/*
 * 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.eigenbase.sql;

import java.util.List;

import org.eigenbase.sql.parser.*;
import org.eigenbase.sql.validate.*;
import org.eigenbase.util.ImmutableNullableList;

/**
 * A <code>SqlDelete</code> is a node of a parse tree which represents a DELETE
 * statement.
 */
public class SqlDelete extends SqlCall {
  public static final SqlSpecialOperator OPERATOR =
      new SqlSpecialOperator("DELETE", SqlKind.DELETE);

  SqlIdentifier targetTable;
  SqlNode condition;
  SqlSelect sourceSelect;
  SqlIdentifier alias;

  //~ Constructors -----------------------------------------------------------

  public SqlDelete(
      SqlParserPos pos,
      SqlIdentifier targetTable,
      SqlNode condition,
      SqlSelect sourceSelect,
      SqlIdentifier alias) {
    super(pos);
    this.targetTable = targetTable;
    this.condition = condition;
    this.sourceSelect = sourceSelect;
    this.alias = alias;
  }

  //~ Methods ----------------------------------------------------------------

  @Override public SqlKind getKind() {
    return SqlKind.DELETE;
  }

  public SqlOperator getOperator() {
    return OPERATOR;
  }

  public List<SqlNode> getOperandList() {
    return ImmutableNullableList.of(targetTable, condition, alias);
  }

  @Override public void setOperand(int i, SqlNode operand) {
    switch (i) {
    case 0:
      targetTable = (SqlIdentifier) operand;
      break;
    case 1:
      condition = operand;
      break;
    case 2:
      sourceSelect = (SqlSelect) operand;
      break;
    case 3:
      alias = (SqlIdentifier) operand;
      break;
    default:
      throw new AssertionError(i);
    }
  }

  /**
   * @return the identifier for the target table of the deletion
   */
  public SqlIdentifier getTargetTable() {
    return targetTable;
  }

  /**
   * @return the alias for the target table of the deletion
   */
  public SqlIdentifier getAlias() {
    return alias;
  }

  /**
   * Gets the filter condition for rows to be deleted.
   *
   * @return the condition expression for the data to be deleted, or null for
   * all rows in the table
   */
  public SqlNode getCondition() {
    return condition;
  }

  /**
   * Gets the source SELECT expression for the data to be deleted. This
   * returns null before the condition has been expanded by
   * {@link SqlValidatorImpl#performUnconditionalRewrites(SqlNode, boolean)}.
   *
   * @return the source SELECT for the data to be inserted
   */
  public SqlSelect getSourceSelect() {
    return sourceSelect;
  }

  @Override public void unparse(SqlWriter writer, int leftPrec, int rightPrec) {
    final SqlWriter.Frame frame =
        writer.startList(SqlWriter.FrameTypeEnum.SELECT, "DELETE FROM", "");
    final int opLeft = getOperator().getLeftPrec();
    final int opRight = getOperator().getRightPrec();
    targetTable.unparse(writer, opLeft, opRight);
    if (alias != null) {
      writer.keyword("AS");
      alias.unparse(writer, opLeft, opRight);
    }
    if (condition != null) {
      writer.sep("WHERE");
      condition.unparse(writer, opLeft, opRight);
    }
    writer.endList(frame);
  }

  public void validate(SqlValidator validator, SqlValidatorScope scope) {
    validator.validateDelete(this);
  }

  public void setSourceSelect(SqlSelect sourceSelect) {
    this.sourceSelect = sourceSelect;
  }
}

// End SqlDelete.java