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/*
 * Copyright 2011,2012 Metamarkets Group Inc.
 *
 * Licensed 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 com.metamx.common.parsers;

import com.google.common.base.Function;
import com.google.common.base.Splitter;
import com.google.common.base.Throwables;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.Iterables;
import com.google.common.collect.Iterators;
import com.google.common.collect.Lists;
import com.metamx.common.collect.Utils;
import com.metamx.common.exception.FormattedException;
import com.metamx.common.exception.SubErrorHolder;

import java.util.List;
import java.util.Map;
import java.util.Set;

public class DelimitedParser implements Parser
{
  public static final String DEFAULT_DELIMITER = "\t";
  public static final String DEFAULT_LIST_DELIMITER = "\u0001";

  protected String delimiter;
  protected String listDelimiter;

  protected Splitter splitter;
  protected Splitter listSplitter;

  protected List fieldNames;

  protected Function valueFunction = new Function()
  {
    @Override
    public Object apply(String input)
    {
      if (input.contains(listDelimiter)) {
        return Lists.newArrayList(Iterables.transform(listSplitter.split(input), ParserUtils.nullEmptyStringFunction));
      } else {
        return ParserUtils.nullEmptyStringFunction.apply(input);
      }
    }
  };

  public DelimitedParser(String delimiter, String listDelimiter)
  {
    init(delimiter, listDelimiter);
  }

  public DelimitedParser(String delimiter)
  {
    this(delimiter, DEFAULT_LIST_DELIMITER);
  }

  public DelimitedParser()
  {
    this(DEFAULT_DELIMITER, DEFAULT_LIST_DELIMITER);
  }

  public DelimitedParser(Iterable fieldNames, String delimiter, String listDelimiter)
  {
    this(delimiter, listDelimiter);
    setFieldNames(fieldNames);
  }

  public DelimitedParser(Iterable fieldNames, String delimiter)
  {
    this(fieldNames, delimiter, DEFAULT_LIST_DELIMITER);
  }

  public DelimitedParser(Iterable fieldNames)
  {
    this(fieldNames, DEFAULT_DELIMITER, DEFAULT_LIST_DELIMITER);
  }

  protected void init(String delimiter, String listDelimiter)
  {
    this.delimiter = delimiter;
    this.listDelimiter = listDelimiter;
    this.splitter = Splitter.on(delimiter);
    this.listSplitter = Splitter.on(listDelimiter);
    this.fieldNames = null;
  }

  @Override
  public List getFieldNames()
  {
    return fieldNames;
  }

  @Override
  public void setFieldNames(Iterable fieldNames)
  {
    ParserUtils.validateFields(fieldNames);
    this.fieldNames = Lists.newArrayList(fieldNames);
  }

  public void setFieldNames(String header)
  {
    try {
      setFieldNames(splitter.split(header));
    }
    catch (Exception e) {
      Throwables.propagateIfInstanceOf(e, FormattedException.class);
      throw new FormattedException.Builder()
          .withErrorCode(FormattedException.ErrorCode.UNPARSABLE_HEADER)
          .withMessage(e.getMessage())
          .build();
    }
  }

  @Override
  public Map parse(String input) throws FormattedException
  {
    try {
      Iterable values = splitter.split(input);

      if (fieldNames == null) {
        setFieldNames(ParserUtils.generateFieldNames(Iterators.size(values.iterator())));
      }

      return Utils.zipMapPartial(fieldNames, Iterables.transform(values, valueFunction));
    }
    catch (Exception e) {
      Throwables.propagateIfInstanceOf(e, FormattedException.class);
      throw new FormattedException.Builder()
          .withErrorCode(FormattedException.ErrorCode.UNPARSABLE_ROW)
          .withMessage(e.getMessage())
          .build();
    }
  }
}