/*
 * 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;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

/**
 * <p>
 * Utility library to provide helper methods for Java enums.
 * </p>
 *
 * <p>
 * #ThreadSafe#
 * </p>
 *
 * @since 3.0
 */
public class EnumUtils {

	private static final String NULL_ELEMENTS_NOT_PERMITTED = "null elements not permitted";
	private static final String CANNOT_STORE_S_S_VALUES_IN_S_BITS = "Cannot store %s %s values in %s bits";
	private static final String S_DOES_NOT_SEEM_TO_BE_AN_ENUM_TYPE = "%s does not seem to be an Enum type";
	private static final String ENUM_CLASS_MUST_BE_DEFINED = "EnumClass must be defined.";

	/**
	 * Validate {@code enumClass}.
	 * 
	 * @param <E>       the type of the enumeration
	 * @param enumClass to check
	 * @return {@code enumClass}
	 * @throws NullPointerException     if {@code enumClass} is {@code null}
	 * @throws IllegalArgumentException if {@code enumClass} is not an enum class
	 * @since 3.2
	 */
	private static <E extends Enum<E>> Class<E> asEnum(final Class<E> enumClass) {
		Validate.notNull(enumClass, ENUM_CLASS_MUST_BE_DEFINED);
		Validate.isTrue(enumClass.isEnum(), S_DOES_NOT_SEEM_TO_BE_AN_ENUM_TYPE, enumClass);
		return enumClass;
	}

	/**
	 * Validate that {@code enumClass} is compatible with representation in a
	 * {@code long}.
	 * 
	 * @param <E>       the type of the enumeration
	 * @param enumClass to check
	 * @return {@code enumClass}
	 * @throws NullPointerException     if {@code enumClass} is {@code null}
	 * @throws IllegalArgumentException if {@code enumClass} is not an enum class or
	 *                                  has more than 64 values
	 * @since 3.0.1
	 */
	private static <E extends Enum<E>> Class<E> checkBitVectorable(final Class<E> enumClass) {
		final E[] constants = asEnum(enumClass).getEnumConstants();
		Validate.isTrue(constants.length <= Long.SIZE, CANNOT_STORE_S_S_VALUES_IN_S_BITS,
				Integer.valueOf(constants.length), enumClass.getSimpleName(), Integer.valueOf(Long.SIZE));

		return enumClass;
	}

	/**
	 * <p>
	 * Creates a long bit vector representation of the given array of Enum values.
	 * </p>
	 *
	 * <p>
	 * This generates a value that is usable by {@link EnumUtils#processBitVector}.
	 * </p>
	 *
	 * <p>
	 * Do not use this method if you have more than 64 values in your Enum, as this
	 * would create a value greater than a long can hold.
	 * </p>
	 *
	 * @param enumClass the class of the enum we are working with, not {@code null}
	 * @param values    the values we want to convert, not {@code null}
	 * @param <E>       the type of the enumeration
	 * @return a long whose value provides a binary representation of the given set
	 *         of enum values.
	 * @throws NullPointerException     if {@code enumClass} or {@code values} is
	 *                                  {@code null}
	 * @throws IllegalArgumentException if {@code enumClass} is not an enum class or
	 *                                  has more than 64 values
	 * @since 3.0.1
	 * @see #generateBitVectors(Class, Iterable)
	 */
	@SafeVarargs
	public static <E extends Enum<E>> long generateBitVector(final Class<E> enumClass, final E... values) {
		Validate.noNullElements(values);
		return generateBitVector(enumClass, Arrays.asList(values));
	}

	/**
	 * <p>
	 * Creates a long bit vector representation of the given subset of an Enum.
	 * </p>
	 *
	 * <p>
	 * This generates a value that is usable by {@link EnumUtils#processBitVector}.
	 * </p>
	 *
	 * <p>
	 * Do not use this method if you have more than 64 values in your Enum, as this
	 * would create a value greater than a long can hold.
	 * </p>
	 *
	 * @param enumClass the class of the enum we are working with, not {@code null}
	 * @param values    the values we want to convert, not {@code null}, neither
	 *                  containing {@code null}
	 * @param <E>       the type of the enumeration
	 * @return a long whose value provides a binary representation of the given set
	 *         of enum values.
	 * @throws NullPointerException     if {@code enumClass} or {@code values} is
	 *                                  {@code null}
	 * @throws IllegalArgumentException if {@code enumClass} is not an enum class or
	 *                                  has more than 64 values, or if any
	 *                                  {@code values} {@code null}
	 * @since 3.0.1
	 * @see #generateBitVectors(Class, Iterable)
	 */
	public static <E extends Enum<E>> long generateBitVector(final Class<E> enumClass,
			final Iterable<? extends E> values) {
		checkBitVectorable(enumClass);
		Validate.notNull(values);
		long total = 0;
		for (final E constant : values) {
			Validate.notNull(constant, NULL_ELEMENTS_NOT_PERMITTED);
			total |= 1L << constant.ordinal();
		}
		return total;
	}

	/**
	 * <p>
	 * Gets the enum for the class, returning {@code null} if not found.
	 * </p>
	 *
	 * <p>
	 * This method differs from {@link Enum#valueOf} in that it does not throw an
	 * exception for an invalid enum name.
	 * </p>
	 *
	 * @param <E>       the type of the enumeration
	 * @param enumClass the class of the enum to query, not null
	 * @param enumName  the enum name, null returns null
	 * @return the enum, null if not found
	 */
	public static <E extends Enum<E>> E getEnum(final Class<E> enumClass, final String enumName) {
		return getEnum(enumClass, enumName, null);
	}

	/**
	 * <p>
	 * Gets the enum for the class, returning {@code defaultEnum} if not found.
	 * </p>
	 *
	 * <p>
	 * This method differs from {@link Enum#valueOf} in that it does not throw an
	 * exception for an invalid enum name.
	 * </p>
	 *
	 * @param <E>         the type of the enumeration
	 * @param enumClass   the class of the enum to query, not null
	 * @param enumName    the enum name, null returns default enum
	 * @param defaultEnum the default enum
	 * @return the enum, default enum if not found
	 * @since 3.10
	 */
	public static <E extends Enum<E>> E getEnum(final Class<E> enumClass, final String enumName, final E defaultEnum) {
		if (enumName == null) {
			return defaultEnum;
		}
		try {
			return Enum.valueOf(enumClass, enumName);
		} catch (final IllegalArgumentException ex) {
			return defaultEnum;
		}
	}

	/**
	 * <p>
	 * Gets the enum for the class, returning {@code null} if not found.
	 * </p>
	 *
	 * <p>
	 * This method differs from {@link Enum#valueOf} in that it does not throw an
	 * exception for an invalid enum name and performs case insensitive matching of
	 * the name.
	 * </p>
	 *
	 * @param <E>       the type of the enumeration
	 * @param enumClass the class of the enum to query, not null
	 * @param enumName  the enum name, null returns null
	 * @return the enum, null if not found
	 * @since 3.8
	 */
	public static <E extends Enum<E>> E getEnumIgnoreCase(final Class<E> enumClass, final String enumName) {
		return getEnumIgnoreCase(enumClass, enumName, null);
	}

	/**
	 * <p>
	 * Gets the enum for the class, returning {@code defaultEnum} if not found.
	 * </p>
	 *
	 * <p>
	 * This method differs from {@link Enum#valueOf} in that it does not throw an
	 * exception for an invalid enum name and performs case insensitive matching of
	 * the name.
	 * </p>
	 *
	 * @param <E>         the type of the enumeration
	 * @param enumClass   the class of the enum to query, not null
	 * @param enumName    the enum name, null returns default enum
	 * @param defaultEnum the default enum
	 * @return the enum, default enum if not found
	 * @since 3.10
	 */
	public static <E extends Enum<E>> E getEnumIgnoreCase(final Class<E> enumClass, final String enumName,
			final E defaultEnum) {
		if (enumName == null || !enumClass.isEnum()) {
			return defaultEnum;
		}
		for (final E each : enumClass.getEnumConstants()) {
			if (each.name().equalsIgnoreCase(enumName)) {
				return each;
			}
		}
		return defaultEnum;
	}

	/**
	 * <p>
	 * Gets the {@code List} of enums.
	 * </p>
	 *
	 * <p>
	 * This method is useful when you need a list of enums rather than an array.
	 * </p>
	 *
	 * @param <E>       the type of the enumeration
	 * @param enumClass the class of the enum to query, not null
	 * @return the modifiable list of enums, never null
	 */
	public static <E extends Enum<E>> List<E> getEnumList(final Class<E> enumClass) {
		return new ArrayList<>(Arrays.asList(enumClass.getEnumConstants()));
	}

	/**
	 * <p>
	 * Gets the {@code Map} of enums by name.
	 * </p>
	 *
	 * <p>
	 * This method is useful when you need a map of enums by name.
	 * </p>
	 *
	 * @param <E>       the type of the enumeration
	 * @param enumClass the class of the enum to query, not null
	 * @return the modifiable map of enum names to enums, never null
	 */
	public static <E extends Enum<E>> Map<String, E> getEnumMap(final Class<E> enumClass) {
		final Map<String, E> map = new LinkedHashMap<>();
		for (final E e : enumClass.getEnumConstants()) {
			map.put(e.name(), e);
		}
		return map;
	}

	/**
	 * <p>
	 * Checks if the specified name is a valid enum for the class.
	 * </p>
	 *
	 * <p>
	 * This method differs from {@link Enum#valueOf} in that checks if the name is a
	 * valid enum without needing to catch the exception.
	 * </p>
	 *
	 * @param <E>       the type of the enumeration
	 * @param enumClass the class of the enum to query, not null
	 * @param enumName  the enum name, null returns false
	 * @return true if the enum name is valid, otherwise false
	 */
	public static <E extends Enum<E>> boolean isValidEnum(final Class<E> enumClass, final String enumName) {
		return getEnum(enumClass, enumName) != null;
	}

	/**
	 * <p>
	 * Checks if the specified name is a valid enum for the class.
	 * </p>
	 *
	 * <p>
	 * This method differs from {@link Enum#valueOf} in that checks if the name is a
	 * valid enum without needing to catch the exception and performs case
	 * insensitive matching of the name.
	 * </p>
	 *
	 * @param <E>       the type of the enumeration
	 * @param enumClass the class of the enum to query, not null
	 * @param enumName  the enum name, null returns false
	 * @return true if the enum name is valid, otherwise false
	 * @since 3.8
	 */
	public static <E extends Enum<E>> boolean isValidEnumIgnoreCase(final Class<E> enumClass, final String enumName) {
		return getEnumIgnoreCase(enumClass, enumName) != null;
	}

	/**
	 * This constructor is public to permit tools that require a JavaBean instance
	 * to operate.
	 */
	public EnumUtils() {
	}
}