/*
 * Copyright Elasticsearch B.V., and/or licensed to Elasticsearch B.V.
 * under one or more license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright
 * ownership. Elasticsearch B.V. 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.
 *
 * This file is based on a modification of https://github.com/open-telemetry/opentelemetry-java which is licensed under the Apache 2.0 License.
 */

package org.elasticsearch.exponentialhistogram;

class BucketArrayIterator implements CopyableBucketIterator {

    private final int scale;
    private final long[] bucketCounts;
    private final long[] bucketIndices;

    private int currentSlot;
    private final int limit;

    BucketArrayIterator(int scale, long[] bucketCounts, long[] bucketIndices, int startSlot, int limit) {
        this.scale = scale;
        this.bucketCounts = bucketCounts;
        this.bucketIndices = bucketIndices;
        this.currentSlot = startSlot;
        this.limit = limit;
    }

    @Override
    public boolean hasNext() {
        return currentSlot < limit;
    }

    @Override
    public long peekCount() {
        ensureEndNotReached();
        return bucketCounts[currentSlot];
    }

    @Override
    public long peekIndex() {
        ensureEndNotReached();
        return bucketIndices[currentSlot];
    }

    @Override
    public void advance() {
        ensureEndNotReached();
        currentSlot++;
    }

    @Override
    public int scale() {
        return scale;
    }

    @Override
    public CopyableBucketIterator copy() {
        return new BucketArrayIterator(scale, bucketCounts, bucketIndices, currentSlot, limit);
    }

    private void ensureEndNotReached() {
        if (hasNext() == false) {
            throw new IllegalStateException("Iterator has no more buckets");
        }
    }
}