/*
 * Copyright 2002-2015 the original author or authors.
 *
 * 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.springframework.cache.jcache.interceptor;

import java.util.Collection;

import org.springframework.beans.BeanUtils;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.BeanFactoryAware;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.beans.factory.NoSuchBeanDefinitionException;
import org.springframework.beans.factory.NoUniqueBeanDefinitionException;
import org.springframework.beans.factory.SmartInitializingSingleton;
import org.springframework.cache.Cache;
import org.springframework.cache.CacheManager;
import org.springframework.cache.interceptor.CacheOperationInvocationContext;
import org.springframework.cache.interceptor.CacheResolver;
import org.springframework.cache.interceptor.KeyGenerator;
import org.springframework.cache.interceptor.SimpleCacheResolver;
import org.springframework.cache.interceptor.SimpleKeyGenerator;
import org.springframework.util.Assert;

/**
 * The default {@link JCacheOperationSource} implementation delegating
 * default operations to configurable services with sensible defaults
 * when not present.
 *
 * @author Stephane Nicoll
 * @since 4.1
 */
public class DefaultJCacheOperationSource extends AnnotationJCacheOperationSource
                implements BeanFactoryAware, InitializingBean, SmartInitializingSingleton {

        private CacheManager cacheManager;

        private CacheResolver cacheResolver;

        private CacheResolver exceptionCacheResolver;

        private KeyGenerator keyGenerator = new SimpleKeyGenerator();

        private KeyGenerator adaptedKeyGenerator;

        private BeanFactory beanFactory;


        /**
         * Set the default {@link CacheManager} to use to lookup cache by name. Only mandatory
         * if the {@linkplain CacheResolver cache resolvers} have not been set.
         */
        public void setCacheManager(CacheManager cacheManager) {
                this.cacheManager = cacheManager;
        }

        /**
         * Return the specified cache manager to use, if any.
         */
        public CacheManager getCacheManager() {
                return this.cacheManager;
        }

        /**
         * Set the {@link CacheResolver} to resolve regular caches. If none is set, a default
         * implementation using the specified cache manager will be used.
         */
        public void setCacheResolver(CacheResolver cacheResolver) {
                this.cacheResolver = cacheResolver;
        }

        /**
         * Return the specified cache resolver to use, if any.
         */
        public CacheResolver getCacheResolver() {
                return this.cacheResolver;
        }

        /**
         * Set the {@link CacheResolver} to resolve exception caches. If none is set, a default
         * implementation using the specified cache manager will be used.
         */
        public void setExceptionCacheResolver(CacheResolver exceptionCacheResolver) {
                this.exceptionCacheResolver = exceptionCacheResolver;
        }

        /**
         * Return the specified exception cache resolver to use, if any.
         */
        public CacheResolver getExceptionCacheResolver() {
                return this.exceptionCacheResolver;
        }

        /**
         * Set the default {@link KeyGenerator}. If none is set, a {@link SimpleKeyGenerator}
         * honoring the JSR-107 {@link javax.cache.annotation.CacheKey} and
         * {@link javax.cache.annotation.CacheValue} will be used.
         */
        public void setKeyGenerator(KeyGenerator keyGenerator) {
                this.keyGenerator = keyGenerator;
        }

        /**
         * Return the specified key generator to use, if any.
         */
        public KeyGenerator getKeyGenerator() {
                return this.keyGenerator;
        }

        @Override
        public void setBeanFactory(BeanFactory beanFactory) {
                this.beanFactory = beanFactory;
        }


        @Override
        public void afterPropertiesSet() {
                this.adaptedKeyGenerator = new KeyGeneratorAdapter(this, this.keyGenerator);
        }

        @Override
        public void afterSingletonsInstantiated() {
                // Make sure that the cache resolver is initialized. An exception cache resolver is only
                // required if the exceptionCacheName attribute is set on an operation
                Assert.notNull(getDefaultCacheResolver(), "Cache resolver should have been initialized");
        }


        @Override
        protected <T> T getBean(Class<T> type) {
                try {
                        return this.beanFactory.getBean(type);
                }
                catch (NoUniqueBeanDefinitionException ex) {
                        throw new IllegalStateException("No unique [" + type.getName() + "] bean found in application context - " +
                                        "mark one as primary, or declare a more specific implementation type for your cache", ex);
                }
                catch (NoSuchBeanDefinitionException ex) {
                        if (logger.isDebugEnabled()) {
                                logger.debug("No bean of type [" + type.getName() + "] found in application context", ex);
                        }
                        return BeanUtils.instantiateClass(type);
                }
        }

        protected CacheManager getDefaultCacheManager() {
                if (this.cacheManager == null) {
                        try {
                                this.cacheManager = this.beanFactory.getBean(CacheManager.class);
                        }
                        catch (NoUniqueBeanDefinitionException ex) {
                                throw new IllegalStateException("No unique bean of type CacheManager found. "+
                                                "Mark one as primary or declare a specific CacheManager to use.");
                        }
                        catch (NoSuchBeanDefinitionException ex) {
                                throw new IllegalStateException("No bean of type CacheManager found. Register a CacheManager "+
                                                "bean or remove the @EnableCaching annotation from your configuration.");
                        }
                }
                return this.cacheManager;
        }

        @Override
        protected CacheResolver getDefaultCacheResolver() {
                if (this.cacheResolver == null) {
                        this.cacheResolver = new SimpleCacheResolver(getDefaultCacheManager());
                }
                return this.cacheResolver;
        }

        @Override
        protected CacheResolver getDefaultExceptionCacheResolver() {
                if (this.exceptionCacheResolver == null) {
                        this.exceptionCacheResolver = new LazyCacheResolver();
                }
                return this.exceptionCacheResolver;
        }

        @Override
        protected KeyGenerator getDefaultKeyGenerator() {
                return this.adaptedKeyGenerator;
        }


        /**
         * Only resolve the default exception cache resolver when an exception needs to be handled.
         * <p>A non-JSR-107 setup requires either a {@link CacheManager} or a {@link CacheResolver}. If only
         * the latter is specified, it is not possible to extract a default exception {@code CacheResolver}
         * from a custom {@code CacheResolver} implementation so we have to fallback on the {@code CacheManager}.
         * <p>This gives this weird situation of a perfectly valid configuration that breaks all the sudden
         * because the JCache support is enabled. To avoid this we resolve the default exception {@code CacheResolver}
         * as late as possible to avoid such hard requirement in other cases.
         */
        class LazyCacheResolver implements CacheResolver {

                private CacheResolver cacheResolver;

                @Override
                public Collection<? extends Cache> resolveCaches(CacheOperationInvocationContext<?> context) {
                        if (this.cacheResolver == null) {
                                this.cacheResolver = new SimpleExceptionCacheResolver(getDefaultCacheManager());
                        }
                        return this.cacheResolver.resolveCaches(context);
                }
        }

}