'use strict';

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

const DriftAssessor = require('../../src/drift/driftAssessor');

/* ---- fakes ---- */
function fakeMeasurements(predictedValue) {
  return {
    type() { return this; },
    variant() { return this; },
    position() { return this; },
    getCurrentValue() { return predictedValue; },
    getAllValues() { return { values: [predictedValue], timestamps: [1] }; },
  };
}

function makeErrorMetrics(driftFactory) {
  return {
    assessPoint: (metricId, predicted, measured, opts) => driftFactory(metricId, predicted, measured, opts),
    assessDrift: () => ({ nrmse: 0.1, valid: true }),
  };
}

const SILENT = { warn() {}, debug() {} };

test('updateMetricDrift returns drift object when predicted+measured both finite', () => {
  const drift = { valid: true, nrmse: 0.05, immediateLevel: 0, longTermLevel: 0 };
  const assessor = new DriftAssessor({
    errorMetrics: makeErrorMetrics(() => drift),
    measurements: fakeMeasurements(10),
    driftProfiles: { flow: {} },
    logger: SILENT,
  });

  const out = assessor.updateMetricDrift('flow', 11);
  assert.deepEqual(out, drift);
  assert.equal(assessor.latest.flow, drift);
});

test('updateMetricDrift returns null when predicted is non-finite', () => {
  const assessor = new DriftAssessor({
    errorMetrics: makeErrorMetrics(() => ({ valid: true })),
    measurements: fakeMeasurements(NaN),
    driftProfiles: {},
    logger: SILENT,
  });
  assert.equal(assessor.updateMetricDrift('flow', 5), null);
});

test('updateMetricDrift catches errorMetrics throw and logs', () => {
  const warns = [];
  const assessor = new DriftAssessor({
    errorMetrics: { assessPoint() { throw new Error('boom'); } },
    measurements: fakeMeasurements(10),
    driftProfiles: {},
    logger: { warn(m) { warns.push(m); }, debug() {} },
  });
  const out = assessor.updateMetricDrift('flow', 11);
  assert.equal(out, null);
  assert.match(warns[0], /Drift update failed for metric 'flow'/);
});

test('applyDriftPenalty leaves confidence unchanged for null/invalid drift', () => {
  const assessor = new DriftAssessor({ logger: SILENT });
  const flags = [];
  assert.equal(assessor.applyDriftPenalty(null, 0.9, flags, 'flow'), 0.9);
  assert.equal(assessor.applyDriftPenalty({ valid: false }, 0.9, flags, 'flow'), 0.9);
  assert.deepEqual(flags, []);
});

test('applyDriftPenalty level 1 reduces confidence by 0.1 + flag', () => {
  const assessor = new DriftAssessor({ logger: SILENT });
  const flags = [];
  const c = assessor.applyDriftPenalty(
    { valid: true, nrmse: 0.1, immediateLevel: 1, longTermLevel: 0 },
    0.9, flags, 'flow',
  );
  assert.ok(Math.abs(c - 0.8) < 1e-9);
  assert.deepEqual(flags, ['flow_low_immediate_drift']);
});

test('applyDriftPenalty level 2 reduces confidence by 0.2 + flag', () => {
  const assessor = new DriftAssessor({ logger: SILENT });
  const flags = [];
  const c = assessor.applyDriftPenalty(
    { valid: true, nrmse: 0.2, immediateLevel: 2, longTermLevel: 0 },
    0.9, flags, 'power',
  );
  assert.ok(Math.abs(c - 0.7) < 1e-9);
  assert.deepEqual(flags, ['power_medium_immediate_drift']);
});

test('applyDriftPenalty level 3 reduces confidence by 0.3 + flag', () => {
  const assessor = new DriftAssessor({ logger: SILENT });
  const flags = [];
  const c = assessor.applyDriftPenalty(
    { valid: true, nrmse: 0.5, immediateLevel: 3, longTermLevel: 0 },
    0.9, flags, 'flow',
  );
  assert.ok(Math.abs(c - 0.6) < 1e-9);
  assert.deepEqual(flags, ['flow_high_immediate_drift']);
});

test('applyDriftPenalty stacks long-term penalty', () => {
  const assessor = new DriftAssessor({ logger: SILENT });
  const flags = [];
  const c = assessor.applyDriftPenalty(
    { valid: true, nrmse: 0.4, immediateLevel: 2, longTermLevel: 2 },
    0.9, flags, 'flow',
  );
  assert.ok(Math.abs(c - 0.6) < 1e-9);
  assert.deepEqual(flags, ['flow_medium_immediate_drift', 'flow_long_term_drift']);
});

test('assessDrift returns null if no stored series', () => {
  const assessor = new DriftAssessor({
    errorMetrics: makeErrorMetrics(() => ({ valid: true })),
    measurements: {
      type() { return this; },
      variant() { return this; },
      position() { return this; },
      getAllValues() { return {}; },
    },
    driftProfiles: {},
    logger: SILENT,
  });
  assert.equal(assessor.assessDrift('flow', 0, 1), null);
});