content: /*
   * 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.cql3.statements.schema;
  
  import java.nio.ByteBuffer;
  
  import org.apache.cassandra.audit.AuditLogContext;
  import org.apache.cassandra.audit.AuditLogEntryType;
  import org.apache.cassandra.auth.Permission;
  import org.apache.cassandra.cql3.CQLStatement;
  import org.apache.cassandra.cql3.UTName;
  import org.apache.cassandra.cql3.functions.UserFunction;
  import org.apache.cassandra.db.marshal.UserType;
  import org.apache.cassandra.schema.KeyspaceMetadata;
  import org.apache.cassandra.schema.Keyspaces.KeyspacesDiff;
  import org.apache.cassandra.schema.Keyspaces;
  import org.apache.cassandra.schema.TableMetadata;
  import org.apache.cassandra.service.ClientState;
  import org.apache.cassandra.tcm.ClusterMetadata;
  import org.apache.cassandra.transport.Event.SchemaChange.Change;
  import org.apache.cassandra.transport.Event.SchemaChange.Target;
  import org.apache.cassandra.transport.Event.SchemaChange;
  
  import static java.lang.String.join;
  
  import static com.google.common.collect.Iterables.isEmpty;
  import static com.google.common.collect.Iterables.transform;
  
  import static org.apache.cassandra.utils.ByteBufferUtil.bytes;
  
  public final class DropTypeStatement extends AlterSchemaStatement
  {
      private final String typeName;
      private final boolean ifExists;
  
      public DropTypeStatement(String keyspaceName, String typeName, boolean ifExists)
      {
          super(keyspaceName);
          this.typeName = typeName;
          this.ifExists = ifExists;
      }
  
      // TODO: expand types into tuples in all dropped columns of all tables
      @Override
      public Keyspaces apply(ClusterMetadata metadata)
      {
          ByteBuffer name = bytes(typeName);
  
          Keyspaces schema = metadata.schema.getKeyspaces();
          KeyspaceMetadata keyspace = schema.getNullable(keyspaceName);
  
          UserType type = null == keyspace
                        ? null
                        : keyspace.types.getNullable(name);
  
          if (null == type)
          {
              if (ifExists)
                  return schema;
  
              throw ire("Type '%s.%s' doesn't exist", keyspaceName, typeName);
          }
  
          /*
           * We don't want to drop a type unless it's not used anymore (mainly because
           * if someone drops a type and recreates one with the same name but different
           * definition with the previous name still in use, things can get messy).
           * We have three places to check:
           * 1) UDFs and UDAs using the type
           * 2) other user type that can nest the one we drop and
           * 3) existing tables referencing the type (maybe in a nested way).
           */
          Iterable<UserFunction> functions = keyspace.userFunctions.referencingUserType(name);
          if (!isEmpty(functions))
          {
              throw ire("Cannot drop user type '%s.%s' as it is still used by functions %s",
                        keyspaceName,
                        typeName,
                        join(", ", transform(functions, f -> f.name().toString())));
          }
  
          Iterable<UserType> types = keyspace.types.referencingUserType(name);
          if (!isEmpty(types))
          {
              throw ire("Cannot drop user type '%s.%s' as it is still used by user types %s",
                        keyspaceName,
                        typeName,
                        join(", ", transform(types, UserType::getNameAsString)));
  
          }
  
          Iterable<TableMetadata> tables = keyspace.tables.referencingUserType(name);
          if (!isEmpty(tables))
          {
              throw ire("Cannot drop user type '%s.%s' as it is still used by tables %s",
                        keyspaceName,
                        typeName,
                        join(", ", transform(tables, t -> t.name)));
          }
  
          return schema.withAddedOrUpdated(keyspace.withSwapped(keyspace.types.without(type)));
      }
  
      SchemaChange schemaChangeEvent(KeyspacesDiff diff)
      {
          return new SchemaChange(Change.DROPPED, Target.TYPE, keyspaceName, typeName);
      }
  
      public void authorize(ClientState client)
      {
          client.ensureAllTablesPermission(keyspaceName, Permission.DROP);
      }
  
      @Override
      public AuditLogContext getAuditLogContext()
      {
          return new AuditLogContext(AuditLogEntryType.DROP_TYPE, keyspaceName, typeName);
      }
  
      public String toString()
      {
          return String.format("%s (%s, %s)", getClass().getSimpleName(), keyspaceName, typeName);
      }
  
      public static final class Raw extends CQLStatement.Raw
      {
          private final UTName name;
          private final boolean ifExists;
  
          public Raw(UTName name, boolean ifExists)
          {
              this.name = name;
              this.ifExists = ifExists;
          }
  
          public DropTypeStatement prepare(ClientState state)
          {
              String keyspaceName = name.hasKeyspace() ? name.getKeyspace() : state.getKeyspace();
              return new DropTypeStatement(keyspaceName, name.getStringTypeName(), ifExists);
          }
      }
  }
  