/*
 * Copyright (c) MuleSoft, Inc.  All rights reserved.  http://www.mulesoft.com
 * The software in this package is published under the terms of the CPAL v1.0
 * license, a copy of which has been included with this distribution in the
 * LICENSE.txt file.
 */
package org.mule.runtime.config.spring.internal;

import static org.apache.commons.lang3.StringUtils.EMPTY;
import static org.mule.runtime.api.i18n.I18nMessageFactory.createStaticMessage;
import static org.springframework.beans.factory.support.BeanDefinitionBuilder.genericBeanDefinition;
import org.mule.runtime.api.exception.MuleException;
import org.mule.runtime.api.exception.MuleRuntimeException;
import org.mule.runtime.api.lifecycle.InitialisationException;
import org.mule.runtime.api.lifecycle.LifecycleException;
import org.mule.runtime.config.spring.internal.dsl.model.ConfigurationDependencyResolver;
import org.mule.runtime.config.spring.internal.factories.ConstantFactoryBean;
import org.mule.runtime.core.api.Injector;
import org.mule.runtime.core.api.MuleContext;
import org.mule.runtime.core.api.lifecycle.LifecycleManager;
import org.mule.runtime.core.api.registry.LifecycleRegistry;
import org.mule.runtime.core.api.registry.RegistrationException;
import org.mule.runtime.core.api.util.StringUtils;
import org.mule.runtime.core.internal.lifecycle.phases.NotInLifecyclePhase;
import org.mule.runtime.core.internal.registry.AbstractRegistry;

import org.springframework.beans.BeansException;
import org.springframework.beans.FatalBeanException;
import org.springframework.beans.factory.BeanFactoryUtils;
import org.springframework.beans.factory.NoSuchBeanDefinitionException;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.beans.factory.support.BeanDefinitionRegistryPostProcessor;
import org.springframework.beans.factory.support.DefaultListableBeanFactory;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.support.AbstractApplicationContext;

import java.util.Collection;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.atomic.AtomicBoolean;

public class SpringRegistry extends AbstractRegistry implements LifecycleRegistry, Injector {

  public static final String REGISTRY_ID = "org.mule.Registry.Spring";

  /**
   * Key used to lookup Spring Application Context from SpringRegistry via Mule's Registry interface.
   */
  public static final String SPRING_APPLICATION_CONTEXT = "springApplicationContext";
  private BeanDependencyResolver beanDependencyResolver;

  protected ApplicationContext applicationContext;

  private boolean readOnly;

  private RegistrationDelegate registrationDelegate;

  // This is used to track the Spring context lifecycle since there is no way to confirm the
  // lifecycle phase from the application context
  protected AtomicBoolean springContextInitialised = new AtomicBoolean(false);

  // Registered objects before the spring registry has been initialised.
  private final Map<String, BeanDefinition> registeredBeanDefinitionsBeforeInitialization = new HashMap<>();

  public SpringRegistry(ApplicationContext applicationContext, MuleContext muleContext,
                        ConfigurationDependencyResolver dependencyResolver) {
    super(REGISTRY_ID, muleContext);
    setApplicationContext(applicationContext);
    this.beanDependencyResolver = new DefaultBeanDependencyResolver(dependencyResolver, this);
  }

  private void setApplicationContext(ApplicationContext applicationContext) {
    this.applicationContext = applicationContext;
    if (applicationContext instanceof ConfigurableApplicationContext) {
      readOnly = false;
      registrationDelegate = new ConfigurableRegistrationDelegate((ConfigurableApplicationContext) applicationContext);
    } else {
      readOnly = true;
      registrationDelegate = new ReadOnlyRegistrationDelegate();
    }
  }

  @Override
  protected void doInitialise() throws InitialisationException {
    ((AbstractApplicationContext) applicationContext)
        .addBeanFactoryPostProcessor(createBeforeInitialisationRegisteredObjectsPostProcessor());

    // This is used to track the Spring context lifecycle since there is no way to confirm the lifecycle phase from the
    // application context
    springContextInitialised.set(true);

    if (!readOnly) {
      ((ConfigurableApplicationContext) applicationContext).refresh();
    }

  }

  private BeanDefinitionRegistryPostProcessor createBeforeInitialisationRegisteredObjectsPostProcessor() {
    return new BeanDefinitionRegistryPostProcessor() {

      @Override
      public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException {
        registeredBeanDefinitionsBeforeInitialization.entrySet().stream().forEach(beanDefinitionEntry -> {
          registry.registerBeanDefinition(beanDefinitionEntry.getKey(), beanDefinitionEntry.getValue());
        });
      }

      @Override
      public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException {
        // do nothing
      }
    };
  }

  @Override
  public void doDispose() {
    // check we aren't trying to close a context which has never been started,
    // spring's appContext.isActive() isn't working for this case
    if (!springContextInitialised.get()) {
      return;
    }

    if (!isReadOnly() && ((ConfigurableApplicationContext) applicationContext).isActive()) {
      ((ConfigurableApplicationContext) applicationContext).close();
    }

    // release the circular implicit ref to MuleContext
    applicationContext = null;
    this.springContextInitialised.set(false);
  }

  @Override
  protected LifecycleManager createLifecycleManager() {
    return new SpringRegistryLifecycleManager(getRegistryId(), this, muleContext);
  }

  /**
   * {@inheritDoc}
   *
   * @return the result of invoking {@link #lookupObject(String, boolean)} with {@code true} as the second argument
   */
  @Override
  public <T> T lookupObject(String key) {
    try {
      return (T) lookupObject(key, true);
    } catch (NoSuchBeanDefinitionException e) {
      return null;
    }
  }

  /**
   * If looks for the bean registered under {@code key}. If the returned bean is a prototype and {@code applyLifecycle} is
   * {@code true}, then the completed lifecycle phases are applied to the returning bean
   *
   * @param key the key of the object you're looking for
   * @param applyLifecycle if lifecycle should be applied to the returned object. Passing {@code true} doesn't guarantee that the
   *        lifecycle is applied
   * @return object or {@code null} if not found
   */
  @SuppressWarnings("unchecked")
  @Override
  public Object lookupObject(String key, boolean applyLifecycle) {
    if (StringUtils.isBlank(key)) {
      logger.warn(createStaticMessage("Detected a lookup attempt with an empty or null key").getMessage(),
                  new Throwable().fillInStackTrace());
      return null;
    }

    if (key.equals(SPRING_APPLICATION_CONTEXT) && applicationContext != null) {
      return applicationContext;
    } else {
      Object object;
      try {
        object = applicationContext.getBean(key);
      } catch (NoSuchBeanDefinitionException e) {
        if (logger.isDebugEnabled()) {
          logger.debug(e.getMessage(), e);
        }
        return null;
      }

      if (applyLifecycle && !isSingleton(key)) {
        try {
          getLifecycleManager().applyCompletedPhases(object);
        } catch (Exception e) {
          throw new MuleRuntimeException(createStaticMessage("Could not apply lifecycle into prototype object " + key), e);
        }
      }

      return object;
    }
  }

  @Override
  public <T> Collection<T> lookupObjects(Class<T> type) {
    return lookupByType(type).values();
  }

  @Override
  public <T> Collection<T> lookupLocalObjects(Class<T> type) {
    return internalLookupByTypeWithoutAncestorsAndObjectProviders(type, true, true).values();
  }

  /**
   * For lifecycle we only want spring to return singleton objects from it's application context
   */
  @Override
  public <T> Collection<T> lookupObjectsForLifecycle(Class<T> type) {
    return lookupEntriesForLifecycle(type).values();
  }

  @Override
  public <T> Map<String, T> lookupByType(Class<T> type) {
    return internalLookupByType(type, true, true);
  }

  @Override
  public boolean isSingleton(String key) {
    return applicationContext.isSingleton(key);
  }

  @Override
  public void registerObject(String key, Object value) throws RegistrationException {
    registrationDelegate.registerObject(key, value);
  }

  @Override
  public void registerObject(String key, Object value, Object metadata) throws RegistrationException {
    registrationDelegate.registerObject(key, value, metadata);
  }

  @Override
  public void registerObjects(Map<String, Object> objects) throws RegistrationException {
    registrationDelegate.registerObjects(objects);
  }

  @Override
  protected Object doUnregisterObject(String key) throws RegistrationException {
    return registrationDelegate.unregisterObject(key);
  }

  /**
   * Will fire any lifecycle methods according to the current lifecycle without actually registering the object in the registry.
   * This is useful for prototype objects that are created per request and would clutter the registry with single use objects.
   *
   * @param object the object to process
   * @return the same object with lifecycle methods called (if it has any)
   * @throws MuleException if the registry fails to perform the lifecycle change for the object.
   */
  @Override
  public Object applyLifecycle(Object object) throws MuleException {
    getLifecycleManager().applyCompletedPhases(object);
    return object;
  }

  /**
   * {@inheritDoc}
   */
  @Override
  public Object applyLifecycle(Object object, String phase) throws MuleException {
    if (phase == null) {
      getLifecycleManager().applyCompletedPhases(object);
    } else {
      getLifecycleManager().applyPhase(object, NotInLifecyclePhase.PHASE_NAME, phase);
    }
    return object;
  }

  /**
   * {@inheritDoc}
   */
  @Override
  public void applyLifecycle(Object object, String startPhase, String toPhase) throws MuleException {
    getLifecycleManager().applyPhase(object, startPhase, toPhase);
  }

  /**
   * {@inheritDoc}
   */
  @Override
  public <T> T inject(T object) {
    try {
      return initialiseObject((ConfigurableApplicationContext) applicationContext, EMPTY, object);
    } catch (LifecycleException e) {
      throw new MuleRuntimeException(e);
    }
  }

  private <T> T initialiseObject(ConfigurableApplicationContext applicationContext, String key, T object)
      throws LifecycleException {
    applicationContext.getBeanFactory().autowireBean(object);
    T initialised = (T) applicationContext.getBeanFactory().initializeBean(object, key);

    return initialised;
  }

  protected <T> Map<String, T> internalLookupByType(Class<T> type, boolean nonSingletons, boolean eagerInit) {
    try {
      return BeanFactoryUtils.beansOfTypeIncludingAncestors(applicationContext, type, nonSingletons, eagerInit);
    } catch (FatalBeanException fbex) {
      // FBE is a result of a broken config, propagate it (see MULE-3297 for more details)
      String message = String.format("Failed to lookup beans of type %s from the Spring registry", type);
      throw new MuleRuntimeException(createStaticMessage(message), fbex);
    } catch (Exception e) {
      logger.debug(e.getMessage(), e);
      return Collections.emptyMap();
    }
  }

  protected <T> Map<String, T> internalLookupByTypeWithoutAncestorsAndObjectProviders(Class<T> type, boolean nonSingletons,
                                                                                      boolean eagerInit) {
    try {
      return ((ObjectProviderAwareBeanFactory) applicationContext.getAutowireCapableBeanFactory())
          .getBeansOfTypeWithObjectProviderObjects(type, nonSingletons, eagerInit);
    } catch (FatalBeanException fbex) {
      // FBE is a result of a broken config, propagate it (see MULE-3297 for more details)
      String message = String.format("Failed to lookup beans of type %s from the Spring registry", type);
      throw new MuleRuntimeException(createStaticMessage(message), fbex);
    } catch (Exception e) {
      if (logger.isDebugEnabled()) {
        logger.debug(e.getMessage(), e);
      }
      return Collections.emptyMap();
    }
  }

  // TODO(pablo.kraan): MULE-12609 - making public to be able to use it from a different package
  public <T> Map<String, T> lookupEntriesForLifecycle(Class<T> type) {
    return internalLookupByTypeWithoutAncestorsAndObjectProviders(type, false, false);
  }

  // TODO(pablo.kraan): MULE-12609 - making public to be able to use it from a different package
  public Map<String, Object> getDependencies(String key) {
    if (!readOnly) {
      Map<String, Object> dependents = new HashMap<>();
      for (String dependentKey : ((ConfigurableApplicationContext) applicationContext).getBeanFactory()
          .getDependenciesForBean(key)) {
        boolean isBeanDefinition =
            ((ConfigurableApplicationContext) applicationContext).getBeanFactory().containsBeanDefinition(dependentKey);

        if (isBeanDefinition && applicationContext.isSingleton(dependentKey)) {
          dependents.put(dependentKey, get(dependentKey));
        }
      }

      return dependents;
    }

    throw new UnsupportedOperationException("This operation is only available when this registry is backed by a ConfigurableApplicationContext");
  }

  private class ConfigurableRegistrationDelegate implements RegistrationDelegate {

    private final ConfigurableApplicationContext applicationContext;

    private ConfigurableRegistrationDelegate(ConfigurableApplicationContext applicationContext) {
      this.applicationContext = applicationContext;
    }

    @Override
    public void registerObject(String key, Object value) throws RegistrationException {
      doRegisterObject(key, value);
    }

    @Override
    public void registerObject(String key, Object value, Object metadata) throws RegistrationException {
      registerObject(key, value);
    }

    @Override
    public void registerObjects(Map<String, Object> objects) throws RegistrationException {
      if (objects == null || objects.isEmpty()) {
        return;
      }

      for (Map.Entry<String, Object> entry : objects.entrySet()) {
        registerObject(entry.getKey(), entry.getValue());
      }
    }

    @Override
    public Object unregisterObject(String key) throws RegistrationException {
      Object object = applicationContext.getBean(key);

      if (applicationContext.getBeanFactory().containsBeanDefinition(key)) {
        ((BeanDefinitionRegistry) applicationContext.getBeanFactory()).removeBeanDefinition(key);
      }

      ((DefaultListableBeanFactory) applicationContext.getBeanFactory()).destroySingleton(key);

      return object;
    }

    private void doRegisterObject(String key, Object value) throws RegistrationException {
      synchronized (muleContext) {
        if (springContextInitialised.get()) {
          if (applicationContext.containsBean(key)) {
            if (logger.isWarnEnabled()) {
              logger.warn(String
                  .format("Spring registry already contains an object named '%s'. The previous object will be overwritten.",
                          key));
            }
            SpringRegistry.this.unregisterObject(key);
          }

          try {
            value = initialiseObject(applicationContext, key, value);
            applyLifecycle(value);
            applicationContext.getBeanFactory().registerSingleton(key, value);
          } catch (Exception e) {
            throw new RegistrationException(createStaticMessage("Could not register object for key " + key), e);
          }
        } else {
          // since the context has not yet bean initialized, we register a bean definition instead.
          registeredBeanDefinitionsBeforeInitialization.put(key, genericBeanDefinition(ConstantFactoryBean.class)
              .addConstructorArgValue(value).getBeanDefinition());
        }
      }
    }
  }

  public BeanDependencyResolver getBeanDependencyResolver() {
    return beanDependencyResolver;
  }

  ////////////////////////////////////////////////////////////////////////////////////
  // Registry meta-data
  ////////////////////////////////////////////////////////////////////////////////////

  @Override
  public boolean isReadOnly() {
    return readOnly;
  }

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

}
