/*
 * Copyright 2002-2018 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
 *
 *      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.springframework.ui;

import java.util.Collection;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

import org.springframework.core.Conventions;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;

Implementation of the Model interface based on a ConcurrentHashMap for use in concurrent scenarios. 
Exposed to handler methods by Spring WebFlux, typically via a declaration of the Model interface. There is typically no need to create it within user code. If necessary a handler method can return a regular java.util.Map, likely a java.util.ConcurrentMap, for a pre-determined model. 
Author:
Rossen Stoyanchev
Since:
5.0/**
 * Implementation of the {@link Model} interface based on a {@link ConcurrentHashMap}
 * for use in concurrent scenarios.
 *
 * <p>Exposed to handler methods by Spring WebFlux, typically via a declaration of the
 * {@link Model} interface. There is typically no need to create it within user code.
 * If necessary a handler method can return a regular {@code java.util.Map},
 * likely a {@code java.util.ConcurrentMap}, for a pre-determined model.
 *
 * @author Rossen Stoyanchev
 * @since 5.0
 */
@SuppressWarnings("serial")
public class ConcurrentModel extends ConcurrentHashMap<String, Object> implements Model {

	
Construct a new, empty ConcurrentModel. /**
	 * Construct a new, empty {@code ConcurrentModel}.
	 */
	public ConcurrentModel() {
	}

	
Construct a new ModelMap containing the supplied attribute under the supplied name. 
See Also:
addAttribute(String, Object)/**
	 * Construct a new {@code ModelMap} containing the supplied attribute
	 * under the supplied name.
	 * @see #addAttribute(String, Object)
	 */
	public ConcurrentModel(String attributeName, Object attributeValue) {
		addAttribute(attributeName, attributeValue);
	}

	
Construct a new ModelMap containing the supplied attribute. Uses attribute name generation to generate the key for the supplied model object. 
See Also:
addAttribute(Object)/**
	 * Construct a new {@code ModelMap} containing the supplied attribute.
	 * Uses attribute name generation to generate the key for the supplied model
	 * object.
	 * @see #addAttribute(Object)
	 */
	public ConcurrentModel(Object attributeValue) {
		addAttribute(attributeValue);
	}


	@Override
	public Object put(String key, Object value) {
		if (value != null) {
			return super.put(key, value);
		}
		else {
			return remove(key);
		}
	}

	@Override
	public void putAll(Map<? extends String, ?> map) {
		for (Map.Entry<? extends String, ?> entry : map.entrySet()) {
			put(entry.getKey(), entry.getValue());
		}
	}

	
Add the supplied attribute under the supplied name.
Params:
attributeName – the name of the model attribute (never null)
attributeValue – the model attribute value (ignored if null, just removing an existing entry if any)/**
	 * Add the supplied attribute under the supplied name.
	 * @param attributeName the name of the model attribute (never {@code null})
	 * @param attributeValue the model attribute value (ignored if {@code null},
	 * just removing an existing entry if any)
	 */
	public ConcurrentModel addAttribute(String attributeName, @Nullable Object attributeValue) {
		Assert.notNull(attributeName, "Model attribute name must not be null");
		put(attributeName, attributeValue);
		return this;
	}

	
Add the supplied attribute to this Map using a generated name. 
Note: Empty Collections are not added to the model when using this method because we cannot correctly determine the true convention name. View code should check for null rather than for empty collections as is already done by JSTL tags.
Params:
attributeValue – the model attribute value (never null)/**
	 * Add the supplied attribute to this {@code Map} using a
	 * {@link org.springframework.core.Conventions#getVariableName generated name}.
	 * <p><i>Note: Empty {@link Collection Collections} are not added to
	 * the model when using this method because we cannot correctly determine
	 * the true convention name. View code should check for {@code null} rather
	 * than for empty collections as is already done by JSTL tags.</i>
	 * @param attributeValue the model attribute value (never {@code null})
	 */
	public ConcurrentModel addAttribute(Object attributeValue) {
		Assert.notNull(attributeValue, "Model attribute value must not be null");
		if (attributeValue instanceof Collection && ((Collection<?>) attributeValue).isEmpty()) {
			return this;
		}
		return addAttribute(Conventions.getVariableName(attributeValue), attributeValue);
	}

	
Copy all attributes in the supplied Collection into this Map, using attribute name generation for each element. 
See Also:
addAttribute(Object)/**
	 * Copy all attributes in the supplied {@code Collection} into this
	 * {@code Map}, using attribute name generation for each element.
	 * @see #addAttribute(Object)
	 */
	public ConcurrentModel addAllAttributes(@Nullable Collection<?> attributeValues) {
		if (attributeValues != null) {
			for (Object attributeValue : attributeValues) {
				addAttribute(attributeValue);
			}
		}
		return this;
	}

	
Copy all attributes in the supplied Map into this Map. 
See Also:
addAttribute(String, Object)/**
	 * Copy all attributes in the supplied {@code Map} into this {@code Map}.
	 * @see #addAttribute(String, Object)
	 */
	public ConcurrentModel addAllAttributes(@Nullable Map<String, ?> attributes) {
		if (attributes != null) {
			putAll(attributes);
		}
		return this;
	}

	
Copy all attributes in the supplied Map into this Map, with existing objects of the same name taking precedence (i.e. not getting replaced). /**
	 * Copy all attributes in the supplied {@code Map} into this {@code Map},
	 * with existing objects of the same name taking precedence (i.e. not getting
	 * replaced).
	 */
	public ConcurrentModel mergeAttributes(@Nullable Map<String, ?> attributes) {
		if (attributes != null) {
			attributes.forEach((key, value) -> {
				if (!containsKey(key)) {
					put(key, value);
				}
			});
		}
		return this;
	}

	
Does this model contain an attribute of the given name?
Params:
attributeName – the name of the model attribute (never null)
Returns:
whether this model contains a corresponding attribute/**
	 * Does this model contain an attribute of the given name?
	 * @param attributeName the name of the model attribute (never {@code null})
	 * @return whether this model contains a corresponding attribute
	 */
	public boolean containsAttribute(String attributeName) {
		return containsKey(attributeName);
	}

	@Override
	public Map<String, Object> asMap() {
		return this;
	}

}