cdi-extender/src/main/java/org/apache/aries/cdi/container/internal/util/Maps.java

/**
 * 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 org.apache.aries.cdi.container.internal.util;

import static java.util.Collections.list;
import static java.util.Objects.requireNonNull;

import java.lang.annotation.Annotation;
import java.util.AbstractMap;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Dictionary;
import java.util.HashMap;
import java.util.Hashtable;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.stream.Collectors;
import java.util.stream.Stream;

import org.osgi.service.cdi.annotations.BeanPropertyType;
import org.osgi.util.converter.TypeReference;

public class Maps {

	private Maps() {
		// no instances
	}

	public static void appendFilter(StringBuilder sb, Map<String, String> map) {
		if (map.isEmpty()) {
			return;
		}

		for (Map.Entry<String, String> entry : map.entrySet()) {
			sb.append("(");
			sb.append(entry.getKey());
			sb.append("=");
			sb.append(entry.getValue());
			sb.append(")");
		}
	}

	public static <T> Stream<Map.Entry<String, T>> streamOf(Dictionary<String, T> dictionary) {
		return list(dictionary.keys()).stream().map(key -> new AbstractMap.SimpleEntry<>(key, dictionary.get(key)));
	}

	public static Map<String, Object> of(Dictionary<String, ?> dict) {
		Map<String, Object> map = new HashMap<>();

		streamOf(dict).forEach(e -> map.put(e.getKey(), e.getValue()));

		return map;
	}

	public static Dictionary<String, ?> dict(Map<String, Object> map) {
		Dictionary<String, Object> dict = new Hashtable<>();

		requireNonNull(map).forEach(dict::put);

		return dict;
	}

	public static Dictionary<String, ?> dict(Object... args) {
		Dictionary<String, Object> map = new Hashtable<>();

		if ((args.length % 2) != 0) throw new IllegalArgumentException("requires even number of args");

		for (int i = 0; i < args.length; i+=2) {
			map.put(String.valueOf(args[i]), args[i+1]);
		}

		return map;
	}

	@SafeVarargs
	public static <T> Map<String, T> of(T... args) {
		Map<String, T> map = new HashMap<>();

		if ((args.length % 2) != 0) throw new IllegalArgumentException("requires even number of args");

		for (int i = 0; i < args.length; i+=2) {
			map.put(String.valueOf(args[i]), args[i+1]);
		}

		return map;
	}

	public static Map<String, Object> merge(Collection<Annotation> annotations) {
		return merge(annotations.stream().filter(
			ann -> Objects.nonNull(ann.annotationType().getAnnotation(BeanPropertyType.class))
		).map(
			ann -> Conversions.convert(ann).sourceAs(ann.annotationType()).to(new TypeReference<Map<String, Object>>() {})
		).map(Map::entrySet).flatMap(Collection::stream));
	}

	public static Map<String, Object> merge(Stream<Map.Entry<String, Object>> mapEntries) {
		return mapEntries.collect(
			Collectors.toMap(
				Map.Entry::getKey,
				Map.Entry::getValue,
				Maps::mergeValues
			)
		);
	}

	@SuppressWarnings("unchecked")
	public static List<?> mergeValues(Object a, Object b) {
		List<?> aList = Conversions.convert(a).to(new TypeReference<List<?>>() {});
		List<?> bList = Conversions.convert(b).to(new TypeReference<List<?>>() {});
		@SuppressWarnings({ "rawtypes" })
		List checkedList = Collections.checkedList(new ArrayList(), aList.get(0).getClass());
		checkedList.addAll(aList);
		checkedList.addAll(bList);
		return checkedList;
	}

}