/*
 * Copyright 2010-2013 Ning, Inc.
 * Copyright 2014-2016 Groupon, Inc
 * Copyright 2014-2016 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.entitlement.dao;

import java.io.IOException;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Comparator;
import java.util.Date;
import java.util.HashSet;
import java.util.List;
import java.util.Map;
import java.util.UUID;

import javax.annotation.Nullable;

import org.joda.time.DateTime;
import org.killbill.billing.ErrorCode;
import org.killbill.billing.ObjectType;
import org.killbill.billing.callcontext.InternalCallContext;
import org.killbill.billing.callcontext.InternalTenantContext;
import org.killbill.billing.entitlement.DefaultEntitlementService;
import org.killbill.billing.entitlement.EntitlementService;
import org.killbill.billing.entitlement.api.BlockingApiException;
import org.killbill.billing.entitlement.api.BlockingState;
import org.killbill.billing.entitlement.api.BlockingStateType;
import org.killbill.billing.entitlement.api.DefaultBlockingTransitionInternalEvent;
import org.killbill.billing.entitlement.api.EntitlementApiException;
import org.killbill.billing.entitlement.block.BlockingChecker.BlockingAggregator;
import org.killbill.billing.entitlement.block.StatelessBlockingChecker;
import org.killbill.billing.entitlement.engine.core.BlockingTransitionNotificationKey;
import org.killbill.billing.util.cache.Cachable.CacheType;
import org.killbill.billing.util.cache.CacheControllerDispatcher;
import org.killbill.billing.util.callcontext.InternalCallContextFactory;
import org.killbill.billing.util.dao.NonEntityDao;
import org.killbill.billing.util.entity.dao.EntityDaoBase;
import org.killbill.billing.util.entity.dao.EntitySqlDaoTransactionWrapper;
import org.killbill.billing.util.entity.dao.EntitySqlDaoTransactionalJdbiWrapper;
import org.killbill.billing.util.entity.dao.EntitySqlDaoWrapperFactory;
import org.killbill.bus.api.BusEvent;
import org.killbill.bus.api.PersistentBus;
import org.killbill.bus.api.PersistentBus.EventBusException;
import org.killbill.clock.Clock;
import org.killbill.notificationq.api.NotificationEvent;
import org.killbill.notificationq.api.NotificationQueue;
import org.killbill.notificationq.api.NotificationQueueService;
import org.killbill.notificationq.api.NotificationQueueService.NoSuchNotificationQueue;
import org.skife.jdbi.v2.Handle;
import org.skife.jdbi.v2.IDBI;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.google.common.base.Function;
import com.google.common.base.Optional;
import com.google.common.base.Predicate;
import com.google.common.collect.Collections2;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Ordering;

public class DefaultBlockingStateDao extends EntityDaoBase<BlockingStateModelDao, BlockingState, EntitlementApiException> implements BlockingStateDao {

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

    // Assume the input is blocking states for a single blockable id
    private static final Ordering<BlockingStateModelDao> BLOCKING_STATE_MODEL_DAO_ORDERING = Ordering.<BlockingStateModelDao>from(new Comparator<BlockingStateModelDao>() {
        @Override
        public int compare(final BlockingStateModelDao o1, final BlockingStateModelDao o2) {
            // effective_date column NOT NULL
            final int comparison = o1.getEffectiveDate().compareTo(o2.getEffectiveDate());
            if (comparison == 0) {
                // Keep a stable ordering for ties
                final int comparison2 = o1.getCreatedDate().compareTo(o2.getCreatedDate());
                if (comparison2 == 0) {
                    // New element is last
                    if (o1.getRecordId() == null) {
                        return 1;
                    } else if (o2.getRecordId() == null) {
                        return -1;
                    } else {
                        return o1.getRecordId().compareTo(o2.getRecordId());
                    }
                } else {
                    return comparison2;
                }
            } else {
                return comparison;
            }
        }
    });

    private final Clock clock;
    private final NotificationQueueService notificationQueueService;
    private final PersistentBus eventBus;
    private final CacheControllerDispatcher cacheControllerDispatcher;
    private final NonEntityDao nonEntityDao;

    private final StatelessBlockingChecker statelessBlockingChecker = new StatelessBlockingChecker();

    public DefaultBlockingStateDao(final IDBI dbi, final Clock clock, final NotificationQueueService notificationQueueService, final PersistentBus eventBus,
                                   final CacheControllerDispatcher cacheControllerDispatcher, final NonEntityDao nonEntityDao, final InternalCallContextFactory internalCallContextFactory) {
        super(new EntitySqlDaoTransactionalJdbiWrapper(dbi, clock, cacheControllerDispatcher, nonEntityDao, internalCallContextFactory), BlockingStateSqlDao.class);
        this.clock = clock;
        this.notificationQueueService = notificationQueueService;
        this.eventBus = eventBus;
        this.cacheControllerDispatcher = cacheControllerDispatcher;
        this.nonEntityDao = nonEntityDao;
    }

    @Override
    protected EntitlementApiException generateAlreadyExistsException(final BlockingStateModelDao blockingStateModelDao, final InternalCallContext context) {
        return new EntitlementApiException(ErrorCode.ENT_ALREADY_BLOCKED, blockingStateModelDao.getBlockableId());
    }

    @Override
    public BlockingState getBlockingStateForService(final UUID blockableId, final BlockingStateType blockingStateType, final String serviceName, final InternalTenantContext context) {
        return transactionalSqlDao.execute(new EntitySqlDaoTransactionWrapper<BlockingState>() {
            @Override
            public BlockingState inTransaction(final EntitySqlDaoWrapperFactory entitySqlDaoWrapperFactory) throws Exception {
                // Upper bound time limit is now
                final Date upTo = clock.getUTCNow().toDate();
                final BlockingStateModelDao model = entitySqlDaoWrapperFactory.become(BlockingStateSqlDao.class).getBlockingStateForService(blockableId, serviceName, upTo, context);
                return (model != null && model.getType().equals(blockingStateType)) ? BlockingStateModelDao.toBlockingState(model) : null;
            }
        });
    }

    @Override
    public List<BlockingState> getBlockingState(final UUID blockableId, final BlockingStateType blockingStateType, final DateTime upToDate, final InternalTenantContext context) {
        return transactionalSqlDao.execute(new EntitySqlDaoTransactionWrapper<List<BlockingState>>() {
            @Override
            public List<BlockingState> inTransaction(final EntitySqlDaoWrapperFactory entitySqlDaoWrapperFactory) throws Exception {
                final BlockingStateSqlDao sqlDao = entitySqlDaoWrapperFactory.become(BlockingStateSqlDao.class);
                return getBlockingState(sqlDao, blockableId, blockingStateType, upToDate, context);
            }
        });
    }

    private List<BlockingState> getBlockingState(final BlockingStateSqlDao sqlDao, final UUID blockableId, final BlockingStateType blockingStateType, final DateTime upToDate, final InternalTenantContext context) {
        final Date upTo = upToDate.toDate();
        final List<BlockingStateModelDao> models = sqlDao.getBlockingState(blockableId, upTo, context);
        final Collection<BlockingStateModelDao> modelsFiltered = filterBlockingStates(models, blockingStateType);
        return new ArrayList<BlockingState>(Collections2.transform(modelsFiltered,
                                                                   new Function<BlockingStateModelDao, BlockingState>() {
                                                                       @Override
                                                                       public BlockingState apply(@Nullable final BlockingStateModelDao src) {
                                                                           return BlockingStateModelDao.toBlockingState(src);
                                                                       }
                                                                   }));
    }

    @Override
    public List<BlockingState> getBlockingAllForAccountRecordId(final InternalTenantContext context) {
        return transactionalSqlDao.execute(new EntitySqlDaoTransactionWrapper<List<BlockingState>>() {
            @Override
            public List<BlockingState> inTransaction(final EntitySqlDaoWrapperFactory entitySqlDaoWrapperFactory) throws Exception {
                final BlockingStateSqlDao sqlDao = entitySqlDaoWrapperFactory.become(BlockingStateSqlDao.class);
                return new ArrayList<BlockingState>(Collections2.transform(sqlDao.getByAccountRecordId(context),
                                                                           new Function<BlockingStateModelDao, BlockingState>() {
                                                                               @Override
                                                                               public BlockingState apply(@Nullable final BlockingStateModelDao src) {
                                                                                   return BlockingStateModelDao.toBlockingState(src);
                                                                               }
                                                                           }));
            }
        });
    }

    @Override
    public void setBlockingStatesAndPostBlockingTransitionEvent(final Map<BlockingState, Optional<UUID>> states, final InternalCallContext context) {
        transactionalSqlDao.execute(new EntitySqlDaoTransactionWrapper<Void>() {
            @Override
            public Void inTransaction(final EntitySqlDaoWrapperFactory entitySqlDaoWrapperFactory) throws Exception {
                final BlockingStateSqlDao sqlDao = entitySqlDaoWrapperFactory.become(BlockingStateSqlDao.class);

                for (final BlockingState state : states.keySet()) {
                    final DateTime upToDate = state.getEffectiveDate();
                    final UUID bundleId = states.get(state).orNull();
                    final BlockingAggregator previousState = getBlockedStatus(sqlDao, entitySqlDaoWrapperFactory.getHandle(), state.getBlockedId(), state.getType(), bundleId, upToDate, context);

                    final BlockingStateModelDao newBlockingStateModelDao = new BlockingStateModelDao(state, context);

                    // Get all blocking states for that blocked id and service
                    final List<BlockingStateModelDao> allForBlockedItAndService = sqlDao.getBlockingHistoryForService(state.getBlockedId(), state.getService(), context);

                    // Add the new one (we rely below on the fact that the ID for newBlockingStateModelDao is now set)
                    allForBlockedItAndService.add(newBlockingStateModelDao);

                    // Re-order what should be the final list (allForBlockedItAndService is ordered by record_id in the SQL and we just added a new state)
                    final List<BlockingStateModelDao> allForBlockedItAndServiceOrdered = BLOCKING_STATE_MODEL_DAO_ORDERING.immutableSortedCopy(allForBlockedItAndService);

                    // Go through the (ordered) stream of blocking states for that blocked id and service and check
                    // if there is one or more blocking states for the same state following each others.
                    // If there are, delete them, as they are not needed anymore. A picture being worth a thousand words,
                    // if the current stream is: t0 S1 t1 S2 t3 S3 and we want to insert S2 at t0 < t1' < t1,
                    // the final stream should be: t0 S1 t1' S2 t3 S3 (and not t0 S1 t1' S2 t1 S2 t3 S3)
                    // Note that we also take care of the use case t0 S1 t1 S2 t2 S2 t3 S3 to cleanup legacy systems, although
                    // it shouldn't happen anymore
                    final Collection<UUID> blockingStatesToRemove = new HashSet<UUID>();
                    BlockingStateModelDao prevBlockingStateModelDao = null;
                    for (final BlockingStateModelDao blockingStateModelDao : allForBlockedItAndServiceOrdered) {
                        if (prevBlockingStateModelDao != null && prevBlockingStateModelDao.getState().equals(blockingStateModelDao.getState())) {
                            blockingStatesToRemove.add(blockingStateModelDao.getId());
                        }
                        prevBlockingStateModelDao = blockingStateModelDao;
                    }

                    // Delete unnecessary states (except newBlockingStateModelDao, which doesn't exist in the database)
                    for (final UUID blockedId : blockingStatesToRemove) {
                        if (!newBlockingStateModelDao.getId().equals(blockedId)) {
                            sqlDao.unactiveEvent(blockedId.toString(), context);
                        }
                    }

                    // Create the state, if needed
                    if (!blockingStatesToRemove.contains(newBlockingStateModelDao.getId())) {
                        sqlDao.create(newBlockingStateModelDao, context);
                    }

                    final BlockingAggregator currentState = getBlockedStatus(sqlDao, entitySqlDaoWrapperFactory.getHandle(), state.getBlockedId(), state.getType(), bundleId, upToDate, context);
                    if (previousState != null && currentState != null) {
                        recordBusOrFutureNotificationFromTransaction(entitySqlDaoWrapperFactory,
                                                                     state.getId(),
                                                                     state.getEffectiveDate(),
                                                                     state.getBlockedId(),
                                                                     state.getType(),
                                                                     state.getService(),
                                                                     previousState,
                                                                     currentState,
                                                                     context);
                    }
                }

                return null;
            }
        });
    }

    private BlockingAggregator getBlockedStatus(final BlockingStateSqlDao sqlDao, final Handle handle, final UUID blockableId, final BlockingStateType type, @Nullable final UUID bundleId, final DateTime upToDate, final InternalTenantContext context) throws BlockingApiException {
        final List<BlockingState> accountBlockingStates;
        final List<BlockingState> bundleBlockingStates;
        final List<BlockingState> subscriptionBlockingStates;
        if (type == BlockingStateType.SUBSCRIPTION) {
            final UUID accountId = nonEntityDao.retrieveIdFromObjectInTransaction(context.getAccountRecordId(), ObjectType.ACCOUNT, cacheControllerDispatcher.getCacheController(CacheType.OBJECT_ID), handle);
            accountBlockingStates = getBlockingState(sqlDao, accountId, BlockingStateType.ACCOUNT, upToDate, context);
            bundleBlockingStates = getBlockingState(sqlDao, bundleId, BlockingStateType.SUBSCRIPTION_BUNDLE, upToDate, context);
            subscriptionBlockingStates = getBlockingState(sqlDao, blockableId, BlockingStateType.SUBSCRIPTION, upToDate, context);
        } else if (type == BlockingStateType.SUBSCRIPTION_BUNDLE) {
            final UUID accountId = nonEntityDao.retrieveIdFromObjectInTransaction(context.getAccountRecordId(), ObjectType.ACCOUNT, cacheControllerDispatcher.getCacheController(CacheType.OBJECT_ID), handle);
            accountBlockingStates = getBlockingState(sqlDao, accountId, BlockingStateType.ACCOUNT, upToDate, context);
            bundleBlockingStates = getBlockingState(sqlDao, blockableId, BlockingStateType.SUBSCRIPTION_BUNDLE, upToDate, context);
            subscriptionBlockingStates = ImmutableList.<BlockingState>of();
        } else { // BlockingStateType.ACCOUNT {
            accountBlockingStates = getBlockingState(sqlDao, blockableId, BlockingStateType.ACCOUNT, upToDate, context);
            bundleBlockingStates = ImmutableList.<BlockingState>of();
            subscriptionBlockingStates = ImmutableList.<BlockingState>of();
        }
        return statelessBlockingChecker.getBlockedState(accountBlockingStates, bundleBlockingStates, subscriptionBlockingStates);
    }

    private void recordBusOrFutureNotificationFromTransaction(final EntitySqlDaoWrapperFactory entitySqlDaoWrapperFactory,
                                                              final UUID blockingStateId,
                                                              final DateTime effectiveDate,
                                                              final UUID blockableId,
                                                              final BlockingStateType type,
                                                              final String serviceName,
                                                              final BlockingAggregator previousState,
                                                              final BlockingAggregator currentState,
                                                              final InternalCallContext context) {
        final boolean isTransitionToBlockedBilling = !previousState.isBlockBilling() && currentState.isBlockBilling();
        final boolean isTransitionToUnblockedBilling = previousState.isBlockBilling() && !currentState.isBlockBilling();

        final boolean isTransitionToBlockedEntitlement = !previousState.isBlockEntitlement() && currentState.isBlockEntitlement();
        final boolean isTransitionToUnblockedEntitlement = previousState.isBlockEntitlement() && !currentState.isBlockEntitlement();

        if (effectiveDate.compareTo(clock.getUTCNow()) > 0) {
            // Add notification entry to send the bus event at the effective date
            final NotificationEvent notificationEvent = new BlockingTransitionNotificationKey(blockingStateId, blockableId, type,
                                                                                              isTransitionToBlockedBilling, isTransitionToUnblockedBilling,
                                                                                              isTransitionToBlockedEntitlement, isTransitionToUnblockedEntitlement);
            recordFutureNotificationFromTransaction(entitySqlDaoWrapperFactory, effectiveDate, notificationEvent, context);
        } else {
            // TODO Do we want to send a DefaultEffectiveEntitlementEvent for entitlement specific blocking states?
            // Don't post if nothing has changed for entitlement-service
            if (!serviceName.equals(EntitlementService.ENTITLEMENT_SERVICE_NAME) || !previousState.equals(currentState)) {
                final BusEvent event = new DefaultBlockingTransitionInternalEvent(blockableId, type,
                                                                                  isTransitionToBlockedBilling, isTransitionToUnblockedBilling,
                                                                                  isTransitionToBlockedEntitlement, isTransitionToUnblockedEntitlement,
                                                                                  context.getAccountRecordId(), context.getTenantRecordId(), context.getUserToken());
                notifyBusFromTransaction(entitySqlDaoWrapperFactory, event);
            } else {
                log.debug("Skipping event for service {} and blockableId {} (previousState={}, currentState={})", serviceName, blockableId, previousState, currentState);
            }

        }
    }

    private void recordFutureNotificationFromTransaction(final EntitySqlDaoWrapperFactory entitySqlDaoWrapperFactory,
                                                         final DateTime effectiveDate,
                                                         final NotificationEvent notificationEvent,
                                                         final InternalCallContext context) {
        try {
            final NotificationQueue subscriptionEventQueue = notificationQueueService.getNotificationQueue(DefaultEntitlementService.ENTITLEMENT_SERVICE_NAME,
                                                                                                           DefaultEntitlementService.NOTIFICATION_QUEUE_NAME);
            subscriptionEventQueue.recordFutureNotificationFromTransaction(entitySqlDaoWrapperFactory.getHandle().getConnection(),
                                                                           effectiveDate,
                                                                           notificationEvent,
                                                                           context.getUserToken(),
                                                                           context.getAccountRecordId(),
                                                                           context.getTenantRecordId());
        } catch (final NoSuchNotificationQueue e) {
            throw new RuntimeException(e);
        } catch (final IOException e) {
            throw new RuntimeException(e);
        }
    }

    private void notifyBusFromTransaction(final EntitySqlDaoWrapperFactory entitySqlDaoWrapperFactory, final BusEvent event) {
        try {
            eventBus.postFromTransaction(event, entitySqlDaoWrapperFactory.getHandle().getConnection());
        } catch (final EventBusException e) {
            log.warn("Failed to post event {}", event, e);
        }
    }

    @Override
    public void unactiveBlockingState(final UUID id, final InternalCallContext context) {
        transactionalSqlDao.execute(new EntitySqlDaoTransactionWrapper<Void>() {
            @Override
            public Void inTransaction(final EntitySqlDaoWrapperFactory entitySqlDaoWrapperFactory) throws Exception {
                final BlockingStateSqlDao sqlDao = entitySqlDaoWrapperFactory.become(BlockingStateSqlDao.class);
                sqlDao.unactiveEvent(id.toString(), context);
                return null;
            }
        });
    }

    private Collection<BlockingStateModelDao> filterBlockingStates(final Collection<BlockingStateModelDao> models, final BlockingStateType blockingStateType) {
        return Collections2.<BlockingStateModelDao>filter(models,
                                                          new Predicate<BlockingStateModelDao>() {
                                                              @Override
                                                              public boolean apply(final BlockingStateModelDao input) {
                                                                  return input.getType().equals(blockingStateType);
                                                              }
                                                          });
    }
}
