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package org.apache.james.imap.processor;

import java.io.Closeable;
import java.util.Iterator;
import java.util.List;

import org.apache.james.imap.api.ImapCommand;
import org.apache.james.imap.api.ImapConstants;
import org.apache.james.imap.api.ImapSessionUtils;
import org.apache.james.imap.api.display.HumanReadableText;
import org.apache.james.imap.api.message.IdRange;
import org.apache.james.imap.api.message.response.StatusResponse.ResponseCode;
import org.apache.james.imap.api.message.response.StatusResponseFactory;
import org.apache.james.imap.api.process.ImapProcessor;
import org.apache.james.imap.api.process.ImapSession;
import org.apache.james.imap.api.process.SelectedMailbox;
import org.apache.james.imap.message.request.ExpungeRequest;
import org.apache.james.mailbox.MailboxManager;
import org.apache.james.mailbox.MailboxSession;
import org.apache.james.mailbox.MessageManager;
import org.apache.james.mailbox.MessageManager.MetaData;
import org.apache.james.mailbox.MessageManager.MetaData.FetchGroup;
import org.apache.james.mailbox.MessageUid;
import org.apache.james.mailbox.exception.MailboxException;
import org.apache.james.mailbox.exception.MessageRangeException;
import org.apache.james.mailbox.model.MessageRange;
import org.apache.james.metrics.api.MetricFactory;
import org.apache.james.util.MDCBuilder;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.google.common.collect.ImmutableList;

public class ExpungeProcessor extends AbstractMailboxProcessor<ExpungeRequest> implements CapabilityImplementingProcessor {
    private static final Logger LOGGER = LoggerFactory.getLogger(ExpungeProcessor.class);

    private static final List<String> UIDPLUS = ImmutableList.of("UIDPLUS");

    public ExpungeProcessor(ImapProcessor next, MailboxManager mailboxManager, StatusResponseFactory factory,
            MetricFactory metricFactory) {
        super(ExpungeRequest.class, next, mailboxManager, factory, metricFactory);
    }

    @Override
    protected void doProcess(ExpungeRequest request, ImapSession session, String tag, ImapCommand command, Responder responder) {
        try {
            final MessageManager mailbox = getSelectedMailbox(session);
            final MailboxSession mailboxSession = ImapSessionUtils.getMailboxSession(session);

            int expunged = 0;
            MetaData mdata = mailbox.getMetaData(false, mailboxSession, FetchGroup.NO_COUNT);

            if (!mdata.isWriteable()) {
                no(command, tag, responder, HumanReadableText.MAILBOX_IS_READ_ONLY);
            } else {
                IdRange[] ranges = request.getUidSet();
                if (ranges == null) {
                   expunged = expunge(mailbox, MessageRange.all(), session, mailboxSession);
                } else {
                    // Handle UID EXPUNGE which is part of UIDPLUS
                    // See http://tools.ietf.org/html/rfc4315
                    for (IdRange range : ranges) {
                        MessageRange mRange = messageRange(session.getSelected(), range, true);
                        if (mRange != null) {
                            expunged += expunge(mailbox, mRange, session, mailboxSession);
                        }

                    }

                }
                unsolicitedResponses(session, responder, false);
                
                
                // Check if QRESYNC was enabled and at least one message was expunged. If so we need to respond with an OK response that contain the HIGHESTMODSEQ
                //
                // See RFC5162 3.3 EXPUNGE Command 3.5. UID EXPUNGE Command
                if (EnableProcessor.getEnabledCapabilities(session).contains(ImapConstants.SUPPORTS_QRESYNC)  && expunged > 0) {
                    okComplete(command, tag, ResponseCode.highestModSeq(mdata.getHighestModSeq()), responder);
                } else {
                    okComplete(command, tag, responder);
                }
            }
        } catch (MessageRangeException e) {
            LOGGER.debug("Expunge failed", e);
            taggedBad(command, tag, responder, HumanReadableText.INVALID_MESSAGESET);
        } catch (MailboxException e) {
            LOGGER.error("Expunge failed for mailbox {}", session.getSelected().getMailboxId(), e);
            no(command, tag, responder, HumanReadableText.GENERIC_FAILURE_DURING_PROCESSING);
        }
    }

    private int expunge(MessageManager mailbox, MessageRange range, ImapSession session, MailboxSession mailboxSession) throws MailboxException {
        final Iterator<MessageUid> it = mailbox.expunge(range, mailboxSession);
        final SelectedMailbox selected = session.getSelected();
        int expunged = 0;
        if (mailboxSession != null) {
            while (it.hasNext()) {
                final MessageUid uid = it.next();
                selected.removeRecent(uid);
                expunged++;
            }
        }
        return expunged;
    }

    @Override
    public List<String> getImplementedCapabilities(ImapSession session) {
        return UIDPLUS;
    }

    @Override
    protected Closeable addContextToMDC(ExpungeRequest message) {
        return MDCBuilder.create()
            .addContext(MDCBuilder.ACTION, "EXPUNGE")
            .addContext("uidSet", IdRange.toString(message.getUidSet()))
            .build();
    }
}
