/*
 * 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.sling.jmx.provider.impl;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

import javax.management.Attribute;
import javax.management.AttributeList;
import javax.management.InstanceNotFoundException;
import javax.management.MBeanAttributeInfo;
import javax.management.MBeanInfo;
import javax.management.MBeanServer;
import javax.management.ObjectName;
import javax.management.ReflectionException;

import org.apache.sling.api.resource.AbstractResource;
import org.apache.sling.api.resource.ResourceMetadata;
import org.apache.sling.api.resource.ResourceResolver;
import org.apache.sling.api.resource.ValueMap;
import org.apache.sling.api.wrappers.DeepReadValueMapDecorator;
import org.apache.sling.api.wrappers.ValueMapDecorator;

public class MBeanResource extends AbstractResource {

    private final String path;

    private final ResourceResolver resourceResolver;

    private final ResourceMetadata metadata = new ResourceMetadata();

    private final MBeanInfo info;

    private final ObjectName objectName;

    private final String resourceType;

    /** The mbean server. */
    private final MBeanServer mbeanServer;

    private volatile AttributeList attributeList;

    public MBeanResource(final MBeanServer mbeanServer,
            final ResourceResolver resolver,
            final String resourceType,
            final String path,
            final MBeanInfo info,
            final ObjectName objectName) {
        this.mbeanServer = mbeanServer;
        this.resourceResolver = resolver;
        this.path = path;
        this.info = info;
        this.objectName = objectName;
        final int pos = resourceType.lastIndexOf(':');
        if ( pos == -1 ) {
            this.resourceType = resourceType;
        } else {
            this.resourceType = resourceType.substring(0, pos);
        }
    }

    public AttributeList getAttributes() {
        if ( this.attributeList == null ) {
            final MBeanAttributeInfo[] infos = info.getAttributes();
            final String[] names = new String[infos.length];
            int index = 0;
            for(final MBeanAttributeInfo i : infos) {
                names[index] = i.getName();
                index++;
            }
            try {
                this.attributeList = mbeanServer.getAttributes(objectName, names);
            } catch (InstanceNotFoundException e) {
                // ignore
                this.attributeList = new AttributeList();
            } catch (ReflectionException e) {
                // ignore
                this.attributeList = new AttributeList();
            }
        }
        return this.attributeList;
    }

    /**
     * @see org.apache.sling.api.resource.Resource#getPath()
     */
    public String getPath() {
        return this.path;
    }

    /**
     * @see org.apache.sling.api.resource.Resource#getResourceType()
     */
    public String getResourceType() {
        return resourceType;
    }

    /**
     * @see org.apache.sling.api.resource.Resource#getResourceSuperType()
     */
    public String getResourceSuperType() {
        return Constants.TYPE_MBEAN;
    }

    /**
     * @see org.apache.sling.api.resource.Resource#getResourceMetadata()
     */
    public ResourceMetadata getResourceMetadata() {
        return metadata;
    }

    /**
     * @see org.apache.sling.api.resource.Resource#getResourceResolver()
     */
    public ResourceResolver getResourceResolver() {
        return this.resourceResolver;
    }

    @Override
    public <AdapterType> AdapterType adaptTo(final Class<AdapterType> type) {
        if ( type == ValueMap.class || type == Map.class ) {
            final Map<String, Object> propMap = this.getPropertiesMap();
            return (AdapterType) new DeepReadValueMapDecorator(this, new ValueMapDecorator(propMap));
        }
        return super.adaptTo(type);
    }

    private Map<String, Object> getPropertiesMap() {
        final Map<String, Object> result = new HashMap<String, Object>();
        result.put(Constants.PROP_RESOURCE_TYPE, this.getResourceType());
        result.put(Constants.PROP_RESOURCE_SUPER_TYPE, this.getResourceSuperType());

        if ( this.info.getDescription() != null ) {
            result.put(Constants.PROP_DESCRIPTION, this.info.getDescription());
        }
        result.put(Constants.PROP_CLASSNAME, this.info.getClassName());
        result.put(Constants.PROP_OBJECTNAME, this.objectName.getCanonicalName());

        final AttributeList values = this.getAttributes();
        final Iterator iter = values.iterator();
        while ( iter.hasNext() ) {
            final Attribute a = (Attribute)iter.next();
            final Object value = a.getValue();
            if ( value != null ) {
                result.put(a.getName(), value);
            }
        }

        return result;
    }
}