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 * 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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 * software distributed under the License is distributed on an  *
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 * under the License.                                           *
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package org.apache.james.mailbox.cassandra.mail;

import static org.apache.james.backends.cassandra.Scenario.Builder.fail;
import static org.assertj.core.api.Assertions.assertThat;
import static org.mockito.Mockito.mock;
import static org.mockito.Mockito.when;

import javax.mail.Flags;

import org.apache.james.backends.cassandra.CassandraCluster;
import org.apache.james.backends.cassandra.CassandraClusterExtension;
import org.apache.james.backends.cassandra.components.CassandraModule;
import org.apache.james.core.Username;
import org.apache.james.mailbox.FlagsBuilder;
import org.apache.james.mailbox.MessageUid;
import org.apache.james.mailbox.ModSeq;
import org.apache.james.mailbox.cassandra.ids.CassandraId;
import org.apache.james.mailbox.cassandra.ids.CassandraMessageId;
import org.apache.james.mailbox.cassandra.modules.CassandraApplicableFlagsModule;
import org.apache.james.mailbox.cassandra.modules.CassandraDeletedMessageModule;
import org.apache.james.mailbox.cassandra.modules.CassandraFirstUnseenModule;
import org.apache.james.mailbox.cassandra.modules.CassandraMailboxCounterModule;
import org.apache.james.mailbox.cassandra.modules.CassandraMailboxRecentsModule;
import org.apache.james.mailbox.model.ComposedMessageId;
import org.apache.james.mailbox.model.ComposedMessageIdWithMetaData;
import org.apache.james.mailbox.model.Mailbox;
import org.apache.james.mailbox.model.MailboxPath;
import org.apache.james.mailbox.model.MessageRange;
import org.apache.james.mailbox.model.UidValidity;
import org.apache.james.mailbox.model.UpdatedFlags;
import org.apache.james.mailbox.store.MessageBuilder;
import org.apache.james.mailbox.store.mail.model.MailboxMessage;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Nested;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.extension.RegisterExtension;

import reactor.core.publisher.Mono;

class CassandraIndexTableHandlerTest {

    private static final CassandraId MAILBOX_ID = CassandraId.timeBased();
    private static final MessageUid MESSAGE_UID = MessageUid.of(18L);
    private static final CassandraMessageId CASSANDRA_MESSAGE_ID = new CassandraMessageId.Factory().generate();
    private static final UidValidity UID_VALIDITY = UidValidity.of(15);
    private static final ModSeq MODSEQ = ModSeq.of(17);

    @RegisterExtension
    static CassandraClusterExtension cassandraCluster = new CassandraClusterExtension(
        CassandraModule.aggregateModules(
            CassandraMailboxCounterModule.MODULE,
            CassandraMailboxRecentsModule.MODULE,
            CassandraFirstUnseenModule.MODULE,
            CassandraApplicableFlagsModule.MODULE,
            CassandraDeletedMessageModule.MODULE));

    private CassandraMailboxCounterDAO mailboxCounterDAO;
    private CassandraMailboxRecentsDAO mailboxRecentsDAO;
    private CassandraApplicableFlagDAO applicableFlagDAO;
    private CassandraFirstUnseenDAO firstUnseenDAO;
    private CassandraIndexTableHandler testee;
    private CassandraDeletedMessageDAO deletedMessageDAO;
    private Mailbox mailbox;

    @BeforeEach
    void setUp(CassandraCluster cassandra) {
        mailboxCounterDAO = new CassandraMailboxCounterDAO(cassandra.getConf());
        mailboxRecentsDAO = new CassandraMailboxRecentsDAO(cassandra.getConf());
        firstUnseenDAO = new CassandraFirstUnseenDAO(cassandra.getConf());
        applicableFlagDAO = new CassandraApplicableFlagDAO(cassandra.getConf());
        deletedMessageDAO = new CassandraDeletedMessageDAO(cassandra.getConf());

        testee = new CassandraIndexTableHandler(mailboxRecentsDAO,
                                                mailboxCounterDAO,
                                                firstUnseenDAO,
                                                applicableFlagDAO,
                                                deletedMessageDAO);

        mailbox = new Mailbox(MailboxPath.forUser(Username.of("user"), "name"),
            UID_VALIDITY,
            MAILBOX_ID);
    }

    @Nested
    class Failures {
        @Test
        void messageCountShouldBeUpdatedUponDeletedMessageFailure(CassandraCluster cassandra) throws Exception {
            MailboxMessage message = new MessageBuilder()
                .flags(FlagsBuilder.builder()
                    .add(Flags.Flag.DELETED, Flags.Flag.RECENT)
                    .add("customFlag")
                    .build())
                .build();

            cassandra.getConf().registerScenario(fail()
                .times(1)
                .whenQueryStartsWith("INSERT INTO messageDeleted (mailboxId,uid) VALUES (:mailboxId,:uid);"));

            testee.updateIndexOnAdd(message, MAILBOX_ID)
                .onErrorResume(any -> Mono.empty())
                .block();

            Long actual = mailboxCounterDAO.countMessagesInMailbox(mailbox).block();
            assertThat(actual).isEqualTo(1);
        }
    }

    @Test
    void updateIndexOnAddShouldIncrementMessageCount() throws Exception {
        MailboxMessage message = mock(MailboxMessage.class);
        when(message.createFlags()).thenReturn(new Flags());
        when(message.getUid()).thenReturn(MESSAGE_UID);

        testee.updateIndexOnAdd(message, MAILBOX_ID).block();

        Long actual = mailboxCounterDAO.countMessagesInMailbox(mailbox).block();
        assertThat(actual).isEqualTo(1);
    }

    @Test
    void updateIndexOnAddShouldIncrementUnseenMessageCountWhenUnseen() throws Exception {
        MailboxMessage message = mock(MailboxMessage.class);
        when(message.createFlags()).thenReturn(new Flags());
        when(message.getUid()).thenReturn(MESSAGE_UID);

        testee.updateIndexOnAdd(message, MAILBOX_ID).block();

        Long actual = mailboxCounterDAO.countUnseenMessagesInMailbox(mailbox).block();
        assertThat(actual).isEqualTo(1);
    }

    @Test
    void updateIndexOnAddShouldNotIncrementUnseenMessageCountWhenSeen() throws Exception {
        MailboxMessage message = mock(MailboxMessage.class);
        when(message.createFlags()).thenReturn(new Flags(Flags.Flag.SEEN));
        when(message.getUid()).thenReturn(MESSAGE_UID);

        testee.updateIndexOnAdd(message, MAILBOX_ID).block();

        Long actual = mailboxCounterDAO.countUnseenMessagesInMailbox(mailbox).block();
        assertThat(actual).isEqualTo(0);
    }

    @Test
    void updateIndexOnAddShouldNotAddRecentWhenNoRecent() {
        MailboxMessage message = mock(MailboxMessage.class);
        when(message.createFlags()).thenReturn(new Flags());
        when(message.getUid()).thenReturn(MESSAGE_UID);

        testee.updateIndexOnAdd(message, MAILBOX_ID).block();

        assertThat(mailboxRecentsDAO.getRecentMessageUidsInMailbox(MAILBOX_ID)
            .collectList()
            .block())
            .isEmpty();
    }

    @Test
    void updateIndexOnAddShouldAddRecentWhenRecent() {
        MailboxMessage message = mock(MailboxMessage.class);
        when(message.createFlags()).thenReturn(new Flags(Flags.Flag.RECENT));
        when(message.getUid()).thenReturn(MESSAGE_UID);

        testee.updateIndexOnAdd(message, MAILBOX_ID).block();

        assertThat(mailboxRecentsDAO.getRecentMessageUidsInMailbox(MAILBOX_ID)
            .collectList()
            .block())
            .containsOnly(MESSAGE_UID);
    }

    @Test
    void updateIndexOnDeleteShouldDecrementMessageCount() throws Exception {
        MailboxMessage message = mock(MailboxMessage.class);
        when(message.createFlags()).thenReturn(new Flags());
        when(message.getUid()).thenReturn(MESSAGE_UID);
        testee.updateIndexOnAdd(message, MAILBOX_ID).block();

        testee.updateIndexOnDelete(new ComposedMessageIdWithMetaData(
                new ComposedMessageId(MAILBOX_ID, CASSANDRA_MESSAGE_ID, MESSAGE_UID),
                new Flags(Flags.Flag.RECENT),
                MODSEQ),
            MAILBOX_ID).block();

        Long actual = mailboxCounterDAO.countMessagesInMailbox(mailbox).block();
        assertThat(actual).isEqualTo(0);
    }

    @Test
    void updateIndexOnDeleteShouldDecrementUnseenMessageCountWhenUnseen() throws Exception {
        MailboxMessage message = mock(MailboxMessage.class);
        when(message.createFlags()).thenReturn(new Flags());
        when(message.getUid()).thenReturn(MESSAGE_UID);
        testee.updateIndexOnAdd(message, MAILBOX_ID).block();

        testee.updateIndexOnDelete(new ComposedMessageIdWithMetaData(
                new ComposedMessageId(MAILBOX_ID, CASSANDRA_MESSAGE_ID, MESSAGE_UID),
                new Flags(),
                MODSEQ),
            MAILBOX_ID).block();

        Long actual = mailboxCounterDAO.countUnseenMessagesInMailbox(mailbox).block();
        assertThat(actual).isEqualTo(0);
    }

    @Test
    void updateIndexOnDeleteShouldNotDecrementUnseenMessageCountWhenSeen() throws Exception {
        MailboxMessage message = mock(MailboxMessage.class);
        when(message.createFlags()).thenReturn(new Flags());
        when(message.getUid()).thenReturn(MESSAGE_UID);
        testee.updateIndexOnAdd(message, MAILBOX_ID).block();

        testee.updateIndexOnDelete(new ComposedMessageIdWithMetaData(
                new ComposedMessageId(MAILBOX_ID, CASSANDRA_MESSAGE_ID, MESSAGE_UID),
                new Flags(Flags.Flag.SEEN),
                MODSEQ),
            MAILBOX_ID).block();

        Long actual = mailboxCounterDAO.countUnseenMessagesInMailbox(mailbox).block();
        assertThat(actual).isEqualTo(1);
    }

    @Test
    void updateIndexOnDeleteShouldRemoveRecentWhenRecent() {
        MailboxMessage message = mock(MailboxMessage.class);
        when(message.createFlags()).thenReturn(new Flags(Flags.Flag.RECENT));
        when(message.getUid()).thenReturn(MESSAGE_UID);
        testee.updateIndexOnAdd(message, MAILBOX_ID).block();

        testee.updateIndexOnDelete(new ComposedMessageIdWithMetaData(
                new ComposedMessageId(MAILBOX_ID, CASSANDRA_MESSAGE_ID, MESSAGE_UID),
                new Flags(Flags.Flag.RECENT),
                MODSEQ),
            MAILBOX_ID).block();

        assertThat(mailboxRecentsDAO.getRecentMessageUidsInMailbox(MAILBOX_ID)
            .collectList()
            .block())
            .isEmpty();
    }

    @Test
    void updateIndexOnDeleteShouldRemoveUidFromRecentAnyway() {
        // Clean up strategy if some flags updates missed
        MailboxMessage message = mock(MailboxMessage.class);
        when(message.createFlags()).thenReturn(new Flags(Flags.Flag.RECENT));
        when(message.getUid()).thenReturn(MESSAGE_UID);
        testee.updateIndexOnAdd(message, MAILBOX_ID).block();

        testee.updateIndexOnDelete(new ComposedMessageIdWithMetaData(
                new ComposedMessageId(MAILBOX_ID, CASSANDRA_MESSAGE_ID, MESSAGE_UID),
                new Flags(),
                MODSEQ),
            MAILBOX_ID).block();

        assertThat(mailboxRecentsDAO.getRecentMessageUidsInMailbox(MAILBOX_ID)
            .collectList()
            .block())
            .isEmpty();
    }

    @Test
    void updateIndexOnDeleteShouldDeleteMessageFromDeletedMessage() {
        MailboxMessage message = mock(MailboxMessage.class);
        when(message.getUid()).thenReturn(MESSAGE_UID);
        deletedMessageDAO.addDeleted(MAILBOX_ID, MESSAGE_UID).block();

        testee.updateIndexOnDelete(new ComposedMessageIdWithMetaData(
                new ComposedMessageId(MAILBOX_ID, CASSANDRA_MESSAGE_ID, MESSAGE_UID),
                new Flags(Flags.Flag.DELETED),
                MODSEQ),
            MAILBOX_ID).block();

        assertThat(
            deletedMessageDAO
                .retrieveDeletedMessage(MAILBOX_ID, MessageRange.all())
                .collectList()
                .block())
            .isEmpty();
    }

    @Test
    void updateIndexOnFlagsUpdateShouldNotChangeMessageCount() throws Exception {
        MailboxMessage message = mock(MailboxMessage.class);
        when(message.createFlags()).thenReturn(new Flags());
        when(message.getUid()).thenReturn(MESSAGE_UID);
        testee.updateIndexOnAdd(message, MAILBOX_ID).block();

        testee.updateIndexOnFlagsUpdate(MAILBOX_ID, UpdatedFlags.builder()
            .uid(MESSAGE_UID)
            .newFlags(new Flags(Flags.Flag.RECENT))
            .oldFlags(new Flags())
            .modSeq(MODSEQ)
            .build()).block();

        Long actual = mailboxCounterDAO.countMessagesInMailbox(mailbox).block();
        assertThat(actual).isEqualTo(1);
    }

    @Test
    void updateIndexOnFlagsUpdateShouldDecrementUnseenMessageCountWhenSeenIsSet() throws Exception {
        MailboxMessage message = mock(MailboxMessage.class);
        when(message.createFlags()).thenReturn(new Flags());
        when(message.getUid()).thenReturn(MESSAGE_UID);
        testee.updateIndexOnAdd(message, MAILBOX_ID).block();

        testee.updateIndexOnFlagsUpdate(MAILBOX_ID, UpdatedFlags.builder()
            .uid(MESSAGE_UID)
            .newFlags(new Flags(Flags.Flag.SEEN))
            .oldFlags(new Flags())
            .modSeq(MODSEQ)
            .build()).block();

        Long actual = mailboxCounterDAO.countUnseenMessagesInMailbox(mailbox).block();
        assertThat(actual).isEqualTo(0);
    }

    @Test
    void updateIndexOnFlagsUpdateShouldSaveMessageInDeletedMessageWhenDeletedFlagIsSet() {
        MailboxMessage message = mock(MailboxMessage.class);
        when(message.createFlags()).thenReturn(new Flags());
        when(message.getUid()).thenReturn(MESSAGE_UID);
        testee.updateIndexOnAdd(message, MAILBOX_ID).block();

        testee.updateIndexOnFlagsUpdate(MAILBOX_ID, UpdatedFlags.builder()
            .uid(MESSAGE_UID)
            .newFlags(new Flags(Flags.Flag.DELETED))
            .oldFlags(new Flags())
            .modSeq(MODSEQ)
            .build()).block();

        assertThat(
            deletedMessageDAO
                .retrieveDeletedMessage(MAILBOX_ID, MessageRange.all())
                .collectList()
                .block())
            .containsExactly(MESSAGE_UID);
    }

    @Test
    void updateIndexOnFlagsUpdateShouldRemoveMessageInDeletedMessageWhenDeletedFlagIsUnset() {
        MailboxMessage message = mock(MailboxMessage.class);
        when(message.createFlags()).thenReturn(new Flags());
        when(message.getUid()).thenReturn(MESSAGE_UID);
        testee.updateIndexOnAdd(message, MAILBOX_ID).block();

        deletedMessageDAO.addDeleted(MAILBOX_ID, MESSAGE_UID).block();

        testee.updateIndexOnFlagsUpdate(MAILBOX_ID, UpdatedFlags.builder()
            .uid(MESSAGE_UID)
            .newFlags(new Flags())
            .oldFlags(new Flags(Flags.Flag.DELETED))
            .modSeq(MODSEQ)
            .build()).block();

        assertThat(
            deletedMessageDAO
                .retrieveDeletedMessage(MAILBOX_ID, MessageRange.all())
                .collectList()
                .block())
            .isEmpty();
    }

    @Test
    void updateIndexOnFlagsUpdateShouldNotRemoveMessageInDeletedMessageWhenDeletedFlagIsNotUnset() {
        MailboxMessage message = mock(MailboxMessage.class);
        when(message.createFlags()).thenReturn(new Flags());
        when(message.getUid()).thenReturn(MESSAGE_UID);
        testee.updateIndexOnAdd(message, MAILBOX_ID).block();

        deletedMessageDAO.addDeleted(MAILBOX_ID, MESSAGE_UID).block();

        testee.updateIndexOnFlagsUpdate(MAILBOX_ID, UpdatedFlags.builder()
            .uid(MESSAGE_UID)
            .newFlags(new Flags())
            .oldFlags(new Flags(Flags.Flag.SEEN))
            .modSeq(MODSEQ)
            .build()).block();

        assertThat(
            deletedMessageDAO
                .retrieveDeletedMessage(MAILBOX_ID, MessageRange.all())
                .collectList()
                .block())
            .containsExactly(MESSAGE_UID);
    }

    @Test
    void updateIndexOnFlagsUpdateShouldNotSaveMessageInDeletedMessageWhenDeletedFlagIsNotSet() {
        MailboxMessage message = mock(MailboxMessage.class);
        when(message.createFlags()).thenReturn(new Flags());
        when(message.getUid()).thenReturn(MESSAGE_UID);
        testee.updateIndexOnAdd(message, MAILBOX_ID).block();

        testee.updateIndexOnFlagsUpdate(MAILBOX_ID, UpdatedFlags.builder()
            .uid(MESSAGE_UID)
            .newFlags(new Flags(Flags.Flag.RECENT))
            .oldFlags(new Flags())
            .modSeq(MODSEQ)
            .build()).block();

        assertThat(
            deletedMessageDAO
                .retrieveDeletedMessage(MAILBOX_ID, MessageRange.all())
                .collectList()
                .block())
            .isEmpty();
    }

    @Test
    void updateIndexOnFlagsUpdateShouldIncrementUnseenMessageCountWhenSeenIsUnset() throws Exception {
        MailboxMessage message = mock(MailboxMessage.class);
        when(message.createFlags()).thenReturn(new Flags(Flags.Flag.SEEN));
        when(message.getUid()).thenReturn(MESSAGE_UID);
        testee.updateIndexOnAdd(message, MAILBOX_ID).block();

        testee.updateIndexOnFlagsUpdate(MAILBOX_ID, UpdatedFlags.builder()
            .uid(MESSAGE_UID)
            .newFlags(new Flags())
            .oldFlags(new Flags(Flags.Flag.SEEN))
            .modSeq(MODSEQ)
            .build()).block();

        Long actual = mailboxCounterDAO.countUnseenMessagesInMailbox(mailbox).block();
        assertThat(actual).isEqualTo(1);
    }

    @Test
    void updateIndexOnFlagsUpdateShouldNotChangeUnseenCountWhenBothSeen() throws Exception {
        MailboxMessage message = mock(MailboxMessage.class);
        when(message.createFlags()).thenReturn(new Flags(Flags.Flag.SEEN));
        when(message.getUid()).thenReturn(MESSAGE_UID);
        testee.updateIndexOnAdd(message, MAILBOX_ID).block();

        testee.updateIndexOnFlagsUpdate(MAILBOX_ID, UpdatedFlags.builder()
            .uid(MESSAGE_UID)
            .newFlags(new Flags(Flags.Flag.SEEN))
            .oldFlags(new Flags(Flags.Flag.SEEN))
            .modSeq(MODSEQ)
            .build()).block();

        Long actual = mailboxCounterDAO.countUnseenMessagesInMailbox(mailbox).block();
        assertThat(actual).isEqualTo(0);
    }

    @Test
    void updateIndexOnFlagsUpdateShouldNotChangeUnseenCountWhenBothUnSeen() throws Exception {
        MailboxMessage message = mock(MailboxMessage.class);
        when(message.createFlags()).thenReturn(new Flags());
        when(message.getUid()).thenReturn(MESSAGE_UID);
        testee.updateIndexOnAdd(message, MAILBOX_ID).block();

        testee.updateIndexOnFlagsUpdate(MAILBOX_ID, UpdatedFlags.builder()
            .uid(MESSAGE_UID)
            .newFlags(new Flags())
            .oldFlags(new Flags())
            .modSeq(MODSEQ)
            .build()).block();

        Long actual = mailboxCounterDAO.countUnseenMessagesInMailbox(mailbox).block();
        assertThat(actual).isEqualTo(1);
    }

    @Test
    void updateIndexOnFlagsUpdateShouldAddRecentOnSettingRecentFlag() {
        // Clean up strategy if some flags updates missed
        MailboxMessage message = mock(MailboxMessage.class);
        when(message.createFlags()).thenReturn(new Flags());
        when(message.getUid()).thenReturn(MESSAGE_UID);
        testee.updateIndexOnAdd(message, MAILBOX_ID).block();

        testee.updateIndexOnFlagsUpdate(MAILBOX_ID, UpdatedFlags.builder()
            .uid(MESSAGE_UID)
            .newFlags(new Flags(Flags.Flag.RECENT))
            .oldFlags(new Flags())
            .modSeq(MODSEQ)
            .build()).block();

        assertThat(mailboxRecentsDAO.getRecentMessageUidsInMailbox(MAILBOX_ID)
            .collectList()
            .block())
            .containsOnly(MESSAGE_UID);
    }

    @Test
    void updateIndexOnFlagsUpdateShouldRemoveRecentOnUnsettingRecentFlag() {
        // Clean up strategy if some flags updates missed
        MailboxMessage message = mock(MailboxMessage.class);
        when(message.createFlags()).thenReturn(new Flags(Flags.Flag.RECENT));
        when(message.getUid()).thenReturn(MESSAGE_UID);
        testee.updateIndexOnAdd(message, MAILBOX_ID).block();

        testee.updateIndexOnFlagsUpdate(MAILBOX_ID, UpdatedFlags.builder()
            .uid(MESSAGE_UID)
            .newFlags(new Flags())
            .oldFlags(new Flags(Flags.Flag.RECENT))
            .modSeq(MODSEQ)
            .build()).block();

        assertThat(mailboxRecentsDAO.getRecentMessageUidsInMailbox(MAILBOX_ID)
            .collectList()
            .block())
            .isEmpty();
    }

    @Test
    void updateIndexOnAddShouldUpdateFirstUnseenWhenUnseen() {
        MailboxMessage message = mock(MailboxMessage.class);
        when(message.createFlags()).thenReturn(new Flags());
        when(message.getUid()).thenReturn(MESSAGE_UID);
        testee.updateIndexOnAdd(message, MAILBOX_ID).block();

        MessageUid actual = firstUnseenDAO.retrieveFirstUnread(MAILBOX_ID).block();
        assertThat(actual).isEqualTo(MESSAGE_UID);
    }

    @Test
    void updateIndexOnAddShouldSaveMessageInDeletedWhenDeleted() {
        MailboxMessage message = mock(MailboxMessage.class);
        when(message.createFlags()).thenReturn(new Flags(Flags.Flag.DELETED));
        when(message.getUid()).thenReturn(MESSAGE_UID);
        testee.updateIndexOnAdd(message, MAILBOX_ID).block();

        assertThat(
            deletedMessageDAO
                .retrieveDeletedMessage(MAILBOX_ID, MessageRange.all())
                .collectList()
                .block())
            .containsExactly(MESSAGE_UID);
    }

    @Test
    void updateIndexOnAddShouldNotSaveMessageInDeletedWhenNotDeleted() {
        MailboxMessage message = mock(MailboxMessage.class);
        when(message.createFlags()).thenReturn(new Flags());
        when(message.getUid()).thenReturn(MESSAGE_UID);
        testee.updateIndexOnAdd(message, MAILBOX_ID).block();

        assertThat(
            deletedMessageDAO
                .retrieveDeletedMessage(MAILBOX_ID, MessageRange.all())
                .collectList()
                .block())
            .isEmpty();
    }

    @Test
    void updateIndexOnAddShouldNotUpdateFirstUnseenWhenSeen() {
        MailboxMessage message = mock(MailboxMessage.class);
        when(message.createFlags()).thenReturn(new Flags(Flags.Flag.SEEN));
        when(message.getUid()).thenReturn(MESSAGE_UID);
        testee.updateIndexOnAdd(message, MAILBOX_ID).block();

        Boolean actual = firstUnseenDAO.retrieveFirstUnread(MAILBOX_ID).hasElement().block();
        assertThat(actual).isFalse();
    }

    @Test
    void updateIndexOnFlagsUpdateShouldUpdateLastUnseenWhenSetToSeen() {
        MailboxMessage message = mock(MailboxMessage.class);
        when(message.createFlags()).thenReturn(new Flags());
        when(message.getUid()).thenReturn(MESSAGE_UID);
        testee.updateIndexOnAdd(message, MAILBOX_ID).block();

        testee.updateIndexOnFlagsUpdate(MAILBOX_ID, UpdatedFlags.builder()
            .uid(MESSAGE_UID)
            .newFlags(new Flags(Flags.Flag.SEEN))
            .oldFlags(new Flags())
            .modSeq(MODSEQ)
            .build()).block();

        Boolean actual = firstUnseenDAO.retrieveFirstUnread(MAILBOX_ID).hasElement().block();
        assertThat(actual).isFalse();
    }

    @Test
    void updateIndexOnFlagsUpdateShouldUpdateLastUnseenWhenSetToUnseen() {
        MailboxMessage message = mock(MailboxMessage.class);
        when(message.createFlags()).thenReturn(new Flags(Flags.Flag.SEEN));
        when(message.getUid()).thenReturn(MESSAGE_UID);
        testee.updateIndexOnAdd(message, MAILBOX_ID).block();

        testee.updateIndexOnFlagsUpdate(MAILBOX_ID, UpdatedFlags.builder()
            .uid(MESSAGE_UID)
            .newFlags(new Flags())
            .oldFlags(new Flags(Flags.Flag.SEEN))
            .modSeq(MODSEQ)
            .build()).block();

        MessageUid actual = firstUnseenDAO.retrieveFirstUnread(MAILBOX_ID).block();
        assertThat(actual).isEqualTo(MESSAGE_UID);
    }

    @Test
    void updateIndexOnFlagsUpdateShouldNotUpdateLastUnseenWhenKeepUnseen() {
        MailboxMessage message = mock(MailboxMessage.class);
        when(message.createFlags()).thenReturn(new Flags());
        when(message.getUid()).thenReturn(MESSAGE_UID);
        testee.updateIndexOnAdd(message, MAILBOX_ID).block();

        testee.updateIndexOnFlagsUpdate(MAILBOX_ID, UpdatedFlags.builder()
            .uid(MESSAGE_UID)
            .newFlags(new Flags())
            .oldFlags(new Flags())
            .modSeq(MODSEQ)
            .build()).block();

        MessageUid actual = firstUnseenDAO.retrieveFirstUnread(MAILBOX_ID).block();
        assertThat(actual).isEqualTo(MESSAGE_UID);
    }

    @Test
    void updateIndexOnFlagsUpdateShouldNotUpdateLastUnseenWhenKeepSeen() {
        MailboxMessage message = mock(MailboxMessage.class);
        when(message.createFlags()).thenReturn(new Flags(Flags.Flag.SEEN));
        when(message.getUid()).thenReturn(MESSAGE_UID);
        testee.updateIndexOnAdd(message, MAILBOX_ID).block();

        testee.updateIndexOnFlagsUpdate(MAILBOX_ID, UpdatedFlags.builder()
            .uid(MESSAGE_UID)
            .newFlags(new Flags(Flags.Flag.SEEN))
            .oldFlags(new Flags(Flags.Flag.SEEN))
            .modSeq(MODSEQ)
            .build()).block();

        Boolean actual = firstUnseenDAO.retrieveFirstUnread(MAILBOX_ID).hasElement().block();
        assertThat(actual).isFalse();
    }

    @Test
    void updateIndexOnDeleteShouldUpdateFirstUnseenWhenUnseen() {
        MailboxMessage message = mock(MailboxMessage.class);
        when(message.createFlags()).thenReturn(new Flags());
        when(message.getUid()).thenReturn(MESSAGE_UID);
        testee.updateIndexOnAdd(message, MAILBOX_ID).block();

        testee.updateIndexOnDelete(new ComposedMessageIdWithMetaData(
            new ComposedMessageId(MAILBOX_ID, CASSANDRA_MESSAGE_ID, MESSAGE_UID),
            new Flags(),
            MODSEQ), MAILBOX_ID).block();

        Boolean actual = firstUnseenDAO.retrieveFirstUnread(MAILBOX_ID).hasElement().block();
        assertThat(actual).isFalse();
    }

    @Test
    void updateIndexOnAddShouldUpdateApplicableFlag() {
        Flags customFlags = new Flags("custom");
        MailboxMessage message = mock(MailboxMessage.class);
        when(message.createFlags()).thenReturn(customFlags);
        when(message.getUid()).thenReturn(MESSAGE_UID);
        testee.updateIndexOnAdd(message, MAILBOX_ID).block();

        Flags applicableFlag = applicableFlagDAO.retrieveApplicableFlag(MAILBOX_ID).block();

        assertThat(applicableFlag).isEqualTo(customFlags);
    }

    @Test
    void updateIndexOnFlagsUpdateShouldUnionApplicableFlag() {
        Flags customFlag = new Flags("custom");
        MailboxMessage message = mock(MailboxMessage.class);
        when(message.createFlags()).thenReturn(customFlag);
        when(message.getUid()).thenReturn(MESSAGE_UID);
        testee.updateIndexOnAdd(message, MAILBOX_ID).block();

        Flags customBis = new Flags("customBis");
        testee.updateIndexOnFlagsUpdate(MAILBOX_ID, UpdatedFlags.builder()
            .uid(MESSAGE_UID)
            .newFlags(customBis)
            .oldFlags(customFlag)
            .modSeq(MODSEQ)
            .build()).block();

        Flags applicableFlag = applicableFlagDAO.retrieveApplicableFlag(MAILBOX_ID).block();

        assertThat(applicableFlag).isEqualTo(new FlagsBuilder().add(customFlag, customBis).build());
    }

    @Test
    void applicableFlagShouldKeepAllFlagsEvenTheMessageRemovesFlag() {
        Flags messageFlags = FlagsBuilder.builder()
            .add("custom1", "custom2", "custom3")
            .build();

        MailboxMessage message = mock(MailboxMessage.class);
        when(message.createFlags()).thenReturn(messageFlags);
        when(message.getUid()).thenReturn(MESSAGE_UID);

        testee.updateIndexOnAdd(message, MAILBOX_ID).block();

        testee.updateIndexOnFlagsUpdate(MAILBOX_ID, UpdatedFlags.builder()
            .uid(MESSAGE_UID)
            .newFlags(new Flags())
            .oldFlags(messageFlags)
            .modSeq(MODSEQ)
            .build()).block();

        Flags applicableFlag = applicableFlagDAO.retrieveApplicableFlag(MAILBOX_ID).block();
        assertThat(applicableFlag).isEqualTo(messageFlags);
    }
}
