001package ezvcard.util;
002
003import java.lang.reflect.Field;
004import java.lang.reflect.Modifier;
005import java.util.Arrays;
006
007import ezvcard.SupportedVersions;
008import ezvcard.VCardVersion;
009
010/*
011 Copyright (c) 2012-2026, Michael Angstadt
012 All rights reserved.
013
014 Redistribution and use in source and binary forms, with or without
015 modification, are permitted provided that the following conditions are met: 
016
017 1. Redistributions of source code must retain the above copyright notice, this
018 list of conditions and the following disclaimer. 
019 2. Redistributions in binary form must reproduce the above copyright notice,
020 this list of conditions and the following disclaimer in the documentation
021 and/or other materials provided with the distribution. 
022
023 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
024 ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
025 WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
026 DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
027 ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
028 (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
029 LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
030 ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
031 (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
032 SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
033
034 The views and conclusions contained in the software and documentation are those
035 of the authors and should not be interpreted as representing official policies, 
036 either expressed or implied, of the FreeBSD Project.
037 */
038
039/**
040 * Provides methods for getting the value of the {@link SupportedVersions}
041 * annotation for "public static" fields.
042 * @author Michael Angstadt
043 */
044public class SupportedVersionsHelper {
045        /**
046         * Gets the vCard versions that are defined by the given object's
047         * {@link SupportedVersions} annotation.
048         * @param obj the object, must be "public static"
049         * @return the versions in the annotation, all versions if the annotation is
050         * not present, or all versions if the object is not a public static field
051         * of its class
052         */
053        public static VCardVersion[] getSupportedVersions(Object obj) {
054                //@formatter:off
055                return Arrays.stream(obj.getClass().getFields())
056                        .filter(SupportedVersionsHelper::isFieldStatic)
057                        .filter(field -> isFieldMe(field, obj))
058                        .map(field -> field.getAnnotation(SupportedVersions.class))
059                        .map(annotation -> (annotation == null) ? VCardVersion.values() : annotation.value())
060                .findFirst().orElseGet(VCardVersion::values);
061                //@formatter:on
062        }
063
064        private static boolean isFieldStatic(Field field) {
065                return Modifier.isStatic(field.getModifiers());
066        }
067
068        private static boolean isFieldMe(Field field, Object obj) {
069                Object fieldValue;
070                try {
071                        fieldValue = field.get(null);
072                } catch (IllegalArgumentException e) {
073                        //should never be thrown because we check for the static modified
074                        return false;
075                } catch (IllegalAccessException e) {
076                        //if the field is not accessible
077                        return false;
078                }
079
080                return fieldValue == obj;
081        }
082
083        /**
084         * Determines if this object is supported by the given vCard version. Uses
085         * the object's {@link SupportedVersions} annotation.
086         * @param version the vCard version
087         * @param obj the object
088         * @return true if it is supported, false if not
089         */
090        public static boolean isSupportedBy(VCardVersion version, Object obj) {
091                return Arrays.stream(getSupportedVersions(obj)).anyMatch(supportedVersion -> supportedVersion == version);
092        }
093
094        private SupportedVersionsHelper() {
095                //hide
096        }
097}