content: /*
   * Copyright 2012-2019 the original author or authors.
   *
   * 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
   *
   *      https://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.springframework.boot.convert;
  
  import java.util.Arrays;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.Set;
  import java.util.stream.Stream;
  
  import org.springframework.core.CollectionFactory;
  import org.springframework.core.convert.ConversionService;
  import org.springframework.core.convert.TypeDescriptor;
  import org.springframework.core.convert.converter.ConditionalGenericConverter;
  import org.springframework.util.Assert;
  import org.springframework.util.StringUtils;
  
  /**
   * Converts a {@link Delimiter delimited} String to a Collection.
   *
   * @author Phillip Webb
   */
  final class DelimitedStringToCollectionConverter implements ConditionalGenericConverter {
  
  	private final ConversionService conversionService;
  
  	DelimitedStringToCollectionConverter(ConversionService conversionService) {
  		Assert.notNull(conversionService, "ConversionService must not be null");
  		this.conversionService = conversionService;
  	}
  
  	@Override
  	public Set<ConvertiblePair> getConvertibleTypes() {
  		return Collections.singleton(new ConvertiblePair(String.class, Collection.class));
  	}
  
  	@Override
  	public boolean matches(TypeDescriptor sourceType, TypeDescriptor targetType) {
  		return targetType.getElementTypeDescriptor() == null
  				|| this.conversionService.canConvert(sourceType, targetType.getElementTypeDescriptor());
  	}
  
  	@Override
  	public Object convert(Object source, TypeDescriptor sourceType, TypeDescriptor targetType) {
  		if (source == null) {
  			return null;
  		}
  		return convert((String) source, sourceType, targetType);
  	}
  
  	private Object convert(String source, TypeDescriptor sourceType, TypeDescriptor targetType) {
  		Delimiter delimiter = targetType.getAnnotation(Delimiter.class);
  		String[] elements = getElements(source, (delimiter != null) ? delimiter.value() : ",");
  		TypeDescriptor elementDescriptor = targetType.getElementTypeDescriptor();
  		Collection<Object> target = createCollection(targetType, elementDescriptor, elements.length);
  		Stream<Object> stream = Arrays.stream(elements).map(String::trim);
  		if (elementDescriptor != null) {
  			stream = stream.map((element) -> this.conversionService.convert(element, sourceType, elementDescriptor));
  		}
  		stream.forEach(target::add);
  		return target;
  	}
  
  	private Collection<Object> createCollection(TypeDescriptor targetType, TypeDescriptor elementDescriptor,
  			int length) {
  		return CollectionFactory.createCollection(targetType.getType(),
  				(elementDescriptor != null) ? elementDescriptor.getType() : null, length);
  	}
  
  	private String[] getElements(String source, String delimiter) {
  		return StringUtils.delimitedListToStringArray(source, Delimiter.NONE.equals(delimiter) ? null : delimiter);
  	}
  
  }
  