/*
 * 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.ode.jacob;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import java.lang.reflect.Method;
import java.util.Collections;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;


/**
 * Base-class for method-list objects. Method-lists objects should extends
 * this class <em>and</em> implement one <code>Channel</code> interface.
 */
public abstract class ChannelListener<CT extends Channel> extends JacobObject {
  private static Log __log = LogFactory.getLog(ChannelListener.class);

  private transient Set<Method> _implementedMethods;
  private transient CT _channel;

  protected ChannelListener(CT channel)
        throws IllegalStateException {

    if (this.getClass()
                  .getSuperclass()
                  .getSuperclass() != ChannelListener.class) {
      throw new IllegalStateException("Inheritence in ChannelListener classes not allowed!");
    }

    if (channel == null)
      throw new IllegalArgumentException("Null channel!");
    _channel = channel;

  }

  public CT getChannel() { return _channel; }

  public void setChannel(CT channel) { _channel = channel; }

  public Set<ChannelListener> or(ChannelListener other) {
    HashSet<ChannelListener> retval = new HashSet<ChannelListener>();
    retval.add(this);
    retval.add(other);
    return retval;
  }

  public Set<ChannelListener> or(Set<ChannelListener> other) {
    HashSet<ChannelListener> retval = new HashSet<ChannelListener>(other);
    retval.add(this);
    return retval;
  }
  /**
   * DOCUMENTME
   *
   * @return DOCUMENTME
   */
  public Set<Method> getImplementedMethods() {
    if (_implementedMethods == null) {
    	Set<Method> implementedMethods = new HashSet<Method>();
      getImplementedMethods(implementedMethods, getClass().getSuperclass()); 
      _implementedMethods = Collections.unmodifiableSet(implementedMethods);
    }

    return _implementedMethods;
  }
  
  private Set<Method> getImplementedMethods(Set<Method> methods, Class clazz){
  	Class[] interfaces = clazz.getInterfaces();

    for (int i = 0 ; i < interfaces.length; ++i) {
      if (interfaces[i] != Channel.class) {
      	Method[] allmethods = interfaces[i].getDeclaredMethods();

        for (int j = 0; j < allmethods.length; ++j) {
        	methods.add(allmethods[j]);
        }
        
        getImplementedMethods(methods, interfaces[i]);
      }
    }
  	return methods;
  }

  /**
   * DOCUMENTME
   *
   * @param method DOCUMENTME
   *
   * @return DOCUMENTME
   */
  public Method getMethod(String method) {
    for (Iterator<Method> i = getImplementedMethods().iterator();i.hasNext();) {
      Method meth = i.next();
      if (meth.getName().equals(method)) {
        return meth;
      }
    }
    
    assert !_implementedMethods.contains(method);

    throw new IllegalArgumentException("No such method: " + method + " in " +  _implementedMethods);

  }

  /**
   * Get a description of the object for debugging purposes.
   *
   * @return human-readable description.
   */
  public String toString() {
    StringBuffer buf = new StringBuffer(getClassName());
    buf.append('{');
    for (Iterator<Method> i = getImplementedMethods().iterator(); i.hasNext();) {
      Method method = i.next();
      buf.append(method.getName());
      buf.append("()");

      if (i.hasNext()) {
        buf.append("&");
      }
    }

    buf.append('}');

    return buf.toString();
  }

  protected Log log() {
    return __log;
  }
}