/*
 * Hibernate Validator, declare and validate application constraints
 *
 * License: Apache License, Version 2.0
 * See the license.txt file in the root directory or <http://www.apache.org/licenses/LICENSE-2.0>.
 */
package org.hibernate.validator.internal.engine.valueextraction;

import java.lang.reflect.Type;
import java.lang.reflect.TypeVariable;
import java.security.AccessController;
import java.security.PrivilegedAction;
import java.util.Collection;
import java.util.Collections;
import java.util.HashSet;
import java.util.LinkedHashMap;
import java.util.LinkedHashSet;
import java.util.Map;
import java.util.Set;
import java.util.stream.Collectors;

import javax.validation.ConstraintDeclarationException;
import javax.validation.ValidationException;
import javax.validation.valueextraction.ValueExtractor;

import org.hibernate.validator.internal.util.privilegedactions.LoadClass;
import org.hibernate.validator.internal.util.stereotypes.Immutable;

Author:
Gunnar Morling, Guillaume Smet, Marko Bekhta/**
 * @author Gunnar Morling
 * @author Guillaume Smet
 * @author Marko Bekhta
 */
public class ValueExtractorManager {

	@Immutable
	public static final Set<ValueExtractorDescriptor> SPEC_DEFINED_EXTRACTORS;

	static {
		LinkedHashSet<ValueExtractorDescriptor> specDefinedExtractors = new LinkedHashSet<>();

		if ( isJavaFxInClasspath() ) {
			specDefinedExtractors.add( ObservableValueValueExtractor.DESCRIPTOR );
			specDefinedExtractors.add( ListPropertyValueExtractor.DESCRIPTOR );
			specDefinedExtractors.add( ReadOnlyListPropertyValueExtractor.DESCRIPTOR );
			specDefinedExtractors.add( MapPropertyValueExtractor.DESCRIPTOR );
			specDefinedExtractors.add( ReadOnlyMapPropertyValueExtractor.DESCRIPTOR );
			specDefinedExtractors.add( MapPropertyKeyExtractor.DESCRIPTOR );
			specDefinedExtractors.add( ReadOnlyMapPropertyKeyExtractor.DESCRIPTOR );
			specDefinedExtractors.add( SetPropertyValueExtractor.DESCRIPTOR );
			specDefinedExtractors.add( ReadOnlySetPropertyValueExtractor.DESCRIPTOR );
		}

		specDefinedExtractors.add( ByteArrayValueExtractor.DESCRIPTOR );
		specDefinedExtractors.add( ShortArrayValueExtractor.DESCRIPTOR );
		specDefinedExtractors.add( IntArrayValueExtractor.DESCRIPTOR );
		specDefinedExtractors.add( LongArrayValueExtractor.DESCRIPTOR );
		specDefinedExtractors.add( FloatArrayValueExtractor.DESCRIPTOR );
		specDefinedExtractors.add( DoubleArrayValueExtractor.DESCRIPTOR );
		specDefinedExtractors.add( CharArrayValueExtractor.DESCRIPTOR );
		specDefinedExtractors.add( BooleanArrayValueExtractor.DESCRIPTOR );
		specDefinedExtractors.add( ObjectArrayValueExtractor.DESCRIPTOR );

		specDefinedExtractors.add( ListValueExtractor.DESCRIPTOR );

		specDefinedExtractors.add( MapValueExtractor.DESCRIPTOR );
		specDefinedExtractors.add( MapKeyExtractor.DESCRIPTOR );

		specDefinedExtractors.add( IterableValueExtractor.DESCRIPTOR );

		specDefinedExtractors.add( OptionalValueExtractor.DESCRIPTOR );
		specDefinedExtractors.add( OptionalIntValueExtractor.DESCRIPTOR );
		specDefinedExtractors.add( OptionalDoubleValueExtractor.DESCRIPTOR );
		specDefinedExtractors.add( OptionalLongValueExtractor.DESCRIPTOR );

		SPEC_DEFINED_EXTRACTORS = Collections.unmodifiableSet( specDefinedExtractors );
	}

	@Immutable
	private final Map<ValueExtractorDescriptor.Key, ValueExtractorDescriptor> registeredValueExtractors;

	private final ValueExtractorResolver valueExtractorResolver;

	public ValueExtractorManager(Set<ValueExtractor<?>> externalExtractors) {
		LinkedHashMap<ValueExtractorDescriptor.Key, ValueExtractorDescriptor> tmpValueExtractors = new LinkedHashMap<>();

		// first all built-in extractors
		for ( ValueExtractorDescriptor descriptor : SPEC_DEFINED_EXTRACTORS ) {
			tmpValueExtractors.put( descriptor.getKey(), descriptor );
		}

		// then any custom ones, overriding the built-in ones
		for ( ValueExtractor<?> valueExtractor : externalExtractors ) {
			ValueExtractorDescriptor descriptor = new ValueExtractorDescriptor( valueExtractor );
			tmpValueExtractors.put( descriptor.getKey(), descriptor );
		}

		registeredValueExtractors = Collections.unmodifiableMap( tmpValueExtractors );
		valueExtractorResolver = new ValueExtractorResolver( new HashSet<>( registeredValueExtractors.values() ) );
	}

	public ValueExtractorManager(ValueExtractorManager template,
			Map<ValueExtractorDescriptor.Key, ValueExtractorDescriptor> externalValueExtractorDescriptors) {
		LinkedHashMap<ValueExtractorDescriptor.Key, ValueExtractorDescriptor> tmpValueExtractors = new LinkedHashMap<>( template.registeredValueExtractors );
		tmpValueExtractors.putAll( externalValueExtractorDescriptors );

		registeredValueExtractors = Collections.unmodifiableMap( tmpValueExtractors );
		valueExtractorResolver = new ValueExtractorResolver( new HashSet<>( registeredValueExtractors.values() ) );
	}

	public static Set<ValueExtractor<?>> getDefaultValueExtractors() {
		return SPEC_DEFINED_EXTRACTORS.stream()
				.map( d -> d.getValueExtractor() )
				.collect( Collectors.collectingAndThen( Collectors.toSet(), Collections::unmodifiableSet ) );
	}

	
Used to find the maximally specific and container element compliant value extractor based on the runtime type.

The maximally specific one is chosen among the candidates passed to this method.

Used for cascading validation.
Throws:
ConstraintDeclarationException – if more than 2 maximally specific container-element-compliant value extractors are found
See Also:
getMaximallySpecificAndRuntimeContainerElementCompliantValueExtractor.getMaximallySpecificAndRuntimeContainerElementCompliantValueExtractor(Type, TypeVariable, Class, Collection)/**
	 * Used to find the maximally specific and container element compliant value extractor based on the runtime type.
	 * <p>
	 * The maximally specific one is chosen among the candidates passed to this method.
	 * <p>
	 * Used for cascading validation.
	 *
	 * @see ValueExtractorResolver#getMaximallySpecificAndRuntimeContainerElementCompliantValueExtractor(Type,
	 * TypeVariable, Class, Collection)
	 * @throws ConstraintDeclarationException if more than 2 maximally specific container-element-compliant value extractors are found
	 */
	public ValueExtractorDescriptor getMaximallySpecificAndRuntimeContainerElementCompliantValueExtractor(Type declaredType, TypeVariable<?> typeParameter,
			Class<?> runtimeType, Collection<ValueExtractorDescriptor> valueExtractorCandidates) {

		if ( valueExtractorCandidates.size() == 1 ) {
			return valueExtractorCandidates.iterator().next();
		}
		else if ( !valueExtractorCandidates.isEmpty() ) {
			return valueExtractorResolver.getMaximallySpecificAndRuntimeContainerElementCompliantValueExtractor(
					declaredType,
					typeParameter,
					runtimeType,
					valueExtractorCandidates
			);
		}
		else {
			return valueExtractorResolver.getMaximallySpecificAndRuntimeContainerElementCompliantValueExtractor(
					declaredType,
					typeParameter,
					runtimeType,
					registeredValueExtractors.values()
			);
		}
	}

	public ValueExtractorResolver getResolver() {
		return valueExtractorResolver;
	}

	@Override
	public int hashCode() {
		final int prime = 31;
		int result = 1;
		result = prime * result + ( ( registeredValueExtractors == null ) ? 0 : registeredValueExtractors.hashCode() );
		return result;
	}

	@Override
	public boolean equals(Object obj) {
		if ( this == obj ) {
			return true;
		}
		if ( obj == null ) {
			return false;
		}
		if ( getClass() != obj.getClass() ) {
			return false;
		}
		ValueExtractorManager other = (ValueExtractorManager) obj;

		return registeredValueExtractors.equals( other.registeredValueExtractors );
	}

	private static boolean isJavaFxInClasspath() {
		return isClassPresent( "javafx.beans.value.ObservableValue", false );
	}

	private static boolean isClassPresent(String className, boolean fallbackOnTCCL) {
		try {
			run( LoadClass.action( className, ValueExtractorManager.class.getClassLoader(), fallbackOnTCCL ) );
			return true;
		}
		catch (ValidationException e) {
			return false;
		}
	}

	public void clear() {
		valueExtractorResolver.clear();
	}

	
Runs the given privileged action, using a privileged block if required.

NOTE: This must never be changed into a publicly available method to avoid execution of arbitrary
privileged actions within HV's protection domain.
/**
	 * Runs the given privileged action, using a privileged block if required.
	 * <p>
	 * <b>NOTE:</b> This must never be changed into a publicly available method to avoid execution of arbitrary
	 * privileged actions within HV's protection domain.
	 */
	private static <T> T run(PrivilegedAction<T> action) {
		return System.getSecurityManager() != null ? AccessController.doPrivileged( action ) : action.run();
	}
}