"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.formatSignificanceLevel = exports.computeChi2PValue = void 0;
var _constants = require("./constants");
/*
 * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
 * or more contributor license agreements. Licensed under the Elastic License
 * 2.0; you may not use this file except in compliance with the Elastic License
 * 2.0.
 */

const criticalTableLookup = (chi2Statistic, df) => {
  if (df < 1) return 1;
  if (!Number.isInteger(df)) throw Error('Degrees of freedom must be a valid integer');

  // Get the row index
  const rowIndex = df - 1;

  // Get the column index
  let minDiff = Math.abs(_constants.CRITICAL_VALUES_TABLE[rowIndex][0] - chi2Statistic);
  let columnIndex = 0;
  for (let j = 1; j < _constants.CRITICAL_VALUES_TABLE[rowIndex].length; j++) {
    const diff = Math.abs(_constants.CRITICAL_VALUES_TABLE[rowIndex][j] - chi2Statistic);
    if (diff < minDiff) {
      minDiff = diff;
      columnIndex = j;
    }
  }
  const significanceLevel = _constants.SIGNIFICANCE_LEVELS[columnIndex];
  return significanceLevel;
};

/**
 * Compute the p-value for how similar the datasets are.
 * Returned value ranges from 0 to 1, with 1 meaning the datasets are identical.
 * @param normalizedBaselineTerms
 * @param normalizedDriftedTerms
 */
const computeChi2PValue = (normalizedBaselineTerms, normalizedDriftedTerms) => {
  // Get all unique keys from both arrays
  const allKeys = Array.from(new Set([...normalizedBaselineTerms.map(term => term.key.toString()), ...normalizedDriftedTerms.map(term => term.key.toString())])).slice(0, 100);

  // Calculate the chi-squared statistic and degrees of freedom
  let chiSquared = 0;
  const degreesOfFreedom = allKeys.length - 1;
  if (degreesOfFreedom === 0) return 1;
  allKeys.forEach(key => {
    var _driftedTerm$percenta, _baselineTerm$percent;
    const baselineTerm = normalizedBaselineTerms.find(term => term.key === key);
    const driftedTerm = normalizedDriftedTerms.find(term => term.key === key);
    const observed = (_driftedTerm$percenta = driftedTerm === null || driftedTerm === void 0 ? void 0 : driftedTerm.percentage) !== null && _driftedTerm$percenta !== void 0 ? _driftedTerm$percenta : 0;
    const expected = (_baselineTerm$percent = baselineTerm === null || baselineTerm === void 0 ? void 0 : baselineTerm.percentage) !== null && _baselineTerm$percent !== void 0 ? _baselineTerm$percent : 0;
    chiSquared += Math.pow(observed - expected, 2) / (expected > 0 ? expected : 1e-6); // Prevent divide by zero
  });

  return criticalTableLookup(chiSquared, degreesOfFreedom);
};

/**
 * formatSignificanceLevel
 * @param significanceLevel
 */
exports.computeChi2PValue = computeChi2PValue;
const formatSignificanceLevel = significanceLevel => {
  if (typeof significanceLevel !== 'number' || isNaN(significanceLevel)) return '';
  if (significanceLevel < 1e-6) {
    return '< 0.000001';
  } else if (significanceLevel < 0.01) {
    return significanceLevel.toExponential(0);
  } else {
    return significanceLevel.toFixed(2);
  }
};
exports.formatSignificanceLevel = formatSignificanceLevel;