/*
 * 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.beam.sdk.extensions.sql.impl.parser;

import static org.apache.calcite.util.Static.RESOURCE;

import com.google.common.collect.ImmutableList;
import java.util.List;
import org.apache.beam.sdk.extensions.sql.impl.BeamCalciteSchema;
import org.apache.calcite.jdbc.CalcitePrepare;
import org.apache.calcite.jdbc.CalciteSchema;
import org.apache.calcite.sql.SqlDrop;
import org.apache.calcite.sql.SqlExecutableStatement;
import org.apache.calcite.sql.SqlIdentifier;
import org.apache.calcite.sql.SqlNode;
import org.apache.calcite.sql.SqlOperator;
import org.apache.calcite.sql.SqlUtil;
import org.apache.calcite.sql.SqlWriter;
import org.apache.calcite.sql.parser.SqlParserPos;

/**
 * Base class for parse trees of {@code DROP TABLE}, {@code DROP VIEW} and {@code DROP MATERIALIZED
 * VIEW} statements.
 */
abstract class SqlDropObject extends SqlDrop implements SqlExecutableStatement {
  protected final SqlIdentifier name;

  /** Creates a SqlDropObject. */
  SqlDropObject(SqlOperator operator, SqlParserPos pos, boolean ifExists, SqlIdentifier name) {
    super(operator, pos, ifExists);
    this.name = name;
  }

  @Override
  public List<SqlNode> getOperandList() {
    return ImmutableList.<SqlNode>of(name);
  }

  @Override
  public void unparse(SqlWriter writer, int leftPrec, int rightPrec) {
    writer.keyword(getOperator().getName()); // "DROP TABLE" etc.
    if (ifExists) {
      writer.keyword("IF EXISTS");
    }
    name.unparse(writer, leftPrec, rightPrec);
  }

  @Override
  public void execute(CalcitePrepare.Context context) {
    final List<String> path = context.getDefaultSchemaPath();
    CalciteSchema schema = context.getRootSchema();
    for (String p : path) {
      schema = schema.getSubSchema(p, true);
    }
    final boolean existed;
    switch (getKind()) {
      case DROP_TABLE:
        if (schema.schema instanceof BeamCalciteSchema) {
          BeamCalciteSchema beamSchema = (BeamCalciteSchema) schema.schema;
          beamSchema.getTableProvider().dropTable(name.getSimple());
          existed = true;
        } else {
          existed = schema.removeTable(name.getSimple());
        }
        if (!existed && !ifExists) {
          throw SqlUtil.newContextException(
              name.getParserPosition(), RESOURCE.tableNotFound(name.getSimple()));
        }
        break;
      default:
        throw new AssertionError(getKind());
    }
  }
}

// End SqlDropObject.java
