/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF 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
 *
 *      http://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.apache.tomcat.util.modeler;


import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;
import java.lang.management.ManagementFactory;
import java.net.URL;
import java.util.HashMap;
import java.util.Hashtable;
import java.util.Iterator;
import java.util.List;

import javax.management.DynamicMBean;
import javax.management.MBeanAttributeInfo;
import javax.management.MBeanInfo;
import javax.management.MBeanOperationInfo;
import javax.management.MBeanRegistration;
import javax.management.MBeanServer;
import javax.management.MBeanServerFactory;
import javax.management.MalformedObjectNameException;
import javax.management.ObjectName;

import org.apache.juli.logging.Log;
import org.apache.juli.logging.LogFactory;
import org.apache.tomcat.util.modeler.modules.ModelerSource;

/*
   Issues:
   - exceptions - too many "throws Exception"
   - double check the interfaces
   - start removing the use of the experimental methods in tomcat, then remove
     the methods ( before 1.1 final )
   - is the security enough to prevent Registry being used to avoid the permission
    checks in the mbean server ?
*/

/**
 * Registry for modeler MBeans.
 *
 * This is the main entry point into modeler. It provides methods to create
 * and manipulate model mbeans and simplify their use.
 *
 * This class is itself an mbean.
 *
 * IMPORTANT: public methods not marked with @since x.x are experimental or
 * internal. Should not be used.
 *
 * @author Craig R. McClanahan
 * @author Costin Manolache
 */
public class Registry implements RegistryMBean, MBeanRegistration  {
    /**
     * The Log instance to which we will write our log messages.
     */
    private static final Log log = LogFactory.getLog(Registry.class);

    // Support for the factory methods

    /** Will be used to isolate different apps and enhance security.
     */
    private static final HashMap<Object,Registry> perLoaderRegistries = null;

    /**
     * The registry instance created by our factory method the first time
     * it is called.
     */
    private static Registry registry = null;

    // Per registry fields

    /**
     * The <code>MBeanServer</code> instance that we will use to register
     * management beans.
     */
    private MBeanServer server = null;

    /**
     * The set of ManagedBean instances for the beans this registry
     * knows about, keyed by name.
     */
    private HashMap<String,ManagedBean> descriptors = new HashMap<>();

    /** List of managed beans, keyed by class name
     */
    private HashMap<String,ManagedBean> descriptorsByClass = new HashMap<>();

    // map to avoid duplicated searching or loading descriptors
    private HashMap<String,URL> searchedPaths = new HashMap<>();

    private Object guard;

    // Id - small ints to use array access. No reset on stop()
    // Used for notifications
    private final Hashtable<String,Hashtable<String,Integer>> idDomains =
        new Hashtable<>();
    private final Hashtable<String,int[]> ids = new Hashtable<>();


    // ----------------------------------------------------------- Constructors

    /**
     */
     public Registry() {
        super();
    }

    // -------------------- Static methods  --------------------
    // Factories

    /**
     * Factory method to create (if necessary) and return our
     * <code>Registry</code> instance.
     *
     * The current version uses a static - future versions could use
     * the thread class loader.
     *
     * @param key Support for application isolation. If null, the context class
     * loader will be used ( if setUseContextClassLoader is called ) or the
     * default registry is returned.
     * @param guard Prevent access to the registry by untrusted components
     * @return the registry
     * @since 1.1
     */
    public static synchronized Registry getRegistry(Object key, Object guard) {
        Registry localRegistry;
        if( perLoaderRegistries!=null ) {
            if( key==null )
                key=Thread.currentThread().getContextClassLoader();
            if( key != null ) {
                localRegistry = perLoaderRegistries.get(key);
                if( localRegistry == null ) {
                    localRegistry=new Registry();
//                    localRegistry.key=key;
                    localRegistry.guard=guard;
                    perLoaderRegistries.put( key, localRegistry );
                    return localRegistry;
                }
                if( localRegistry.guard != null &&
                        localRegistry.guard != guard ) {
                    return null; // XXX Should I throw a permission ex ?
                }
                return localRegistry;
            }
        }

        // static
        if (registry == null) {
            registry = new Registry();
        }
        if( registry.guard != null &&
                registry.guard != guard ) {
            return null;
        }
        return (registry);
    }

    // -------------------- Generic methods  --------------------

    /** Lifecycle method - clean up the registry metadata.
     *  Called from resetMetadata().
     *
     * @since 1.1
     */
    @Override
    public void stop() {
        descriptorsByClass = new HashMap<>();
        descriptors = new HashMap<>();
        searchedPaths=new HashMap<>();
    }

    /**
     * Register a bean by creating a modeler mbean and adding it to the
     * MBeanServer.
     *
     * If metadata is not loaded, we'll look up and read a file named
     * "mbeans-descriptors.ser" or "mbeans-descriptors.xml" in the same package
     * or parent.
     *
     * If the bean is an instance of DynamicMBean. it's metadata will be converted
     * to a model mbean and we'll wrap it - so modeler services will be supported
     *
     * If the metadata is still not found, introspection will be used to extract
     * it automatically.
     *
     * If an mbean is already registered under this name, it'll be first
     * unregistered.
     *
     * If the component implements MBeanRegistration, the methods will be called.
     * If the method has a method "setRegistry" that takes a RegistryMBean as
     * parameter, it'll be called with the current registry.
     *
     *
     * @param bean Object to be registered
     * @param oname Name used for registration
     * @param type The type of the mbean, as declared in mbeans-descriptors. If
     * null, the name of the class will be used. This can be used as a hint or
     * by subclasses.
     * @throws Exception if a registration error occurred
     * @since 1.1
     */
    @Override
    public void registerComponent(Object bean, String oname, String type)
           throws Exception
    {
        registerComponent(bean, new ObjectName(oname), type);
    }

    /**
     * Unregister a component. We'll first check if it is registered,
     * and mask all errors. This is mostly a helper.
     *
     * @param oname Name used for unregistration
     *
     * @since 1.1
     */
    @Override
    public void unregisterComponent( String oname ) {
        try {
            unregisterComponent(new ObjectName(oname));
        } catch (MalformedObjectNameException e) {
            log.info("Error creating object name " + e );
        }
    }


    /**
     * Invoke a operation on a list of mbeans. Can be used to implement
     * lifecycle operations.
     *
     * @param mbeans list of ObjectName on which we'll invoke the operations
     * @param operation  Name of the operation ( init, start, stop, etc)
     * @param failFirst  If false, exceptions will be ignored
     * @throws Exception Error invoking operation
     * @since 1.1
     */
    @Override
    public void invoke(List<ObjectName> mbeans, String operation,
            boolean failFirst ) throws Exception {
        if( mbeans==null ) {
            return;
        }
        Iterator<ObjectName> itr = mbeans.iterator();
        while(itr.hasNext()) {
            ObjectName current = itr.next();
            try {
                if(current == null) {
                    continue;
                }
                if(getMethodInfo(current, operation) == null) {
                    continue;
                }
                getMBeanServer().invoke(current, operation,
                        new Object[] {}, new String[] {});

            } catch( Exception t ) {
                if( failFirst ) throw t;
                log.info("Error initializing " + current + " " + t.toString());
            }
        }
    }

    // -------------------- ID registry --------------------

    /**
     * Return an int ID for faster access. Will be used for notifications
     * and for other operations we want to optimize.
     *
     * @param domain Namespace
     * @param name Type of the notification
     * @return An unique id for the domain:name combination
     * @since 1.1
     */
    @Override
    public synchronized int getId( String domain, String name) {
        if( domain==null) {
            domain="";
        }
        Hashtable<String,Integer> domainTable = idDomains.get(domain);
        if( domainTable == null ) {
            domainTable = new Hashtable<>();
            idDomains.put( domain, domainTable);
        }
        if( name==null ) {
            name="";
        }
        Integer i = domainTable.get(name);

        if( i!= null ) {
            return i.intValue();
        }

        int id[] = ids.get(domain);
        if( id == null ) {
            id=new int[1];
            ids.put( domain, id);
        }
        int code=id[0]++;
        domainTable.put( name, Integer.valueOf( code ));
        return code;
    }

    // -------------------- Metadata   --------------------
    // methods from 1.0

    /**
     * Add a new bean metadata to the set of beans known to this registry.
     * This is used by internal components.
     *
     * @param bean The managed bean to be added
     * @since 1.0
     */
    public void addManagedBean(ManagedBean bean) {
        // XXX Use group + name
        descriptors.put(bean.getName(), bean);
        if( bean.getType() != null ) {
            descriptorsByClass.put( bean.getType(), bean );
        }
    }


    /**
     * Find and return the managed bean definition for the specified
     * bean name, if any; otherwise return <code>null</code>.
     *
     * @param name Name of the managed bean to be returned. Since 1.1, both
     *   short names or the full name of the class can be used.
     * @return the managed bean
     * @since 1.0
     */
    public ManagedBean findManagedBean(String name) {
        // XXX Group ?? Use Group + Type
        ManagedBean mb = descriptors.get(name);
        if( mb==null )
            mb = descriptorsByClass.get(name);
        return mb;
    }

    // -------------------- Helpers  --------------------

    /**
     * Get the type of an attribute of the object, from the metadata.
     *
     * @param oname The bean name
     * @param attName The attribute name
     * @return null if metadata about the attribute is not found
     * @since 1.1
     */
    public String getType( ObjectName oname, String attName )
    {
        String type=null;
        MBeanInfo info=null;
        try {
            info=server.getMBeanInfo(oname);
        } catch (Exception e) {
            log.info( "Can't find metadata for object" + oname );
            return null;
        }

        MBeanAttributeInfo attInfo[]=info.getAttributes();
        for( int i=0; i<attInfo.length; i++ ) {
            if( attName.equals(attInfo[i].getName())) {
                type=attInfo[i].getType();
                return type;
            }
        }
        return null;
    }

    /**
     * Find the operation info for a method
     *
     * @param oname The bean name
     * @param opName The operation name
     * @return the operation info for the specified operation
     */
    public MBeanOperationInfo getMethodInfo( ObjectName oname, String opName )
    {
        MBeanInfo info=null;
        try {
            info=server.getMBeanInfo(oname);
        } catch (Exception e) {
            log.info( "Can't find metadata " + oname );
            return null;
        }
        MBeanOperationInfo attInfo[]=info.getOperations();
        for( int i=0; i<attInfo.length; i++ ) {
            if( opName.equals(attInfo[i].getName())) {
                return attInfo[i];
            }
        }
        return null;
    }

    /**
     * Unregister a component. This is just a helper that
     * avoids exceptions by checking if the mbean is already registered
     *
     * @param oname The bean name
     */
    public void unregisterComponent( ObjectName oname ) {
        try {
            if (oname != null && getMBeanServer().isRegistered(oname)) {
                getMBeanServer().unregisterMBean(oname);
            }
        } catch (Throwable t) {
            log.error("Error unregistering mbean", t);
        }
    }

    /**
     * Factory method to create (if necessary) and return our
     * <code>MBeanServer</code> instance.
     * @return the MBean server
     */
    public synchronized MBeanServer getMBeanServer() {
        if (server == null) {
            long t1 = System.currentTimeMillis();
            if (MBeanServerFactory.findMBeanServer(null).size() > 0) {
                server = MBeanServerFactory.findMBeanServer(null).get(0);
                if (log.isDebugEnabled()) {
                    log.debug("Using existing MBeanServer " + (System.currentTimeMillis() - t1));
                }
            } else {
                server = ManagementFactory.getPlatformMBeanServer();
                if (log.isDebugEnabled()) {
                    log.debug("Creating MBeanServer" + (System.currentTimeMillis() - t1));
                }
            }
        }
        return server;
    }

    /**
     * Find or load metadata.
     * @param bean The bean
     * @param beanClass The bean class
     * @param type The registry type
     * @return the managed bean
     * @throws Exception An error occurred
     */
    public ManagedBean findManagedBean(Object bean, Class<?> beanClass,
            String type) throws Exception {
        if( bean!=null && beanClass==null ) {
            beanClass=bean.getClass();
        }

        if( type==null ) {
            type=beanClass.getName();
        }

        // first look for existing descriptor
        ManagedBean managed = findManagedBean(type);

        // Search for a descriptor in the same package
        if( managed==null ) {
            // check package and parent packages
            if( log.isDebugEnabled() ) {
                log.debug( "Looking for descriptor ");
            }
            findDescriptor( beanClass, type );

            managed=findManagedBean(type);
        }

        // Still not found - use introspection
        if( managed==null ) {
            if( log.isDebugEnabled() ) {
                log.debug( "Introspecting ");
            }

            // introspection
            load("MbeansDescriptorsIntrospectionSource", beanClass, type);

            managed=findManagedBean(type);
            if( managed==null ) {
                log.warn( "No metadata found for " + type );
                return null;
            }
            managed.setName( type );
            addManagedBean(managed);
        }
        return managed;
    }


    /**
     * EXPERIMENTAL Convert a string to object, based on type. Used by several
     * components. We could provide some pluggability. It is here to keep
     * things consistent and avoid duplication in other tasks
     *
     * @param type Fully qualified class name of the resulting value
     * @param value String value to be converted
     * @return Converted value
     */
    public Object convertValue(String type, String value)
    {
        Object objValue=value;

        if( type==null || "java.lang.String".equals( type )) {
            // string is default
            objValue=value;
        } else if( "javax.management.ObjectName".equals( type ) ||
                "ObjectName".equals( type )) {
            try {
                objValue=new ObjectName( value );
            } catch (MalformedObjectNameException e) {
                return null;
            }
        } else if( "java.lang.Integer".equals( type ) ||
                "int".equals( type )) {
            objValue=Integer.valueOf( value );
        } else if( "java.lang.Long".equals( type ) ||
                "long".equals( type )) {
            objValue=Long.valueOf( value );
        } else if( "java.lang.Boolean".equals( type ) ||
                "boolean".equals( type )) {
            objValue=Boolean.valueOf( value );
        }
        return objValue;
    }

    /**
     * Experimental. Load descriptors.
     *
     * @param sourceType The source type
     * @param source The bean
     * @param param A type to load
     * @return List of descriptors
     * @throws Exception Error loading descriptors
     */
    public List<ObjectName> load( String sourceType, Object source,
            String param) throws Exception {
        if( log.isTraceEnabled()) {
            log.trace("load " + source );
        }
        String location=null;
        String type=null;
        Object inputsource=null;

        if( source instanceof URL ) {
            URL url=(URL)source;
            location=url.toString();
            type=param;
            inputsource=url.openStream();
            if (sourceType == null && location.endsWith(".xml")) {
                sourceType = "MbeansDescriptorsDigesterSource";
            }
        } else if( source instanceof File ) {
            location=((File)source).getAbsolutePath();
            inputsource=new FileInputStream((File)source);
            type=param;
            if (sourceType == null && location.endsWith(".xml")) {
                sourceType = "MbeansDescriptorsDigesterSource";
            }
        } else if( source instanceof InputStream ) {
            type=param;
            inputsource=source;
        } else if( source instanceof Class<?> ) {
            location=((Class<?>)source).getName();
            type=param;
            inputsource=source;
            if( sourceType== null ) {
                sourceType="MbeansDescriptorsIntrospectionSource";
            }
        }

        if( sourceType==null ) {
            sourceType="MbeansDescriptorsDigesterSource";
        }
        ModelerSource ds=getModelerSource(sourceType);
        List<ObjectName> mbeans =
            ds.loadDescriptors(this, type, inputsource);

        return mbeans;
    }


    /**
     * Register a component
     *
     * @param bean The bean
     * @param oname The object name
     * @param type The registry type
     * @throws Exception Error registering component
     */
    public void registerComponent(Object bean, ObjectName oname, String type)
           throws Exception
    {
        if( log.isDebugEnabled() ) {
            log.debug( "Managed= "+ oname);
        }

        if( bean ==null ) {
            log.error("Null component " + oname );
            return;
        }

        try {
            if( type==null ) {
                type=bean.getClass().getName();
            }

            ManagedBean managed = findManagedBean(null, bean.getClass(), type);

            // The real mbean is created and registered
            DynamicMBean mbean = managed.createMBean(bean);

            if(  getMBeanServer().isRegistered( oname )) {
                if( log.isDebugEnabled()) {
                    log.debug("Unregistering existing component " + oname );
                }
                getMBeanServer().unregisterMBean( oname );
            }

            getMBeanServer().registerMBean( mbean, oname);
        } catch( Exception ex) {
            log.error("Error registering " + oname, ex );
            throw ex;
        }
    }

    /**
     * Lookup the component descriptor in the package and
     * in the parent packages.
     *
     * @param packageName The package name
     * @param classLoader The class loader
     */
    public void loadDescriptors( String packageName, ClassLoader classLoader  ) {
        String res=packageName.replace( '.', '/');

        if( log.isTraceEnabled() ) {
            log.trace("Finding descriptor " + res );
        }

        if( searchedPaths.get( packageName ) != null ) {
            return;
        }

        String descriptors = res + "/mbeans-descriptors.xml";
        URL dURL = classLoader.getResource( descriptors );

        if (dURL == null) {
            return;
        }

        log.debug( "Found " + dURL);
        searchedPaths.put( packageName,  dURL );
        try {
            load("MbeansDescriptorsDigesterSource", dURL, null);
        } catch(Exception ex ) {
            log.error("Error loading " + dURL);
        }
    }

    /**
     * Lookup the component descriptor in the package and
     * in the parent packages.
     */
    private void findDescriptor(Class<?> beanClass, String type) {
        if( type==null ) {
            type=beanClass.getName();
        }
        ClassLoader classLoader=null;
        if( beanClass!=null ) {
            classLoader=beanClass.getClassLoader();
        }
        if( classLoader==null ) {
            classLoader=Thread.currentThread().getContextClassLoader();
        }
        if( classLoader==null ) {
            classLoader=this.getClass().getClassLoader();
        }

        String className=type;
        String pkg=className;
        while( pkg.indexOf( ".") > 0 ) {
            int lastComp=pkg.lastIndexOf( ".");
            if( lastComp <= 0 ) return;
            pkg=pkg.substring(0, lastComp);
            if( searchedPaths.get( pkg ) != null ) {
                return;
            }
            loadDescriptors(pkg, classLoader);
        }
        return;
    }

    private ModelerSource getModelerSource( String type )
            throws Exception
    {
        if( type==null ) type="MbeansDescriptorsDigesterSource";
        if( type.indexOf( ".") < 0 ) {
            type="org.apache.tomcat.util.modeler.modules." + type;
        }

        Class<?> c = Class.forName(type);
        ModelerSource ds=(ModelerSource)c.getConstructor().newInstance();
        return ds;
    }


    // -------------------- Registration  --------------------

    @Override
    public ObjectName preRegister(MBeanServer server,
                                  ObjectName name) throws Exception
    {
        this.server=server;
        return name;
    }

    @Override
    public void postRegister(Boolean registrationDone) {
    }

    @Override
    public void preDeregister() throws Exception {
    }

    @Override
    public void postDeregister() {
    }
}
