/*

  * 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.Collections;

 import java.util.EnumSet;

 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

  * @version $Id: EnumUtils.java 1436770 2013-01-22 07:09:45Z ggregory $

  */

 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.";

     /**

      * This constructor is public to permit tools that require a JavaBean

      * instance to operate.

      */

     public EnumUtils() {

     }

     /**

      * <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<String, E>();

         for (final E e: enumClass.getEnumConstants()) {

             map.put(e.name(), e);

         }

         return map;

     }

     /**

      * <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<E>(Arrays.asList(enumClass.getEnumConstants()));

     }

     /**

      * <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) {

         if (enumName == null) {

             return false;

         }

         try {

             Enum.valueOf(enumClass, enumName);

             return true;

         } catch (final IllegalArgumentException ex) {

             return false;

         }

     }

     /**

      * <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) {

         if (enumName == null) {

             return null;

         }

         try {

             return Enum.valueOf(enumClass, enumName);

         } catch (final IllegalArgumentException ex) {

             return null;

         }

     }

     /**

      * <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<E> values) {

         checkBitVectorable(enumClass);

         Validate.notNull(values);

         long total = 0;

         for (final E constant : values) {

             Validate.isTrue(constant != null, NULL_ELEMENTS_NOT_PERMITTED);

             total |= 1 << constant.ordinal();

         }

         return total;

     }

     /**

      * <p>Creates a bit vector representation of the given subset of an Enum using as many {@code long}s as needed.</p>

      *

      * <p>This generates a value that is usable by {@link EnumUtils#processBitVectors}.</p>

      *

      * <p>Use this method if you have more than 64 values in your Enum.</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 values provide a binary representation of the given set of enum values

      *         with least significant digits rightmost.

      * @throws NullPointerException if {@code enumClass} or {@code values} is {@code null}

      * @throws IllegalArgumentException if {@code enumClass} is not an enum class, or if any {@code values} {@code null}

      * @since 3.2

      */

     public static <E extends Enum<E>> long[] generateBitVectors(final Class<E> enumClass, final Iterable<E> values) {

         asEnum(enumClass);

         Validate.notNull(values);

         final EnumSet<E> condensed = EnumSet.noneOf(enumClass);

         for (final E constant : values) {

             Validate.isTrue(constant != null, NULL_ELEMENTS_NOT_PERMITTED);

             condensed.add(constant);

         }

         final long[] result = new long[(enumClass.getEnumConstants().length - 1) / Long.SIZE + 1];

         for (final E value : condensed) {

             result[value.ordinal() / Long.SIZE] |= 1 << (value.ordinal() % Long.SIZE);

         }

         ArrayUtils.reverse(result);

         return result;

     }

     /**

      * <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)

      */

     public static <E extends Enum<E>> long generateBitVector(final Class<E> enumClass, final E... values) {

         Validate.noNullElements(values);

         return generateBitVector(enumClass, Arrays.<E> asList(values));

     }

     /**

      * <p>Creates a bit vector representation of the given subset of an Enum using as many {@code long}s as needed.</p>

      *

      * <p>This generates a value that is usable by {@link EnumUtils#processBitVectors}.</p>

      *

      * <p>Use this method if you have more than 64 values in your Enum.</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 values provide a binary representation of the given set of enum values

      *         with least significant digits rightmost.

      * @throws NullPointerException if {@code enumClass} or {@code values} is {@code null}

      * @throws IllegalArgumentException if {@code enumClass} is not an enum class, or if any {@code values} {@code null}

      * @since 3.2

      */

     public static <E extends Enum<E>> long[] generateBitVectors(final Class<E> enumClass, final E... values) {

         asEnum(enumClass);

         Validate.noNullElements(values);

         final EnumSet<E> condensed = EnumSet.noneOf(enumClass);

         Collections.addAll(condensed, values);

         final long[] result = new long[(enumClass.getEnumConstants().length - 1) / Long.SIZE + 1];

         for (final E value : condensed) {

             result[value.ordinal() / Long.SIZE] |= 1 << (value.ordinal() % Long.SIZE);

         }

         ArrayUtils.reverse(result);

         return result;

     }

     /**

      * <p>Convert a long value created by {@link EnumUtils#generateBitVector} into the set of

      * enum values that it represents.</p>

      *

      * <p>If you store this value, beware any changes to the enum that would affect ordinal values.</p>

      * @param enumClass the class of the enum we are working with, not {@code null}

      * @param value     the long value representation of a set of enum values

      * @param <E>       the type of the enumeration

      * @return a set of enum values

      * @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

      */

     public static <E extends Enum<E>> EnumSet<E> processBitVector(final Class<E> enumClass, final long value) {

         checkBitVectorable(enumClass).getEnumConstants();

         return processBitVectors(enumClass, value);

     }

     /**

      * <p>Convert a {@code long[]} created by {@link EnumUtils#generateBitVectors} into the set of

      * enum values that it represents.</p>

      *

      * <p>If you store this value, beware any changes to the enum that would affect ordinal values.</p>

      * @param enumClass the class of the enum we are working with, not {@code null}

      * @param values     the long[] bearing the representation of a set of enum values, least significant digits rightmost, not {@code null}

      * @param <E>       the type of the enumeration

      * @return a set of enum values

      * @throws NullPointerException if {@code enumClass} is {@code null}

      * @throws IllegalArgumentException if {@code enumClass} is not an enum class

      * @since 3.2

      */

     public static <E extends Enum<E>> EnumSet<E> processBitVectors(final Class<E> enumClass, long... values) {

         final EnumSet<E> results = EnumSet.noneOf(asEnum(enumClass));

         values = ArrayUtils.clone(Validate.notNull(values));

         ArrayUtils.reverse(values);

         for (final E constant : enumClass.getEnumConstants()) {

             final int block = constant.ordinal() / Long.SIZE;

             if (block < values.length && (values[block] & 1 << (constant.ordinal() % Long.SIZE)) != 0) {

                 results.add(constant);

             }

         }

         return results;

     }

     /**

      * 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, constants.length,

             enumClass.getSimpleName(), Long.SIZE);

         return enumClass;

     }

     /**

      * 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;

     }

 }