/*
 * Copyright (c) nosqlbench
 *
 * 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 io.nosqlbench.virtdata.userlibs.streams.fillers;

import org.jetbrains.annotations.NotNull;

import java.util.Iterator;
import java.util.function.LongFunction;

public class LongFunctionIterable<T> implements Iterable<T> {

    private final long startCycle;
    private final LongFunction<T> f;
    private final long endCycle;

    public LongFunctionIterable(long startCycle,long endCycle, LongFunction<T> f) {
        this.startCycle = startCycle;
        this.endCycle = endCycle;
        this.f = f;
    }

    @NotNull
    @Override
    public Iterator<T> iterator() {
        return new LongFunctionIterator(startCycle, endCycle, f);
    }

    private class LongFunctionIterator implements Iterator<T> {
        private final long endCycle;
        private long cycle;
        private final LongFunction<T> f;

        public LongFunctionIterator(long startCycle, long endCycle, LongFunction<T> f) {
            this.cycle = startCycle;
            this.endCycle = endCycle;
            this.f = f;
        }

        @Override
        public boolean hasNext() {
            return cycle<endCycle;
        }

        @Override
        public T next() {
            return f.apply(cycle++);
        }
    }
}
