/*
    * Licensed under the GPL License. You may not use this file except in compliance with the License.
    * You may obtain a copy of the License at
    *
    *   https://www.gnu.org/licenses/old-licenses/gpl-2.0.html
    *
    * THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
    * WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR
    * PURPOSE.
   */
  package psiprobe.beans;
  
  import java.lang.management.ManagementFactory;
  import java.util.ArrayList;
  import java.util.List;
  import java.util.Set;
  
  import javax.inject.Inject;
  import javax.management.AttributeNotFoundException;
  import javax.management.InstanceNotFoundException;
  import javax.management.MBeanException;
  import javax.management.MBeanServer;
  import javax.management.MalformedObjectNameException;
  import javax.management.ObjectName;
  import javax.management.ReflectionException;
  import javax.naming.InitialContext;
  import javax.naming.NamingException;
  import javax.sql.DataSource;
  
  import org.apache.catalina.Context;
  import org.apache.catalina.Server;
  import org.apache.catalina.core.StandardServer;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  import psiprobe.beans.accessors.DatasourceAccessor;
  import psiprobe.model.ApplicationResource;
  import psiprobe.model.DataSourceInfo;
  
  /**
   * The Class ResourceResolverBean.
   */
  public class ResourceResolverBean implements ResourceResolver {
  
    /** The Constant logger. */
    private static final Logger logger = LoggerFactory.getLogger(ResourceResolverBean.class);
  
    /**
     * The default resource prefix for JNDI objects in the global scope: <code>java:</code>.
     */
    public static final String DEFAULT_GLOBAL_RESOURCE_PREFIX = "";
  
    /**
     * The default resource prefix for objects in a private application scope:
     * <code>java:comp/env/</code>.
     */
    public static final String DEFAULT_RESOURCE_PREFIX =
        DEFAULT_GLOBAL_RESOURCE_PREFIX + "java:comp/env/";
  
    /** The datasource mappers. */
    @Inject
    private List<String> datasourceMappers;
  
    @Override
    public List<ApplicationResource> getApplicationResources() throws NamingException {
      logger.debug("Reading GLOBAL resources");
      List<ApplicationResource> resources = new ArrayList<>();
  
      MBeanServer server = getMBeanServer();
      if (server != null) {
        try {
          Set<ObjectName> dsNames =
              server.queryNames(new ObjectName("Catalina:type=Resource,resourcetype=Global,*"), null);
          for (ObjectName objectName : dsNames) {
            ApplicationResource resource = new ApplicationResource();
  
            logger.debug("reading resource: {}", objectName);
            resource.setName(getStringAttribute(server, objectName, "name"));
            resource.setType(getStringAttribute(server, objectName, "type"));
            resource.setScope(getStringAttribute(server, objectName, "scope"));
            resource.setAuth(getStringAttribute(server, objectName, "auth"));
            resource.setDescription(getStringAttribute(server, objectName, "description"));
  
            lookupResource(resource, true, true);
  
            resources.add(resource);
          }
        } catch (Exception e) {
          logger.error("There was an error querying JMX server:", e);
        }
      }
      return resources;
    }
  
    @Override
    public synchronized List<ApplicationResource> getApplicationResources(Context context,
        ContainerWrapperBean containerWrapper) throws NamingException {
  
      List<ApplicationResource> resourceList = new ArrayList<>();
 
     boolean contextAvailable = containerWrapper.getTomcatContainer().getAvailable(context);
     if (contextAvailable) {
 
       logger.debug("Reading CONTEXT {}", context.getName());
 
       boolean contextBound = false;
 
       try {
         containerWrapper.getTomcatContainer().bindToContext(context);
         contextBound = true;
       } catch (NamingException e) {
         logger.error("Cannot bind to context. useNaming=false ?");
         logger.debug("", e);
       }
 
       try {
         containerWrapper.getTomcatContainer().addContextResource(context, resourceList);
 
         containerWrapper.getTomcatContainer().addContextResourceLink(context, resourceList);
 
         for (ApplicationResource resourceList1 : resourceList) {
           lookupResource(resourceList1, contextBound, false);
         }
 
       } finally {
         if (contextBound) {
           containerWrapper.getTomcatContainer().unbindFromContext(context);
         }
       }
     }
 
     return resourceList;
   }
 
   /**
    * Lookup resource.
    *
    * @param resource the resource
    * @param contextBound the context bound
    * @param global the global
    */
   public void lookupResource(ApplicationResource resource, boolean contextBound, boolean global) {
     DataSourceInfo dataSourceInfo = null;
     if (contextBound) {
       try {
         javax.naming.Context ctx = !global ? new InitialContext() : getGlobalNamingContext();
         if (ctx == null) {
           logger.error(
               "Unable to find context. This may indicate invalid setup. Check global resources versus requested resources");
           resource.setLookedUp(false);
           return;
         }
         String jndiName = resolveJndiName(resource.getName(), global);
         logger.debug("reading resource jndi name: {}", jndiName);
         Object obj = ctx.lookup(jndiName);
         resource.setLookedUp(true);
         for (String accessorString : datasourceMappers) {
           logger.debug("Looking up datasource adapter: {}", accessorString);
           DatasourceAccessor accessor = Class.forName(accessorString)
               .asSubclass(DatasourceAccessor.class).getDeclaredConstructor().newInstance();
           dataSourceInfo = accessor.getInfo(obj);
           if (dataSourceInfo != null) {
             break;
           }
         }
       } catch (Exception e) {
         resource.setLookedUp(false);
         dataSourceInfo = null;
         logger.error("Failed to lookup: '{}'", resource.getName(), e);
       }
     } else {
       resource.setLookedUp(false);
     }
 
     if (resource.isLookedUp() && dataSourceInfo != null) {
       resource.setDataSourceInfo(dataSourceInfo);
     }
   }
 
   @Override
   public synchronized boolean resetResource(final Context context, String resourceName,
       ContainerWrapperBean containerWrapper) throws NamingException {
 
     if (context != null) {
       containerWrapper.getTomcatContainer().bindToContext(context);
     }
     try {
       javax.naming.Context ctx = context != null ? new InitialContext() : getGlobalNamingContext();
       String jndiName = resolveJndiName(resourceName, context == null);
       try {
         for (String accessorString : datasourceMappers) {
           logger.debug("Resetting datasource adapter: {}", accessorString);
           DatasourceAccessor accessor = Class.forName(accessorString)
               .asSubclass(DatasourceAccessor.class).getDeclaredConstructor().newInstance();
           if (ctx == null) {
             return false;
           }
           Object obj = ctx.lookup(jndiName);
           if (accessor.reset(obj)) {
             return true;
           }
         }
         return false;
       } catch (Exception e) {
         logger.trace("", e);
         return false;
       }
     } finally {
       if (context != null) {
         containerWrapper.getTomcatContainer().unbindFromContext(context);
       }
     }
   }
 
   @Override
   public synchronized DataSource lookupDataSource(final Context context, String resourceName,
       ContainerWrapperBean containerWrapper) throws NamingException {
 
     if (context != null) {
       containerWrapper.getTomcatContainer().bindToContext(context);
     }
     try {
       javax.naming.Context ctx = context != null ? new InitialContext() : getGlobalNamingContext();
       String jndiName = resolveJndiName(resourceName, context == null);
       if (ctx == null) {
         return null;
       }
       Object obj = ctx.lookup(jndiName);
 
       if (obj instanceof DataSource) {
         return (DataSource) obj;
       }
       return null;
     } finally {
       if (context != null) {
         containerWrapper.getTomcatContainer().unbindFromContext(context);
       }
     }
   }
 
   /**
    * Gets the datasource mappers.
    *
    * @return the datasource mappers
    */
   public List<String> getDatasourceMappers() {
     return datasourceMappers;
   }
 
   /**
    * Sets the datasource mappers.
    *
    * @param datasourceMappers the new datasource mappers
    */
   public void setDatasourceMappers(List<String> datasourceMappers) {
     this.datasourceMappers = datasourceMappers;
   }
 
   @Override
   public boolean supportsPrivateResources() {
     return true;
   }
 
   @Override
   public boolean supportsGlobalResources() {
     return true;
   }
 
   @Override
   public boolean supportsDataSourceLookup() {
     return true;
   }
 
   @Override
   public MBeanServer getMBeanServer() {
     return ManagementFactory.getPlatformMBeanServer();
   }
 
   /**
    * Resolves a JNDI resource name by prepending the scope-appropriate prefix.
    *
    * @param name the JNDI name of the resource
    * @param global whether to use the global prefix
    *
    * @return the JNDI resource name with the prefix appended
    *
    * @see #DEFAULT_GLOBAL_RESOURCE_PREFIX
    * @see #DEFAULT_RESOURCE_PREFIX
    */
   protected static String resolveJndiName(String name, boolean global) {
     return (global ? DEFAULT_GLOBAL_RESOURCE_PREFIX : DEFAULT_RESOURCE_PREFIX) + name;
   }
 
   /**
    * Gets the string attribute.
    *
    * @param server the server
    * @param objectName the object name
    * @param attributeName the attribute name
    *
    * @return the string attribute
    */
   private String getStringAttribute(MBeanServer server, ObjectName objectName,
       String attributeName) {
 
     try {
       return (String) server.getAttribute(objectName, attributeName);
     } catch (Exception e) {
       logger.error("Error getting attribute '{}' from '{}'", attributeName, objectName, e);
       return null;
     }
   }
 
   /**
    * Returns the Server's global naming context.
    *
    * @return the global JNDI context
    */
   public static javax.naming.Context getGlobalNamingContext() {
 
     javax.naming.Context globalContext = null;
     MBeanServer mbeanServer = ManagementFactory.getPlatformMBeanServer();
     if (mbeanServer != null) {
       for (String domain : mbeanServer.getDomains()) {
 
         ObjectName name;
         try {
           name = new ObjectName(domain + ":type=Server");
         } catch (MalformedObjectNameException e) {
           logger.error("", e);
           return null;
         }
 
         Server server = null;
         try {
           server = (Server) mbeanServer.getAttribute(name, "managedResource");
         } catch (AttributeNotFoundException | InstanceNotFoundException | MBeanException
             | ReflectionException e) {
           logger.trace("JMX objectName {} does not contain any managedResource", name, e);
         }
 
         // Get Global Naming Context
         if (server instanceof StandardServer) {
           globalContext = server.getGlobalNamingContext();
           break;
         }
       }
     }
 
     return globalContext;
   }
 }