/*******************************************************************************
 * Copyright 2011 See AUTHORS file.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 ******************************************************************************/

package com.badlogic.gdx.tests;

import com.badlogic.gdx.tests.utils.GdxTest;
import com.badlogic.gdx.utils.GdxRuntimeException;
import com.badlogic.gdx.utils.TimeUtils;

/** Test utility functions in TimeUtils.java
 * @author Jon Renner */
public class TimeUtilsTest extends GdxTest {
	final long oneMilliInNanos = 1000000;

	@Override
	public void create () {
		// test nanos -> millis -> nanos
		long now = TimeUtils.nanoTime();
		long nowConvertToMillis = TimeUtils.nanosToMillis(now);
		long nowConvertBackToNanos = TimeUtils.millisToNanos(nowConvertToMillis);

		assertEpsilonEqual(now, nowConvertBackToNanos, "Nano -> Millis conversion");

		// test millis -> nanos -> millis
		long millis = TimeUtils.millis();
		long millisToNanos = TimeUtils.millisToNanos(millis);
		long nanosToMillis = TimeUtils.nanosToMillis(millisToNanos);

		assertAbsoluteEqual(millis, nanosToMillis, "Millis -> Nanos conversion");

		// test comparison for 1 sec
		long oneSecondMillis = 1000;
		long oneSecondNanos = 1000000000;

		assertAbsoluteEqual(oneSecondMillis, TimeUtils.nanosToMillis(oneSecondNanos), "One Second Comparison, Nano -> Millis");
		assertAbsoluteEqual(TimeUtils.millisToNanos(oneSecondMillis), oneSecondNanos, "One Second Comparison, Millis -> Nanos");
	}

	@Override
	public void render () {

	}

	private void failTest (String testName) {
		throw new GdxRuntimeException("FAILED TEST: [" + testName + "]");
	}

	private void assertAbsoluteEqual (long a, long b, String testName) {
		// because of precision loss in conversion, epsilon = 1 ms worth of nanos
		System.out.println("Compare " + a + " to " + b);
		if (a != b) {
			failTest(testName + " - NOT EQUAL");
		} else {
			System.out.println("TEST PASSED: " + testName);
		}
	}

	private void assertEpsilonEqual (long a, long b, String testName) {
		System.out.println("Compare " + a + " to " + b);
		if (Math.abs(a - b) > oneMilliInNanos) {
			failTest(testName + " - NOT EQUAL");
		} else {
			System.out.println("TEST PASSED: " + testName);
		}
	}

}