package com.atlassian.plugin.spring;
   
   import com.atlassian.plugin.osgi.hostcomponents.ComponentRegistrar;
   import com.atlassian.plugin.osgi.hostcomponents.ContextClassLoaderStrategy;
   import com.atlassian.plugin.osgi.hostcomponents.HostComponentProvider;
   import com.google.common.collect.ImmutableMap;
   import com.google.common.collect.ImmutableSet;
   import com.google.common.collect.Sets;
   import org.apache.commons.lang.ClassUtils;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  import org.springframework.aop.support.AopUtils;
  import org.springframework.beans.factory.BeanFactory;
  import org.springframework.beans.factory.BeanIsAbstractException;
  import org.springframework.beans.factory.HierarchicalBeanFactory;
  import org.springframework.beans.factory.ListableBeanFactory;
  import org.springframework.beans.factory.NoSuchBeanDefinitionException;
  import org.springframework.beans.factory.annotation.Autowired;
  import org.springframework.beans.factory.config.AbstractFactoryBean;
  import org.springframework.core.annotation.AnnotationUtils;
  
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.HashSet;
  import java.util.List;
  import java.util.Map;
  import java.util.Set;
  
  import static com.atlassian.plugin.osgi.hostcomponents.ContextClassLoaderStrategy.USE_HOST;
  import static com.atlassian.plugin.util.Assertions.notNull;
  
  public class SpringHostComponentProviderFactoryBean extends AbstractFactoryBean {
      private static final Logger log = LoggerFactory.getLogger(SpringHostComponentProviderFactoryBean.class);
  
      private SpringHostComponentProviderConfig springHostComponentProviderConfig;
  
      /**
       * A set of bean names to make available to plugins
       */
      private Set<String> beanNames = Collections.emptySet();
  
      /**
       * Mapping of beanNames to the interfaces it should be exposed as. Note that if a bean name is present an no interface
       * is defined then all its interfaces should be 'exposed'.
       */
      private Map<String, Class[]> beanInterfaces = Collections.emptyMap();
  
      /**
       * Mapping of beanNames with their {@link com.atlassian.plugin.osgi.hostcomponents.ContextClassLoaderStrategy}.
       * Default value is {@link com.atlassian.plugin.osgi.hostcomponents.ContextClassLoaderStrategy#USE_HOST}.
       */
      private Map<String, ContextClassLoaderStrategy> beanContextClassLoaderStrategies = Collections.emptyMap();
  
      private Set<String> bundleTrackingBeans = Collections.emptySet();
  
      public Class getObjectType() {
          return HostComponentProvider.class;
      }
  
      protected Object createInstance() throws Exception {
          if (springHostComponentProviderConfig == null) {
              return new SpringHostComponentProvider(getBeanFactory(), beanNames, beanInterfaces,
                      beanContextClassLoaderStrategies, bundleTrackingBeans, false);
          } else {
              // whatever defined in {@link SpringHostComponentProviderConfig} takes precedence
              return new SpringHostComponentProvider(getBeanFactory(),
                      Sets.union(beanNames, springHostComponentProviderConfig.getBeanNames()),
                      new ImmutableMap.Builder().putAll(beanInterfaces).putAll(springHostComponentProviderConfig.getBeanInterfaces()).build(),
                      new ImmutableMap.Builder().putAll(beanContextClassLoaderStrategies).putAll(springHostComponentProviderConfig.getBeanContextClassLoaderStrategies()).build(),
                      new ImmutableSet.Builder().addAll(bundleTrackingBeans).addAll(springHostComponentProviderConfig.getBundleTrackingBeans()).build(),
                      springHostComponentProviderConfig.isUseAnnotation());
          }
      }
  
      @Autowired(required = false)
      public void setSpringHostComponentProviderConfig(SpringHostComponentProviderConfig springHostComponentProviderConfig) {
          this.springHostComponentProviderConfig = springHostComponentProviderConfig;
      }
  
      // These beanNames, beanInterfaces, beanContextClassLoaderStrategies only exist for keeping plugin framework's custom attributes during the parsing of spring context.
      public void setBeanNames(Set<String> beanNames) {
          this.beanNames = beanNames;
      }
  
      public void setBeanInterfaces(Map<String, Class[]> beanInterfaces) {
          this.beanInterfaces = beanInterfaces;
      }
  
      public void setBeanContextClassLoaderStrategies(Map<String, ContextClassLoaderStrategy> beanContextClassLoaderStrategies) {
          this.beanContextClassLoaderStrategies = beanContextClassLoaderStrategies;
      }
  
      public void setBundleTrackingBeans(Set<String> bundleTrackingBeans) {
          this.bundleTrackingBeans = bundleTrackingBeans;
      }
  
      private static class SpringHostComponentProvider implements HostComponentProvider {
         private final BeanFactory beanFactory;
         private boolean useAnnotation;
         private final Set<String> beanNames;
         private final Map<String, Class[]> beanInterfaces;
         private final Map<String, ContextClassLoaderStrategy> beanContextClassLoaderStrategies;
         private final Set<String> bundleTrackingBeans;
 
         public SpringHostComponentProvider(BeanFactory beanFactory, Set<String> beanNames, Map<String, Class[]> beanInterfaces,
                                            Map<String, ContextClassLoaderStrategy> beanContextClassLoaderStrategies,
                                            Set<String> bundleTrackingBeans, boolean useAnnotation) {
             this.beanFactory = notNull("beanFactory", beanFactory);
             this.useAnnotation = useAnnotation;
             this.beanNames = beanNames != null ? beanNames : new HashSet<String>();
             this.beanInterfaces = beanInterfaces != null ? beanInterfaces : new HashMap<String, Class[]>();
             this.beanContextClassLoaderStrategies = beanContextClassLoaderStrategies != null ? beanContextClassLoaderStrategies : new HashMap<String, ContextClassLoaderStrategy>();
             this.bundleTrackingBeans = bundleTrackingBeans != null ? bundleTrackingBeans : new HashSet<String>();
         }
 
         public void provide(ComponentRegistrar registrar) {
             final Set<String> beansToProvide = new HashSet<String>(beanNames);
             final Map<String, Class[]> interfacesToProvide = new HashMap<String, Class[]>(beanInterfaces);
             final Map<String, ContextClassLoaderStrategy> contextClassLoaderStrategiesToProvide = new HashMap<String, ContextClassLoaderStrategy>(beanContextClassLoaderStrategies);
             final Set<String> bundleTrackingBeansToProvide = new HashSet<String>(bundleTrackingBeans);
 
             if (useAnnotation) {
                 scanForAnnotatedBeans(beansToProvide, interfacesToProvide, contextClassLoaderStrategiesToProvide, bundleTrackingBeansToProvide);
             }
 
             provideBeans(registrar, beansToProvide, interfacesToProvide, contextClassLoaderStrategiesToProvide, bundleTrackingBeansToProvide);
 
             // make sure that host component providers we might have defined in parent bean factories also get a chance to provide their beans.
             if (beanFactory instanceof HierarchicalBeanFactory) {
                 final BeanFactory parentBeanFactory = ((HierarchicalBeanFactory) beanFactory).getParentBeanFactory();
                 if (parentBeanFactory != null) {
                     try {
                         HostComponentProvider provider = (HostComponentProvider) parentBeanFactory.getBean(PluginBeanDefinitionRegistry.HOST_COMPONENT_PROVIDER);
                         if (provider != null) {
                             provider.provide(registrar);
                         }
                     } catch (NoSuchBeanDefinitionException e) {
                         log.debug("Unable to find '" + PluginBeanDefinitionRegistry.HOST_COMPONENT_PROVIDER + "' in the parent bean factory " + parentBeanFactory);
                     }
                 }
             }
         }
 
         private void provideBeans(ComponentRegistrar registrar, Set<String> beanNames, Map<String, Class[]> beanInterfaces,
                                   Map<String, ContextClassLoaderStrategy> beanContextClassLoaderStrategies, Set<String> bundleTrackingBeans) {
             for (String beanName : beanNames) {
                 if (beanFactory.isSingleton(beanName)) {
                     final Object bean = beanFactory.getBean(beanName);
                     Class[] interfaces = beanInterfaces.get(beanName);
                     if (interfaces == null) {
                         interfaces = findInterfaces(getBeanClass(bean));
                     }
                     registrar.register(interfaces)
                             .forInstance(bean)
                             .withName(beanName)
                             .withContextClassLoaderStrategy(beanContextClassLoaderStrategies.containsKey(beanName) ? beanContextClassLoaderStrategies.get(beanName) : USE_HOST)
                             .withTrackBundleEnabled(bundleTrackingBeans.contains(beanName));
                 } else {
                     log.warn("Cannot register bean '{}' as it's scope is not singleton", beanName);
                 }
             }
         }
 
         /**
          * The logic in this method is very similar to the logic in {@link AvailableToPluginsBeanDefinitionRegistryProcessor},
          * but where this class works off the AvailableToPlugins annotation object directly, that class has to work off the
          * lower-level MethodMetadata interface. If the logic in here is altered, then it should most likely be altered
          * there also.
          */
         private void scanForAnnotatedBeans(Set<String> beansToProvide, Map<String, Class[]> interfacesToProvide,
                                            Map<String, ContextClassLoaderStrategy> contextClassLoaderStrategiesToProvide,
                                            Set<String> bundleTrackingBeansToProvide) {
             if (beanFactory instanceof ListableBeanFactory) {
                 for (String beanName : ((ListableBeanFactory) beanFactory).getBeanDefinitionNames()) {
                     try {
                         // Only singleton beans can be registered as service.
                         if (beanFactory.isSingleton(beanName)) {
                             final Class beanClass = getBeanClass(beanFactory.getBean(beanName));
                             final AvailableToPlugins annotation = AnnotationUtils.findAnnotation(beanClass, AvailableToPlugins.class);
                             if (annotation != null) {
                                 beansToProvide.add(beanName);
 
                                 // if interface(s) is defined in the annotation
                                 if (annotation.value() != Void.class || annotation.interfaces().length != 0) {
                                     if (!interfacesToProvide.containsKey(beanName)) {
                                         List<Class> effectiveInterfaces = new ArrayList<Class>();
                                         if (annotation.value() != Void.class) {
                                             effectiveInterfaces.add(annotation.value());
                                         }
 
                                         if (annotation.interfaces().length != 0) {
                                             effectiveInterfaces.addAll(Arrays.asList(annotation.interfaces()));
                                         }
 
                                         interfacesToProvide.put(beanName, effectiveInterfaces.toArray(new Class[0]));
                                     } else {
                                         log.debug("Interfaces for bean '{}' have been defined in XML or in a Module definition, ignoring the interface defined in the annotation", beanName);
                                     }
                                 }
 
                                 if (!contextClassLoaderStrategiesToProvide.containsKey(beanName)) {
                                     contextClassLoaderStrategiesToProvide.put(beanName, annotation.contextClassLoaderStrategy());
                                 } else {
                                     log.debug("Context class loader strategy for bean '{}' has been defined in XML or in a Module definition, ignoring the one defined in the annotation", beanName);
                                 }
 
                                 if (annotation.trackBundle()) {
                                     bundleTrackingBeansToProvide.add(beanName);
                                 }
                             }
                         } else {
                             log.debug("Bean: " + beanName + " skipped during @AvailableToPlugins scanning since it's not a singleton bean");
                         }
                     } catch (BeanIsAbstractException ex) {
                         // skipping abstract beans (is there a better way to check for this?)
                     }
                 }
             } else {
                 log.warn("Could not scan bean factory for beans to make available to plugins, bean factory is not 'listable'");
             }
         }
 
         private Class[] findInterfaces(Class cls) {
             final List<Class> validInterfaces = new ArrayList<Class>();
             for (Class inf : getAllInterfaces(cls)) {
                 if (!inf.getName().startsWith("org.springframework")) {
                     validInterfaces.add(inf);
                 }
             }
             return validInterfaces.toArray(new Class[validInterfaces.size()]);
         }
 
         @SuppressWarnings("unchecked")
         private List<Class> getAllInterfaces(Class cls) {
             return (List<Class>) ClassUtils.getAllInterfaces(cls);
         }
 
         private Class getBeanClass(Object bean) {
             return AopUtils.getTargetClass(bean);
         }
     }
 }