'use strict';

import chai from 'chai';
import MathUtil from '../../lib/utils/math.js';
const assert = chai.assert;

describe('Math', () => {

	it('should calculate sum', () => {
		assert.isTrue(MathUtil.sum([1, 2, 3, 4]) == 10);
	});


	it('should calculate average', () => {
		assert.isTrue(MathUtil.average([1, 2, 3, 4]) == 2.5);
	});


	it('should calculate median', () => {
		assert.isTrue(MathUtil.median([1, 1, 2, 3, 16, 1, 2]) == 2);
		assert.isTrue(MathUtil.median([1, 1, 2, 2, 3, 3, 3, 16]) == 2.5);
	});

	it('should calculate variance', () => {
		let items_1 = [1, 2, 3, 4, 5];
		let items_2 = [1, 2, 3, 4, 5, 1];

		//Sample Mode
		assert.isTrue(MathUtil.variance(items_1) == 2.5);
		assert.isTrue(MathUtil.variance(items_2).toFixed(2) == 2.67);

		//Population Mode
		assert.isTrue(MathUtil.variance(items_1, 'population') == 2);
		assert.isTrue(MathUtil.variance(items_2, 'population').toFixed(2) == 2.22);
	});

	it('should calculate standard deviation', () => {
		let items_1 = [1, 2, 3, 4, 5];
		let items_2 = [1, 2, 3, 4, 5, 1];

		//Sample Mode
		assert.isTrue(MathUtil.standardDeviation(items_1).toFixed(2) == 1.58);
		assert.isTrue(MathUtil.standardDeviation(items_2).toFixed(2) == 1.63);

		//Population Mode
		assert.isTrue(MathUtil.standardDeviation(items_1, 'population').toFixed(2) == 1.41);
		assert.isTrue(MathUtil.standardDeviation(items_2, 'population').toFixed(2) == 1.49);
	});

	it('should calculate the mean deviation', () => {
		let items = [3, 6, 6, 7, 8, 11, 15, 16];
		assert.isTrue(MathUtil.meanDeviation(items) == 3.75);
	});

	it('should calculate range', () => {
		let items = [8, 11, 5, 9, 7, 6, 3616];
		assert.isTrue(MathUtil.range(items) == 3611);
	});

	it('should calculate mode', () => {
		let items = [2, 10, 21, 23, 23, 38, 38, 4];
		let result = MathUtil.modes(items);
		assert.isTrue(result.length == 2);
		assert.isTrue(result.indexOf(23) >= 0 && result.indexOf(38) >= 0);
	});

});