/**
 * 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.hadoop.record;

import java.io.InputStreamReader;
import java.io.InputStream;
import java.io.IOException;
import java.io.PushbackReader;
import java.io.UnsupportedEncodingException;

/**
 */
public class CsvRecordInput implements RecordInput {
    
  private PushbackReader stream;
    
  private class CsvIndex implements Index {
    public boolean done() {
      char c = '\0';
      try {
        c = (char) stream.read();
        stream.unread(c);
      } catch (IOException ex) {
      }
      return (c == '}') ? true : false;
    }
    public void incr() {}
  }
    
  private void throwExceptionOnError(String tag) throws IOException {
    throw new IOException("Error deserializing "+tag);
  }
    
  private String readField(String tag) throws IOException {
    try {
      StringBuffer buf = new StringBuffer();
      while (true) {
        char c = (char) stream.read();
        switch (c) {
        case ',':
          return buf.toString();
        case '}':
        case '\n':
        case '\r':
          stream.unread(c);
          return buf.toString();
        default:
          buf.append(c);
        }
      }
    } catch (IOException ex) {
      throw new IOException("Error reading "+tag);
    }
  }
    
  /** Creates a new instance of CsvRecordInput */
  public CsvRecordInput(InputStream in) {
    try {
      stream = new PushbackReader(new InputStreamReader(in, "UTF-8"));
    } catch (UnsupportedEncodingException ex) {
      throw new RuntimeException(ex);
    }
  }
    
  public byte readByte(String tag) throws IOException {
    return (byte) readLong(tag);
  }
    
  public boolean readBool(String tag) throws IOException {
    String sval = readField(tag);
    return "T".equals(sval) ? true : false;
  }
    
  public int readInt(String tag) throws IOException {
    return (int) readLong(tag);
  }
    
  public long readLong(String tag) throws IOException {
    String sval = readField(tag);
    try {
      long lval = Long.parseLong(sval);
      return lval;
    } catch (NumberFormatException ex) {
      throw new IOException("Error deserializing "+tag);
    }
  }
    
  public float readFloat(String tag) throws IOException {
    return (float) readDouble(tag);
  }
    
  public double readDouble(String tag) throws IOException {
    String sval = readField(tag);
    try {
      double dval = Double.parseDouble(sval);
      return dval;
    } catch (NumberFormatException ex) {
      throw new IOException("Error deserializing "+tag);
    }
  }
    
  public String readString(String tag) throws IOException {
    String sval = readField(tag);
    return Utils.fromCSVString(sval);
  }
    
  public Buffer readBuffer(String tag) throws IOException {
    String sval = readField(tag);
    return Utils.fromCSVBuffer(sval);
  }
    
  public void startRecord(String tag) throws IOException {
    if (tag != null && !"".equals(tag)) {
      char c1 = (char) stream.read();
      char c2 = (char) stream.read();
      if (c1 != 's' || c2 != '{') {
        throw new IOException("Error deserializing "+tag);
      }
    }
  }
    
  public void endRecord(String tag) throws IOException {
    char c = (char) stream.read();
    if (tag == null || "".equals(tag)) {
      if (c != '\n' && c != '\r') {
        throw new IOException("Error deserializing record.");
      } else {
        return;
      }
    }
        
    if (c != '}') {
      throw new IOException("Error deserializing "+tag);
    }
    c = (char) stream.read();
    if (c != ',') {
      stream.unread(c);
    }
        
    return;
  }
    
  public Index startVector(String tag) throws IOException {
    char c1 = (char) stream.read();
    char c2 = (char) stream.read();
    if (c1 != 'v' || c2 != '{') {
      throw new IOException("Error deserializing "+tag);
    }
    return new CsvIndex();
  }
    
  public void endVector(String tag) throws IOException {
    char c = (char) stream.read();
    if (c != '}') {
      throw new IOException("Error deserializing "+tag);
    }
    c = (char) stream.read();
    if (c != ',') {
      stream.unread(c);
    }
    return;
  }
    
  public Index startMap(String tag) throws IOException {
    char c1 = (char) stream.read();
    char c2 = (char) stream.read();
    if (c1 != 'm' || c2 != '{') {
      throw new IOException("Error deserializing "+tag);
    }
    return new CsvIndex();
  }
    
  public void endMap(String tag) throws IOException {
    char c = (char) stream.read();
    if (c != '}') {
      throw new IOException("Error deserializing "+tag);
    }
    c = (char) stream.read();
    if (c != ',') {
      stream.unread(c);
    }
    return;
  }
}