/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     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.apache.cassandra.config;

import java.util.*;
import java.util.stream.Collectors;

import com.google.common.collect.ImmutableList;
import com.google.common.collect.Sets;
import org.cliffc.high_scale_lib.NonBlockingHashMap;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import org.apache.cassandra.cql3.functions.*;
import org.apache.cassandra.db.ColumnFamilyStore;
import org.apache.cassandra.db.Keyspace;
import org.apache.cassandra.db.SystemKeyspace;
import org.apache.cassandra.db.commitlog.CommitLog;
import org.apache.cassandra.db.compaction.CompactionManager;
import org.apache.cassandra.db.marshal.AbstractType;
import org.apache.cassandra.db.marshal.UserType;
import org.apache.cassandra.gms.Gossiper;
import org.apache.cassandra.index.Index;
import org.apache.cassandra.io.sstable.Descriptor;
import org.apache.cassandra.locator.LocalStrategy;
import org.apache.cassandra.schema.*;
import org.apache.cassandra.service.MigrationManager;
import org.apache.cassandra.utils.ConcurrentBiMap;
import org.apache.cassandra.utils.Pair;

public class Schema
{
    private static final Logger logger = LoggerFactory.getLogger(Schema.class);

    public static final Schema instance = new Schema();

    /* metadata map for faster keyspace lookup */
    private final Map<String, KeyspaceMetadata> keyspaces = new NonBlockingHashMap<>();

    /* Keyspace objects, one per keyspace. Only one instance should ever exist for any given keyspace. */
    private final Map<String, Keyspace> keyspaceInstances = new NonBlockingHashMap<>();

    /* metadata map for faster ColumnFamily lookup */
    private final ConcurrentBiMap<Pair<String, String>, UUID> cfIdMap = new ConcurrentBiMap<>();

    private volatile UUID version;
    private volatile UUID altVersion;

    /**
     * Initialize empty schema object and load the hardcoded system tables
     */
    public Schema()
    {
        if (DatabaseDescriptor.isDaemonInitialized() || DatabaseDescriptor.isToolInitialized())
        {
            load(SchemaKeyspace.metadata());
            load(SystemKeyspace.metadata());
        }
    }

    /**
     * load keyspace (keyspace) definitions, but do not initialize the keyspace instances.
     * Schema version may be updated as the result.
     */
    public Schema loadFromDisk()
    {
        return loadFromDisk(true);
    }

    /**
     * Load schema definitions from disk.
     *
     * @param updateVersion true if schema version needs to be updated
     */
    public Schema loadFromDisk(boolean updateVersion)
    {
        load(SchemaKeyspace.fetchNonSystemKeyspaces());
        if (updateVersion)
            updateVersion();
        return this;
    }

    /**
     * Load up non-system keyspaces
     *
     * @param keyspaceDefs The non-system keyspace definitions
     *
     * @return self to support chaining calls
     */
    public Schema load(Iterable<KeyspaceMetadata> keyspaceDefs)
    {
        keyspaceDefs.forEach(this::load);
        return this;
    }

    /**
     * Load specific keyspace into Schema
     *
     * @param keyspaceDef The keyspace to load up
     *
     * @return self to support chaining calls
     */
    public Schema load(KeyspaceMetadata keyspaceDef)
    {
        keyspaceDef.tables.forEach(this::load);
        keyspaceDef.views.forEach(this::load);
        setKeyspaceMetadata(keyspaceDef);
        return this;
    }

    /**
     * Get keyspace instance by name
     *
     * @param keyspaceName The name of the keyspace
     *
     * @return Keyspace object or null if keyspace was not found
     */
    public Keyspace getKeyspaceInstance(String keyspaceName)
    {
        return keyspaceInstances.get(keyspaceName);
    }

    /**
     * Retrieve a CFS by name even if that CFS is an index
     *
     * An index is identified by looking for '.' in the CF name and separating to find the base table
     * containing the index
     * @param ksNameAndCFName
     * @return The named CFS or null if the keyspace, base table, or index don't exist
     */
    public ColumnFamilyStore getColumnFamilyStoreIncludingIndexes(Pair<String, String> ksNameAndCFName)
    {
        String ksName = ksNameAndCFName.left;
        String cfName = ksNameAndCFName.right;
        Pair<String, String> baseTable;

        /*
         * Split does special case a one character regex, and it looks like it can detect
         * if you use two characters to escape '.', but it still allocates a useless array.
         */
        int indexOfSeparator = cfName.indexOf('.');
        if (indexOfSeparator > -1)
            baseTable = Pair.create(ksName, cfName.substring(0, indexOfSeparator));
        else
            baseTable = ksNameAndCFName;

        UUID cfId = cfIdMap.get(baseTable);
        if (cfId == null)
            return null;

        Keyspace ks = keyspaceInstances.get(ksName);
        if (ks == null)
            return null;

        ColumnFamilyStore baseCFS = ks.getColumnFamilyStore(cfId);

        //Not an index
        if (indexOfSeparator == -1)
            return baseCFS;

        if (baseCFS == null)
            return null;

        Index index = baseCFS.indexManager.getIndexByName(cfName.substring(indexOfSeparator + 1, cfName.length()));
        if (index == null)
            return null;

        //Shouldn't ask for a backing table if there is none so just throw?
        //Or should it return null?
        return index.getBackingTable().get();
    }

    public ColumnFamilyStore getColumnFamilyStoreInstance(UUID cfId)
    {
        Pair<String, String> pair = cfIdMap.inverse().get(cfId);
        if (pair == null)
            return null;
        Keyspace instance = getKeyspaceInstance(pair.left);
        if (instance == null)
            return null;
        return instance.getColumnFamilyStore(cfId);
    }

    /**
     * Store given Keyspace instance to the schema
     *
     * @param keyspace The Keyspace instance to store
     *
     * @throws IllegalArgumentException if Keyspace is already stored
     */
    public void storeKeyspaceInstance(Keyspace keyspace)
    {
        if (keyspaceInstances.containsKey(keyspace.getName()))
            throw new IllegalArgumentException(String.format("Keyspace %s was already initialized.", keyspace.getName()));

        keyspaceInstances.put(keyspace.getName(), keyspace);
    }

    /**
     * Remove keyspace from schema
     *
     * @param keyspaceName The name of the keyspace to remove
     *
     * @return removed keyspace instance or null if it wasn't found
     */
    public Keyspace removeKeyspaceInstance(String keyspaceName)
    {
        return keyspaceInstances.remove(keyspaceName);
    }

    /**
     * Remove keyspace definition from system
     *
     * @param ksm The keyspace definition to remove
     */
    public void clearKeyspaceMetadata(KeyspaceMetadata ksm)
    {
        keyspaces.remove(ksm.name);
    }

    /**
     * Given a keyspace name and column family name, get the column family
     * meta data. If the keyspace name or column family name is not valid
     * this function returns null.
     *
     * @param keyspaceName The keyspace name
     * @param cfName The ColumnFamily name
     *
     * @return ColumnFamily Metadata object or null if it wasn't found
     */
    public CFMetaData getCFMetaData(String keyspaceName, String cfName)
    {
        assert keyspaceName != null;

        KeyspaceMetadata ksm = keyspaces.get(keyspaceName);
        return ksm == null
             ? null
             : ksm.getTableOrViewNullable(cfName);
    }

    /**
     * Get ColumnFamily metadata by its identifier
     *
     * @param cfId The ColumnFamily identifier
     *
     * @return metadata about ColumnFamily
     */
    public CFMetaData getCFMetaData(UUID cfId)
    {
        Pair<String,String> cf = getCF(cfId);
        return (cf == null) ? null : getCFMetaData(cf.left, cf.right);
    }

    public CFMetaData getCFMetaData(Descriptor descriptor)
    {
        return getCFMetaData(descriptor.ksname, descriptor.cfname);
    }

    public int getNumberOfTables()
    {
        return cfIdMap.size();
    }

    public ViewDefinition getView(String keyspaceName, String viewName)
    {
        assert keyspaceName != null;
        KeyspaceMetadata ksm = keyspaces.get(keyspaceName);
        return (ksm == null) ? null : ksm.views.getNullable(viewName);
    }

    /**
     * Get metadata about keyspace by its name
     *
     * @param keyspaceName The name of the keyspace
     *
     * @return The keyspace metadata or null if it wasn't found
     */
    public KeyspaceMetadata getKSMetaData(String keyspaceName)
    {
        assert keyspaceName != null;
        return keyspaces.get(keyspaceName);
    }

    private Set<String> getNonSystemKeyspacesSet()
    {
        return Sets.difference(keyspaces.keySet(), SchemaConstants.LOCAL_SYSTEM_KEYSPACE_NAMES);
    }

    /**
     * @return collection of the non-system keyspaces (note that this count as system only the
     * non replicated keyspaces, so keyspace like system_traces which are replicated are actually
     * returned. See getUserKeyspace() below if you don't want those)
     */
    public List<String> getNonSystemKeyspaces()
    {
        return ImmutableList.copyOf(getNonSystemKeyspacesSet());
    }

    /**
     * @return a collection of keyspaces that do not use LocalStrategy for replication
     */
    public List<String> getNonLocalStrategyKeyspaces()
    {
        return keyspaces.values().stream()
                .filter(keyspace -> keyspace.params.replication.klass != LocalStrategy.class)
                .map(keyspace -> keyspace.name)
                .collect(Collectors.toList());
    }

    /**
     * @return collection of the user defined keyspaces
     */
    public List<String> getUserKeyspaces()
    {
        return ImmutableList.copyOf(Sets.difference(getNonSystemKeyspacesSet(), SchemaConstants.REPLICATED_SYSTEM_KEYSPACE_NAMES));
    }

    public Keyspaces getReplicatedKeyspaces()
    {
        Keyspaces.Builder builder = Keyspaces.builder();

        keyspaces.values()
                 .stream()
                 .filter(k -> !SchemaConstants.isLocalSystemKeyspace(k.name))
                 .forEach(builder::add);

        return builder.build();
    }

    /**
     * Get metadata about keyspace inner ColumnFamilies
     *
     * @param keyspaceName The name of the keyspace
     *
     * @return metadata about ColumnFamilies the belong to the given keyspace
     */
    public Iterable<CFMetaData> getTablesAndViews(String keyspaceName)
    {
        assert keyspaceName != null;
        KeyspaceMetadata ksm = keyspaces.get(keyspaceName);
        assert ksm != null;
        return ksm.tablesAndViews();
    }

    /**
     * @return collection of the all keyspace names registered in the system (system and non-system)
     */
    public Set<String> getKeyspaces()
    {
        return keyspaces.keySet();
    }

    public Keyspaces getKeyspaces(Set<String> includedKeyspaceNames)
    {
        Keyspaces.Builder builder = Keyspaces.builder();
        keyspaces.values()
                 .stream()
                 .filter(k -> includedKeyspaceNames.contains(k.name))
                 .forEach(builder::add);
        return builder.build();
    }

    /**
     * Update (or insert) new keyspace definition
     *
     * @param ksm The metadata about keyspace
     */
    public void setKeyspaceMetadata(KeyspaceMetadata ksm)
    {
        assert ksm != null;

        keyspaces.put(ksm.name, ksm);
        Keyspace keyspace = getKeyspaceInstance(ksm.name);
        if (keyspace != null)
            keyspace.setMetadata(ksm);
    }

    /* ColumnFamily query/control methods */

    /**
     * @param cfId The identifier of the ColumnFamily to lookup
     * @return The (ksname,cfname) pair for the given id, or null if it has been dropped.
     */
    public Pair<String,String> getCF(UUID cfId)
    {
        return cfIdMap.inverse().get(cfId);
    }

    /**
     * @param ksAndCFName The identifier of the ColumnFamily to lookup
     * @return true if the KS and CF pair is a known one, false otherwise.
     */
    public boolean hasCF(Pair<String, String> ksAndCFName)
    {
        return cfIdMap.containsKey(ksAndCFName);
    }

    /**
     * Lookup keyspace/ColumnFamily identifier
     *
     * @param ksName The keyspace name
     * @param cfName The ColumnFamily name
     *
     * @return The id for the given (ksname,cfname) pair, or null if it has been dropped.
     */
    public UUID getId(String ksName, String cfName)
    {
        return cfIdMap.get(Pair.create(ksName, cfName));
    }

    /**
     * Load individual ColumnFamily Definition to the schema
     * (to make ColumnFamily lookup faster)
     *
     * @param cfm The ColumnFamily definition to load
     */
    public void load(CFMetaData cfm)
    {
        Pair<String, String> key = Pair.create(cfm.ksName, cfm.cfName);

        if (cfIdMap.containsKey(key))
            throw new RuntimeException(String.format("Attempting to load already loaded table %s.%s", cfm.ksName, cfm.cfName));

        logger.debug("Adding {} to cfIdMap", cfm);
        cfIdMap.put(key, cfm.cfId);
    }

    /**
     * Load individual View Definition to the schema
     * (to make View lookup faster)
     *
     * @param view The View definition to load
     */
    public void load(ViewDefinition view)
    {
        CFMetaData cfm = view.metadata;
        Pair<String, String> key = Pair.create(cfm.ksName, cfm.cfName);

        if (cfIdMap.containsKey(key))
            throw new RuntimeException(String.format("Attempting to load already loaded view %s.%s", cfm.ksName, cfm.cfName));

        logger.debug("Adding {} to cfIdMap", cfm);
        cfIdMap.put(key, cfm.cfId);
    }

    /**
     * Used for ColumnFamily data eviction out from the schema
     *
     * @param cfm The ColumnFamily Definition to evict
     */
    public void unload(CFMetaData cfm)
    {
        cfIdMap.remove(Pair.create(cfm.ksName, cfm.cfName));
    }

    /**
     * Used for View eviction from the schema
     *
     * @param view The view definition to evict
     */
    private void unload(ViewDefinition view)
    {
        cfIdMap.remove(Pair.create(view.ksName, view.viewName));
    }

    /* Function helpers */

    /**
     * Get all function overloads with the specified name
     *
     * @param name fully qualified function name
     * @return an empty list if the keyspace or the function name are not found;
     *         a non-empty collection of {@link Function} otherwise
     */
    public Collection<Function> getFunctions(FunctionName name)
    {
        if (!name.hasKeyspace())
            throw new IllegalArgumentException(String.format("Function name must be fully quallified: got %s", name));

        KeyspaceMetadata ksm = getKSMetaData(name.keyspace);
        return ksm == null
             ? Collections.emptyList()
             : ksm.functions.get(name);
    }

    /**
     * Find the function with the specified name
     *
     * @param name fully qualified function name
     * @param argTypes function argument types
     * @return an empty {@link Optional} if the keyspace or the function name are not found;
     *         a non-empty optional of {@link Function} otherwise
     */
    public Optional<Function> findFunction(FunctionName name, List<AbstractType<?>> argTypes)
    {
        if (!name.hasKeyspace())
            throw new IllegalArgumentException(String.format("Function name must be fully quallified: got %s", name));

        KeyspaceMetadata ksm = getKSMetaData(name.keyspace);
        return ksm == null
             ? Optional.empty()
             : ksm.functions.find(name, argTypes);
    }

    /* Version control */

    /**
     * The schema version to announce.
     * This will be either the "real" schema version including the {@code cdc} column,
     * if no node in the cluster is running at 3.0, or a 3.0 compatible
     * schema version, with the {@code cdc} column excluded, if at least one node is
     * running 3.0.
     *
     * @return "current" schema version
     */
    public UUID getVersion()
    {
        return Gossiper.instance.isEnabled() && Gossiper.instance.isAnyNodeOn30()
               ? altVersion
               : version;
    }

    /**
     * The 3.11 schema version, always includes the {@code cdc} column.
     */
    public UUID getRealVersion()
    {
        return version;
    }

    /**
     * The "alternative" schema version, compatible to 3.0, always excludes the
     * {@code cdc} column.
     */
    public UUID getAltVersion()
    {
        return altVersion;
    }

    /**
     * Checks whether the given schema version is the same as the current local schema
     * version, either the 3.0 compatible or "real" one.
     */
    public boolean isSameVersion(UUID schemaVersion)
    {
        return schemaVersion != null
               && (schemaVersion.equals(version) || schemaVersion.equals(altVersion));
    }

    /**
     * Checks whether the current schema is empty.
     */
    public boolean isEmpty()
    {
        return SchemaConstants.emptyVersion.equals(version);
    }

    /**
     * Read schema from system keyspace and calculate MD5 digest of every row, resulting digest
     * will be converted into UUID which would act as content-based version of the schema.
     *
     * 3.11 note: we calculate the "real" schema version and the 3.0 compatible schema
     * version here.
     */
    public void updateVersion()
    {
        Pair<UUID, UUID> mixedVersions = SchemaKeyspace.calculateSchemaDigest();
        version = mixedVersions.left;
        altVersion = mixedVersions.right;
        SystemKeyspace.updateSchemaVersion(getVersion());
    }

    /**
     * Like updateVersion, but also announces via gossip
     *
     * 3.11 note: we announce the "current" schema version, which can be either the 3.0
     * compatible one, if at least one node is still running 3.0, or the "real" schema version.
     */
    public void updateVersionAndAnnounce()
    {
        updateVersion();
        UUID current = getVersion();
        MigrationManager.passiveAnnounce(current, current == getAltVersion());
    }

    /**
     * Clear all KS/CF metadata and reset version.
     */
    public synchronized void clear()
    {
        for (String keyspaceName : getNonSystemKeyspaces())
        {
            KeyspaceMetadata ksm = getKSMetaData(keyspaceName);
            ksm.tables.forEach(this::unload);
            ksm.views.forEach(this::unload);
            clearKeyspaceMetadata(ksm);
        }

        updateVersionAndAnnounce();
    }

    public void addKeyspace(KeyspaceMetadata ksm)
    {
        assert getKSMetaData(ksm.name) == null;
        load(ksm);

        Keyspace.open(ksm.name);
        MigrationManager.instance.notifyCreateKeyspace(ksm);
    }

    public void updateKeyspace(String ksName, KeyspaceParams newParams)
    {
        KeyspaceMetadata ksm = update(ksName, ks -> ks.withSwapped(newParams));
        MigrationManager.instance.notifyUpdateKeyspace(ksm);
    }

    public void dropKeyspace(String ksName)
    {
        KeyspaceMetadata ksm = Schema.instance.getKSMetaData(ksName);
        String snapshotName = Keyspace.getTimestampedSnapshotNameWithPrefix(ksName, ColumnFamilyStore.SNAPSHOT_DROP_PREFIX);

        CompactionManager.instance.interruptCompactionFor(ksm.tablesAndViews(), true);

        Keyspace keyspace = Keyspace.open(ksm.name);

        // remove all cfs from the keyspace instance.
        List<UUID> droppedCfs = new ArrayList<>();
        for (CFMetaData cfm : ksm.tablesAndViews())
        {
            ColumnFamilyStore cfs = keyspace.getColumnFamilyStore(cfm.cfName);

            unload(cfm);

            if (DatabaseDescriptor.isAutoSnapshot())
                cfs.snapshot(snapshotName);
            Keyspace.open(ksm.name).dropCf(cfm.cfId);

            droppedCfs.add(cfm.cfId);
        }

        // remove the keyspace from the static instances.
        Keyspace.clear(ksm.name);
        clearKeyspaceMetadata(ksm);

        Keyspace.writeOrder.awaitNewBarrier();

        // force a new segment in the CL
        CommitLog.instance.forceRecycleAllSegments(droppedCfs);

        MigrationManager.instance.notifyDropKeyspace(ksm);
    }

    public void addTable(CFMetaData cfm)
    {
        assert getCFMetaData(cfm.ksName, cfm.cfName) == null;

        // Make sure the keyspace is initialized
        // and init the new CF before switching the KSM to the new one
        // to avoid races as in CASSANDRA-10761
        Keyspace.open(cfm.ksName).initCf(cfm, true);
        // Update the keyspaces map with the updated metadata
        update(cfm.ksName, ks -> ks.withSwapped(ks.tables.with(cfm)));
        // Update the table ID <-> table name map (cfIdMap)
        load(cfm);
        MigrationManager.instance.notifyCreateColumnFamily(cfm);
    }

    public void updateTable(CFMetaData table)
    {
        CFMetaData current = getCFMetaData(table.ksName, table.cfName);
        assert current != null;
        boolean changeAffectsStatements = current.apply(table);

        Keyspace keyspace = Keyspace.open(current.ksName);
        keyspace.getColumnFamilyStore(current.cfName).reload();
        MigrationManager.instance.notifyUpdateColumnFamily(current, changeAffectsStatements);
    }

    public void dropTable(String ksName, String tableName)
    {
        KeyspaceMetadata oldKsm = getKSMetaData(ksName);
        assert oldKsm != null;
        ColumnFamilyStore cfs = Keyspace.open(ksName).getColumnFamilyStore(tableName);
        assert cfs != null;

        // make sure all the indexes are dropped, or else.
        cfs.indexManager.markAllIndexesRemoved();

        // reinitialize the keyspace.
        CFMetaData cfm = oldKsm.tables.get(tableName).get();
        KeyspaceMetadata newKsm = oldKsm.withSwapped(oldKsm.tables.without(tableName));

        unload(cfm);
        setKeyspaceMetadata(newKsm);

        CompactionManager.instance.interruptCompactionFor(Collections.singleton(cfm), true);

        if (DatabaseDescriptor.isAutoSnapshot())
            cfs.snapshot(Keyspace.getTimestampedSnapshotNameWithPrefix(cfs.name, ColumnFamilyStore.SNAPSHOT_DROP_PREFIX));
        Keyspace.open(ksName).dropCf(cfm.cfId);
        MigrationManager.instance.notifyDropColumnFamily(cfm);

        CommitLog.instance.forceRecycleAllSegments(Collections.singleton(cfm.cfId));
    }

    public void addView(ViewDefinition view)
    {
        assert getCFMetaData(view.ksName, view.viewName) == null;

        Keyspace keyspace = Keyspace.open(view.ksName);

        // Make sure the keyspace is initialized and initialize the table.
        keyspace.initCf(view.metadata, true);
        // Update the keyspaces map with the updated metadata
        update(view.ksName, ks -> ks.withSwapped(ks.views.with(view)));
        // Update the table ID <-> table name map (cfIdMap)
        load(view);

        keyspace.viewManager.reload();
        MigrationManager.instance.notifyCreateView(view);
    }

    public void updateView(ViewDefinition view)
    {
        ViewDefinition current = getKSMetaData(view.ksName).views.get(view.viewName).get();
        boolean changeAffectsStatements = current.metadata.apply(view.metadata);

        Keyspace keyspace = Keyspace.open(current.ksName);
        keyspace.getColumnFamilyStore(current.viewName).reload();
        Keyspace.open(current.ksName).viewManager.update(current.viewName);
        MigrationManager.instance.notifyUpdateView(current, changeAffectsStatements);
    }

    public void dropView(String ksName, String viewName)
    {
        KeyspaceMetadata oldKsm = getKSMetaData(ksName);
        assert oldKsm != null;
        ColumnFamilyStore cfs = Keyspace.open(ksName).getColumnFamilyStore(viewName);
        assert cfs != null;

        // make sure all the indexes are dropped, or else.
        cfs.indexManager.markAllIndexesRemoved();

        // reinitialize the keyspace.
        ViewDefinition view = oldKsm.views.get(viewName).get();
        KeyspaceMetadata newKsm = oldKsm.withSwapped(oldKsm.views.without(viewName));

        unload(view);
        setKeyspaceMetadata(newKsm);

        CompactionManager.instance.interruptCompactionFor(Collections.singleton(view.metadata), true);

        if (DatabaseDescriptor.isAutoSnapshot())
            cfs.snapshot(Keyspace.getTimestampedSnapshotName(cfs.name));
        Keyspace.open(ksName).dropCf(view.metadata.cfId);
        Keyspace.open(ksName).viewManager.reload();
        MigrationManager.instance.notifyDropView(view);

        CommitLog.instance.forceRecycleAllSegments(Collections.singleton(view.metadata.cfId));
    }

    public void addType(UserType ut)
    {
        update(ut.keyspace, ks -> ks.withSwapped(ks.types.with(ut)));
        MigrationManager.instance.notifyCreateUserType(ut);
    }

    public void updateType(UserType ut)
    {
        update(ut.keyspace, ks -> ks.withSwapped(ks.types.without(ut.name).with(ut)));
        MigrationManager.instance.notifyUpdateUserType(ut);
    }

    public void dropType(UserType ut)
    {
        update(ut.keyspace, ks -> ks.withSwapped(ks.types.without(ut.name)));
        MigrationManager.instance.notifyDropUserType(ut);
    }

    public void addFunction(UDFunction udf)
    {
        update(udf.name().keyspace, ks -> ks.withSwapped(ks.functions.with(udf)));
        MigrationManager.instance.notifyCreateFunction(udf);
    }

    public void updateFunction(UDFunction udf)
    {
        update(udf.name().keyspace, ks -> ks.withSwapped(ks.functions.without(udf.name(), udf.argTypes()).with(udf)));
        MigrationManager.instance.notifyUpdateFunction(udf);
    }

    public void dropFunction(UDFunction udf)
    {
        update(udf.name().keyspace, ks -> ks.withSwapped(ks.functions.without(udf.name(), udf.argTypes())));
        MigrationManager.instance.notifyDropFunction(udf);
    }

    public void addAggregate(UDAggregate uda)
    {
        update(uda.name().keyspace, ks -> ks.withSwapped(ks.functions.with(uda)));
        MigrationManager.instance.notifyCreateAggregate(uda);
    }

    public void updateAggregate(UDAggregate uda)
    {
        update(uda.name().keyspace, ks -> ks.withSwapped(ks.functions.without(uda.name(), uda.argTypes()).with(uda)));
        MigrationManager.instance.notifyUpdateAggregate(uda);
    }

    public void dropAggregate(UDAggregate uda)
    {
        update(uda.name().keyspace, ks -> ks.withSwapped(ks.functions.without(uda.name(), uda.argTypes())));
        MigrationManager.instance.notifyDropAggregate(uda);
    }

    private synchronized KeyspaceMetadata update(String keyspaceName, java.util.function.Function<KeyspaceMetadata, KeyspaceMetadata> transformation)
    {
        KeyspaceMetadata current = getKSMetaData(keyspaceName);
        if (current == null)
            throw new IllegalStateException(String.format("Keyspace %s doesn't exist", keyspaceName));

        KeyspaceMetadata transformed = transformation.apply(current);
        setKeyspaceMetadata(transformed);

        return transformed;
    }

    /**
     * Converts the given schema version to a string. Returns {@code unknown}, if {@code version} is {@code null}
     * or {@code "(empty)"}, if {@code version} refers to an {@link SchemaConstants#emptyVersion empty) schema.
     */
    public static String schemaVersionToString(UUID version)
    {
        return version == null
               ? "unknown"
               : SchemaConstants.emptyVersion.equals(version)
                 ? "(empty)"
                 : version.toString();
    }
}