// 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.impala.catalog;

import java.util.Map;

import org.apache.hadoop.hive.metastore.api.StorageDescriptor;

import org.apache.impala.analysis.StringLiteral;
import org.apache.impala.thrift.TTableRowFormat;
import com.google.common.base.Preconditions;

/**
 * Defines the physical (on-disk) format for a table's data. This is used when creating
 * a new table to specify how to interpret the fields (columns) and lines (rows) in a
 * a data file.
 */
public class RowFormat {
  // Default row format
  public final static RowFormat DEFAULT_ROW_FORMAT = new RowFormat(null, null, null);

  private final String fieldDelimiter_;
  private final String lineDelimiter_;
  private final String escapeChar_;

  private RowFormat(String fieldDelimiter, String lineDelimiter, String escapeChar,
      boolean unescape) {
    if (unescape) {
      fieldDelimiter_ = getUnescapedValueOrNull(fieldDelimiter);
      lineDelimiter_ = getUnescapedValueOrNull(lineDelimiter);
      escapeChar_ = getUnescapedValueOrNull(escapeChar);
    } else {
      fieldDelimiter_ = fieldDelimiter;
      lineDelimiter_ = lineDelimiter;
      escapeChar_ = escapeChar;
    }
  }

  /**
   * Creates a new instance of the RowFormat class, unescaping the values of
   * field delimiter, line delimiter, and escape char.
   */
  public RowFormat(String fieldDelimiter, String lineDelimiter, String escapeChar) {
    this(fieldDelimiter, lineDelimiter, escapeChar, true);
  }

  public String getFieldDelimiter() {
    return fieldDelimiter_;
  }

  public String getLineDelimiter() {
    return lineDelimiter_;
  }

  public String getEscapeChar() {
    return escapeChar_;
  }

  public boolean isDefault() {
    return fieldDelimiter_ == null && lineDelimiter_ == null && escapeChar_ == null;
  }

  private static String getUnescapedValueOrNull(String value) {
    return value == null ? null : new StringLiteral(value).getUnescapedValue();
  }

  public TTableRowFormat toThrift() {
    TTableRowFormat tableRowFormat = new TTableRowFormat();
    tableRowFormat.setField_terminator(getFieldDelimiter());
    tableRowFormat.setLine_terminator(getLineDelimiter());
    tableRowFormat.setEscaped_by(getEscapeChar());
    return tableRowFormat;
  }

  public static RowFormat fromThrift(TTableRowFormat tableRowFormat) {
    if (tableRowFormat == null) {
      return RowFormat.DEFAULT_ROW_FORMAT;
    }
    // When creating a RowFormat from thrift, don't unescape the values, they should have
    // already been unescaped.
    return new RowFormat(tableRowFormat.getField_terminator(),
        tableRowFormat.getLine_terminator(), tableRowFormat.getEscaped_by(), false);
  }

  /**
   * Returns the RowFormat for the storage descriptor.
   */
  public static RowFormat fromStorageDescriptor(StorageDescriptor sd) {
    Preconditions.checkNotNull(sd);
    Map<String, String> params = sd.getSerdeInfo().getParameters();
    return new RowFormat(params.get("field.delim"), params.get("line.delim"),
        params.get("escape.delim"));
  }
}