/*
 * Transport.java
 * Copyright (C) 2002 The Free Software Foundation
 * 
 * This file is part of GNU JavaMail, a library.
 * 
 * GNU JavaMail is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 * 
 * GNU JavaMail is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * As a special exception, if you link this library with other files to
 * produce an executable, this library does not by itself cause the
 * resulting executable to be covered by the GNU General Public License.
 * This exception does not however invalidate any other reasons why the
 * executable file might be covered by the GNU General Public License.
 */

package javax.mail;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Iterator;
import javax.mail.event.TransportEvent;
import javax.mail.event.TransportListener;

/**
 * An abstract class that models a message transport.
 * Subclasses provide actual implementations.
 * <p>
 * Note that Transport extends the Service class, which provides many common
 * methods for naming transports, connecting to transports, and listening to
 * connection events.
 *
 * @author <a href='mailto:dog@gnu.org'>Chris Burdess</a>
 * @version 1.3
 */
public abstract class Transport 
  extends Service
{

  /*
   * Transport listener list.
   */
  private ArrayList transportListeners = null;

  /**
   * Constructor.
   * @param session Session object for this Transport.
   * @param url URLName object to be used for this Transport
   */
  public Transport(Session session, URLName url)
  {
    super(session, url);
  }

  /**
   * Send a message.
   * The message will be sent to all recipient addresses specified in the 
   * message (as returned from the Message method 
   * <code>getAllRecipients</code>), using message transports appropriate to
   * each address. The <code>send</code> method calls the 
   * <code>saveChanges</code> method on the message before sending it.
   * <p>
   * If any of the recipient addresses is detected to be invalid by the
   * Transport during message submission, a SendFailedException is thrown.
   * Clients can get more detail about the failure by examining the exception.
   * Whether or not the message is still sent succesfully to any valid 
   * addresses depends on the Transport implementation. See 
   * SendFailedException for more details. Note also that success does not 
   * imply that the message was delivered to the ultimate recipient, as 
   * failures may occur in later stages of delivery. Once a Transport 
   * accepts a message for delivery to a recipient, failures that occur 
   * later should be reported to the user via another mechanism, such as 
   * returning the undeliverable message.
   * @param msg the message to send
   * @exception SendFailedException if the message could not be sent to 
   * some or any of the recipients.
   */
  public static void send(Message msg)
    throws MessagingException
  {
    msg.saveChanges();
    /*
    try
    {
      msg.writeTo(System.out);
    } catch (java.io.IOException e)
    {
      e.printStackTrace();
    }
    */
    doSend(msg, msg.getAllRecipients());
  }

  /**
   * Send the message to the specified addresses, ignoring any recipients
   * specified in the message itself. The <code>send</code> method calls 
   * the <code>saveChanges</code> method on the message before sending it.
   * @param msg the message to send
   * @param addresses the addresses to which to send the message
   * @exception SendFailedException if the message could not be sent to 
   * some or any of the recipients.
   */
  public static void send(Message msg, Address[] addresses)
    throws MessagingException
  {
    msg.saveChanges();
    doSend(msg, addresses);
  }

  /*
   * Performs the send after saveChanges() has been called.
   */
  private static void doSend(Message msg, Address[] addresses)
    throws MessagingException
  {
    if (addresses==null || addresses.length==0)
      throw new SendFailedException("No recipient addresses");

    HashMap addressesByType = new HashMap();
    for (int i = 0; i<addresses.length; i++)
    {
      String type = addresses[i].getType();
      if (addressesByType.containsKey(type))
        ((ArrayList)addressesByType.get(type)).add(addresses[i]);
      else
      {
        ArrayList addressList = new ArrayList();
        addressList.add(addresses[i]);
        addressesByType.put(type, addressList);
      }
    }
    
    int size = addressesByType.size();
    if (size==0)
      throw new SendFailedException("No recipient addresses");
    
    Session session = msg.session;
    if (msg.session==null) 
      msg.session = Session.getDefaultInstance(System.getProperties(), null);

    MessagingException ex = null;
    boolean error = false;
    ArrayList validSent = new ArrayList();
    ArrayList validUnsent = new ArrayList();
    ArrayList invalid = new ArrayList();
    
    for (Iterator i = addressesByType.values().iterator(); i.hasNext();)
    {
      ArrayList addressList = (ArrayList)i.next();
      Address[] addressArray = new Address[addressList.size()];
      addressList.toArray(addressArray);

      if (addressArray.length<1)
        break;
      
      Transport transport = session.getTransport(addressArray[0]);
      if (transport==null)
        invalid.addAll(Arrays.asList(addressArray));
      else
      {
        try
        {
          transport.connect();
          transport.sendMessage(msg, addressArray);
        }
        catch (SendFailedException sfex)
        {
          error = true;
          if (ex==null)
            ex = sfex;
          else
            ex.setNextException(sfex);

          Address[] a;
          
          a = sfex.getValidSentAddresses();
          if (a!=null)
            validSent.addAll(Arrays.asList(a));
          a = sfex.getValidUnsentAddresses();
          if (a!=null)
            validUnsent.addAll(Arrays.asList(a));
          a = sfex.getInvalidAddresses();
          if (a!=null)
            invalid.addAll(Arrays.asList(a));
        }
        catch (MessagingException mex)
        {
          error = true;
          if (ex==null)
            ex = mex;
          else
            ex.setNextException(mex);
        }
        finally
        {
          transport.close();
        }
      }
    }

    if (error || invalid.size()!=0 || validSent.size()!=0)
    {
      Address[] validSentAddresses = null;
      Address[] validUnsentAddresses = null;
      Address[] invalidAddresses = null;
      
      if (validSent.size() > 0)
      {
        validSentAddresses = new Address[validSent.size()];
        validSent.toArray(validSentAddresses);
      }
      if (validUnsent.size() > 0)
      {
        validUnsentAddresses = new Address[validUnsent.size()];
        validUnsent.toArray(validUnsentAddresses);
      }
      if (invalid.size() > 0)
      {
        invalidAddresses = new Address[invalid.size()];
        invalid.toArray(invalidAddresses);
      }
      throw new SendFailedException("Send failed", ex,
          validSentAddresses, validUnsentAddresses, invalidAddresses);
    }
  }

  /**
   * Send the Message to the specified list of addresses.
   * An appropriate TransportEvent indicating the delivery status is 
   * delivered to any TransportListener registered on this Transport. 
   * Also, if any of the addresses is invalid, a SendFailedException is 
   * thrown. Note however, that the message is sent to the valid addresses.
   * <p>
   * Unlike the static <code>send</code> method, the <code>sendMessage</code>
   * method does not call the <code>saveChanges</code> method on the message;
   * the caller should do so.
   * @param msg The Message to be sent
   * @param addresses List of addresses to send this message to
   * @exception SendFailedException if the send failed because of 
   * invalid addresses.
   * @exception MessagingException if the connection is dead 
   * or not in the connected state
   */
  public abstract void sendMessage(Message msg, Address[] addresses)
    throws MessagingException;

  // -- Event management --
  
  /*
   * Because the propagation of events of different kinds in the JavaMail
   * API is so haphazard, I have here sacrificed a small time advantage for
   * readability and consistency.
   *
   * All the various propagation methods now call a method with a name based
   * on the eventual listener method name prefixed by 'fire', as is the
   * preferred pattern for usage of the EventListenerList in Swing.
   *
   * Note that all events are currently delivered synchronously, where in
   * Sun's implementation a different thread is used for event delivery.
   * 
   * TODO Examine the impact of this.
   */
  
  // -- Transport events --

  /**
   * Add a listener for Transport events.
   */
  public void addTransportListener(TransportListener l)
  {
    if (transportListeners==null)
      transportListeners = new ArrayList();
    synchronized (transportListeners)
    {
      transportListeners.add(l);
    }
  }

  /**
   * Remove a listener for Transport events.
   */
  public void removeTransportListener(TransportListener l)
  {
    if (transportListeners!=null)
    {
      synchronized (transportListeners)
      {
        transportListeners.remove(l);
      }
    }
  }

  /**
   * Notify all TransportListeners. Transport implementations are expected to
   * use this method to broadcast TransportEvents.
   */
  protected void notifyTransportListeners(int type, 
      Address[] validSent, Address[] validUnsent, Address[] invalid,
      Message msg)
  {
    TransportEvent event = 
      new TransportEvent(this, type, validSent, validUnsent, invalid, msg);
    switch (type)
    {
      case TransportEvent.MESSAGE_DELIVERED:
        fireMessageDelivered(event);
        break;
      case TransportEvent.MESSAGE_NOT_DELIVERED:
        fireMessageNotDelivered(event);
        break;
      case TransportEvent.MESSAGE_PARTIALLY_DELIVERED:
        fireMessagePartiallyDelivered(event);
        break;
    }
  }

  /*
   * Propagates a MESSAGE_DELIVERED TransportEvent 
   * to all registered listeners.
   */
  void fireMessageDelivered(TransportEvent event)
  {
    if (transportListeners!=null)
    {
      TransportListener[] l = null;
      synchronized (transportListeners)
      {
        l = new TransportListener[transportListeners.size()];
        transportListeners.toArray(l);
      }
      for (int i=0; i<l.length; i++)
        l[i].messageDelivered(event);
    }
  }
  
  /*
   * Propagates a MESSAGE_NOT_DELIVERED TransportEvent 
   * to all registered listeners.
   */
  void fireMessageNotDelivered(TransportEvent event)
  {
    if (transportListeners!=null)
    {
      TransportListener[] l = null;
      synchronized (transportListeners)
      {
        l = new TransportListener[transportListeners.size()];
        transportListeners.toArray(l);
      }
      for (int i=0; i<l.length; i++)
        l[i].messageNotDelivered(event);
    }
  }
  
  /*
   * Propagates a MESSAGE_PARTIALLY_DELIVERED TransportEvent 
   * to all registered listeners.
   */
  void fireMessagePartiallyDelivered(TransportEvent event)
  {
    if (transportListeners!=null)
    {
      TransportListener[] l = null;
      synchronized (transportListeners)
      {
        l = new TransportListener[transportListeners.size()];
        transportListeners.toArray(l);
      }
      for (int i=0; i<l.length; i++)
        l[i].messagePartiallyDelivered(event);
    }
  }
  
}