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package org.glassfish.jersey.server.internal.inject;

import java.lang.annotation.Annotation;
import java.lang.reflect.AnnotatedElement;
import java.lang.reflect.Constructor;
import java.lang.reflect.Method;
import java.lang.reflect.Type;
import java.util.Set;

import javax.ws.rs.Encoded;

import javax.inject.Inject;

import org.glassfish.jersey.internal.inject.Providers;
import org.glassfish.jersey.internal.util.ReflectionHelper;
import org.glassfish.jersey.server.model.Parameter;
import org.glassfish.jersey.server.spi.internal.ValueFactoryProvider;

import org.glassfish.hk2.api.Factory;
import org.glassfish.hk2.api.Injectee;
import org.glassfish.hk2.api.InjectionResolver;
import org.glassfish.hk2.api.ServiceHandle;
import org.glassfish.hk2.api.ServiceLocator;

import jersey.repackaged.com.google.common.base.Predicate;
import jersey.repackaged.com.google.common.collect.Sets;

/**
 * Abstract base class for resolving JAX-RS {@code &#64;XxxParam} injection.
 *
 * @param <A> supported parameter injection annotation.
 * @author Marek Potociar (marek.potociar at oracle.com)
 */
public abstract class ParamInjectionResolver<A extends Annotation> implements InjectionResolver<A> {

    @Inject
    private ServiceLocator locator;
    private final Predicate<ValueFactoryProvider> concreteValueFactoryClassFilter;

    /**
     * Initialize the base parameter injection resolver.
     *
     * @param valueFactoryProviderClass parameter value factory provider class.
     */
    public ParamInjectionResolver(final Class<? extends ValueFactoryProvider> valueFactoryProviderClass) {
        this.concreteValueFactoryClassFilter = new Predicate<ValueFactoryProvider>() {

            @Override
            public boolean apply(ValueFactoryProvider input) {
                return valueFactoryProviderClass.isInstance(input);
            }
        };
    }

    @Override
    @SuppressWarnings("unchecked")
    public Object resolve(Injectee injectee, ServiceHandle<?> root) {

        AnnotatedElement annotated = injectee.getParent();
        Annotation[] annotations;
        if (annotated.getClass().equals(Constructor.class)) {
            annotations = ((Constructor) annotated).getParameterAnnotations()[injectee.getPosition()];
        } else {
            annotations = annotated.getDeclaredAnnotations();
        }

        Class componentClass = injectee.getInjecteeClass();
        Type genericType = injectee.getRequiredType();
        boolean isHk2Factory = ReflectionHelper.isSubClassOf(genericType, Factory.class);

        final Type targetGenericType;
        if (isHk2Factory) {
            targetGenericType = ReflectionHelper.getTypeArgument(genericType, 0);
        } else {
            targetGenericType = genericType;
        }
        final Class<?> targetType = ReflectionHelper.erasure(targetGenericType);

        Set<ValueFactoryProvider> providers = Sets.filter(Providers.getProviders(locator, ValueFactoryProvider.class),
                concreteValueFactoryClassFilter);
        final ValueFactoryProvider valueFactoryProvider = providers.iterator().next(); // get first provider in the set
        final Parameter parameter = Parameter.create(
                componentClass,
                componentClass,
                hasEncodedAnnotation(injectee),
                targetType,
                targetGenericType,
                annotations);

        final Factory<?> valueFactory = valueFactoryProvider.getValueFactory(parameter);
        if (valueFactory != null) {
            if (isHk2Factory) {
                return valueFactory;
            } else {
                return valueFactory.provide();
            }
        }

        return null;
    }

    private boolean hasEncodedAnnotation(Injectee injectee) {
        AnnotatedElement element = injectee.getParent();

        final boolean isConstructor = element instanceof Constructor;
        final boolean isMethod = element instanceof Method;

        // if injectee is method or constructor, check its parameters
        if (isConstructor || isMethod) {
            Annotation annotations[];
            if (isMethod) {
                annotations = ((Method) element).getParameterAnnotations()[injectee.getPosition()];
            } else {
                annotations = ((Constructor) element).getParameterAnnotations()[injectee.getPosition()];
            }

            for (Annotation annotation : annotations) {
                if (annotation.annotationType().equals(Encoded.class)) {
                    return true;
                }
            }
        }

        // check injectee itself (method, constructor or field)
        if (element.isAnnotationPresent(Encoded.class)) {
            return true;
        }

        // check class which contains injectee
        Class<?> clazz = injectee.getInjecteeClass();
        return clazz.isAnnotationPresent(Encoded.class);
    }


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

    @Override
    public boolean isMethodParameterIndicator() {
        return false;
    }
}
