/*
 * 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.java.typeutils.runtime;

import org.apache.flink.annotation.Internal;
import org.apache.flink.annotation.VisibleForTesting;
import org.apache.flink.api.common.typeutils.TypeSerializer;
import org.apache.flink.core.memory.DataInputView;
import org.apache.flink.core.memory.DataOutputView;

import java.io.IOException;
import java.util.Arrays;
import java.util.Objects;

import static org.apache.flink.util.Preconditions.checkNotNull;

@Internal
public abstract class TupleSerializerBase<T> extends TypeSerializer<T> {

    private static final long serialVersionUID = 1L;

    protected final Class<T> tupleClass;

    protected TypeSerializer<Object>[] fieldSerializers;

    protected final int arity;

    private int length = -2;

    @SuppressWarnings("unchecked")
    public TupleSerializerBase(Class<T> tupleClass, TypeSerializer<?>[] fieldSerializers) {
        this.tupleClass = checkNotNull(tupleClass);
        this.fieldSerializers = (TypeSerializer<Object>[]) checkNotNull(fieldSerializers);
        this.arity = fieldSerializers.length;
    }

    public Class<T> getTupleClass() {
        return this.tupleClass;
    }

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

    @Override
    public int getLength() {
        if (length == -2) {
            int sum = 0;
            for (TypeSerializer<Object> serializer : fieldSerializers) {
                if (serializer.getLength() > 0) {
                    sum += serializer.getLength();
                } else {
                    length = -1;
                    return length;
                }
            }
            length = sum;
        }
        return length;
    }

    public int getArity() {
        return arity;
    }

    // We use this in the Aggregate and Distinct Operators to create instances
    // of immutable Tuples (i.e. Scala Tuples)
    public abstract T createInstance(Object[] fields);

    public abstract T createOrReuseInstance(Object[] fields, T reuse);

    @Override
    public void copy(DataInputView source, DataOutputView target) throws IOException {
        for (int i = 0; i < arity; i++) {
            fieldSerializers[i].copy(source, target);
        }
    }

    @Override
    public int hashCode() {
        return 31 * Arrays.hashCode(fieldSerializers) + Objects.hash(tupleClass, arity);
    }

    @Override
    public boolean equals(Object obj) {
        if (obj instanceof TupleSerializerBase) {
            TupleSerializerBase<?> other = (TupleSerializerBase<?>) obj;

            return tupleClass == other.tupleClass
                    && Arrays.equals(fieldSerializers, other.fieldSerializers)
                    && arity == other.arity;
        } else {
            return false;
        }
    }

    @VisibleForTesting
    public TypeSerializer<Object>[] getFieldSerializers() {
        return fieldSerializers;
    }
}
