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/*
 * JBoss, Home of Professional Open Source
 * Copyright 2012, Red Hat, Inc., and individual contributors
 * by the @authors tag. See the copyright.txt in the distribution for a
 * full listing of individual contributors.
 *
 * 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
 * http://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.jboss.weld.resources;

import static org.jboss.weld.util.cache.LoadingCacheUtils.getCacheValue;

import java.lang.annotation.Annotation;
import java.lang.reflect.AnnotatedElement;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.HashSet;
import java.util.Set;

import javax.enterprise.context.NormalScope;
import javax.inject.Scope;

import org.jboss.weld.bootstrap.api.helpers.AbstractBootstrapService;
import org.jboss.weld.metadata.TypeStore;
import org.jboss.weld.util.Annotations;
import org.jboss.weld.util.reflection.Reflections;

import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheLoader;
import com.google.common.cache.LoadingCache;
import com.google.common.collect.ImmutableSet;

public class DefaultReflectionCache extends AbstractBootstrapService implements ReflectionCache {

    private final TypeStore store;
    private final CacheLoader> ANNOTATIONS_FUNCTION = new CacheLoader>() {
        @Override
        public Set load(AnnotatedElement input) {
            return ImmutableSet.copyOf(internalGetAnnotations(input));
        }
    };
    private final CacheLoader> DECLARED_ANNOTATIONS_FUNCTION = new CacheLoader>() {
        @Override
        public Set load(AnnotatedElement input) {
            return ImmutableSet.copyOf(internalGetDeclaredAnnotations(input));
        }
    };

    protected Annotation[] internalGetAnnotations(AnnotatedElement element) {
        return element.getAnnotations();
    }

    protected Annotation[] internalGetDeclaredAnnotations(AnnotatedElement element) {
        return element.getDeclaredAnnotations();
    }

    private final LoadingCache> annotations;
    private final LoadingCache> declaredAnnotations;
    private final LoadingCache, Set> backedAnnotatedTypeAnnotations;
    private final LoadingCache, AnnotationClass> annotationClasses;

    public DefaultReflectionCache(TypeStore store) {
        this.store = store;
        CacheBuilder cacheBuilder = CacheBuilder.newBuilder();
        this.annotations = cacheBuilder.build(ANNOTATIONS_FUNCTION);
        this.declaredAnnotations = cacheBuilder.build(DECLARED_ANNOTATIONS_FUNCTION);
        this.backedAnnotatedTypeAnnotations = cacheBuilder.build(new BackedAnnotatedTypeAnnotationsFunction());
        this.annotationClasses =  cacheBuilder.build(new AnnotationClassFunction());
    }

    @Override
    public void cleanupAfterBoot() {
        annotations.invalidateAll();
        declaredAnnotations.invalidateAll();
        backedAnnotatedTypeAnnotations.invalidateAll();
        annotationClasses.invalidateAll();
    }

    @Override
    public Set getAnnotations(AnnotatedElement element) {
        return getCacheValue(annotations, element);
    }

    @Override
    public Set getDeclaredAnnotations(AnnotatedElement element) {
        return getCacheValue(declaredAnnotations, element);
    }

    @Override
    public Set getBackedAnnotatedTypeAnnotationSet(Class javaClass) {
        return getCacheValue(backedAnnotatedTypeAnnotations, javaClass);
    }

    private class BackedAnnotatedTypeAnnotationsFunction extends CacheLoader, Set> {

        @Override
        public Set load(Class javaClass) {
            Set annotations = getAnnotations(javaClass);
            boolean scopeFound = false;
            for (Annotation annotation : annotations) {
                boolean isScope = getAnnotationClass(annotation.annotationType()).isScope();
                if (isScope && scopeFound) {
                    // there are at least two scopes, we need to choose one using scope inheritance rules (4.1)
                    return applyScopeInheritanceRules(annotations, javaClass);
                }
                if (isScope) {
                    scopeFound = true;
                }
            }
            return annotations;
        }

        public Set applyScopeInheritanceRules(Set annotations, Class javaClass) {
            Set result = new HashSet();
            for (Annotation annotation : annotations) {
                if (!getAnnotationClass(annotation.annotationType()).isScope()) {
                    result.add(annotation);
                }
            }
            result.addAll(findTopLevelScopeDefinitions(javaClass));
            return ImmutableSet.copyOf(result);
        }

        public Set findTopLevelScopeDefinitions(Class javaClass) {
            for (Class clazz = javaClass; clazz != null && clazz != Object.class; clazz = clazz.getSuperclass()) {
                Set scopes = new HashSet();
                for (Annotation annotation : getDeclaredAnnotations(clazz)) {
                    if (getAnnotationClass(annotation.annotationType()).isScope()) {
                        scopes.add(annotation);
                    }
                }
                if (scopes.size() > 0) {
                    return scopes;
                }
            }
            throw new IllegalStateException();
        }
    }

    private class AnnotationClassFunction extends CacheLoader, AnnotationClass> {
        @Override
        public AnnotationClass load(Class input) {
            boolean scope = input.isAnnotationPresent(NormalScope.class) || input.isAnnotationPresent(Scope.class) || store.isExtraScope(input);
            Method repeatableAnnotationAccessor = Annotations.getRepeatableAnnotationAccessor(input);
            Set metaAnnotations = ImmutableSet.copyOf(internalGetAnnotations(input));
            return new AnnotationClassImpl<>(scope, repeatableAnnotationAccessor, metaAnnotations);
        }
    }

    private static class AnnotationClassImpl implements AnnotationClass {

        private final boolean scope;
        private final Method repeatableAnnotationAccessor;
        private final Set metaAnnotations;

        public AnnotationClassImpl(boolean scope, Method repeatableAnnotationAccessor, Set metaAnnotations) {
            this.scope = scope;
            this.repeatableAnnotationAccessor = repeatableAnnotationAccessor;
            this.metaAnnotations = metaAnnotations;
        }

        @Override
        public Set getMetaAnnotations() {
            return metaAnnotations;
        }

        @Override
        public boolean isScope() {
            return scope;
        }

        @Override
        public boolean isRepeatableAnnotationContainer() {
            return repeatableAnnotationAccessor != null;
        }

        @Override
        public Annotation[] getRepeatableAnnotations(Annotation annotation) {
            if (!isRepeatableAnnotationContainer()) {
                throw new IllegalStateException("Not a repeatable annotation container " + annotation);
            }
            try {
                return (Annotation[]) repeatableAnnotationAccessor.invoke(annotation);
            } catch (IllegalAccessException | IllegalArgumentException | InvocationTargetException e) {
                throw new RuntimeException("Error reading repeatable annotations on " + annotation.annotationType(), e);
            }
        }
    }

    @Override
    public  AnnotationClass getAnnotationClass(Class clazz) {
        return Reflections.cast(getCacheValue(annotationClasses, clazz));
    }
}