/**
 * Copyright (C) 2019 Adrien Hopkins
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */
package sevenUnits.utils;

import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertThrows;

import java.util.List;
import java.util.stream.IntStream;
import java.util.stream.Stream;

import org.junit.jupiter.params.ParameterizedTest;
import org.junit.jupiter.params.provider.Arguments;
import org.junit.jupiter.params.provider.MethodSource;

/**
 * A test for the {@code ExpressionParser} class. This is NOT part of this
 * program's public API.
 * 
 * @author Adrien Hopkins
 * @since 2019-03-22
 * @since v0.2.0
 */
class ExpressionParserTest {
	private static final ExpressionParser<Integer> numberParser = new ExpressionParser.Builder<>(
			Integer::parseInt).addBinaryOperator("+", (o1, o2) -> o1 + o2, 0)
			.addBinaryOperator("-", (o1, o2) -> o1 - o2, 0)
			.addUnaryOperator("neg", o1 -> -o1, 1)
			.addBinaryOperator("*", (o1, o2) -> o1 * o2, 2)
			.addBinaryOperator("/", (o1, o2) -> o1 / o2, 2)
			.addUnaryOperator("recip", o1 -> 1 / o1, 3)
			.addBinaryOperator("^", (o1, o2) -> (int) Math.pow(o1, o2), 4).build();

	/**
	 * The expressions used in the expression parsing tests
	 */
	private static final List<String> TEST_EXPRESSIONS = List.of(
			// test parsing of expressions
			"1 + 2 ^ 5 * 3", "(1 + 2) ^ 5 * 3",
			"12 * 5 + (3 ^ (2 * 3) - 72) / (3 + 3 * 2)",

			// ensure it normally goes from left to right
			"1 + 2 + 3 + 4", "12 - 4 - 3", "12 - (4 - 3)", "1 / 2 + 3");

	/**
	 * The expected results for evaluating these expressions
	 */
	private static final int[] RESULTS = { 97, 729, 133, 10, 5, 11, 3 };

	/**
	 * @return A stream of objects, where each one is an expression and the
	 *         expected result
	 * @since 2021-09-27
	 */
	private static final Stream<Arguments> testParseExpressionData() {
		return IntStream.range(0, TEST_EXPRESSIONS.size())
				.mapToObj(i -> Arguments.of(TEST_EXPRESSIONS.get(i), RESULTS[i]));
	}

	private static final Stream<Arguments> testConvertExpressionToRPN() {
		return Stream.of(Arguments.of("1 + 2 ^ 5 * 3", "1 2 5 ^ 3 * +"),
				Arguments.of("(1 + 2) ^ 5 * 3", "1 2 + 5 ^ 3 *"),
				Arguments.of("12 * 5 + (3 ^ (2 * 3) - 72) / (3 + 3 * 2)",
						"12 5 * 3 2 3 * ^ 72 - 3 3 2 * + / +"),
				Arguments.of("1 + 2 + 3 + 4", "1 2 + 3 + 4 +"),
				Arguments.of("12 - 4 - 3", "12 4 - 3 -"),
				Arguments.of("12 - (4 - 3)", "12 4 3 - -"),
				Arguments.of("1 / 2 + 3", "1 2 / 3 +"), Arguments.of("12", "12"),
				Arguments.of("2 * 3 + 4", "2 3 * 4 +"),
				Arguments.of("(2 * 3) + 4", "2 3 * 4 +"),
				Arguments.of("2 * 3 - 4", "2 3 * 4 -"),
				Arguments.of("(2 * 3) - 4", "2 3 * 4 -"),
				Arguments.of("2 * (3 + 4)", "2 3 4 + *"),
				Arguments.of("2 * (3 - 4)", "2 3 4 - *"),
				Arguments.of("neg 2", "2 neg"),
				Arguments.of("1 + neg 2", "1 2 neg +"));
	}

	private static final Stream<Arguments> testParseRPN() {
		return Stream.of(Arguments.of("1 2 5 ^ 3 * +", 97),
				Arguments.of("1 2 + 5 ^ 3 *", 729),
				Arguments.of("12 5 * 3 2 3 * ^ 72 - 3 3 2 * + / +", 133),
				Arguments.of("1 2 + 3 + 4 +", 10), Arguments.of("12 4 - 3 -", 5),
				Arguments.of("12 4 3 - -", 11), Arguments.of("1 2 / 3 +", 3),
				Arguments.of("12", 12), Arguments.of("2 3 * 4 +", 10),
				Arguments.of("2 3 * 4 -", 2), Arguments.of("2 3 4 + *", 14),
				Arguments.of("2 3 4 - *", -2), Arguments.of("2 neg", -2),
				Arguments.of("1 2 neg +", -1));
	}

	private static final Stream<String> testInvalidExpression() {
		return Stream.of("+", "1 +", "1 + * 2", "1 (+ 1)", "neg");
	}

	private static final Stream<String> testInvalidRPN() {
		return Stream.of("+", "1 +", "1 + * 2", "1 * 2", "1 2", "neg");
	}

	/**
	 * Test method for
	 * {@link sevenUnits.utils.ExpressionParser#parseExpression(java.lang.String)}.
	 */
	@ParameterizedTest
	@MethodSource("testParseExpressionData")
	public void testParseExpression(String expression, int value) {
		assertEquals(value, numberParser.parseExpression(expression));
	}

	@ParameterizedTest
	@MethodSource
	public void testConvertExpressionToRPN(String expression,
			String expectedRPN) {
		assertEquals(expectedRPN,
				numberParser.convertExpressionToReversePolish(expression));
	}

	@ParameterizedTest
	@MethodSource
	public void testInvalidExpression(String expression) {
		assertThrows(RuntimeException.class,
				() -> numberParser.convertExpressionToReversePolish(expression));
	}

	@ParameterizedTest
	@MethodSource
	public void testParseRPN(String expressionRPN, int value) {
		assertEquals(value,
				numberParser.parseReversePolishExpression(expressionRPN));
	}

	@ParameterizedTest
	@MethodSource
	public void testInvalidRPN(String expressionRPN) {
		assertThrows(RuntimeException.class,
				() -> numberParser.parseReversePolishExpression(expressionRPN));
	}
}