/*
 * 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 org.apache.flink.annotation.Internal;
import org.apache.flink.core.memory.DataInputView;
import org.apache.flink.core.memory.MemorySegment;

import java.io.IOException;
import java.util.Date;

@Internal
public final class DateComparator extends BasicTypeComparator<Date> {

	private static final long serialVersionUID = 1L;

	public DateComparator(boolean ascending) {
		super(ascending);
	}

	@Override
	public int compareSerialized(DataInputView firstSource, DataInputView secondSource) throws IOException {
		return compareSerializedDate(firstSource, secondSource, ascendingComparison);
	}

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

	@Override
	public int getNormalizeKeyLen() {
		return 8;
	}

	@Override
	public boolean isNormalizedKeyPrefixOnly(int keyBytes) {
		return keyBytes < 8;
	}

	@Override
	public void putNormalizedKey(Date record, MemorySegment target, int offset, int numBytes) {
		putNormalizedKeyDate(record, target, offset, numBytes);
	}

	@Override
	public DateComparator duplicate() {
		return new DateComparator(ascendingComparison);
	}

	// --------------------------------------------------------------------------------------------
	//                           Static Helpers for Date Comparison
	// --------------------------------------------------------------------------------------------

	public static int compareSerializedDate(DataInputView firstSource, DataInputView secondSource,
			boolean ascendingComparison) throws IOException {
		final long l1 = firstSource.readLong();
		final long l2 = secondSource.readLong();
		final int comp = (l1 < l2 ? -1 : (l1 == l2 ? 0 : 1));
		return ascendingComparison ? comp : -comp;
	}

	public static void putNormalizedKeyDate(Date record, MemorySegment target, int offset, int numBytes) {
		final long value = record.getTime() - Long.MIN_VALUE;

		// see IntValue for an explanation of the logic
		if (numBytes == 8) {
			// default case, full normalized key
			target.putLongBigEndian(offset, value);
		}
		else if (numBytes < 8) {
			for (int i = 0; numBytes > 0; numBytes--, i++) {
				target.put(offset + i, (byte) (value >>> ((7-i)<<3)));
			}
		}
		else {
			target.putLongBigEndian(offset, value);
			for (int i = 8; i < numBytes; i++) {
				target.put(offset + i, (byte) 0);
			}
		}
	}
}