# MultiCallback.java

    /*
    ** Module   : MultiCallback.java
    ** Abstract : Multiple service callbacks.
    **
    ** Copyright (c) 2017, Golden Code Development Corporation.
    **
    ** -#- -I- --Date-- --------------------------------Description-----------------------------------
    ** 001 HC  20170612 Initial version.
    */
    /*
    ** This program is free software: you can redistribute it and/or modify
    ** it under the terms of the GNU Affero General Public License as
    ** published by the Free Software Foundation, either version 3 of the
    ** License, or (at your option) any later version.
    **
    ** This program 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 Affero General Public License for more details.
    **
    ** You may find a copy of the GNU Affero GPL version 3 at the following
    ** location: https://www.gnu.org/licenses/agpl-3.0.en.html
    **
    ** Additional terms under GNU Affero GPL version 3 section 7:
    **
    **   Under Section 7 of the GNU Affero GPL version 3, the following additional
    **   terms apply to the works covered under the License.  These additional terms
    **   are non-permissive additional terms allowed under Section 7 of the GNU
    **   Affero GPL version 3 and may not be removed by you.
    **
    **   0. Attribution Requirement.
    **
    **     You must preserve all legal notices or author attributions in the covered
    **     work or Appropriate Legal Notices displayed by works containing the covered
    **     work.  You may not remove from the covered work any author or developer
    **     credit already included within the covered work.
    **
    **   1. No License To Use Trademarks.
    **
    **     This license does not grant any license or rights to use the trademarks
    **     Golden Code, FWD, any Golden Code or FWD logo, or any other trademarks
    **     of Golden Code Development Corporation. You are not authorized to use the
    **     name Golden Code, FWD, or the names of any author or contributor, for
    **     publicity purposes without written authorization.
    **
    **   2. No Misrepresentation of Affiliation.
    **
    **     You may not represent yourself as Golden Code Development Corporation or FWD.
    **
    **     You may not represent yourself for publicity purposes as associated with
    **     Golden Code Development Corporation, FWD, or any author or contributor to
    **     the covered work, without written authorization.
    **
    **   3. No Misrepresentation of Source or Origin.
    **
    **     You may not represent the covered work as solely your work.  All modified
    **     versions of the covered work must be marked in a reasonable way to make it
    **     clear that the modified work is not originating from Golden Code Development
    **     Corporation or FWD.  All modified versions must contain the notices of
    **     attribution required in this license.
    */

    package com.goldencode.p2j.admin.client;

    import com.goldencode.p2j.admin.client.application.*;
    import com.goldencode.p2j.admin.shared.*;

    import java.util.*;
    import java.util.logging.*;

    /**
     * The class allows to issue multiple asynchronous service calls and handle results when all
     * calls finish.
     */
    public class MultiCallback
    {
       /** Logger */
       private Logger log = Logger.getLogger(MultiCallback.class.getSimpleName());

       /** Admin service reference */
       private AdminServiceAsync adm;

       /** Alarm service reference */
       private Alarm alarm;

       /* index 0 - Child, 1 - result, 2 - exception */
       private ArrayList<AdminCallback> callbacks = new ArrayList<>();

       /** The number of finished calls */
       private int callbacksDone;

       /** The handler called when all calls finish */
       private Runnable doneHandler;

       /**
        * Default ctor.
        */
       public MultiCallback()
       {
       }

       /**
        * Ctor.
        *
        * @param   adm
        *          Admin service reference
        *
        * @param   alarm
        *          Alarm service reference
        */
       public MultiCallback(AdminServiceAsync adm, Alarm alarm)
       {
          this.adm = adm;
          this.alarm = alarm;
       }

       /**
        * Creates new instance of {@link AdminCallback} that can be used in a service call.
        *
        * @param   <T>
        *          The result type.
        *
        * @return  {@link AdminCallback} reference
        */
       public <T> AdminCallback<T> newCallback()
       {
          AdminCallback<T> cb = new AdminCallback<T>(adm, null)
          {
             @Override
             public void onDone(T result)
             {
                childFinished(this);
             }
          };

          callbacks.add(cb);
          return cb;
       }

       /**
        * Takes a {@link Runnable} that will be called when all service calls finish.
        *
        * @param   run
        *          A {@link Runnable}.
        */
       public void onDone(Runnable run)
       {
          doneHandler = run;
       }

       /**
        * Returns <code>true</code> if all the service calls succeed.
        *
        * @return  success flag
        */
       public boolean isSuccess()
       {
          boolean isSuccess = true;
          for (AdminCallback c : callbacks)
          {
             isSuccess &= c.isSuccess();
          }
          return isSuccess;
       }

       /**
        * Returns all the server messages of all the failed callbacks.
        *
        * @return  list of server messages, an empty list if there are no messages
        */
       public List<String> getServerMessages()
       {
          List<String> messages = new ArrayList<>();
          for (AdminCallback c : callbacks)
          {
             messages.addAll(c.getServerMessages());
          }

          return messages;
       }

       /**
        * All the exceptions of all the failed service calls.
        *
        * @return  list of exceptions or an empty list if no exceptions
        */
       public List<Throwable> getExceptions()
       {
          ArrayList<Throwable> callbackExceptions = new ArrayList<>();
          for (AdminCallback c : callbacks)
          {
             Throwable t = c.getException();
             if (t != null)
             {
                callbackExceptions.add(t);
             }
          }

          return callbackExceptions;
       }

       /**
        * Called when all the child callbacks have finished.
        *
        * @param   doneHandler
        *          The runnable called when all the results are processed.
        */
       protected void handleAllFinished(Runnable doneHandler)
       {
          if (isSuccess())
          {
             // this is a success
             if (doneHandler != null)
             {
                doneHandler.run();
             }
             return;
          }

          List<String> messages = getServerMessages();
          List<Throwable> callbackExceptions = getExceptions();

          if (!callbackExceptions.isEmpty())
          {
             String msg = "Server call error";
             log.severe(msg);
             for (Throwable t : callbackExceptions)
             {
                log.log(Level.SEVERE, "", t);
             }
             messages.add(0, msg);
          }

          if (alarm != null && !messages.isEmpty())
          {
             alarm.ring(messages, doneHandler);
          }
          else
          {
             if (doneHandler != null)
             {
                doneHandler.run();
             }
          }
       }

       /**
        * A handler of single service result.
        *
        * @param   cb
        *          An {@link AdminCallback}.
        */
       private synchronized void childFinished(AdminCallback cb)
       {
          callbacksDone++;
          if (callbacksDone < callbacks.size())
          {
             //  not all callbacks have finished
             return;
          }

          handleAllFinished(doneHandler);
       }
    }