/**
 * Licensed to Apereo under one or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information regarding copyright ownership. Apereo
 * licenses this file to you 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 the
 * following location:
 *
 * <p>http://www.apache.org/licenses/LICENSE-2.0
 *
 * <p>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.apereo.portal.spring.tx;

import com.google.common.collect.MapMaker;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import org.apereo.portal.hibernate.DelegatingHibernateIntegrator.HibernateConfiguration;
import org.apereo.portal.hibernate.HibernateConfigurationAware;
import org.hibernate.dialect.Dialect;
import org.hibernate.engine.spi.SessionFactoryImplementor;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.core.annotation.AnnotationUtils;
import org.springframework.transaction.PlatformTransactionManager;
import org.springframework.transaction.TransactionDefinition;
import org.springframework.transaction.TransactionException;
import org.springframework.transaction.TransactionStatus;
import org.springframework.transaction.interceptor.TransactionAttribute;
import org.springframework.transaction.interceptor.TransactionAttributeSource;
import org.springframework.transaction.support.DefaultTransactionStatus;
import org.springframework.util.ClassUtils;
import org.springframework.util.StringUtils;

public class DialectAwareTransactionInterceptor
        extends TransactionManagerCachingTransactionInterceptor
        implements HibernateConfigurationAware {
    private static final Logger LOGGER =
            LoggerFactory.getLogger(DialectAwareTransactionInterceptor.class);

    private static final long serialVersionUID = 1L;

    /** Returned as the TX manager when skipping the TX. Doesn't actually do any db level TX work */
    private static final PlatformTransactionManager NOOP_TRANSACTION_MANAGER =
            new PlatformTransactionManager() {
                private Map<TransactionDefinition, DefaultTransactionStatus> statusCache =
                        new MapMaker().weakKeys().weakValues().makeMap();

                protected final Logger logger =
                        LoggerFactory.getLogger(
                                DialectAwareTransactionInterceptor.class.getPackage().getName()
                                        + ".NoopTransactionManager");

                @Override
                public TransactionStatus getTransaction(TransactionDefinition definition)
                        throws TransactionException {
                    DefaultTransactionStatus status = statusCache.get(definition);
                    if (status == null) {
                        logger.debug(
                                "Creating new NOOP transaction with name [{}]: {}",
                                definition.getName(),
                                definition);
                        status =
                                new DefaultTransactionStatus(
                                        definition,
                                        true,
                                        false,
                                        definition.isReadOnly(),
                                        logger.isDebugEnabled(),
                                        null);
                        statusCache.put(definition, status);
                    } else {
                        logger.debug(
                                "Using existing NOOP transaction with name [{}]: {}",
                                definition.getName(),
                                definition);
                    }

                    return status;
                }

                @Override
                public void commit(TransactionStatus status) throws TransactionException {
                    if (status instanceof DefaultTransactionStatus) {
                        final TransactionDefinition definition =
                                (TransactionDefinition)
                                        ((DefaultTransactionStatus) status).getTransaction();
                        if (statusCache.remove(definition) != null) {
                            logger.debug(
                                    "Closing NOOP transaction with name [{}] after commit: {}",
                                    definition.getName(),
                                    definition);
                        } else {
                            logger.debug(
                                    "Can't commit NOOP transaction with name [{}], already closed: {}",
                                    definition.getName(),
                                    definition);
                        }
                    } else {
                        logger.warn(
                                "TransactionStatus {} is not a DefaultTransactionStatus, no NOOP commit done: {}",
                                status,
                                status.getClass());
                    }
                }

                @Override
                public void rollback(TransactionStatus status) throws TransactionException {
                    if (status instanceof DefaultTransactionStatus) {
                        final TransactionDefinition definition =
                                (TransactionDefinition)
                                        ((DefaultTransactionStatus) status).getTransaction();
                        if (statusCache.remove(definition) != null) {
                            logger.debug(
                                    "Closing NOOP transaction with name [{}] after rollback: {}",
                                    definition.getName(),
                                    definition);
                        } else {
                            logger.debug(
                                    "Can't rollback NOOP transaction with name [{}], already closed: {}",
                                    definition.getName(),
                                    definition);
                        }
                    } else {
                        logger.warn(
                                "TransactionStatus {} is not a DefaultTransactionStatus, no NOOP rollback done: {}",
                                status,
                                status.getClass());
                    }
                }
            };

    private final Map<String, Class<? extends Dialect>> dialects =
            new ConcurrentHashMap<String, Class<? extends Dialect>>();
    private TransactionAttributeSource wrappedTransactionAttributeSource;

    @Override
    public boolean supports(String persistenceUnit) {
        return true;
    }

    @Override
    public void setConfiguration(
            String persistenceUnit, HibernateConfiguration hibernateConfiguration) {
        final SessionFactoryImplementor sessionFactory = hibernateConfiguration.getSessionFactory();
        this.dialects.put(persistenceUnit, sessionFactory.getDialect().getClass());
    }

    @Override
    public TransactionAttributeSource getTransactionAttributeSource() {
        TransactionAttributeSource tas = this.wrappedTransactionAttributeSource;
        if (tas == null) {
            final TransactionAttributeSource transactionAttributeSource =
                    super.getTransactionAttributeSource();
            if (this.dialects.isEmpty()) {
                return transactionAttributeSource;
            }

            tas = new TransactionAttributeSourceWrapper(this.dialects, transactionAttributeSource);
            this.wrappedTransactionAttributeSource = tas;
        }
        return tas;
    }

    protected PlatformTransactionManager determineTransactionManager(TransactionAttribute txAttr) {
        if (txAttr instanceof SkipTransactionAttribute) {
            return NOOP_TRANSACTION_MANAGER;
        }

        return super.determineTransactionManager(txAttr);
    }

    private static final class TransactionAttributeSourceWrapper
            implements TransactionAttributeSource {
        private final Map<String, Class<? extends Dialect>> dialects;
        private final TransactionAttributeSource transactionAttributeSource;

        public TransactionAttributeSourceWrapper(
                Map<String, Class<? extends Dialect>> dialects,
                TransactionAttributeSource transactionAttributeSource) {
            this.dialects = dialects;
            this.transactionAttributeSource = transactionAttributeSource;
        }

        @Override
        public TransactionAttribute getTransactionAttribute(Method method, Class<?> targetClass) {
            final TransactionAttribute transactionAttribute =
                    transactionAttributeSource.getTransactionAttribute(method, targetClass);

            //No dialect ignore support if transactionAttribute is null
            if (transactionAttribute == null) {
                return transactionAttribute;
            }

            final DialectAwareTransactional ann =
                    getDialectAwareTransactionalAnnotation(method, targetClass);

            //No DialectAwareTransactional annotation, just return the original transactionAttribute
            if (ann == null) {
                return transactionAttribute;
            }

            //Check if a TX is needed for the Dialect
            final Class<? extends Dialect> dialect = determineDialect(method, transactionAttribute);
            final boolean ignored = isDialectIgnored(dialect, ann);

            //Dialect is ignored
            if (!ignored) {
                return transactionAttribute;
            }

            //Determine interfaces to proxy
            @SuppressWarnings("rawtypes")
            final Set<Class> interfaces = ClassUtils.getAllInterfacesAsSet(transactionAttribute);
            interfaces.add(SkipTransactionAttribute.class);

            //Proxy the existing transactionAttribute to mix in our SkipTransactionAttribute interface
            return (TransactionAttribute)
                    Proxy.newProxyInstance(
                            DialectAwareTransactionInterceptor.class.getClassLoader(),
                            interfaces.toArray(new Class<?>[interfaces.size()]),
                            new InvocationHandler() {
                                @Override
                                public Object invoke(Object proxy, Method method, Object[] args)
                                        throws Throwable {
                                    return method.invoke(transactionAttribute, args);
                                }
                            });
        }

        private boolean isDialectIgnored(
                Class<? extends Dialect> dialect, DialectAwareTransactional ann) {
            if (dialect == null) {
                return false;
            }

            boolean ignored = !ann.exclude();
            for (final Class<? extends Dialect> ignoredDialect : ann.value()) {
                if (ignoredDialect.isAssignableFrom(dialect)) {
                    ignored = !ignored;
                    break;
                }
            }
            return ignored;
        }

        private Class<? extends Dialect> determineDialect(
                Method method, TransactionAttribute transactionAttribute) {
            final Class<? extends Dialect> dialect;
            final String qualifier = transactionAttribute.getQualifier();
            if (StringUtils.hasLength(qualifier)) {
                dialect = this.dialects.get(qualifier);
            } else if (this.dialects.size() == 1) {
                dialect = this.dialects.values().iterator().next();
            } else if (!this.dialects.isEmpty()) {
                LOGGER.debug(
                        "No qualifier specified for @Transactional on {} and multiple Dialects are configured: {}",
                        method,
                        this.dialects.keySet());
                return null;
            } else {
                return null;
            }
            return dialect;
        }

        private DialectAwareTransactional getDialectAwareTransactionalAnnotation(
                Method method, Class<?> targetClass) {
            // Ignore CGLIB subclasses - introspect the actual user class.
            Class<?> userClass = ClassUtils.getUserClass(targetClass);
            // The method may be on an interface, but we need attributes from the target class.
            // If the target class is null, the method will be unchanged.
            Method specificMethod = ClassUtils.getMostSpecificMethod(method, userClass);

            DialectAwareTransactional ann =
                    AnnotationUtils.getAnnotation(specificMethod, DialectAwareTransactional.class);
            if (ann == null) {
                ann = AnnotationUtils.getAnnotation(targetClass, DialectAwareTransactional.class);
            }
            return ann;
        }
    }

    private interface SkipTransactionAttribute extends TransactionAttribute {}
}
