[0], /without smoothing/);
});

test('evaluateRepeatability: stable + smoothed → returns stdDev', () => {
  const cfg = { smoothing: { smoothMethod: 'mean' } };
  const { cal } = makeCalibrator([3, 3, 3, 3], cfg);
  const r = cal.evaluateRepeatability();
  assert.strictEqual(r.repeatability, 0);
});

test('evaluateRepeatability: insufficient data → null', () => {
  const cfg = { smoothing: { smoothMethod: 'mean' } };
  const { cal } = makeCalibrator([5], cfg);
  const r = cal.evaluateRepeatability();
  assert.strictEqual(r.repeatability, null);
  assert.strictEqual(r.reason, 'insufficient-data');
});

test('evaluateRepeatability: high-variance still returns stdDev (preserved tautology)', () => {
  // BUG-PRESERVED: see isStable note. Original rule treats any length>=2
  // buffer as stable, so repeatability returns the raw stdDev even when the
  // spread is large.
  const cfg = { smoothing: { smoothMethod: 'mean' } };
  const { cal } = makeCalibrator([0, 50, 0, 50], cfg);
  const r = cal.evaluateRepeatability();
  assert.ok(r.repeatability > 0);
});