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/**************************************************************************************
 https://camel-extra.github.io

 This program is free software; you can redistribute it and/or
 modify it under the terms of the GNU Lesser 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 Lesser General Public License for more details.


 You should have received a copy of the GNU Lesser General Public
 License along with this program; if not, write to the Free Software
 Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 02110-1301, USA.

 http://www.gnu.org/licenses/lgpl-3.0-standalone.html
 ***************************************************************************************/
package org.apache.camel.component.firebase;

import com.google.firebase.database.ChildEventListener;
import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.FirebaseDatabase;
import org.apache.camel.Exchange;
import org.apache.camel.Processor;
import org.apache.camel.RuntimeCamelException;
import org.apache.camel.component.firebase.data.FirebaseMessage;
import org.apache.camel.component.firebase.data.Operation;
import org.apache.camel.impl.DefaultConsumer;

/**
 * Listens to child events of the root reference and forwards the incoming message on the route.
 */
public class FirebaseConsumer extends DefaultConsumer {

    private final FirebaseConfig firebaseConfig;

    private final FirebaseEndpoint endpoint;

    public FirebaseConsumer(FirebaseEndpoint endpoint, Processor processor) {
        super(endpoint, processor);
        this.endpoint = endpoint;
        firebaseConfig = endpoint.getFirebaseConfig();
    }

    @Override
    protected void doStart() throws Exception {
        FirebaseDatabase
                .getInstance(endpoint.getFirebaseApp())
                .getReference(firebaseConfig.getRootReference())
                .addChildEventListener(new FirebaseConsumerEventListener());
    }

    private void forwardMessage(FirebaseMessage o) {
        Exchange exchange = endpoint.createExchange();
        exchange.getIn().setBody(o);

        try {
            // send message to next processor in the route
            getProcessor().process(exchange);
        } catch (Exception e) {
            exchange.setException(new RuntimeCamelException("Message forwarding failed", e));
        } finally {
            // log exception if an exception occurred and was not handled
            if (exchange.getException() != null) {
                getExceptionHandler().handleException("Error processing exchange", exchange, exchange.getException());
            }
        }
    }

    private class FirebaseConsumerEventListener implements ChildEventListener {
        @Override
        public void onChildAdded(DataSnapshot dataSnapshot, String s) {
            forwardMessage(new FirebaseMessage.Builder(Operation.CHILD_ADD, dataSnapshot)
                    .setPreviousChildName(s).build());
        }

        @Override
        public void onChildChanged(DataSnapshot dataSnapshot, String s) {
            forwardMessage(new FirebaseMessage.Builder(Operation.CHILD_CHANGED, dataSnapshot)
                    .setPreviousChildName(s).build());
        }

        @Override
        public void onChildRemoved(DataSnapshot dataSnapshot) {
            forwardMessage(new FirebaseMessage.Builder(Operation.CHILD_REMOVED, dataSnapshot).build());
        }

        @Override
        public void onChildMoved(DataSnapshot dataSnapshot, String s) {
            forwardMessage(new FirebaseMessage.Builder(Operation.CHILD_MOVED, dataSnapshot)
                    .setPreviousChildName(s).build());
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {
            forwardMessage(new FirebaseMessage.Builder(Operation.CANCELLED).setDatabaseError(databaseError)
                    .build());
        }
    }
}