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 * 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   *
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 *   http://www.apache.org/licenses/LICENSE-2.0                 *
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 * 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.                                           *
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package org.apache.james.protocols.smtp.core.fastfail;

import java.util.Collection;

import org.apache.commons.configuration2.Configuration;
import org.apache.commons.configuration2.ex.ConfigurationException;
import org.apache.james.core.MailAddress;
import org.apache.james.core.MaybeSender;
import org.apache.james.protocols.api.ProtocolSession.State;
import org.apache.james.protocols.smtp.SMTPRetCode;
import org.apache.james.protocols.smtp.SMTPSession;
import org.apache.james.protocols.smtp.dsn.DSNStatus;
import org.apache.james.protocols.smtp.hook.HookResult;
import org.apache.james.protocols.smtp.hook.HookReturnCode;
import org.apache.james.protocols.smtp.hook.RcptHook;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

/**
 * This handler can be used to just ignore duplicated recipients. 
 */
public class SupressDuplicateRcptHandler implements RcptHook {
    private static final Logger LOGGER = LoggerFactory.getLogger(SupressDuplicateRcptHandler.class);

    @Override
    public void init(Configuration config) throws ConfigurationException {

    }

    @Override
    public void destroy() {

    }

    @Override
    @SuppressWarnings("unchecked")
    public HookResult doRcpt(SMTPSession session, MaybeSender sender, MailAddress rcpt) {
        Collection<MailAddress> rcptList = (Collection<MailAddress>) session.getAttachment(SMTPSession.RCPT_LIST, State.Transaction);
    
        // Check if the recipient is already in the rcpt list
        if (rcptList != null && rcptList.contains(rcpt)) {
            StringBuilder responseBuffer = new StringBuilder();
        
            responseBuffer.append(DSNStatus.getStatus(DSNStatus.SUCCESS, DSNStatus.ADDRESS_VALID))
                          .append(" Recipient <")
                          .append(rcpt.toString())
                          .append("> OK");
            LOGGER.debug("Duplicate recipient not add to recipient list: {}", rcpt);
            return HookResult.builder()
                .hookReturnCode(HookReturnCode.ok())
                .smtpReturnCode(SMTPRetCode.MAIL_OK)
                .smtpDescription(responseBuffer.toString())
                .build();
        }
        return HookResult.DECLINED;
    }
}
