/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.commons.lang3.math;

import org.apache.commons.lang3.Validate;

/**
 * <p>
 * Provides IEEE-754r variants of NumberUtils methods.
 * </p>
 *
 * <p>
 * See: <a href=
 * "http://en.wikipedia.org/wiki/IEEE_754r">http://en.wikipedia.org/wiki/IEEE_754r</a>
 * </p>
 *
 * @since 2.4
 */
public class IEEE754rUtils {

	/**
	 * <p>
	 * Returns the minimum value in an array.
	 * </p>
	 *
	 * @param array an array, must not be null or empty
	 * @return the minimum value in the array
	 * @throws NullPointerException     if {@code array} is {@code null}
	 * @throws IllegalArgumentException if {@code array} is empty
	 * @since 3.4 Changed signature from min(double[]) to min(double...)
	 */
	public static double min(final double... array) {
		Validate.notNull(array, "array");
		Validate.isTrue(array.length != 0, "Array cannot be empty.");

		// Finds and returns min
		double min = array[0];
		for (int i = 1; i < array.length; i++) {
			min = min(array[i], min);
		}

		return min;
	}

	/**
	 * <p>
	 * Returns the minimum value in an array.
	 * </p>
	 *
	 * @param array an array, must not be null or empty
	 * @return the minimum value in the array
	 * @throws NullPointerException     if {@code array} is {@code null}
	 * @throws IllegalArgumentException if {@code array} is empty
	 * @since 3.4 Changed signature from min(float[]) to min(float...)
	 */
	public static float min(final float... array) {
		Validate.notNull(array, "array");
		Validate.isTrue(array.length != 0, "Array cannot be empty.");

		// Finds and returns min
		float min = array[0];
		for (int i = 1; i < array.length; i++) {
			min = min(array[i], min);
		}

		return min;
	}

	/**
	 * <p>
	 * Gets the minimum of three {@code double} values.
	 * </p>
	 *
	 * <p>
	 * NaN is only returned if all numbers are NaN as per IEEE-754r.
	 * </p>
	 *
	 * @param a value 1
	 * @param b value 2
	 * @param c value 3
	 * @return the smallest of the values
	 */
	public static double min(final double a, final double b, final double c) {
		return min(min(a, b), c);
	}

	/**
	 * <p>
	 * Gets the minimum of two {@code double} values.
	 * </p>
	 *
	 * <p>
	 * NaN is only returned if all numbers are NaN as per IEEE-754r.
	 * </p>
	 *
	 * @param a value 1
	 * @param b value 2
	 * @return the smallest of the values
	 */
	public static double min(final double a, final double b) {
		if (Double.isNaN(a)) {
			return b;
		} else if (Double.isNaN(b)) {
			return a;
		} else {
			return Math.min(a, b);
		}
	}

	/**
	 * <p>
	 * Gets the minimum of three {@code float} values.
	 * </p>
	 *
	 * <p>
	 * NaN is only returned if all numbers are NaN as per IEEE-754r.
	 * </p>
	 *
	 * @param a value 1
	 * @param b value 2
	 * @param c value 3
	 * @return the smallest of the values
	 */
	public static float min(final float a, final float b, final float c) {
		return min(min(a, b), c);
	}

	/**
	 * <p>
	 * Gets the minimum of two {@code float} values.
	 * </p>
	 *
	 * <p>
	 * NaN is only returned if all numbers are NaN as per IEEE-754r.
	 * </p>
	 *
	 * @param a value 1
	 * @param b value 2
	 * @return the smallest of the values
	 */
	public static float min(final float a, final float b) {
		if (Float.isNaN(a)) {
			return b;
		} else if (Float.isNaN(b)) {
			return a;
		} else {
			return Math.min(a, b);
		}
	}

	/**
	 * <p>
	 * Returns the maximum value in an array.
	 * </p>
	 *
	 * @param array an array, must not be null or empty
	 * @return the minimum value in the array
	 * @throws NullPointerException     if {@code array} is {@code null}
	 * @throws IllegalArgumentException if {@code array} is empty
	 * @since 3.4 Changed signature from max(double[]) to max(double...)
	 */
	public static double max(final double... array) {
		Validate.notNull(array, "array");
		Validate.isTrue(array.length != 0, "Array cannot be empty.");

		// Finds and returns max
		double max = array[0];
		for (int j = 1; j < array.length; j++) {
			max = max(array[j], max);
		}

		return max;
	}

	/**
	 * <p>
	 * Returns the maximum value in an array.
	 * </p>
	 *
	 * @param array an array, must not be null or empty
	 * @return the minimum value in the array
	 * @throws NullPointerException     if {@code array} is {@code null}
	 * @throws IllegalArgumentException if {@code array} is empty
	 * @since 3.4 Changed signature from max(float[]) to max(float...)
	 */
	public static float max(final float... array) {
		Validate.notNull(array, "array");
		Validate.isTrue(array.length != 0, "Array cannot be empty.");

		// Finds and returns max
		float max = array[0];
		for (int j = 1; j < array.length; j++) {
			max = max(array[j], max);
		}

		return max;
	}

	/**
	 * <p>
	 * Gets the maximum of three {@code double} values.
	 * </p>
	 *
	 * <p>
	 * NaN is only returned if all numbers are NaN as per IEEE-754r.
	 * </p>
	 *
	 * @param a value 1
	 * @param b value 2
	 * @param c value 3
	 * @return the largest of the values
	 */
	public static double max(final double a, final double b, final double c) {
		return max(max(a, b), c);
	}

	/**
	 * <p>
	 * Gets the maximum of two {@code double} values.
	 * </p>
	 *
	 * <p>
	 * NaN is only returned if all numbers are NaN as per IEEE-754r.
	 * </p>
	 *
	 * @param a value 1
	 * @param b value 2
	 * @return the largest of the values
	 */
	public static double max(final double a, final double b) {
		if (Double.isNaN(a)) {
			return b;
		} else if (Double.isNaN(b)) {
			return a;
		} else {
			return Math.max(a, b);
		}
	}

	/**
	 * <p>
	 * Gets the maximum of three {@code float} values.
	 * </p>
	 *
	 * <p>
	 * NaN is only returned if all numbers are NaN as per IEEE-754r.
	 * </p>
	 *
	 * @param a value 1
	 * @param b value 2
	 * @param c value 3
	 * @return the largest of the values
	 */
	public static float max(final float a, final float b, final float c) {
		return max(max(a, b), c);
	}

	/**
	 * <p>
	 * Gets the maximum of two {@code float} values.
	 * </p>
	 *
	 * <p>
	 * NaN is only returned if all numbers are NaN as per IEEE-754r.
	 * </p>
	 *
	 * @param a value 1
	 * @param b value 2
	 * @return the largest of the values
	 */
	public static float max(final float a, final float b) {
		if (Float.isNaN(a)) {
			return b;
		} else if (Float.isNaN(b)) {
			return a;
		} else {
			return Math.max(a, b);
		}
	}

}
