/*
 * Copyright 2011-2020 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.data.mapping.context;

import lombok.AccessLevel;
import lombok.NonNull;
import lombok.RequiredArgsConstructor;

import java.beans.PropertyDescriptor;
import java.lang.reflect.Field;
import java.lang.reflect.Modifier;
import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map;
import java.util.Optional;
import java.util.Set;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantReadWriteLock;
import java.util.function.Predicate;
import java.util.stream.Collectors;

import org.springframework.beans.BeanUtils;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.context.ApplicationEventPublisher;
import org.springframework.context.ApplicationEventPublisherAware;
import org.springframework.data.mapping.MappingException;
import org.springframework.data.mapping.PersistentEntity;
import org.springframework.data.mapping.PersistentProperty;
import org.springframework.data.mapping.PersistentPropertyPath;
import org.springframework.data.mapping.PersistentPropertyPaths;
import org.springframework.data.mapping.PropertyPath;
import org.springframework.data.mapping.model.ClassGeneratingPropertyAccessorFactory;
import org.springframework.data.mapping.model.MutablePersistentEntity;
import org.springframework.data.mapping.model.PersistentPropertyAccessorFactory;
import org.springframework.data.mapping.model.Property;
import org.springframework.data.mapping.model.SimpleTypeHolder;
import org.springframework.data.spel.EvaluationContextProvider;
import org.springframework.data.spel.ExtensionAwareEvaluationContextProvider;
import org.springframework.data.util.ClassTypeInformation;
import org.springframework.data.util.Optionals;
import org.springframework.data.util.Streamable;
import org.springframework.data.util.TypeInformation;
import org.springframework.lang.Nullable;
import org.springframework.util.Assert;
import org.springframework.util.ReflectionUtils;
import org.springframework.util.ReflectionUtils.FieldCallback;
import org.springframework.util.ReflectionUtils.FieldFilter;

Base class to build mapping metadata and thus create instances of PersistentEntity and PersistentProperty. 
 The implementation uses a ReentrantReadWriteLock to make sure PersistentEntity are completely populated before accessing them from outside. 
Author:
Jon Brisbin, Oliver Gierke, Michael Hunger, Thomas Darimont, Tomasz Wysocki, Mark Paluch, Mikael Klamra, Christoph Strobl
Type parameters:
<E> – the concrete PersistentEntity type the MappingContext implementation creates
<P> – the concrete PersistentProperty type the MappingContext implementation creates/**
 * Base class to build mapping metadata and thus create instances of {@link PersistentEntity} and
 * {@link PersistentProperty}.
 * <p>
 * The implementation uses a {@link ReentrantReadWriteLock} to make sure {@link PersistentEntity} are completely
 * populated before accessing them from outside.
 *
 * @param <E> the concrete {@link PersistentEntity} type the {@link MappingContext} implementation creates
 * @param <P> the concrete {@link PersistentProperty} type the {@link MappingContext} implementation creates
 * @author Jon Brisbin
 * @author Oliver Gierke
 * @author Michael Hunger
 * @author Thomas Darimont
 * @author Tomasz Wysocki
 * @author Mark Paluch
 * @author Mikael Klamra
 * @author Christoph Strobl
 */
public abstract class AbstractMappingContext<E extends MutablePersistentEntity<?, P>, P extends PersistentProperty<P>>
		implements MappingContext<E, P>, ApplicationEventPublisherAware, ApplicationContextAware, InitializingBean {

	private final Optional<E> NONE = Optional.empty();
	private final Map<TypeInformation<?>, Optional<E>> persistentEntities = new HashMap<>();
	private final PersistentPropertyAccessorFactory persistentPropertyAccessorFactory = new ClassGeneratingPropertyAccessorFactory();
	private final PersistentPropertyPathFactory<E, P> persistentPropertyPathFactory;

	private @Nullable ApplicationEventPublisher applicationEventPublisher;
	private EvaluationContextProvider evaluationContextProvider = EvaluationContextProvider.DEFAULT;

	private Set<? extends Class<?>> initialEntitySet = new HashSet<>();
	private boolean strict = false;
	private SimpleTypeHolder simpleTypeHolder = SimpleTypeHolder.DEFAULT;

	private final ReentrantReadWriteLock lock = new ReentrantReadWriteLock();
	private final Lock read = lock.readLock();
	private final Lock write = lock.writeLock();

	protected AbstractMappingContext() {
		this.persistentPropertyPathFactory = new PersistentPropertyPathFactory<>(this);
	}

	/*
	 * (non-Javadoc)
	 * @see org.springframework.context.ApplicationEventPublisherAware#setApplicationEventPublisher(org.springframework.context.ApplicationEventPublisher)
	 */
	@Override
	public void setApplicationEventPublisher(ApplicationEventPublisher applicationEventPublisher) {
		this.applicationEventPublisher = applicationEventPublisher;
	}

	/*
	 * (non-Javadoc)
	 * @see org.springframework.context.ApplicationContextAware#setApplicationContext(org.springframework.context.ApplicationContext)
	 */
	@Override
	public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {

		this.evaluationContextProvider = new ExtensionAwareEvaluationContextProvider(applicationContext);

		if (applicationEventPublisher == null) {
			this.applicationEventPublisher = applicationContext;
		}
	}

	
Sets the Set of types to populate the context initially. 
Params:
initialEntitySet – /**
	 * Sets the {@link Set} of types to populate the context initially.
	 *
	 * @param initialEntitySet
	 */
	public void setInitialEntitySet(Set<? extends Class<?>> initialEntitySet) {
		this.initialEntitySet = initialEntitySet;
	}

	
Configures whether the MappingContext is in strict mode which means, that it will throw MappingExceptions in case one tries to lookup a PersistentEntity not already in the context. This defaults to false so that unknown types will be transparently added to the MappingContext if not known in advance. 
Params:
strict – /**
	 * Configures whether the {@link MappingContext} is in strict mode which means, that it will throw
	 * {@link MappingException}s in case one tries to lookup a {@link PersistentEntity} not already in the context. This
	 * defaults to {@literal false} so that unknown types will be transparently added to the MappingContext if not known
	 * in advance.
	 *
	 * @param strict
	 */
	public void setStrict(boolean strict) {
		this.strict = strict;
	}

	
Configures the SimpleTypeHolder to be used by the MappingContext. Allows customization of what types will be regarded as simple types and thus not recursively analyzed. 
Params:
simpleTypes – must not be null./**
	 * Configures the {@link SimpleTypeHolder} to be used by the {@link MappingContext}. Allows customization of what
	 * types will be regarded as simple types and thus not recursively analyzed.
	 *
	 * @param simpleTypes must not be {@literal null}.
	 */
	public void setSimpleTypeHolder(SimpleTypeHolder simpleTypes) {

		Assert.notNull(simpleTypes, "SimpleTypeHolder must not be null!");

		this.simpleTypeHolder = simpleTypes;
	}

	/*
	 * (non-Javadoc)
	 * @see org.springframework.data.mapping.model.MappingContext#getPersistentEntities()
	 */
	@Override
	public Collection<E> getPersistentEntities() {

		try {

			read.lock();

			return persistentEntities.values().stream()//
					.flatMap(Optionals::toStream)//
					.collect(Collectors.toSet());

		} finally {
			read.unlock();
		}
	}

	/*
	 * (non-Javadoc)
	 * @see org.springframework.data.mapping.model.MappingContext#getPersistentEntity(java.lang.Class)
	 */
	@Nullable
	public E getPersistentEntity(Class<?> type) {
		return getPersistentEntity(ClassTypeInformation.from(type));
	}

	/*
	 * (non-Javadoc)
	 * @see org.springframework.data.mapping.context.MappingContext#hasPersistentEntityFor(java.lang.Class)
	 */
	@Override
	public boolean hasPersistentEntityFor(Class<?> type) {

		Assert.notNull(type, "Type must not be null!");

		Optional<E> entity = persistentEntities.get(ClassTypeInformation.from(type));

		return entity == null ? false : entity.isPresent();
	}

	/*
	 * (non-Javadoc)
	 * @see org.springframework.data.mapping.model.MappingContext#getPersistentEntity(org.springframework.data.util.TypeInformation)
	 */
	@Nullable
	@Override
	public E getPersistentEntity(TypeInformation<?> type) {

		Assert.notNull(type, "Type must not be null!");

		try {

			read.lock();

			Optional<E> entity = persistentEntities.get(type);

			if (entity != null) {
				return entity.orElse(null);
			}

		} finally {
			read.unlock();
		}

		if (!shouldCreatePersistentEntityFor(type)) {

			try {
				write.lock();
				persistentEntities.put(type, NONE);
			} finally {
				write.unlock();
			}

			return null;
		}

		if (strict) {
			throw new MappingException("Unknown persistent entity " + type);
		}

		return addPersistentEntity(type).orElse(null);
	}

	/*
	 * (non-Javadoc)
	 * @see org.springframework.data.mapping.context.MappingContext#getPersistentEntity(org.springframework.data.mapping.PersistentProperty)
	 */
	@Nullable
	@Override
	public E getPersistentEntity(P persistentProperty) {

		Assert.notNull(persistentProperty, "PersistentProperty must not be null!");

		if (!persistentProperty.isEntity()) {
			return null;
		}

		TypeInformation<?> typeInfo = persistentProperty.getTypeInformation();
		return getPersistentEntity(typeInfo.getRequiredActualType());
	}

	/*
	 * (non-Javadoc)
	 * @see org.springframework.data.mapping.context.MappingContext#getPersistentPropertyPath(java.lang.Class, java.lang.String)
	 */
	@Override
	public PersistentPropertyPath<P> getPersistentPropertyPath(PropertyPath propertyPath) {
		return persistentPropertyPathFactory.from(propertyPath);
	}

	/*
	 * (non-Javadoc)
	 * @see org.springframework.data.mapping.context.MappingContext#getPersistentPropertyPath(java.lang.String, java.lang.Class)
	 */
	@Override
	public PersistentPropertyPath<P> getPersistentPropertyPath(String propertyPath, Class<?> type) {
		return persistentPropertyPathFactory.from(type, propertyPath);
	}

	/*
	 * (non-Javadoc)
	 * @see org.springframework.data.mapping.context.MappingContext#findPersistentPropertyPath(java.lang.Class, java.util.function.Predicate)
	 */
	@Override
	public <T> PersistentPropertyPaths<T, P> findPersistentPropertyPaths(Class<T> type, Predicate<? super P> predicate) {

		Assert.notNull(type, "Type must not be null!");
		Assert.notNull(predicate, "Selection predicate must not be null!");

		return doFindPersistentPropertyPaths(type, predicate, it -> !it.isAssociation());
	}

	
Actually looks up the PersistentPropertyPaths for the given type, selection predicate and traversal guard. Primary purpose is to allow sub-types to alter the default traversal guard, e.g. used by findPersistentPropertyPaths(Class, Predicate). 
Params:
type – will never be null.
predicate – will never be null.
traversalGuard – will never be null.
See Also:
findPersistentPropertyPaths(Class, Predicate)
Returns:
will never be null./**
	 * Actually looks up the {@link PersistentPropertyPaths} for the given type, selection predicate and traversal guard.
	 * Primary purpose is to allow sub-types to alter the default traversal guard, e.g. used by
	 * {@link #findPersistentPropertyPaths(Class, Predicate)}.
	 *
	 * @param type will never be {@literal null}.
	 * @param predicate will never be {@literal null}.
	 * @param traversalGuard will never be {@literal null}.
	 * @return will never be {@literal null}.
	 * @see #findPersistentPropertyPaths(Class, Predicate)
	 */
	protected final <T> PersistentPropertyPaths<T, P> doFindPersistentPropertyPaths(Class<T> type,
			Predicate<? super P> predicate, Predicate<P> traversalGuard) {
		return persistentPropertyPathFactory.from(ClassTypeInformation.from(type), predicate, traversalGuard);
	}

	
Adds the given type to the MappingContext. 
Params:
type – must not be null.
Returns:
/**
	 * Adds the given type to the {@link MappingContext}.
	 *
	 * @param type must not be {@literal null}.
	 * @return
	 */
	protected Optional<E> addPersistentEntity(Class<?> type) {
		return addPersistentEntity(ClassTypeInformation.from(type));
	}

	
Adds the given TypeInformation to the MappingContext. 
Params:
typeInformation – must not be null.
Returns:
/**
	 * Adds the given {@link TypeInformation} to the {@link MappingContext}.
	 *
	 * @param typeInformation must not be {@literal null}.
	 * @return
	 */
	protected Optional<E> addPersistentEntity(TypeInformation<?> typeInformation) {

		Assert.notNull(typeInformation, "TypeInformation must not be null!");

		try {

			read.lock();

			Optional<E> persistentEntity = persistentEntities.get(typeInformation);

			if (persistentEntity != null) {
				return persistentEntity;
			}

		} finally {
			read.unlock();
		}

		Class<?> type = typeInformation.getType();
		E entity = null;

		try {

			write.lock();

			entity = createPersistentEntity(typeInformation);

			entity.setEvaluationContextProvider(evaluationContextProvider);

			// Eagerly cache the entity as we might have to find it during recursive lookups.
			persistentEntities.put(typeInformation, Optional.of(entity));

			PropertyDescriptor[] pds = BeanUtils.getPropertyDescriptors(type);

			final Map<String, PropertyDescriptor> descriptors = new HashMap<>();
			for (PropertyDescriptor descriptor : pds) {
				descriptors.put(descriptor.getName(), descriptor);
			}

			try {

				PersistentPropertyCreator persistentPropertyCreator = new PersistentPropertyCreator(entity, descriptors);
				ReflectionUtils.doWithFields(type, persistentPropertyCreator, PersistentPropertyFilter.INSTANCE);
				persistentPropertyCreator.addPropertiesForRemainingDescriptors();

				entity.verify();

				if (persistentPropertyAccessorFactory.isSupported(entity)) {
					entity.setPersistentPropertyAccessorFactory(persistentPropertyAccessorFactory);
				}

			} catch (RuntimeException e) {
				persistentEntities.remove(typeInformation);
				throw e;
			}

		} catch (BeansException e) {
			throw new MappingException(e.getMessage(), e);
		} finally {
			write.unlock();
		}

		// Inform listeners
		if (applicationEventPublisher != null && entity != null) {
			applicationEventPublisher.publishEvent(new MappingContextEvent<>(this, entity));
		}

		return Optional.of(entity);
	}

	/*
	 * (non-Javadoc)
	 * @see org.springframework.data.mapping.context.PersistentEntityAware#getManagedTypes()
	 */
	@Override
	public Collection<TypeInformation<?>> getManagedTypes() {

		try {

			read.lock();
			return Collections.unmodifiableSet(new HashSet<>(persistentEntities.keySet()));

		} finally {
			read.unlock();
		}
	}

	
Creates the concrete PersistentEntity instance. 
Params:
typeInformation – 
Type parameters:
<T> – 
Returns:
/**
	 * Creates the concrete {@link PersistentEntity} instance.
	 *
	 * @param <T>
	 * @param typeInformation
	 * @return
	 */
	protected abstract <T> E createPersistentEntity(TypeInformation<T> typeInformation);

	
Creates the concrete instance of PersistentProperty. 
Params:
property – 
owner – 
simpleTypeHolder – 
Returns:
/**
	 * Creates the concrete instance of {@link PersistentProperty}.
	 *
	 * @param property
	 * @param owner
	 * @param simpleTypeHolder
	 * @return
	 */
	protected abstract P createPersistentProperty(Property property, E owner, SimpleTypeHolder simpleTypeHolder);

	/*
	 * (non-Javadoc)
	 * @see org.springframework.beans.factory.InitializingBean#afterPropertiesSet()
	 */
	@Override
	public void afterPropertiesSet() {
		initialize();
	}

	
Initializes the mapping context. Will add the types configured through setInitialEntitySet(Set) to the context. /**
	 * Initializes the mapping context. Will add the types configured through {@link #setInitialEntitySet(Set)} to the
	 * context.
	 */
	public void initialize() {
		initialEntitySet.forEach(this::addPersistentEntity);
	}

	
Returns whether a PersistentEntity instance should be created for the given TypeInformation. By default this will reject all types considered simple and non-supported Kotlin classes, but it might be necessary to tweak that in case you have registered custom converters for top level types (which renders them to be considered simple) but still need meta-information about them. 

Params:
type – will never be null.
Returns:
/**
	 * Returns whether a {@link PersistentEntity} instance should be created for the given {@link TypeInformation}. By
	 * default this will reject all types considered simple and non-supported Kotlin classes, but it might be necessary to
	 * tweak that in case you have registered custom converters for top level types (which renders them to be considered
	 * simple) but still need meta-information about them.
	 * <p/>
	 *
	 * @param type will never be {@literal null}.
	 * @return
	 */
	protected boolean shouldCreatePersistentEntityFor(TypeInformation<?> type) {

		if (simpleTypeHolder.isSimpleType(type.getType())) {
			return false;
		}

		return !org.springframework.data.util.ReflectionUtils.isKotlinClass(type.getType())
				|| org.springframework.data.util.ReflectionUtils.isSupportedKotlinClass(type.getType());
	}

	
FieldCallback to create PersistentProperty instances. 
Author:
Oliver Gierke/**
	 * {@link FieldCallback} to create {@link PersistentProperty} instances.
	 *
	 * @author Oliver Gierke
	 */
	@RequiredArgsConstructor(access = AccessLevel.PRIVATE)
	private final class PersistentPropertyCreator implements FieldCallback {

		private final @NonNull E entity;
		private final @NonNull Map<String, PropertyDescriptor> descriptors;
		private final @NonNull Map<String, PropertyDescriptor> remainingDescriptors;

		public PersistentPropertyCreator(E entity, Map<String, PropertyDescriptor> descriptors) {
			this(entity, descriptors, descriptors);
		}

		/*
		 * (non-Javadoc)
		 * @see org.springframework.util.ReflectionUtils.FieldCallback#doWith(java.lang.reflect.Field)
		 */
		public void doWith(Field field) {

			String fieldName = field.getName();
			TypeInformation<?> type = entity.getTypeInformation();

			ReflectionUtils.makeAccessible(field);

			Property property = Optional.ofNullable(descriptors.get(fieldName))//
					.map(it -> Property.of(type, field, it))//
					.orElseGet(() -> Property.of(type, field));

			createAndRegisterProperty(property);

			this.remainingDescriptors.remove(fieldName);
		}

		
Adds PersistentProperty instances for all suitable PropertyDescriptors without a backing Field. 
See Also:
PersistentPropertyFilter/**
		 * Adds {@link PersistentProperty} instances for all suitable {@link PropertyDescriptor}s without a backing
		 * {@link Field}.
		 *
		 * @see PersistentPropertyFilter
		 */
		public void addPropertiesForRemainingDescriptors() {

			remainingDescriptors.values().stream() //
					.filter(Property::supportsStandalone) //
					.map(it -> Property.of(entity.getTypeInformation(), it)) //
					.filter(PersistentPropertyFilter.INSTANCE::matches) //
					.forEach(this::createAndRegisterProperty);
		}

		private void createAndRegisterProperty(Property input) {

			P property = createPersistentProperty(input, entity, simpleTypeHolder);

			if (property.isTransient()) {
				return;
			}

			if (!input.isFieldBacked() && !property.usePropertyAccess()) {
				return;
			}

			entity.addPersistentProperty(property);

			if (property.isAssociation()) {
				entity.addAssociation(property.getRequiredAssociation());
			}

			if (entity.getType().equals(property.getRawType())) {
				return;
			}

			property.getPersistentEntityTypes().forEach(AbstractMappingContext.this::addPersistentEntity);
		}
	}

	
Filter rejecting static fields as well as artificially introduced ones. See UNMAPPED_PROPERTIES for details. 
Author:
Oliver Gierke/**
	 * Filter rejecting static fields as well as artificially introduced ones. See
	 * {@link PersistentPropertyFilter#UNMAPPED_PROPERTIES} for details.
	 *
	 * @author Oliver Gierke
	 */
	static enum PersistentPropertyFilter implements FieldFilter {

		INSTANCE;

		private static final Streamable<PropertyMatch> UNMAPPED_PROPERTIES;

		static {

			Set<PropertyMatch> matches = new HashSet<>();
			matches.add(new PropertyMatch("class", null));
			matches.add(new PropertyMatch("this\\$.*", null));
			matches.add(new PropertyMatch("metaClass", "groovy.lang.MetaClass"));

			UNMAPPED_PROPERTIES = Streamable.of(matches);
		}

		/*
		 * (non-Javadoc)
		 * @see org.springframework.util.ReflectionUtils.FieldFilter#matches(java.lang.reflect.Field)
		 */
		public boolean matches(Field field) {

			if (Modifier.isStatic(field.getModifiers())) {
				return false;
			}

			return !UNMAPPED_PROPERTIES.stream()//
					.anyMatch(it -> it.matches(field.getName(), field.getType()));
		}

		
Returns whether the given PropertyDescriptor is one to create a PersistentProperty for. 
Params:
property – must not be null.
Returns:
/**
		 * Returns whether the given {@link PropertyDescriptor} is one to create a {@link PersistentProperty} for.
		 *
		 * @param property must not be {@literal null}.
		 * @return
		 */
		public boolean matches(Property property) {

			Assert.notNull(property, "Property must not be null!");

			if (!property.hasAccessor()) {
				return false;
			}

			return !UNMAPPED_PROPERTIES.stream()//
					.anyMatch(it -> it.matches(property.getName(), property.getType()));
		}

		
Value object to help defining property exclusion based on name patterns and types.
Author:
Oliver Gierke
Since:
1.4/**
		 * Value object to help defining property exclusion based on name patterns and types.
		 *
		 * @since 1.4
		 * @author Oliver Gierke
		 */
		static class PropertyMatch {

			private final @Nullable String namePattern, typeName;

			
Creates a new PropertyMatch for the given name pattern and type name. At least one of the parameters must not be null. 
Params:
namePattern – a regex pattern to match field names, can be null.
typeName – the name of the type to exclude, can be null./**
			 * Creates a new {@link PropertyMatch} for the given name pattern and type name. At least one of the parameters
			 * must not be {@literal null}.
			 *
			 * @param namePattern a regex pattern to match field names, can be {@literal null}.
			 * @param typeName the name of the type to exclude, can be {@literal null}.
			 */
			public PropertyMatch(@Nullable String namePattern, @Nullable String typeName) {

				Assert.isTrue(!(namePattern == null && typeName == null), "Either name pattern or type name must be given!");

				this.namePattern = namePattern;
				this.typeName = typeName;
			}

			
Returns whether the given Field matches the defined PropertyMatch. 
Params:
name – must not be null.
type – must not be null.
Returns:
/**
			 * Returns whether the given {@link Field} matches the defined {@link PropertyMatch}.
			 *
			 * @param name must not be {@literal null}.
			 * @param type must not be {@literal null}.
			 * @return
			 */
			public boolean matches(String name, Class<?> type) {

				Assert.notNull(name, "Name must not be null!");
				Assert.notNull(type, "Type must not be null!");

				if (namePattern != null && !name.matches(namePattern)) {
					return false;
				}

				if (typeName != null && !type.getName().equals(typeName)) {
					return false;
				}

				return true;
			}
		}
	}
}