package edu.neu.ccs.evergreen.util;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.fail;

import org.junit.Test;

/**
 * Test the polynomial class.
 */
public class PolynomialTest {
	/**
	 * Multiple two polynomials.
	 */
	@Test
	public void testMultiply() {
		Polynomial result = Polynomial.getPolynomial(3, 1).multiply(2);
		assertEquals(2.0, result.getCoefficient(3), Polynomial.DELTA);
		assertEquals(-4.0, result.getCoefficient(2), Polynomial.DELTA);
		assertEquals(2.0, result.getCoefficient(1), Polynomial.DELTA);
		assertEquals(0.0, result.getCoefficient(0), Polynomial.DELTA);
	}

	/**
	 * Add two polynomials.
	 */
	@Test
	public void testAdd() {
		Polynomial result = Polynomial.getPolynomial(3, 1).add(
				Polynomial.getPolynomial(2, 0));
		assertEquals(1.0, result.getCoefficient(3), Polynomial.DELTA);
		assertEquals(-1.0, result.getCoefficient(2), Polynomial.DELTA);
		assertEquals(-1.0, result.getCoefficient(1), Polynomial.DELTA);
		assertEquals(1.0, result.getCoefficient(0), Polynomial.DELTA);
	}

	/**
	 * Differentiate a polynomial.
	 */
	@Test
	public void testDifferentiate() {
		Polynomial result = Polynomial.getPolynomial(3, 0).differentiate();
		assertEquals(0.0, result.getCoefficient(3), Polynomial.DELTA);
		assertEquals(-3.0, result.getCoefficient(2), Polynomial.DELTA);
		assertEquals(6.0, result.getCoefficient(1), Polynomial.DELTA);
		assertEquals(-3.0, result.getCoefficient(0), Polynomial.DELTA);
		result = result.differentiate();
		assertEquals(0.0, result.getCoefficient(3), Polynomial.DELTA);
		assertEquals(0.0, result.getCoefficient(2), Polynomial.DELTA);
		assertEquals(-6.0, result.getCoefficient(1), Polynomial.DELTA);
		assertEquals(6.0, result.getCoefficient(0), Polynomial.DELTA);
	}

	/**
	 * Get polynomial coefficients.
	 */
	@Test
	public void testGetCoefficients() {
		Polynomial polynomial = Polynomial.getPolynomial(2, 1);
		assertEquals(0.0, polynomial.getCoefficient(3), Polynomial.DELTA);
		assertEquals(-1.0, polynomial.getCoefficient(2), Polynomial.DELTA);
		assertEquals(1.0, polynomial.getCoefficient(1), Polynomial.DELTA);
		assertEquals(0.0, polynomial.getCoefficient(0), Polynomial.DELTA);

		try {
			Polynomial.getPolynomial(1, 2);
			fail("No Error");
		} catch (IllegalArgumentException exception) {

		}
	}

	/**
	 * Solve the polynomial for 0.
	 */
	@Test
	public void testSolve0() {
		try {
			new Polynomial(0, 0, 0, 1).solve0();
			fail("No Error");
		} catch (UnsupportedOperationException exception) {

		}
		Polynomial polynomial = new Polynomial(0, 0, 1, 0);
		double results[] = polynomial.solve0();
		assertEquals(1, results.length);
		assertEquals(0.0, results[0], Polynomial.DELTA);

		polynomial = new Polynomial(0, 0, -2, 2);
		results = polynomial.solve0();
		assertEquals(1, results.length, Polynomial.DELTA);
		assertEquals(1.0, results[0], Polynomial.DELTA);

		polynomial = new Polynomial(0, -3, 6, -3);
		results = polynomial.solve0();
		assertEquals(2, results.length);
		assertEquals(1.0, results[0], Polynomial.DELTA);
		assertEquals(1.0, results[1], Polynomial.DELTA);

		polynomial = new Polynomial(0, 3, -4, 1);
		results = polynomial.solve0();
		assertEquals(2, results.length);
		assertEquals(1.0, results[0], Polynomial.DELTA);
		assertEquals(1.0 / 3.0, results[1], Polynomial.DELTA);

		polynomial = new Polynomial(0, 2, 1, 2);
		results = polynomial.solve0();
		assertEquals(0, results.length);

		try {
			new Polynomial(1, 1, 1, 1).solve0();
			fail("No Error");
		} catch (UnsupportedOperationException exception) {

		}
	}

	/**
	 * Evaluate the polynomial.
	 */
	@Test
	public void testEval() {
		Polynomial polynomial = new Polynomial(0, 0, 0, 1);
		assertEquals(1.0, polynomial.eval(0), Polynomial.DELTA);
		assertEquals(1.0, polynomial.eval(1), Polynomial.DELTA);

		polynomial = new Polynomial(0, 0, 2, 1);
		assertEquals(1.0, polynomial.eval(0), Polynomial.DELTA);
		assertEquals(3.0, polynomial.eval(1), Polynomial.DELTA);
		assertEquals(7.0, polynomial.eval(3), Polynomial.DELTA);
		assertEquals(-3.0, polynomial.eval(-2), Polynomial.DELTA);

		polynomial = new Polynomial(0, -3, 2, 1);
		assertEquals(1.0, polynomial.eval(0), Polynomial.DELTA);
		assertEquals(0.0, polynomial.eval(1), Polynomial.DELTA);
		assertEquals(-20.0, polynomial.eval(3), Polynomial.DELTA);
		assertEquals(-15.0, polynomial.eval(-2), Polynomial.DELTA);

		polynomial = new Polynomial(1, -3, 2, 1);
		assertEquals(1.0, polynomial.eval(0), Polynomial.DELTA);
		assertEquals(1.0, polynomial.eval(1), Polynomial.DELTA);
		assertEquals(7.0, polynomial.eval(3), Polynomial.DELTA);
		assertEquals(-23.0, polynomial.eval(-2), Polynomial.DELTA);
	}
}