/*
 * Copyright 2010-2013 Ning, Inc.
 * Copyright 2014-2017 Groupon, Inc
 * Copyright 2014-2017 The Billing Project, LLC
 *
 * The Billing Project 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:
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * 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.
 */

package org.killbill.billing.invoice;

import java.math.BigDecimal;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.TreeSet;
import java.util.UUID;

import javax.annotation.Nullable;

import org.joda.time.DateTime;
import org.joda.time.LocalDate;
import org.killbill.billing.ErrorCode;
import org.killbill.billing.ObjectType;
import org.killbill.billing.account.api.Account;
import org.killbill.billing.account.api.AccountApiException;
import org.killbill.billing.account.api.AccountInternalApi;
import org.killbill.billing.account.api.ImmutableAccountData;
import org.killbill.billing.callcontext.InternalCallContext;
import org.killbill.billing.callcontext.InternalTenantContext;
import org.killbill.billing.catalog.api.BillingActionPolicy;
import org.killbill.billing.catalog.api.CatalogApiException;
import org.killbill.billing.catalog.api.PlanPhasePriceOverride;
import org.killbill.billing.catalog.api.PlanPhaseSpecifier;
import org.killbill.billing.entitlement.api.SubscriptionEventType;
import org.killbill.billing.events.BusInternalEvent;
import org.killbill.billing.events.EffectiveSubscriptionInternalEvent;
import org.killbill.billing.events.InvoiceNotificationInternalEvent;
import org.killbill.billing.invoice.api.DefaultInvoiceService;
import org.killbill.billing.invoice.api.DryRunArguments;
import org.killbill.billing.invoice.api.DryRunType;
import org.killbill.billing.invoice.api.Invoice;
import org.killbill.billing.invoice.api.InvoiceApiException;
import org.killbill.billing.invoice.api.InvoiceItem;
import org.killbill.billing.invoice.api.InvoiceItemType;
import org.killbill.billing.invoice.api.InvoiceStatus;
import org.killbill.billing.invoice.api.user.DefaultInvoiceNotificationInternalEvent;
import org.killbill.billing.invoice.api.user.DefaultNullInvoiceEvent;
import org.killbill.billing.invoice.calculator.InvoiceCalculatorUtils;
import org.killbill.billing.invoice.dao.InvoiceDao;
import org.killbill.billing.invoice.dao.InvoiceItemModelDao;
import org.killbill.billing.invoice.dao.InvoiceModelDao;
import org.killbill.billing.invoice.dao.InvoiceModelDaoHelper;
import org.killbill.billing.invoice.dao.InvoiceParentChildModelDao;
import org.killbill.billing.invoice.generator.InvoiceGenerator;
import org.killbill.billing.invoice.generator.InvoiceWithMetadata;
import org.killbill.billing.invoice.generator.InvoiceWithMetadata.SubscriptionFutureNotificationDates;
import org.killbill.billing.invoice.generator.InvoiceWithMetadata.SubscriptionFutureNotificationDates.UsageDef;
import org.killbill.billing.invoice.model.DefaultInvoice;
import org.killbill.billing.invoice.model.FixedPriceInvoiceItem;
import org.killbill.billing.invoice.model.InvoiceItemFactory;
import org.killbill.billing.invoice.model.ItemAdjInvoiceItem;
import org.killbill.billing.invoice.model.ParentInvoiceItem;
import org.killbill.billing.invoice.model.RecurringInvoiceItem;
import org.killbill.billing.invoice.notification.DefaultNextBillingDateNotifier;
import org.killbill.billing.invoice.notification.NextBillingDateNotificationKey;
import org.killbill.billing.junction.BillingEvent;
import org.killbill.billing.junction.BillingEventSet;
import org.killbill.billing.junction.BillingInternalApi;
import org.killbill.billing.subscription.api.SubscriptionBaseInternalApi;
import org.killbill.billing.subscription.api.user.SubscriptionBaseApiException;
import org.killbill.billing.util.UUIDs;
import org.killbill.billing.util.api.TagApiException;
import org.killbill.billing.util.callcontext.CallContext;
import org.killbill.billing.util.callcontext.InternalCallContextFactory;
import org.killbill.billing.util.callcontext.TenantContext;
import org.killbill.billing.util.config.definition.InvoiceConfig;
import org.killbill.billing.util.globallocker.LockerType;
import org.killbill.bus.api.PersistentBus;
import org.killbill.bus.api.PersistentBus.EventBusException;
import org.killbill.clock.Clock;
import org.killbill.commons.locker.GlobalLock;
import org.killbill.commons.locker.GlobalLocker;
import org.killbill.commons.locker.LockFailedException;
import org.killbill.notificationq.api.NotificationEventWithMetadata;
import org.killbill.notificationq.api.NotificationQueue;
import org.killbill.notificationq.api.NotificationQueueService;
import org.killbill.notificationq.api.NotificationQueueService.NoSuchNotificationQueue;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.google.common.base.Function;
import com.google.common.base.Joiner;
import com.google.common.base.Preconditions;
import com.google.common.base.Predicate;
import com.google.common.collect.Collections2;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.Iterables;
import com.google.common.collect.Lists;
import com.google.common.collect.Ordering;
import com.google.inject.Inject;

public class InvoiceDispatcher {

    private static final Logger log = LoggerFactory.getLogger(InvoiceDispatcher.class);

    private static final Ordering<DateTime> UPCOMING_NOTIFICATION_DATE_ORDERING = Ordering.natural();
    private static final Joiner JOINER_COMMA = Joiner.on(",");
    private static final TargetDateDryRunArguments TARGET_DATE_DRY_RUN_ARGUMENTS = new TargetDateDryRunArguments();

    private final InvoiceGenerator generator;
    private final BillingInternalApi billingApi;
    private final AccountInternalApi accountApi;
    private final SubscriptionBaseInternalApi subscriptionApi;
    private final InvoiceDao invoiceDao;
    private final InternalCallContextFactory internalCallContextFactory;
    private final InvoicePluginDispatcher invoicePluginDispatcher;
    private final GlobalLocker locker;
    private final PersistentBus eventBus;
    private final Clock clock;
    private final NotificationQueueService notificationQueueService;
    private final InvoiceConfig invoiceConfig;
    private final ParkedAccountsManager parkedAccountsManager;

    @Inject
    public InvoiceDispatcher(final InvoiceGenerator generator,
                             final AccountInternalApi accountApi,
                             final BillingInternalApi billingApi,
                             final SubscriptionBaseInternalApi SubscriptionApi,
                             final InvoiceDao invoiceDao,
                             final InternalCallContextFactory internalCallContextFactory,
                             final InvoicePluginDispatcher invoicePluginDispatcher,
                             final GlobalLocker locker,
                             final PersistentBus eventBus,
                             final NotificationQueueService notificationQueueService,
                             final InvoiceConfig invoiceConfig,
                             final Clock clock,
                             final ParkedAccountsManager parkedAccountsManager) {
        this.generator = generator;
        this.billingApi = billingApi;
        this.subscriptionApi = SubscriptionApi;
        this.accountApi = accountApi;
        this.invoiceDao = invoiceDao;
        this.internalCallContextFactory = internalCallContextFactory;
        this.invoicePluginDispatcher = invoicePluginDispatcher;
        this.locker = locker;
        this.eventBus = eventBus;
        this.clock = clock;
        this.notificationQueueService = notificationQueueService;
        this.invoiceConfig = invoiceConfig;
        this.parkedAccountsManager = parkedAccountsManager;
    }

    public void processSubscriptionForInvoiceGeneration(final EffectiveSubscriptionInternalEvent transition,
                                                        final InternalCallContext context) throws InvoiceApiException {
        final UUID subscriptionId = transition.getSubscriptionId();
        final LocalDate targetDate = context.toLocalDate(transition.getEffectiveTransitionTime());
        processSubscriptionForInvoiceGeneration(subscriptionId, targetDate, context);
    }

    public void processSubscriptionForInvoiceGeneration(final UUID subscriptionId, final LocalDate targetDate, final InternalCallContext context) throws InvoiceApiException {
        processSubscriptionInternal(subscriptionId, targetDate, false, context);
    }

    public void processSubscriptionForInvoiceNotification(final UUID subscriptionId, final LocalDate targetDate, final InternalCallContext context) throws InvoiceApiException {
        final Invoice dryRunInvoice = processSubscriptionInternal(subscriptionId, targetDate, true, context);
        if (dryRunInvoice != null && dryRunInvoice.getBalance().compareTo(BigDecimal.ZERO) > 0) {
            final InvoiceNotificationInternalEvent event = new DefaultInvoiceNotificationInternalEvent(dryRunInvoice.getAccountId(), dryRunInvoice.getBalance(), dryRunInvoice.getCurrency(),
                                                                                                       context.toUTCDateTime(targetDate), context.getAccountRecordId(), context.getTenantRecordId(), context.getUserToken());
            try {
                eventBus.post(event);
            } catch (EventBusException e) {
                log.warn("Failed to post event {}", event, e);
            }
        }
    }

    private Invoice processSubscriptionInternal(final UUID subscriptionId, final LocalDate targetDate, final boolean dryRunForNotification, final InternalCallContext context) throws InvoiceApiException {
        try {
            if (subscriptionId == null) {
                log.warn("Failed handling SubscriptionBase change.", new InvoiceApiException(ErrorCode.INVOICE_INVALID_TRANSITION));
                return null;
            }
            final UUID accountId = subscriptionApi.getAccountIdFromSubscriptionId(subscriptionId, context);
            final DryRunArguments dryRunArguments = dryRunForNotification ? TARGET_DATE_DRY_RUN_ARGUMENTS : null;

            return processAccountFromNotificationOrBusEvent(accountId, targetDate, dryRunArguments, context);
        } catch (final SubscriptionBaseApiException e) {
            log.warn("Failed handling SubscriptionBase change.",
                     new InvoiceApiException(ErrorCode.INVOICE_NO_ACCOUNT_ID_FOR_SUBSCRIPTION_ID, subscriptionId.toString()));
            return null;
        }
    }

    public Invoice processAccountFromNotificationOrBusEvent(final UUID accountId,
                                                            @Nullable final LocalDate targetDate,
                                                            @Nullable final DryRunArguments dryRunArguments,
                                                            final InternalCallContext context) throws InvoiceApiException {
        if (!invoiceConfig.isInvoicingSystemEnabled(context)) {
            log.warn("Invoicing system is off, parking accountId='{}'", accountId);
            parkAccount(accountId, context);
            return null;
        }

        return processAccount(false, accountId, targetDate, dryRunArguments, context);
    }

    public Invoice processAccount(final boolean isApiCall,
                                  final UUID accountId,
                                  @Nullable final LocalDate targetDate,
                                  @Nullable final DryRunArguments dryRunArguments,
                                  final InternalCallContext context) throws InvoiceApiException {
        boolean parkedAccount = false;
        try {
            parkedAccount = parkedAccountsManager.isParked(context);
            if (parkedAccount && !isApiCall) {
                log.warn("Ignoring invoice generation process for accountId='{}', targetDate='{}', account is parked", accountId.toString(), targetDate);
                return null;
            }
        } catch (final TagApiException e) {
            log.warn("Unable to determine parking state for accountId='{}'", accountId);
        }

        GlobalLock lock = null;
        try {
            lock = locker.lockWithNumberOfTries(LockerType.ACCNT_INV_PAY.toString(), accountId.toString(), invoiceConfig.getMaxGlobalLockRetries());

            return processAccountWithLock(parkedAccount, accountId, targetDate, dryRunArguments, context);
        } catch (final LockFailedException e) {
            log.warn("Failed to process invoice for accountId='{}', targetDate='{}'", accountId.toString(), targetDate, e);
        } finally {
            if (lock != null) {
                lock.release();
            }
        }
        return null;
    }

    private Invoice processAccountWithLock(final boolean parkedAccount,
                                           final UUID accountId,
                                           @Nullable final LocalDate inputTargetDateMaybeNull,
                                           @Nullable final DryRunArguments dryRunArguments,
                                           final InternalCallContext context) throws InvoiceApiException {
        final boolean isDryRun = dryRunArguments != null;
        final boolean upcomingInvoiceDryRun = isDryRun && DryRunType.UPCOMING_INVOICE.equals(dryRunArguments.getDryRunType());

        LocalDate inputTargetDate = inputTargetDateMaybeNull;
        // A null inputTargetDate is only allowed in UPCOMING_INVOICE dryRun mode to have the system compute it
        if (inputTargetDate == null && !upcomingInvoiceDryRun) {
            inputTargetDate = clock.getUTCToday();
        }
        Preconditions.checkArgument(inputTargetDate != null || upcomingInvoiceDryRun, "inputTargetDate is required in non dryRun mode");

        try {
            // Make sure to first set the BCD if needed then get the account object (to have the BCD set)
            final BillingEventSet billingEvents = billingApi.getBillingEventsForAccountAndUpdateAccountBCD(accountId, dryRunArguments, context);
            if (billingEvents.isEmpty()) {
                return null;
            }

            // Avoid pulling all invoices when AUTO_INVOICING_OFF is set since we will disable invoicing later
            // (Note that we can't return right away as we send a NullInvoice event)
            final List<Invoice> existingInvoices = billingEvents.isAccountAutoInvoiceOff() ?
                                                   ImmutableList.<Invoice>of() :
                                                   ImmutableList.<Invoice>copyOf(Collections2.transform(invoiceDao.getInvoicesByAccount(context),
                                                                                                        new Function<InvoiceModelDao, Invoice>() {
                                                                                                            @Override
                                                                                                            public Invoice apply(final InvoiceModelDao input) {
                                                                                                                return new DefaultInvoice(input);
                                                                                                            }
                                                                                                        }));
            Invoice invoice;
            if (!isDryRun) {
                invoice = processAccountWithLockAndInputTargetDate(accountId, inputTargetDate, billingEvents, existingInvoices, false, context);
                if (parkedAccount) {
                    try {
                        log.info("Illegal invoicing state fixed for accountId='{}', unparking account", accountId);
                        parkedAccountsManager.unparkAccount(accountId, context);
                    } catch (final TagApiException ignored) {
                        log.warn("Unable to unpark account", ignored);
                    }
                }
            } else /* Dry run use cases */ {

                final NotificationQueue notificationQueue = notificationQueueService.getNotificationQueue(DefaultInvoiceService.INVOICE_SERVICE_NAME,
                                                                                                          DefaultNextBillingDateNotifier.NEXT_BILLING_DATE_NOTIFIER_QUEUE);
                final Iterable<NotificationEventWithMetadata<NextBillingDateNotificationKey>> futureNotifications = notificationQueue.getFutureNotificationForSearchKeys(context.getAccountRecordId(), context.getTenantRecordId());

                final Map<UUID, DateTime> nextScheduledSubscriptionsEventMap = getNextTransitionsForSubscriptions(billingEvents);

                // List of all existing invoice notifications
                final List<LocalDate> allCandidateTargetDates = getUpcomingInvoiceCandidateDates(futureNotifications, nextScheduledSubscriptionsEventMap, ImmutableList.<UUID>of(), context);

                if (dryRunArguments.getDryRunType() == DryRunType.UPCOMING_INVOICE) {

                    final Iterable<UUID> filteredSubscriptionIdsForDryRun = getFilteredSubscriptionIdsFor_UPCOMING_INVOICE_DryRun(dryRunArguments, billingEvents);

                    // List of existing invoice notifications associated to the filter set of subscriptionIds
                    final List<LocalDate> filteredCandidateTargetDates = Iterables.isEmpty(filteredSubscriptionIdsForDryRun) ?
                                                                         allCandidateTargetDates :
                                                                         getUpcomingInvoiceCandidateDates(futureNotifications, nextScheduledSubscriptionsEventMap, filteredSubscriptionIdsForDryRun, context);

                    if (Iterables.isEmpty(filteredSubscriptionIdsForDryRun)) {
                        invoice = processDryRun_UPCOMING_INVOICE_Invoice(accountId, allCandidateTargetDates, billingEvents, existingInvoices, context);
                    } else {
                        invoice = processDryRun_UPCOMING_INVOICE_FILTERING_Invoice(accountId, filteredCandidateTargetDates, allCandidateTargetDates, billingEvents, existingInvoices, context);
                    }
                } else /* DryRunType.TARGET_DATE, SUBSCRIPTION_ACTION */ {
                    invoice = processDryRun_TARGET_DATE_Invoice(accountId, inputTargetDate, allCandidateTargetDates, billingEvents, existingInvoices, context);
                }
            }
            return invoice;
        } catch (final CatalogApiException e) {
            log.warn("Failed to retrieve BillingEvents for accountId='{}', dryRunArguments='{}'", accountId, dryRunArguments, e);
            return null;
        } catch (final AccountApiException e) {
            log.warn("Failed to retrieve BillingEvents for accountId='{}', dryRunArguments='{}'", accountId, dryRunArguments, e);
            return null;
        } catch (final SubscriptionBaseApiException e) {
            log.warn("Failed to retrieve BillingEvents for accountId='{}', dryRunArguments='{}'", accountId, dryRunArguments, e);
            return null;
        } catch (final InvoiceApiException e) {
            if (e.getCode() == ErrorCode.UNEXPECTED_ERROR.getCode() && !isDryRun) {
                log.warn("Illegal invoicing state detected for accountId='{}', dryRunArguments='{}', parking account", accountId, dryRunArguments, e);
                parkAccount(accountId, context);
            }
            throw e;
        } catch (final NoSuchNotificationQueue e) {
            // Should not happen, notificationQ is only used for dry run mode
            if (!isDryRun) {
                log.warn("Missing notification queue, accountId='{}', dryRunArguments='{}', parking account", accountId, dryRunArguments, e);
                parkAccount(accountId, context);
            }
            throw new InvoiceApiException(ErrorCode.UNEXPECTED_ERROR, "Failed to retrieve future notifications from notificationQ");
        }
    }

    // Return a map of subscriptionId / localDate identifying what is the next upcoming billing transition (PHASE, PAUSE, ..)
    private Map<UUID, DateTime> getNextTransitionsForSubscriptions(final BillingEventSet billingEvents) {

        final DateTime now = clock.getUTCNow();
        final Map<UUID, DateTime> result = new HashMap<UUID, DateTime>();
        for (final BillingEvent evt : billingEvents) {
            final UUID subscriptionId = evt.getSubscription().getId();
            final DateTime evtEffectiveDate = evt.getEffectiveDate();
            if (evtEffectiveDate.compareTo(now) <= 0) {
                continue;
            }
            final DateTime nextUpcomingPerSubscriptionDate = result.get(subscriptionId);
            if (nextUpcomingPerSubscriptionDate == null || nextUpcomingPerSubscriptionDate.compareTo(evtEffectiveDate) > 0) {
                result.put(subscriptionId, evtEffectiveDate);
            }
        }
        return result;
    }

    private Invoice processDryRun_UPCOMING_INVOICE_Invoice(final UUID accountId, final List<LocalDate> allCandidateTargetDates, final BillingEventSet billingEvents, final List<Invoice> existingInvoices, final InternalCallContext context) throws InvoiceApiException {
        for (final LocalDate curTargetDate : allCandidateTargetDates) {
            final Invoice invoice = processAccountWithLockAndInputTargetDate(accountId, curTargetDate, billingEvents, existingInvoices, true, context);
            if (invoice != null) {
                return invoice;
            }
        }
        return null;
    }

    private Invoice processDryRun_UPCOMING_INVOICE_FILTERING_Invoice(final UUID accountId, final List<LocalDate> filteringCandidateTargetDates, final List<LocalDate> allCandidateTargetDates, final BillingEventSet billingEvents, final List<Invoice> existingInvoices, final InternalCallContext context) throws InvoiceApiException {
        for (final LocalDate curTargetDate : filteringCandidateTargetDates) {
            final Invoice invoice = processDryRun_TARGET_DATE_Invoice(accountId, curTargetDate, allCandidateTargetDates, billingEvents, existingInvoices, context);
            if (invoice != null) {
                return invoice;
            }
        }
        return null;
    }

    private Invoice processDryRun_TARGET_DATE_Invoice(final UUID accountId, final LocalDate targetDate, final List<LocalDate> allCandidateTargetDates, final BillingEventSet billingEvents, final List<Invoice> existingInvoices, final InternalCallContext context) throws InvoiceApiException {

        LocalDate prevLocalDate = null;
        for (final LocalDate cur : allCandidateTargetDates) {
            if (cur.compareTo(targetDate) < 0) {
                prevLocalDate = cur;
            } else {
                break;
            }
        }

        // Generate a dryRun invoice for such date if required in such a way that dryRun invoice on our targetDate only contains items that we expect to see
        final Invoice additionalInvoice = prevLocalDate != null ?
                                          processAccountWithLockAndInputTargetDate(accountId, prevLocalDate, billingEvents, existingInvoices, true, context) :
                                          null;

        final List<Invoice> augmentedExistingInvoices = additionalInvoice != null ?
                                                        new ImmutableList.Builder().addAll(existingInvoices).add(additionalInvoice).build() :
                                                        existingInvoices;

        final Invoice targetInvoice = processAccountWithLockAndInputTargetDate(accountId, targetDate, billingEvents, augmentedExistingInvoices, true, context);
        // If our targetDate -- user specified -- did not align with any boundary, we return previous 'additionalInvoice' invoice
        return targetInvoice != null ? targetInvoice : additionalInvoice;
    }

    private void parkAccount(final UUID accountId, final InternalCallContext context) {
        try {
            parkedAccountsManager.parkAccount(accountId, context);
        } catch (final TagApiException ignored) {
            log.warn("Unable to park account", ignored);
        }
    }

    private Iterable<UUID> getFilteredSubscriptionIdsFor_UPCOMING_INVOICE_DryRun(@Nullable final DryRunArguments dryRunArguments, final BillingEventSet billingEvents) {
        if (dryRunArguments == null ||
            !dryRunArguments.getDryRunType().equals(DryRunType.UPCOMING_INVOICE) ||
            (dryRunArguments.getSubscriptionId() == null && dryRunArguments.getBundleId() == null)) {
            return ImmutableList.<UUID>of();
        }

        if (dryRunArguments.getSubscriptionId() != null) {
            return ImmutableList.of(dryRunArguments.getSubscriptionId());
        }

        return Iterables.transform(Iterables.filter(billingEvents, new Predicate<BillingEvent>() {
            @Override
            public boolean apply(final BillingEvent input) {
                return input.getSubscription().getBundleId().equals(dryRunArguments.getBundleId());
            }
        }), new Function<BillingEvent, UUID>() {
            @Override
            public UUID apply(final BillingEvent input) {
                return input.getSubscription().getId();
            }
        });
    }

    private Invoice processAccountWithLockAndInputTargetDate(final UUID accountId,
                                                             final LocalDate targetDate,
                                                             final BillingEventSet billingEvents,
                                                             final List<Invoice> existingInvoices,
                                                             final boolean isDryRun,
                                                             final InternalCallContext internalCallContext) throws InvoiceApiException {
        final ImmutableAccountData account;
        try {
            account = accountApi.getImmutableAccountDataById(accountId, internalCallContext);
        } catch (final AccountApiException e) {
            log.error("Unable to generate invoice for accountId='{}', a future notification has NOT been recorded", accountId, e);
            return null;
        }

        final InvoiceWithMetadata invoiceWithMetadata = generateKillBillInvoice(account, targetDate, billingEvents, existingInvoices, internalCallContext);
        final DefaultInvoice invoice = invoiceWithMetadata.getInvoice();

        // Compute future notifications
        final FutureAccountNotifications futureAccountNotifications = createNextFutureNotificationDate(invoiceWithMetadata, billingEvents, internalCallContext);

        // If invoice comes back null, there is nothing new to generate, we can bail early
        if (invoice == null) {
            if (isDryRun) {
                log.info("Generated null dryRun invoice for accountId='{}', targetDate='{}'", accountId, targetDate);
            } else {
                log.info("Generated null invoice for accountId='{}', targetDate='{}'", accountId, targetDate);

                final BusInternalEvent event = new DefaultNullInvoiceEvent(accountId, clock.getUTCToday(),
                                                                           internalCallContext.getAccountRecordId(), internalCallContext.getTenantRecordId(), internalCallContext.getUserToken());

                commitInvoiceAndSetFutureNotifications(account, null, futureAccountNotifications, internalCallContext);
                postEvent(event);
            }
            return null;
        }

        boolean success = false;
        try {
            // Generate missing credit (> 0 for generation and < 0 for use) prior we call the plugin
            final InvoiceItem cbaItemPreInvoicePlugins = computeCBAOnExistingInvoice(invoice, internalCallContext);
            DefaultInvoice tmpInvoiceForInvoicePlugins = invoice;
            if (cbaItemPreInvoicePlugins != null) {
                tmpInvoiceForInvoicePlugins = (DefaultInvoice) tmpInvoiceForInvoicePlugins.clone();
                tmpInvoiceForInvoicePlugins.addInvoiceItem(cbaItemPreInvoicePlugins);
            }
            //
            // Ask external invoice plugins if additional items (tax, etc) shall be added to the invoice
            //
            final CallContext callContext = buildCallContext(internalCallContext);
            final List<InvoiceItem> additionalInvoiceItemsFromPlugins = invoicePluginDispatcher.getAdditionalInvoiceItems(tmpInvoiceForInvoicePlugins, isDryRun, callContext, internalCallContext);
            if (additionalInvoiceItemsFromPlugins.isEmpty()) {
                // PERF: avoid re-computing the CBA if no change was made
                if (cbaItemPreInvoicePlugins != null) {
                    invoice.addInvoiceItem(cbaItemPreInvoicePlugins);
                }
            } else {

                // Add or update items from generated invoice
                for (final InvoiceItem cur : additionalInvoiceItemsFromPlugins) {
                    final InvoiceItem exitingItem = Iterables.tryFind(tmpInvoiceForInvoicePlugins.getInvoiceItems(), new Predicate<InvoiceItem>() {
                        @Override
                        public boolean apply(final InvoiceItem input) {
                            return input.getId().equals(cur.getId());
                        }
                    }).orNull();
                    if (exitingItem != null) {
                        invoice.removeInvoiceItem(exitingItem);
                    }
                    invoice.addInvoiceItem(cur);
                }

                // Use credit after we call the plugin (https://github.com/killbill/killbill/issues/637)
                final InvoiceItem cbaItemPostInvoicePlugins = computeCBAOnExistingInvoice(invoice, internalCallContext);
                if (cbaItemPostInvoicePlugins != null) {
                    invoice.addInvoiceItem(cbaItemPostInvoicePlugins);
                }
            }

            if (!isDryRun) {

                // Compute whether this is a new invoice object (or just some adjustments on an existing invoice), and extract invoiceIds for later use
                final Set<UUID> uniqueInvoiceIds = getUniqueInvoiceIds(invoice);
                final boolean isRealInvoiceWithItems = uniqueInvoiceIds.remove(invoice.getId());
                final Set<UUID> adjustedUniqueOtherInvoiceId = uniqueInvoiceIds;

                logInvoiceWithItems(account, invoice, targetDate, adjustedUniqueOtherInvoiceId, isRealInvoiceWithItems);

                // Transformation to Invoice -> InvoiceModelDao
                final InvoiceModelDao invoiceModelDao = new InvoiceModelDao(invoice);
                final List<InvoiceItemModelDao> invoiceItemModelDaos = transformToInvoiceModelDao(invoice.getInvoiceItems());
                invoiceModelDao.addInvoiceItems(invoiceItemModelDaos);

                // Commit invoice on disk
                commitInvoiceAndSetFutureNotifications(account, invoiceModelDao, futureAccountNotifications, internalCallContext);
                success = true;

                try {
                    setChargedThroughDates(invoice.getInvoiceItems(FixedPriceInvoiceItem.class), invoice.getInvoiceItems(RecurringInvoiceItem.class), internalCallContext);
                } catch (final SubscriptionBaseApiException e) {
                    log.error("Failed handling SubscriptionBase change.", e);
                    return null;
                }
            }
        } finally {
            // Make sure we always set future notifications in case of errors
            if (!isDryRun && !success) {
                commitInvoiceAndSetFutureNotifications(account, null, futureAccountNotifications, internalCallContext);
            }
        }

        return invoice;
    }

    private InvoiceWithMetadata generateKillBillInvoice(final ImmutableAccountData account, final LocalDate targetDate, final BillingEventSet billingEvents, final List<Invoice> existingInvoices, final InternalCallContext context) throws InvoiceApiException {
        final UUID targetInvoiceId;
        // Filter out DRAFT invoices for computation  of existing items unless Account is in AUTO_INVOICING_REUSE_DRAFT
        if (billingEvents.isAccountAutoInvoiceReuseDraft()) {
            final Invoice existingDraft = Iterables.tryFind(existingInvoices, new Predicate<Invoice>() {
                @Override
                public boolean apply(final Invoice input) {
                    return input.getStatus() == InvoiceStatus.DRAFT;
                }
            }).orNull();
            targetInvoiceId = existingDraft != null ? existingDraft.getId() : null;
        } else {
            targetInvoiceId = null;
        }

        return generator.generateInvoice(account, billingEvents, existingInvoices, targetInvoiceId, targetDate, account.getCurrency(), context);
    }

    private FutureAccountNotifications createNextFutureNotificationDate(final InvoiceWithMetadata invoiceWithMetadata, final BillingEventSet billingEvents, final InternalCallContext context) {

        final Map<LocalDate, Set<UUID>> notificationListForTrigger = new HashMap<LocalDate, Set<UUID>>();

        for (final UUID subscriptionId : invoiceWithMetadata.getPerSubscriptionFutureNotificationDates().keySet()) {

            final SubscriptionFutureNotificationDates subscriptionFutureNotificationDates = invoiceWithMetadata.getPerSubscriptionFutureNotificationDates().get(subscriptionId);

            if (subscriptionFutureNotificationDates.getNextRecurringDate() != null) {
                Set<UUID> subscriptionsForDates = notificationListForTrigger.get(subscriptionFutureNotificationDates.getNextRecurringDate());
                if (subscriptionsForDates == null) {
                    subscriptionsForDates = new HashSet<UUID>();
                    notificationListForTrigger.put(subscriptionFutureNotificationDates.getNextRecurringDate(), subscriptionsForDates);
                }
                subscriptionsForDates.add(subscriptionId);
            }

            if (subscriptionFutureNotificationDates.getNextUsageDates() != null) {
                for (final UsageDef usageDef : subscriptionFutureNotificationDates.getNextUsageDates().keySet()) {

                    final LocalDate nextNotificationDateForUsage = subscriptionFutureNotificationDates.getNextUsageDates().get(usageDef);
                    Set<UUID> subscriptionsForDates = notificationListForTrigger.get(nextNotificationDateForUsage);
                    if (subscriptionsForDates == null) {
                        subscriptionsForDates = new HashSet<UUID>();
                        notificationListForTrigger.put(nextNotificationDateForUsage, subscriptionsForDates);
                    }
                    subscriptionsForDates.add(subscriptionId);
                }
            }
        }

        final long dryRunNotificationTime = invoiceConfig.getDryRunNotificationSchedule(context).getMillis();
        final boolean isInvoiceNotificationEnabled = dryRunNotificationTime > 0;

        final Map<LocalDate, Set<UUID>> notificationListForDryRun = isInvoiceNotificationEnabled ? new HashMap<LocalDate, Set<UUID>>() : ImmutableMap.<LocalDate, Set<UUID>>of();
        if (isInvoiceNotificationEnabled) {
            for (final LocalDate curDate : notificationListForTrigger.keySet()) {
                final LocalDate curDryRunDate = context.toLocalDate(context.toUTCDateTime(curDate).minus(dryRunNotificationTime));
                Set<UUID> subscriptionsForDryRunDates = notificationListForDryRun.get(curDryRunDate);
                if (subscriptionsForDryRunDates == null) {
                    subscriptionsForDryRunDates = new HashSet<UUID>();
                    notificationListForDryRun.put(curDryRunDate, subscriptionsForDryRunDates);
                }
                subscriptionsForDryRunDates.addAll(notificationListForTrigger.get(curDate));
            }

            final Map<UUID, DateTime> upcomingPhasesForSubscriptions = isInvoiceNotificationEnabled ?
                                                                       getNextTransitionsForSubscriptions(billingEvents) :
                                                                       ImmutableMap.<UUID, DateTime>of();

            for (UUID curId : upcomingPhasesForSubscriptions.keySet()) {
                final LocalDate curDryRunDate = context.toLocalDate(upcomingPhasesForSubscriptions.get(curId).minus(dryRunNotificationTime));
                Set<UUID> subscriptionsForDryRunDates = notificationListForDryRun.get(curDryRunDate);
                if (subscriptionsForDryRunDates == null) {
                    subscriptionsForDryRunDates = new HashSet<UUID>();
                    notificationListForDryRun.put(curDryRunDate, subscriptionsForDryRunDates);
                }
                subscriptionsForDryRunDates.add(curId);
            }
        }

        return new FutureAccountNotifications(notificationListForTrigger, notificationListForDryRun);
    }

    private List<InvoiceItemModelDao> transformToInvoiceModelDao(final List<InvoiceItem> invoiceItems) {
        return Lists.transform(invoiceItems,
                               new Function<InvoiceItem, InvoiceItemModelDao>() {
                                   @Override
                                   public InvoiceItemModelDao apply(final InvoiceItem input) {
                                       return new InvoiceItemModelDao(input);
                                   }
                               });
    }

    private Set<UUID> getUniqueInvoiceIds(final Invoice invoice) {
        final Set<UUID> uniqueInvoiceIds = new TreeSet<UUID>();
        uniqueInvoiceIds.addAll(Collections2.transform(invoice.getInvoiceItems(), new Function<InvoiceItem, UUID>() {
            @Nullable
            @Override
            public UUID apply(@Nullable final InvoiceItem input) {
                return input.getInvoiceId();
            }
        }));
        return uniqueInvoiceIds;
    }

    private void logInvoiceWithItems(final ImmutableAccountData account, final Invoice invoice, final LocalDate targetDate, final Set<UUID> adjustedUniqueOtherInvoiceId, final boolean isRealInvoiceWithItems) {
        final StringBuilder tmp = new StringBuilder();
        if (isRealInvoiceWithItems) {
            tmp.append(String.format("Generated invoiceId='%s', numberOfItems='%d', accountId='%s', targetDate='%s':", invoice.getId(), invoice.getNumberOfItems(), account.getId(), targetDate));
        } else {
            final String adjustedInvoices = JOINER_COMMA.join(adjustedUniqueOtherInvoiceId.toArray(new UUID[adjustedUniqueOtherInvoiceId.size()]));
            tmp.append(String.format("Adjusting existing invoiceId='%s', numberOfItems='%d', accountId='%s', targetDate='%s':\n",
                                     adjustedInvoices, invoice.getNumberOfItems(), account.getId(), targetDate));
        }
        for (final InvoiceItem item : invoice.getInvoiceItems()) {
            tmp.append(String.format("\n\t item = %s", item));
        }
        log.info(tmp.toString());
    }

    private void commitInvoiceAndSetFutureNotifications(final ImmutableAccountData account,
                                                        @Nullable final InvoiceModelDao invoiceModelDao,
                                                        final FutureAccountNotifications futureAccountNotifications,
                                                        final InternalCallContext context) {
        final boolean isThereAnyItemsLeft = invoiceModelDao != null && !invoiceModelDao.getInvoiceItems().isEmpty();
        if (isThereAnyItemsLeft) {
            invoiceDao.createInvoice(invoiceModelDao, futureAccountNotifications, context);
        } else {
            invoiceDao.setFutureAccountNotificationsForEmptyInvoice(account.getId(), futureAccountNotifications, context);
        }
    }

    private InvoiceItem computeCBAOnExistingInvoice(final Invoice invoice, final InternalCallContext context) throws InvoiceApiException {
        // Transformation to Invoice -> InvoiceModelDao
        final InvoiceModelDao invoiceModelDao = new InvoiceModelDao(invoice);
        final List<InvoiceItemModelDao> invoiceItemModelDaos = ImmutableList.copyOf(Collections2.transform(invoice.getInvoiceItems(),
                                                                                                           new Function<InvoiceItem, InvoiceItemModelDao>() {
                                                                                                               @Override
                                                                                                               public InvoiceItemModelDao apply(final InvoiceItem input) {
                                                                                                                   return new InvoiceItemModelDao(input);
                                                                                                               }
                                                                                                           }));
        invoiceModelDao.addInvoiceItems(invoiceItemModelDaos);
        final InvoiceItemModelDao cbaItem = invoiceDao.doCBAComplexity(invoiceModelDao, context);
        return cbaItem != null ? InvoiceItemFactory.fromModelDao(cbaItem) : null;
    }

    private TenantContext buildTenantContext(final InternalTenantContext context) {
        return internalCallContextFactory.createTenantContext(context);
    }

    private CallContext buildCallContext(final InternalCallContext context) {
        return internalCallContextFactory.createCallContext(context);
    }

    private void setChargedThroughDates(final Collection<InvoiceItem> fixedPriceItems,
                                        final Collection<InvoiceItem> recurringItems,
                                        final InternalCallContext context) throws SubscriptionBaseApiException {
        final Map<UUID, DateTime> chargeThroughDates = new HashMap<UUID, DateTime>();
        addInvoiceItemsToChargeThroughDates(chargeThroughDates, fixedPriceItems, context);
        addInvoiceItemsToChargeThroughDates(chargeThroughDates, recurringItems, context);

        for (final UUID subscriptionId : chargeThroughDates.keySet()) {
            if (subscriptionId != null) {
                final DateTime chargeThroughDate = chargeThroughDates.get(subscriptionId);
                subscriptionApi.setChargedThroughDate(subscriptionId, chargeThroughDate, context);
            }
        }
    }

    private void postEvent(final BusInternalEvent event) {
        try {
            eventBus.post(event);
        } catch (final EventBusException e) {
            log.warn("Failed to post event {}", event, e);
        }
    }

    private void addInvoiceItemsToChargeThroughDates(final Map<UUID, DateTime> chargeThroughDates,
                                                     final Collection<InvoiceItem> items,
                                                     final InternalTenantContext internalTenantContext) {

        for (final InvoiceItem item : items) {
            final UUID subscriptionId = item.getSubscriptionId();
            final LocalDate endDate = (item.getEndDate() != null) ? item.getEndDate() : item.getStartDate();

            final DateTime proposedChargedThroughDate = internalTenantContext.toUTCDateTime(endDate);
            if (chargeThroughDates.containsKey(subscriptionId)) {
                if (chargeThroughDates.get(subscriptionId).isBefore(proposedChargedThroughDate)) {
                    chargeThroughDates.put(subscriptionId, proposedChargedThroughDate);
                }
            } else {
                chargeThroughDates.put(subscriptionId, proposedChargedThroughDate);
            }
        }
    }

    public static class FutureAccountNotifications {

        private final Map<LocalDate, Set<UUID>> notificationListForTrigger;
        private final Map<LocalDate, Set<UUID>> notificationListForDryRun;

        public FutureAccountNotifications() {
            this(ImmutableMap.<LocalDate, Set<UUID>>of(), ImmutableMap.<LocalDate, Set<UUID>>of());
        }

        public FutureAccountNotifications(final Map<LocalDate, Set<UUID>> notificationListForTrigger, final Map<LocalDate, Set<UUID>> notificationListForDryRun) {
            this.notificationListForTrigger = notificationListForTrigger;
            this.notificationListForDryRun = notificationListForDryRun;
        }

        public Map<LocalDate, Set<UUID>> getNotificationsForTrigger() {
            return notificationListForTrigger;
        }

        public Map<LocalDate, Set<UUID>> getNotificationsForDryRun() {
            return notificationListForDryRun;
        }
    }

    private List<LocalDate> getUpcomingInvoiceCandidateDates(final Iterable<NotificationEventWithMetadata<NextBillingDateNotificationKey>> futureNotifications,
                                                             final Map<UUID, DateTime> nextScheduledSubscriptionsEventMap,
                                                             final Iterable<UUID> filteredSubscriptionIds,
                                                             final InternalCallContext internalCallContext) {

        final Iterable<DateTime> nextScheduledInvoiceDates = getNextScheduledInvoiceEffectiveDate(futureNotifications, filteredSubscriptionIds);

        final Iterable<DateTime> nextScheduledSubscriptionsEvents;
        if (!Iterables.isEmpty(filteredSubscriptionIds)) {
            List<DateTime> tmp = new ArrayList<DateTime>();
            for (final UUID curSubscriptionId : nextScheduledSubscriptionsEventMap.keySet()) {
                if (Iterables.contains(filteredSubscriptionIds, curSubscriptionId)) {
                    tmp.add(nextScheduledSubscriptionsEventMap.get(curSubscriptionId));
                }
            }
            nextScheduledSubscriptionsEvents = tmp;
        } else {
            nextScheduledSubscriptionsEvents = nextScheduledSubscriptionsEventMap.values();
        }

        return Lists.<DateTime, LocalDate>transform(UPCOMING_NOTIFICATION_DATE_ORDERING.sortedCopy(Iterables.<DateTime>concat(nextScheduledInvoiceDates, nextScheduledSubscriptionsEvents)),
                                                    new Function<DateTime, LocalDate>() {
                                                        @Override
                                                        public LocalDate apply(final DateTime input) {
                                                            return internalCallContext.toLocalDate(input);
                                                        }
                                                    });
    }

    private Iterable<DateTime> getNextScheduledInvoiceEffectiveDate(final Iterable<NotificationEventWithMetadata<NextBillingDateNotificationKey>> futureNotifications,
                                                                    final Iterable<UUID> filteredSubscriptionIds) {
        final Collection<DateTime> effectiveDates = new LinkedList<DateTime>();
        for (final NotificationEventWithMetadata<NextBillingDateNotificationKey> input : futureNotifications) {

            // If we don't specify a filter list of subscriptionIds, we look at all events.
            boolean isEventForSubscription = Iterables.isEmpty(filteredSubscriptionIds);
            // If we specify a filter, we keep the date if at least one of the subscriptions from the event list matches one of the subscription from our filter list
            if (!Iterables.isEmpty(filteredSubscriptionIds)) {
                for (final UUID curSubscriptionId : filteredSubscriptionIds) {
                    if (Iterables.contains(input.getEvent().getUuidKeys(), curSubscriptionId)) {
                        isEventForSubscription = true;
                        break;
                    }
                }
            }

            final boolean isEventDryRunForNotifications = input.getEvent().isDryRunForInvoiceNotification() != null ?
                                                          input.getEvent().isDryRunForInvoiceNotification() : false;
            if (isEventForSubscription && !isEventDryRunForNotifications) {
                effectiveDates.add(input.getEffectiveDate());
            }
        }
        return effectiveDates;
    }

    private static final class TargetDateDryRunArguments implements DryRunArguments {

        @Override
        public DryRunType getDryRunType() {
            return DryRunType.TARGET_DATE;
        }

        @Override
        public PlanPhaseSpecifier getPlanPhaseSpecifier() {
            return null;
        }

        @Override
        public SubscriptionEventType getAction() {
            return null;
        }

        @Override
        public UUID getSubscriptionId() {
            return null;
        }

        @Override
        public LocalDate getEffectiveDate() {
            return null;
        }

        @Override
        public UUID getBundleId() {
            return null;
        }

        @Override
        public BillingActionPolicy getBillingActionPolicy() {
            return null;
        }

        @Override
        public List<PlanPhasePriceOverride> getPlanPhasePriceOverrides() {
            return null;
        }

        @Override
        public String toString() {
            final StringBuilder sb = new StringBuilder("TargetDateDryRunArguments{");
            sb.append("dryRunType=").append(DryRunType.TARGET_DATE);
            sb.append('}');
            return sb.toString();
        }
    }

    public void processParentInvoiceForInvoiceGeneration(final Account childAccount, final UUID childInvoiceId, final InternalCallContext context) throws InvoiceApiException {
        GlobalLock lock = null;
        try {
            lock = locker.lockWithNumberOfTries(LockerType.ACCNT_INV_PAY.toString(), childAccount.getParentAccountId().toString(), invoiceConfig.getMaxGlobalLockRetries());

            processParentInvoiceForInvoiceGenerationWithLock(childAccount, childInvoiceId, context);
        } catch (final LockFailedException e) {
            log.warn("Failed to process parent invoice for parentAccountId='{}'", childAccount.getParentAccountId().toString(), e);
        } finally {
            if (lock != null) {
                lock.release();
            }
        }
    }

    private void processParentInvoiceForInvoiceGenerationWithLock(final Account childAccount, final UUID childInvoiceId, final InternalCallContext context) throws InvoiceApiException {
        log.info("Processing parent invoice for parentAccountId='{}', childInvoiceId='{}'", childAccount.getParentAccountId(), childInvoiceId);
        final InvoiceModelDao childInvoiceModelDao = invoiceDao.getById(childInvoiceId, context);
        final Invoice childInvoice = new DefaultInvoice(childInvoiceModelDao);

        final Long parentAccountRecordId = internalCallContextFactory.getRecordIdFromObject(childAccount.getParentAccountId(), ObjectType.ACCOUNT, buildTenantContext(context));
        final InternalCallContext parentContext = internalCallContextFactory.createInternalCallContext(parentAccountRecordId, context);

        BigDecimal childInvoiceAmount = InvoiceCalculatorUtils.computeChildInvoiceAmount(childInvoice.getCurrency(), childInvoice.getInvoiceItems());
        InvoiceModelDao draftParentInvoice = invoiceDao.getParentDraftInvoice(childAccount.getParentAccountId(), parentContext);

        final String description = childAccount.getExternalKey().concat(" summary");
        if (draftParentInvoice != null) {
            for (InvoiceItemModelDao item : draftParentInvoice.getInvoiceItems()) {
                if ((item.getChildAccountId() != null) && item.getChildAccountId().equals(childInvoice.getAccountId())) {
                    // update child item amount for existing parent invoice item
                    BigDecimal newChildInvoiceAmount = childInvoiceAmount.add(item.getAmount());
                    log.info("Updating existing itemId='{}', oldAmount='{}', newAmount='{}' on existing DRAFT invoiceId='{}'", item.getId(), item.getAmount(), newChildInvoiceAmount, draftParentInvoice.getId());
                    invoiceDao.updateInvoiceItemAmount(item.getId(), newChildInvoiceAmount, parentContext);
                    return;
                }
            }

            // new item when the parent invoices does not have this child item yet
            final ParentInvoiceItem newParentInvoiceItem = new ParentInvoiceItem(UUID.randomUUID(), context.getCreatedDate(), draftParentInvoice.getId(), childAccount.getParentAccountId(), childAccount.getId(), childInvoiceAmount, childAccount.getCurrency(), description);
            final InvoiceItemModelDao parentInvoiceItem = new InvoiceItemModelDao(newParentInvoiceItem);
            draftParentInvoice.addInvoiceItem(parentInvoiceItem);

            List<InvoiceModelDao> invoices = new ArrayList<InvoiceModelDao>();
            invoices.add(draftParentInvoice);
            log.info("Adding new itemId='{}', amount='{}' on existing DRAFT invoiceId='{}'", parentInvoiceItem.getId(), childInvoiceAmount, draftParentInvoice.getId());
            invoiceDao.createInvoices(invoices, parentContext);
        } else {
            if (shouldIgnoreChildInvoice(childInvoice, childInvoiceAmount)) {
                return;
            }

            final LocalDate invoiceDate = context.toLocalDate(context.getCreatedDate());
            draftParentInvoice = new InvoiceModelDao(childAccount.getParentAccountId(), invoiceDate, childAccount.getCurrency(), InvoiceStatus.DRAFT, true);
            final InvoiceItem parentInvoiceItem = new ParentInvoiceItem(UUID.randomUUID(), context.getCreatedDate(), draftParentInvoice.getId(), childAccount.getParentAccountId(), childAccount.getId(), childInvoiceAmount, childAccount.getCurrency(), description);
            draftParentInvoice.addInvoiceItem(new InvoiceItemModelDao(parentInvoiceItem));

            log.info("Adding new itemId='{}', amount='{}' on new DRAFT invoiceId='{}'", parentInvoiceItem.getId(), childInvoiceAmount, draftParentInvoice.getId());
            invoiceDao.createInvoices(ImmutableList.<InvoiceModelDao>of(draftParentInvoice), parentContext);
        }

        // save parent child invoice relation
        final InvoiceParentChildModelDao invoiceRelation = new InvoiceParentChildModelDao(draftParentInvoice.getId(), childInvoiceId, childAccount.getId());
        invoiceDao.createParentChildInvoiceRelation(invoiceRelation, parentContext);
    }

    private boolean shouldIgnoreChildInvoice(final Invoice childInvoice, final BigDecimal childInvoiceAmount) {

        switch (childInvoiceAmount.compareTo(BigDecimal.ZERO)) {
            case -1:
                // do nothing if child invoice has negative amount because it's a credit and it will be use in next invoice
                return true;
            case 1:
                return false;
            case 0:
                // only ignore if amount == 0 and any item is not FIXED or RECURRING
                for (InvoiceItem item : childInvoice.getInvoiceItems()) {
                    if (item.getInvoiceItemType().equals(InvoiceItemType.FIXED) || item.getInvoiceItemType().equals(InvoiceItemType.RECURRING)) {
                        return false;
                    }
                }
        }

        return true;
    }

    public void processParentInvoiceForAdjustments(final Account childAccount, final UUID childInvoiceId, final InternalCallContext context) throws InvoiceApiException {
        GlobalLock lock = null;
        try {
            lock = locker.lockWithNumberOfTries(LockerType.ACCNT_INV_PAY.toString(), childAccount.getParentAccountId().toString(), invoiceConfig.getMaxGlobalLockRetries());

            processParentInvoiceForAdjustmentsWithLock(childAccount, childInvoiceId, context);
        } catch (final LockFailedException e) {
            log.warn("Failed to process parent invoice for parentAccountId='{}'", childAccount.getParentAccountId().toString(), e);
        } finally {
            if (lock != null) {
                lock.release();
            }
        }
    }

    public void processParentInvoiceForAdjustmentsWithLock(final Account account, final UUID childInvoiceId, final InternalCallContext context) throws InvoiceApiException {
        final InvoiceModelDao childInvoiceModelDao = invoiceDao.getById(childInvoiceId, context);
        final InvoiceModelDao parentInvoiceModelDao = childInvoiceModelDao.getParentInvoice();

        if (parentInvoiceModelDao == null) {
            throw new InvoiceApiException(ErrorCode.INVOICE_MISSING_PARENT_INVOICE, childInvoiceModelDao.getId());
        } else if (InvoiceModelDaoHelper.getRawBalanceForRegularInvoice(parentInvoiceModelDao).compareTo(BigDecimal.ZERO) == 0) {
            // ignore item adjustments for paid invoices.
            return;
        }

        final Long parentAccountRecordId = internalCallContextFactory.getRecordIdFromObject(account.getParentAccountId(), ObjectType.ACCOUNT, buildTenantContext(context));
        final InternalCallContext parentContext = internalCallContextFactory.createInternalCallContext(parentAccountRecordId, context);
        final String description = "Adjustment for account ".concat(account.getExternalKey());

        // find PARENT_SUMMARY invoice item for this child account
        final InvoiceItemModelDao parentSummaryInvoiceItem = Iterables.find(parentInvoiceModelDao.getInvoiceItems(), new Predicate<InvoiceItemModelDao>() {
            @Override
            public boolean apply(@Nullable final InvoiceItemModelDao input) {
                return input.getType().equals(InvoiceItemType.PARENT_SUMMARY)
                       && input.getChildAccountId().equals(childInvoiceModelDao.getAccountId());
            }
        });

        final Iterable<InvoiceItemModelDao> childAdjustments = Iterables.filter(childInvoiceModelDao.getInvoiceItems(), new Predicate<InvoiceItemModelDao>() {
            @Override
            public boolean apply(@Nullable final InvoiceItemModelDao input) {
                return input.getType().equals(InvoiceItemType.ITEM_ADJ);
            }
        });

        // find last ITEM_ADJ invoice added in child invoice
        final InvoiceItemModelDao lastChildInvoiceItemAdjustment = Collections.max(Lists.newArrayList(childAdjustments), new Comparator<InvoiceItemModelDao>() {
            @Override
            public int compare(InvoiceItemModelDao o1, InvoiceItemModelDao o2) {
                return o1.getCreatedDate().compareTo(o2.getCreatedDate());
            }
        });

        final BigDecimal childInvoiceAdjustmentAmount = lastChildInvoiceItemAdjustment.getAmount();

        if (parentInvoiceModelDao.getStatus().equals(InvoiceStatus.COMMITTED)) {
            ItemAdjInvoiceItem adj = new ItemAdjInvoiceItem(UUIDs.randomUUID(),
                                                            lastChildInvoiceItemAdjustment.getCreatedDate(),
                                                            parentSummaryInvoiceItem.getInvoiceId(),
                                                            parentSummaryInvoiceItem.getAccountId(),
                                                            lastChildInvoiceItemAdjustment.getStartDate(),
                                                            description,
                                                            childInvoiceAdjustmentAmount,
                                                            parentInvoiceModelDao.getCurrency(),
                                                            parentSummaryInvoiceItem.getId());
            parentInvoiceModelDao.addInvoiceItem(new InvoiceItemModelDao(adj));
            invoiceDao.createInvoices(ImmutableList.<InvoiceModelDao>of(parentInvoiceModelDao), parentContext);
            return;
        }

        // update item amount
        final BigDecimal newParentInvoiceItemAmount = childInvoiceAdjustmentAmount.add(parentSummaryInvoiceItem.getAmount());
        invoiceDao.updateInvoiceItemAmount(parentSummaryInvoiceItem.getId(), newParentInvoiceItemAmount, parentContext);
    }

}
