/*

 * Copyright (c) 2019, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 */

package org.reactivestreams.tck.flow.support;

import java.util.Collections;

import java.util.Iterator;

import java.util.concurrent.Executor;

import org.reactivestreams.example.unicast.AsyncIterablePublisher;

public class HelperPublisher<T> extends AsyncIterablePublisher<T> {

    public HelperPublisher(final int from, final int to, final Function<Integer, T> create, final Executor executor) {

        super(new Iterable<T>() {

          { if(from > to) throw new IllegalArgumentException("from must be equal or greater than to!"); }

          @Override public Iterator<T> iterator() {

            return new Iterator<T>() {

              private int at = from;

              @Override public boolean hasNext() { return at < to; }

              @Override public T next() {

                if (!hasNext()) return Collections.<T>emptyList().iterator().next();

                else try {

                  return create.apply(at++);

                } catch (Throwable t) {

                  throw new IllegalStateException(String.format("Failed to create element for id %d!", at - 1), t);

                }

              }

              @Override public void remove() { throw new UnsupportedOperationException(); }

            };

          }

        }, executor);

    }

}