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Jakarta Faces 3.0+ utility library
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/*
 * Copyright OmniFaces
 *
 * 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.omnifaces.cdi.param;

import static java.util.Arrays.stream;
import static java.util.stream.Collectors.toSet;
import static org.omnifaces.util.Reflection.modifyField;

import java.lang.annotation.Annotation;
import java.lang.reflect.Field;
import java.lang.reflect.Member;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.HashSet;
import java.util.Set;

import jakarta.enterprise.context.spi.CreationalContext;
import jakarta.enterprise.event.Observes;
import jakarta.enterprise.inject.spi.AfterBeanDiscovery;
import jakarta.enterprise.inject.spi.Annotated;
import jakarta.enterprise.inject.spi.AnnotatedConstructor;
import jakarta.enterprise.inject.spi.AnnotatedField;
import jakarta.enterprise.inject.spi.AnnotatedParameter;
import jakarta.enterprise.inject.spi.Bean;
import jakarta.enterprise.inject.spi.Extension;
import jakarta.enterprise.inject.spi.InjectionPoint;
import jakarta.enterprise.inject.spi.InjectionTarget;
import jakarta.enterprise.inject.spi.ProcessInjectionTarget;
import jakarta.inject.Inject;
import jakarta.inject.Qualifier;

import org.omnifaces.cdi.InjectionTargetWrapper;
import org.omnifaces.cdi.Param;
import org.omnifaces.util.Beans;

/**
 * CDI extension that works around the fact that CDI insists on doing absolutely
 * guaranteed type safe injections. While generally applaudable this unfortunately
 * impedes writing true generic producers that dynamically do conversion based on
 * the target type.
 * 
 * This extension collects the target types of each injection point qualified with
 * the @{@link Param} annotation and dynamically registers Beans that effectively
 * represents producers for each type.
 * 
 * Since OmniFaces 3.6, this extension also scans for @{@link Param} without
 * @{@link Inject} and manually takes care of them while creating the bean.
 *
 * @since 2.0
 * @author Arjan Tijms
 */
public class ParamExtension implements Extension {

	private Set paramsWithInject = new HashSet<>();

	/**
	 * Collect fields annotated with {@link Param}.
	 * @param  The generic injection target type.
	 * @param event The process injection target event.
	 */
	public  void collectParams(@Observes ProcessInjectionTarget event) {
		Set> paramsWithoutInject = new HashSet<>();

		for (AnnotatedField field : event.getAnnotatedType().getFields()) {
			collectParams(field, paramsWithInject, paramsWithoutInject);
		}

		for (AnnotatedConstructor constructor : event.getAnnotatedType().getConstructors()) {
			for (AnnotatedParameter parameter : constructor.getParameters()) {
				collectParams(parameter, paramsWithInject, null); // Without inject CDI won't invoke constructor in first place, so pass empty list.
			}
		}

		processParamsWithoutInject(event, paramsWithoutInject);
	}

	private static void collectParams(Annotated annotated, Set paramsWithInject, Set> paramsWithoutInject) {
		if (annotated.isAnnotationPresent(Param.class)) {
			Type type = annotated.getBaseType();

			if (type instanceof ParameterizedType && ParamValue.class.isAssignableFrom((Class) ((ParameterizedType) type).getRawType())) {
				return; // Skip ParamValue as it is already handled by RequestParameterProducer.
			}

			if (annotated.isAnnotationPresent(Inject.class) || (annotated instanceof AnnotatedParameter && ((AnnotatedParameter) annotated).getDeclaringCallable().isAnnotationPresent(Inject.class))) {
				paramsWithInject.add(type);
			}
			else if (annotated instanceof AnnotatedField) {
				paramsWithoutInject.add((AnnotatedField) annotated);
			}
		}
	}

	/**
	 * Process {@link Param} fields annotated with {@link Inject}.
	 * @param event The after bean discovery event.
	 */
	public void processParamsWithInject(@Observes AfterBeanDiscovery event) {
		for (Type paramWithInject : paramsWithInject) {
			event.addBean(new DynamicParamValueProducer(paramWithInject));
		}
	}

	/**
	/**
	 * Process {@link Param} fields without {@link Inject} annotation.
	 * @param  The generic injection target type.
	 * @param event The process injection target event.
	 * @param paramsWithoutInject The {@link Param} fields without {@link Inject} annotation.
	 */
	public static  void processParamsWithoutInject(ProcessInjectionTarget event, Set> paramsWithoutInject) {
		if (!paramsWithoutInject.isEmpty()) {
			event.setInjectionTarget(new ParamInjectionTarget<>(event.getInjectionTarget(), paramsWithoutInject));
		}
	}

	private static final class ParamInjectionTarget extends InjectionTargetWrapper {

		private Set> paramsWithoutInject = new HashSet<>();

		public ParamInjectionTarget(InjectionTarget wrapped, Set> paramsWithoutInject) {
			super(wrapped);
			this.paramsWithoutInject = paramsWithoutInject;
		}

		@Override
		public void inject(T instance, CreationalContext ctx) {
			Class beanClass = Beans.unwrapIfNecessary(instance.getClass());

			for (AnnotatedField paramWithoutInject : paramsWithoutInject) {
				ParamValue paramValue = new ParamProducer().produce(new ParamInjectionPoint(beanClass, paramWithoutInject));
				Field field = paramWithoutInject.getJavaMember();
				modifyField(instance, field, paramValue.getValue());
			}

			super.inject(instance, ctx);
		}

		private static final class ParamInjectionPoint implements InjectionPoint {

			private Bean bean;
			private AnnotatedField paramWithoutInject;

			public ParamInjectionPoint(Class beanClass, AnnotatedField paramWithoutInject) {
				this.bean = Beans.resolve(beanClass);
				this.paramWithoutInject = paramWithoutInject;
			}

			@Override
			public Type getType() {
				return paramWithoutInject.getBaseType();
			}

			@Override
			public Set getQualifiers() {
				return stream(paramWithoutInject.getJavaMember().getAnnotations()).filter(annotation -> annotation.annotationType().isAnnotationPresent(Qualifier.class)).collect(toSet());
			}

			@Override
			public Bean getBean() {
				return bean;
			}

			@Override
			public Member getMember() {
				return paramWithoutInject.getJavaMember();
			}

			@Override
			public Annotated getAnnotated() {
				return paramWithoutInject;
			}

			@Override
			public boolean isDelegate() {
				return true;
			}

			@Override
			public boolean isTransient() {
				return true;
			}
		}
	}
}