/*
 * 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.flink.api.common.typeutils.base;

import java.io.IOException;
import java.math.BigDecimal;
import java.math.BigInteger;
import org.apache.flink.annotation.Internal;
import org.apache.flink.core.memory.DataInputView;
import org.apache.flink.core.memory.DataOutputView;

/**
 * Serializer for serializing/deserializing BigDecimal values including null values.
 */
@Internal
public final class BigDecSerializer extends TypeSerializerSingleton<BigDecimal> {

	private static final long serialVersionUID = 1L;

	public static final BigDecSerializer INSTANCE = new BigDecSerializer();

	@Override
	public boolean isImmutableType() {
		return true;
	}

	@Override
	public BigDecimal createInstance() {
		return BigDecimal.ZERO;
	}

	@Override
	public BigDecimal copy(BigDecimal from) {
		return from;
	}
	
	@Override
	public BigDecimal copy(BigDecimal from, BigDecimal reuse) {
		return from;
	}

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

	@Override
	public void serialize(BigDecimal record, DataOutputView target) throws IOException {
		// null value support
		if (record == null) {
			BigIntSerializer.writeBigInteger(null, target);
			return;
		}
		// fast paths for 0, 1, 10
		// only reference equality is checked because equals would be too expensive
		else if (record == BigDecimal.ZERO) {
			BigIntSerializer.writeBigInteger(BigInteger.ZERO, target);
			target.writeInt(0);
			return;
		}
		else if (record == BigDecimal.ONE) {
			BigIntSerializer.writeBigInteger(BigInteger.ONE, target);
			target.writeInt(0);
			return;
		}
		else if (record == BigDecimal.TEN) {
			BigIntSerializer.writeBigInteger(BigInteger.TEN, target);
			target.writeInt(0);
			return;
		}
		// default
		BigIntSerializer.writeBigInteger(record.unscaledValue(), target);
		target.writeInt(record.scale());
	}

	@Override
	public BigDecimal deserialize(DataInputView source) throws IOException {
		return readBigDecimal(source);
	}

	@Override
	public BigDecimal deserialize(BigDecimal reuse, DataInputView source) throws IOException {
		return readBigDecimal(source);
	}

	@Override
	public void copy(DataInputView source, DataOutputView target) throws IOException {
		final boolean isNull = BigIntSerializer.copyBigInteger(source, target);
		if (!isNull) {
			final int scale = source.readInt();
			target.writeInt(scale);
		}
	}

	@Override
	public boolean canEqual(Object obj) {
		return obj instanceof BigDecSerializer;
	}

	// --------------------------------------------------------------------------------------------
	//                           Static Helpers for BigInteger Serialization
	// --------------------------------------------------------------------------------------------

	public static BigDecimal readBigDecimal(DataInputView source) throws IOException {
		final BigInteger unscaledValue = BigIntSerializer.readBigInteger(source);
		if (unscaledValue == null) {
			return null;
		}
		final int scale = source.readInt();
		// fast-path for 0, 1, 10
		if (scale == 0) {
			if (unscaledValue == BigInteger.ZERO) {
				return BigDecimal.ZERO;
			}
			else if (unscaledValue == BigInteger.ONE) {
				return BigDecimal.ONE;
			}
			else if (unscaledValue == BigInteger.TEN) {
				return BigDecimal.TEN;
			}
		}
		// default
		return new BigDecimal(unscaledValue, scale);
	}
}