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/*
 * Copyright 2016-2019 Crown Copyright
 *
 * 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 uk.gov.gchq.gaffer.commonutil.iterable;

import uk.gov.gchq.gaffer.commonutil.CloseableUtil;
import uk.gov.gchq.gaffer.commonutil.ToStringBuilder;

import java.util.Collections;
import java.util.Iterator;

/**
 * A {@code WrappedCloseableIterable} is an {@link CloseableIterable} which provides
 * a wrapper around any non-closeable iterables.
 *
 * @param  the type of items in the iterable.
 */
public class WrappedCloseableIterable implements CloseableIterable {
    private final Iterable iterable;

    public WrappedCloseableIterable() {
        this(Collections.emptyList());
    }

    public WrappedCloseableIterable(final Iterable iterable) {
        if (null == iterable) {
            this.iterable = new EmptyClosableIterable<>();
        } else {
            this.iterable = iterable;
        }
    }

    public WrappedCloseableIterable(final Iterator iterator) {
        if (null == iterator) {
            this.iterable = EmptyCloseableIterator::new;
        } else {
            this.iterable = () -> iterator;
        }
    }

    @Override
    public void close() {
        CloseableUtil.close(iterable);
    }

    @Override
    public CloseableIterator iterator() {
        final Iterator iterator = iterable.iterator();
        if (iterator instanceof CloseableIterator) {
            return (CloseableIterator) iterator;
        }

        return new WrappedCloseableIterator<>(iterator);
    }

    @Override
    public String toString() {
        return new ToStringBuilder(this)
                .append("iterable", iterable)
                .toString();
    }
}