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package org.apache.mailbox.tools.indexer;

import javax.inject.Inject;

import org.apache.james.core.User;
import org.apache.james.mailbox.MailboxManager;
import org.apache.james.mailbox.MailboxSession;
import org.apache.james.mailbox.MessageUid;
import org.apache.james.mailbox.exception.MailboxException;
import org.apache.james.mailbox.indexer.ReIndexer;
import org.apache.james.mailbox.indexer.ReIndexingExecutionFailures;
import org.apache.james.mailbox.model.MailboxId;
import org.apache.james.mailbox.model.MailboxPath;
import org.apache.james.mailbox.store.MailboxSessionMapperFactory;
import org.apache.james.task.Task;

/**
 * Note about live re-indexation handling :
 *
 *  - Data races may arise... If you modify the stored value between the received event check and the index operation,
 *  you have an inconsistent behavior (for mailbox renames).
 *
 *  A mechanism for tracking mailbox renames had been implemented, and is taken into account when starting re-indexing a mailbox.
 *  Note that if a mailbox is renamed during its re-indexation process, it will not be taken into account. (We just reduce the inconsistency window).
 */
public class ReIndexerImpl implements ReIndexer {

    private final ReIndexerPerformer reIndexerPerformer;
    private final MailboxManager mailboxManager;
    private final MailboxSessionMapperFactory mapperFactory;

    @Inject
    public ReIndexerImpl(ReIndexerPerformer reIndexerPerformer, MailboxManager mailboxManager, MailboxSessionMapperFactory mapperFactory) {
        this.reIndexerPerformer = reIndexerPerformer;
        this.mailboxManager = mailboxManager;
        this.mapperFactory = mapperFactory;
    }

    @Override
    public Task reIndex(MailboxPath path) throws MailboxException {
        MailboxSession mailboxSession = mailboxManager.createSystemSession(path.getUser());

        MailboxId mailboxId = mailboxManager.getMailbox(path, mailboxSession).getId();

        return new SingleMailboxReindexingTask(reIndexerPerformer, mailboxId);
    }

    @Override
    public Task reIndex(MailboxId mailboxId) throws MailboxException {
        validateIdExists(mailboxId);

        return new SingleMailboxReindexingTask(reIndexerPerformer, mailboxId);
    }

    @Override
    public Task reIndex() {
        return new FullReindexingTask(reIndexerPerformer);
    }

    @Override
    public Task reIndex(User user) {
        return new UserReindexingTask(reIndexerPerformer, user);
    }

    @Override
    public Task reIndex(MailboxPath path, MessageUid uid) throws MailboxException {
        MailboxSession mailboxSession = mailboxManager.createSystemSession(path.getUser());

        MailboxId mailboxId = mailboxManager.getMailbox(path, mailboxSession).getId();

        return new SingleMessageReindexingTask(reIndexerPerformer, mailboxId, uid);
    }

    @Override
    public Task reIndex(MailboxId mailboxId, MessageUid uid) throws MailboxException {
        validateIdExists(mailboxId);

        return new SingleMessageReindexingTask(reIndexerPerformer, mailboxId, uid);
    }

    @Override
    public Task reIndex(ReIndexingExecutionFailures previousFailures) {
        return new ErrorRecoveryIndexationTask(reIndexerPerformer, previousFailures);
    }

    private void validateIdExists(MailboxId mailboxId) throws MailboxException {
        MailboxSession mailboxSession = mailboxManager.createSystemSession("ReIndexingImap");
        mapperFactory.getMailboxMapper(mailboxSession).findMailboxById(mailboxId);
    }
}
