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 * 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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 * 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.mailbox.inmemory.mail;

import java.util.List;
import java.util.Set;
import java.util.concurrent.locks.ReadWriteLock;
import java.util.concurrent.locks.ReentrantReadWriteLock;
import java.util.function.Predicate;

import org.apache.commons.lang3.StringUtils;
import org.apache.james.mailbox.exception.MailboxException;
import org.apache.james.mailbox.inmemory.InMemoryId;
import org.apache.james.mailbox.model.MailboxAnnotation;
import org.apache.james.mailbox.model.MailboxAnnotationKey;
import org.apache.james.mailbox.model.MailboxId;
import org.apache.james.mailbox.store.mail.AnnotationMapper;
import org.apache.james.util.streams.Iterators;

import com.github.steveash.guavate.Guavate;
import com.google.common.base.Preconditions;
import com.google.common.collect.HashBasedTable;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterables;
import com.google.common.collect.Table;

public class InMemoryAnnotationMapper implements AnnotationMapper {
    private final Table<InMemoryId, String, String> mailboxesAnnotations;
    private final ReadWriteLock lock = new ReentrantReadWriteLock();

    public InMemoryAnnotationMapper() {
        mailboxesAnnotations = HashBasedTable.create();
    }

    @Override
    public void endRequest() {

    }

    @Override
    public <T> T execute(Transaction<T> transaction) throws MailboxException {
        return transaction.run();
    }

    private Iterable<MailboxAnnotation> retrieveAllAnnotations(InMemoryId mailboxId) {
        lock.readLock().lock();
        try {
            return Iterables.transform(
                mailboxesAnnotations.row(mailboxId).entrySet(),
                input -> MailboxAnnotation.newInstance(new MailboxAnnotationKey(input.getKey()), input.getValue()));
        } finally {
            lock.readLock().unlock();
        }
    }
    
    @Override
    public List<MailboxAnnotation> getAllAnnotations(MailboxId mailboxId) {
        return ImmutableList.copyOf(retrieveAllAnnotations((InMemoryId)mailboxId));
    }

    @Override
    public List<MailboxAnnotation> getAnnotationsByKeys(MailboxId mailboxId, final Set<MailboxAnnotationKey> keys) {
        return ImmutableList.copyOf(
            Iterables.filter(retrieveAllAnnotations((InMemoryId)mailboxId),
                input -> keys.contains(input.getKey())));
    }

    @Override
    public List<MailboxAnnotation> getAnnotationsByKeysWithAllDepth(MailboxId mailboxId, final Set<MailboxAnnotationKey> keys) {
        return Iterators.toStream(retrieveAllAnnotations((InMemoryId)mailboxId).iterator())
            .filter(getPredicateFilterByAll(keys))
            .collect(Guavate.toImmutableList());
    }

    @Override
    public List<MailboxAnnotation> getAnnotationsByKeysWithOneDepth(MailboxId mailboxId, final Set<MailboxAnnotationKey> keys) {
        return getAnnotationsByKeysWithAllDepth(mailboxId, keys)
            .stream()
            .filter(getPredicateFilterByOne(keys))
            .collect(Guavate.toImmutableList());
    }

    private Predicate<MailboxAnnotation> getPredicateFilterByAll(final Set<MailboxAnnotationKey> keys) {
        return input -> keys.stream().anyMatch(filterAnnotationsByPrefix(input));
    }

    private Predicate<MailboxAnnotation> getPredicateFilterByOne(final Set<MailboxAnnotationKey> keys) {
        return input -> keys.stream().anyMatch(filterAnnotationsByParentKey(input.getKey()));
    }

    private Predicate<MailboxAnnotationKey> filterAnnotationsByParentKey(final MailboxAnnotationKey input) {
        return key -> input.countComponents() <= (key.countComponents() + 1);
    }

    private Predicate<MailboxAnnotationKey> filterAnnotationsByPrefix(final MailboxAnnotation input) {
        return key -> key.equals(input.getKey()) || StringUtils.startsWith(input.getKey().asString(), key.asString() + "/");
    }

    @Override
    public void insertAnnotation(MailboxId mailboxId, MailboxAnnotation mailboxAnnotation) {
        Preconditions.checkArgument(!mailboxAnnotation.isNil());
        lock.writeLock().lock();
        try {
            mailboxesAnnotations.put((InMemoryId)mailboxId, mailboxAnnotation.getKey().asString(), mailboxAnnotation.getValue().get());
        } finally {
            lock.writeLock().unlock();
        }
    }

    @Override
    public void deleteAnnotation(MailboxId mailboxId, MailboxAnnotationKey key) {
        lock.writeLock().lock();
        try {
            mailboxesAnnotations.remove(mailboxId, key.asString());
        } finally {
            lock.writeLock().unlock();
        }
    }

    @Override
    public boolean exist(MailboxId mailboxId, MailboxAnnotation mailboxAnnotation) {
        return mailboxesAnnotations.contains((InMemoryId)mailboxId, mailboxAnnotation.getKey().asString());
    }

    @Override
    public int countAnnotations(MailboxId mailboxId) {
        return mailboxesAnnotations.row((InMemoryId)mailboxId).size();
    }


}
