/***********************************************************************************************************************
 * Copyright (C) 2010-2013 by the Stratosphere project (http://stratosphere.eu)
 *
 * 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 eu.stratosphere.api.java.typeutils.runtime.record;

import java.io.IOException;

import eu.stratosphere.api.common.typeutils.TypeSerializer;
import eu.stratosphere.core.memory.DataInputView;
import eu.stratosphere.core.memory.DataOutputView;
import eu.stratosphere.types.Record;


/**
 * Implementation of the (de)serialization and copying logic for the {@link Record}.
 */
public final class RecordSerializer extends TypeSerializer<Record> {
	
	private static final long serialVersionUID = 1L;

	private static final RecordSerializer INSTANCE = new RecordSerializer(); // singleton instance
	
	private static final int MAX_BIT = 0x80;	// byte where only the most significant bit is set
	
	// --------------------------------------------------------------------------------------------

	public static final RecordSerializer get() {
		return INSTANCE;
	}
	
	/**
	 * Creates a new instance of the RecordSerializers. Private to prevent instantiation.
	 */
	private RecordSerializer() {}

	// --------------------------------------------------------------------------------------------
	
	@Override
	public boolean isImmutableType() {
		return false;
	}

	@Override
	public boolean isStateful() {
		return false;
	}
	
	@Override
	public Record createInstance() {
		return new Record(); 
	}

	@Override
	public Record copy(Record from, Record reuse) {
		from.copyTo(reuse);
		return reuse;
	}
	

	@Override
	public int getLength() {
		return -1;
	}

	// --------------------------------------------------------------------------------------------
	
	@Override
	public void serialize(Record record, DataOutputView target) throws IOException {
		record.serialize(target);
	}

	@Override
	public Record deserialize(Record target, DataInputView source) throws IOException {
		target.deserialize(source);
		return target;
	}
	
	@Override
	public void copy(DataInputView source, DataOutputView target) throws IOException {
		int val = source.readUnsignedByte();
		target.writeByte(val);
		
		if (val >= MAX_BIT) {
			int shift = 7;
			int curr;
			val = val & 0x7f;
			while ((curr = source.readUnsignedByte()) >= MAX_BIT) {
				target.writeByte(curr);
				val |= (curr & 0x7f) << shift;
				shift += 7;
			}
			target.writeByte(curr);
			val |= curr << shift;
		}
		
		target.write(source, val);
	}
}