Copyright (c) 2016-present, RxJava Contributors.
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.
/**
 * Copyright (c) 2016-present, RxJava Contributors.
 *
 * 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.reactivex.internal.operators.observable;

import java.util.concurrent.TimeUnit;

import io.reactivex.*;
import io.reactivex.disposables.Disposable;
import io.reactivex.internal.disposables.DisposableHelper;
import io.reactivex.schedulers.Timed;

public final class ObservableTimeInterval<T> extends AbstractObservableWithUpstream<T, Timed<T>> {
    final Scheduler scheduler;
    final TimeUnit unit;

    public ObservableTimeInterval(ObservableSource<T> source, TimeUnit unit, Scheduler scheduler) {
        super(source);
        this.scheduler = scheduler;
        this.unit = unit;
    }

    @Override
    public void subscribeActual(Observer<? super Timed<T>> t) {
        source.subscribe(new TimeIntervalObserver<T>(t, unit, scheduler));
    }

    static final class TimeIntervalObserver<T> implements Observer<T>, Disposable {
        final Observer<? super Timed<T>> downstream;
        final TimeUnit unit;
        final Scheduler scheduler;

        long lastTime;

        Disposable upstream;

        TimeIntervalObserver(Observer<? super Timed<T>> actual, TimeUnit unit, Scheduler scheduler) {
            this.downstream = actual;
            this.scheduler = scheduler;
            this.unit = unit;
        }

        @Override
        public void onSubscribe(Disposable d) {
            if (DisposableHelper.validate(this.upstream, d)) {
                this.upstream = d;
                lastTime = scheduler.now(unit);
                downstream.onSubscribe(this);
            }
        }

        @Override
        public void dispose() {
            upstream.dispose();
        }

        @Override
        public boolean isDisposed() {
            return upstream.isDisposed();
        }

        @Override
        public void onNext(T t) {
            long now = scheduler.now(unit);
            long last = lastTime;
            lastTime = now;
            long delta = now - last;
            downstream.onNext(new Timed<T>(t, delta, unit));
        }

        @Override
        public void onError(Throwable t) {
            downstream.onError(t);
        }

        @Override
        public void onComplete() {
            downstream.onComplete();
        }
    }
}