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package org.jvnet.hk2.internal;

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

import javax.inject.Inject;

import org.glassfish.hk2.api.InjectionResolver;
import org.glassfish.hk2.utilities.reflection.Pretty;
import org.jvnet.hk2.annotations.Service;

/**
 * These utilities are per service locator.  Another service locator may have a different view
 * of the caches stored here
 * 
 * @author jwells
 *
 */
public class PerLocatorUtilities {
    /** Must not be static, otherwise it can leak when using thread pools */
    private final ThreadLocal, String>> threadLocalAutoAnalyzerNameCache =
            new ThreadLocal, String>>() {
                @Override
                protected WeakHashMap, String> initialValue() {
                    return new WeakHashMap, String>();
                }
            };

    /** Must not be static, otherwise it can leak when using thread pools */
    private final ThreadLocal>
        threadLocalAnnotationCache =
            new ThreadLocal>() {
                @Override
                protected WeakHashMap initialValue() {
                    return new WeakHashMap();
                }
            };
            
    /**
     * Gets the analyzer name from the Service annotation
     *
     * @param c The class to get the analyzer name from
     * @return The name of the analyzer (null for default)
     */
    public String getAutoAnalyzerName(Class c) {
        String retVal = threadLocalAutoAnalyzerNameCache.get().get(c);
        if (retVal != null) return retVal;
                    
        Service s = c.getAnnotation(Service.class);
        if (s == null) return null;
                    
        retVal = s.analyzer();
        threadLocalAutoAnalyzerNameCache.get().put(c, retVal);

        return retVal;
    }
    
    /**
     * Returns an injection resolver for the injectee
     *
     * @param locator The locator to use when finding the resolver
     * @param injectee Injectee from which the annotation should be extracted
     * @return Injection resolver used to resolve the injection for the injectee
     * @throws IllegalStateException If we could not find a valid resolver
     */
    public InjectionResolver getInjectionResolver(
            ServiceLocatorImpl locator, SystemInjecteeImpl injectee) throws IllegalStateException {
        return getInjectionResolver(locator, injectee.getParent(), injectee.getPosition());
    }
    
    /**
     * Returns an injection resolver for this AnnotatedElement. The method cannot be used for constructors
     * or methods.
     *
     * @param locator The locator to use when finding the resolver
     * @param annotatedGuy The annotated class or producer method
     * @return The scope of this class or producer method.  If no scope is
     * found will return the dependent scope
     * @throws IllegalStateException If we could not find a valid resolver
     */
    /* package */ InjectionResolver getInjectionResolver(
            ServiceLocatorImpl locator, AnnotatedElement annotatedGuy) throws IllegalStateException {
        if (annotatedGuy instanceof Method || annotatedGuy instanceof Constructor) {
            throw new IllegalArgumentException("Annotated element '" + annotatedGuy + "' can be neither a Method nor a Constructor.");
        }
        return getInjectionResolver(locator, annotatedGuy, -1);
    }
    
    private InjectionResolver getInjectionResolver(
            ServiceLocatorImpl locator, AnnotatedElement annotatedGuy, int position) throws IllegalStateException {
        boolean methodOrConstructor = annotatedGuy instanceof Method || annotatedGuy instanceof Constructor;
        Annotation injectAnnotation = getInjectAnnotation(locator, annotatedGuy, methodOrConstructor, position);

        //Annotation injectAnnotation = getInjectAnnotation(locator, annotatedGuy, position);

        Class injectType = (injectAnnotation == null) ?
                Inject.class : injectAnnotation.annotationType();

        InjectionResolver retVal = locator.getInjectionResolver(injectType);
        if (retVal == null) {
            // Not possible to get here, we only are here if we already found a resolver
            throw new IllegalStateException("There is no installed injection resolver for " +
                    Pretty.clazz(injectType) + " for type " + annotatedGuy);
        }

        return retVal;
    }
    
    /**
     * Gets the annotation that was used for the injection
     *
     * @param locator The service locator to use (as it will get all
     * the annotations that were added on as well as the normal Inject)
     * @param annotated the annotated annotated
     * @param checkParams  check the params if true
     * @param position index of constructor or method parameter which which will be checked
     *                 for inject annotations. The {@code position} parameter is only used when
     *                 {@code annotated} is method or constructor otherwise the value will be ignored.
     * @return The annotation that is the inject annotation, or null
     * if no inject annotation was found
     */
    private Annotation getInjectAnnotation(final ServiceLocatorImpl locator, final AnnotatedElement annotated,
            final boolean checkParams, final int position) {
        
        final AnnotatedElementAnnotationInfo annotationInfo = computeElementAnnotationInfo(annotated);

        if (checkParams) {

            if (annotationInfo.hasParams) {
                for (Annotation paramAnno : annotationInfo.paramAnnotations[position]) {
                    if (locator.isInjectAnnotation(paramAnno, annotationInfo.isConstructor)) {
                        return paramAnno;
                    }
                }
            }
        }

        for (Annotation annotation : annotationInfo.elementAnnotations) {
            if (locator.isInjectAnnotation(annotation)) {
                return annotation;
            }
        }

        return null;
    }
    
    private AnnotatedElementAnnotationInfo computeElementAnnotationInfo(AnnotatedElement ae) {
        AnnotatedElementAnnotationInfo hard;
        SoftAnnotatedElementAnnotationInfo soft = threadLocalAnnotationCache.get().get(ae);
        if (soft != null) {
            hard = soft.harden(ae);
        }
        else {
            hard = Utilities.computeAEAI(ae);
            soft = hard.soften();
            threadLocalAnnotationCache.get().put(ae, soft);
        }
        return hard;
    }

}