/*

 * Copyright (c) 2013, 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.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * 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 java.util.stream;

import java.util.DoubleSummaryStatistics;

import java.util.Objects;

import java.util.OptionalDouble;

import java.util.PrimitiveIterator;

import java.util.Spliterator;

import java.util.Spliterators;

import java.util.function.BiConsumer;

import java.util.function.BinaryOperator;

import java.util.function.DoubleBinaryOperator;

import java.util.function.DoubleConsumer;

import java.util.function.DoubleFunction;

import java.util.function.DoublePredicate;

import java.util.function.DoubleToIntFunction;

import java.util.function.DoubleToLongFunction;

import java.util.function.DoubleUnaryOperator;

import java.util.function.IntFunction;

import java.util.function.ObjDoubleConsumer;

import java.util.function.Supplier;

/**

 * Abstract base class for an intermediate pipeline stage or pipeline source

 * stage implementing whose elements are of type {@code double}.

 *

 * @param <E_IN> type of elements in the upstream source

 *

 * @since 1.8

 */

abstract class DoublePipeline<E_IN>

        extends AbstractPipeline<E_IN, Double, DoubleStream>

        implements DoubleStream {

    /**

     * Constructor for the head of a stream pipeline.

     *

     * @param source {@code Supplier<Spliterator>} describing the stream source

     * @param sourceFlags the source flags for the stream source, described in

     * {@link StreamOpFlag}

     */

    DoublePipeline(Supplier<? extends Spliterator<Double>> source,

                   int sourceFlags, boolean parallel) {

        super(source, sourceFlags, parallel);

    }

    /**

     * Constructor for the head of a stream pipeline.

     *

     * @param source {@code Spliterator} describing the stream source

     * @param sourceFlags the source flags for the stream source, described in

     * {@link StreamOpFlag}

     */

    DoublePipeline(Spliterator<Double> source,

                   int sourceFlags, boolean parallel) {

        super(source, sourceFlags, parallel);

    }

    /**

     * Constructor for appending an intermediate operation onto an existing

     * pipeline.

     *

     * @param upstream the upstream element source.

     * @param opFlags the operation flags

     */

    DoublePipeline(AbstractPipeline<?, E_IN, ?> upstream, int opFlags) {

        super(upstream, opFlags);

    }

    /**

     * Adapt a {@code Sink<Double> to a {@code DoubleConsumer}, ideally simply

     * by casting.

     */

    private static DoubleConsumer adapt(Sink<Double> sink) {

        if (sink instanceof DoubleConsumer) {

            return (DoubleConsumer) sink;

        } else {

            if (Tripwire.ENABLED)

                Tripwire.trip(AbstractPipeline.class,

                              "using DoubleStream.adapt(Sink<Double> s)");

            return sink::accept;

        }

    }

    /**

     * Adapt a {@code Spliterator<Double>} to a {@code Spliterator.OfDouble}.

     *

     * @implNote

     * The implementation attempts to cast to a Spliterator.OfDouble, and throws

     * an exception if this cast is not possible.

     */

    private static Spliterator.OfDouble adapt(Spliterator<Double> s) {

        if (s instanceof Spliterator.OfDouble) {

            return (Spliterator.OfDouble) s;

        } else {

            if (Tripwire.ENABLED)

                Tripwire.trip(AbstractPipeline.class,

                              "using DoubleStream.adapt(Spliterator<Double> s)");

            throw new UnsupportedOperationException("DoubleStream.adapt(Spliterator<Double> s)");

        }

    }

    // Shape-specific methods

    @Override

    final StreamShape getOutputShape() {

        return StreamShape.DOUBLE_VALUE;

    }

    @Override

    final <P_IN> Node<Double> evaluateToNode(PipelineHelper<Double> helper,

                                             Spliterator<P_IN> spliterator,

                                             boolean flattenTree,

                                             IntFunction<Double[]> generator) {

        return Nodes.collectDouble(helper, spliterator, flattenTree);

    }

    @Override

    final <P_IN> Spliterator<Double> wrap(PipelineHelper<Double> ph,

                                          Supplier<Spliterator<P_IN>> supplier,

                                          boolean isParallel) {

        return new StreamSpliterators.DoubleWrappingSpliterator<>(ph, supplier, isParallel);

    }

    @Override

    final Spliterator.OfDouble lazySpliterator(Supplier<? extends Spliterator<Double>> supplier) {

        return new StreamSpliterators.DelegatingSpliterator.OfDouble((Supplier<Spliterator.OfDouble>) supplier);

    }

    @Override

    final void forEachWithCancel(Spliterator<Double> spliterator, Sink<Double> sink) {

        Spliterator.OfDouble spl = adapt(spliterator);

        DoubleConsumer adaptedSink = adapt(sink);

        do { } while (!sink.cancellationRequested() && spl.tryAdvance(adaptedSink));

    }

    @Override

    final  Node.Builder<Double> makeNodeBuilder(long exactSizeIfKnown, IntFunction<Double[]> generator) {

        return Nodes.doubleBuilder(exactSizeIfKnown);

    }

    // DoubleStream

    @Override

    public final PrimitiveIterator.OfDouble iterator() {

        return Spliterators.iteratorFromSpliterator(spliterator());

    }

    @Override

    public final Spliterator.OfDouble spliterator() {

        return adapt(super.spliterator());

    }

    // Stateless intermediate ops from DoubleStream

    @Override

    public final Stream<Double> boxed() {

        return mapToObj(Double::valueOf);

    }

    @Override

    public final DoubleStream map(DoubleUnaryOperator mapper) {

        Objects.requireNonNull(mapper);

        return new StatelessOp<Double>(this, StreamShape.DOUBLE_VALUE,

                                       StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT) {

            @Override

            Sink<Double> opWrapSink(int flags, Sink<Double> sink) {

                return new Sink.ChainedDouble(sink) {

                    @Override

                    public void accept(double t) {

                        downstream.accept(mapper.applyAsDouble(t));

                    }

                };

            }

        };

    }

    @Override

    public final <U> Stream<U> mapToObj(DoubleFunction<? extends U> mapper) {

        Objects.requireNonNull(mapper);

        return new ReferencePipeline.StatelessOp<Double, U>(this, StreamShape.DOUBLE_VALUE,

                                                            StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT) {

            @Override

            Sink<Double> opWrapSink(int flags, Sink<U> sink) {

                return new Sink.ChainedDouble(sink) {

                    @Override

                    public void accept(double t) {

                        downstream.accept(mapper.apply(t));

                    }

                };

            }

        };

    }

    @Override

    public final IntStream mapToInt(DoubleToIntFunction mapper) {

        Objects.requireNonNull(mapper);

        return new IntPipeline.StatelessOp<Double>(this, StreamShape.DOUBLE_VALUE,

                                                   StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT) {

            @Override

            Sink<Double> opWrapSink(int flags, Sink<Integer> sink) {

                return new Sink.ChainedDouble(sink) {

                    @Override

                    public void accept(double t) {

                        downstream.accept(mapper.applyAsInt(t));

                    }

                };

            }

        };

    }

    @Override

    public final LongStream mapToLong(DoubleToLongFunction mapper) {

        Objects.requireNonNull(mapper);

        return new LongPipeline.StatelessOp<Double>(this, StreamShape.DOUBLE_VALUE,

                                                    StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT) {

            @Override

            Sink<Double> opWrapSink(int flags, Sink<Long> sink) {

                return new Sink.ChainedDouble(sink) {

                    @Override

                    public void accept(double t) {

                        downstream.accept(mapper.applyAsLong(t));

                    }

                };

            }

        };

    }

    @Override

    public final DoubleStream flatMap(DoubleFunction<? extends DoubleStream> mapper) {

        return new StatelessOp<Double>(this, StreamShape.DOUBLE_VALUE,

                                        StreamOpFlag.NOT_SORTED | StreamOpFlag.NOT_DISTINCT | StreamOpFlag.NOT_SIZED) {

            @Override

            Sink<Double> opWrapSink(int flags, Sink<Double> sink) {

                return new Sink.ChainedDouble(sink) {

                    public void accept(double t) {

                        // We can do better that this too; optimize for depth=0 case and just grab spliterator and forEach it

                        DoubleStream result = mapper.apply(t);

                        if (result != null)

                            result.sequential().forEach(i -> downstream.accept(i));

                    }

                };

            }

        };

    }

    @Override

    public DoubleStream unordered() {

        if (!isOrdered())

            return this;

        return new StatelessOp<Double>(this, StreamShape.DOUBLE_VALUE, StreamOpFlag.NOT_ORDERED) {

            @Override

            Sink<Double> opWrapSink(int flags, Sink<Double> sink) {

                return sink;

            }

        };

    }

    @Override

    public final DoubleStream filter(DoublePredicate predicate) {

        Objects.requireNonNull(predicate);

        return new StatelessOp<Double>(this, StreamShape.DOUBLE_VALUE,

                                       StreamOpFlag.NOT_SIZED) {

            @Override

            Sink<Double> opWrapSink(int flags, Sink<Double> sink) {

                return new Sink.ChainedDouble(sink) {

                    @Override

                    public void accept(double t) {

                        if (predicate.test(t))

                            downstream.accept(t);

                    }

                };

            }

        };

    }

    @Override

    public final DoubleStream peek(DoubleConsumer consumer) {

        Objects.requireNonNull(consumer);

        return new StatelessOp<Double>(this, StreamShape.DOUBLE_VALUE,

                                       0) {

            @Override

            Sink<Double> opWrapSink(int flags, Sink<Double> sink) {

                return new Sink.ChainedDouble(sink) {

                    @Override

                    public void accept(double t) {

                        consumer.accept(t);

                        downstream.accept(t);

                    }

                };

            }

        };

    }

    // Stateful intermediate ops from DoubleStream

    @Override

    public final DoubleStream limit(long maxSize) {

        if (maxSize < 0)

            throw new IllegalArgumentException(Long.toString(maxSize));

        return SliceOps.makeDouble(this, (long) 0, maxSize);

    }

    @Override

    public final DoubleStream substream(long startingOffset) {

        if (startingOffset < 0)

            throw new IllegalArgumentException(Long.toString(startingOffset));

        if (startingOffset == 0)

            return this;

        else {

            long limit = -1;

            return SliceOps.makeDouble(this, startingOffset, limit);

        }

    }

    @Override

    public final DoubleStream substream(long startingOffset, long endingOffset) {

        if (startingOffset < 0 || endingOffset < startingOffset)

            throw new IllegalArgumentException(String.format("substream(%d, %d)", startingOffset, endingOffset));

        return SliceOps.makeDouble(this, startingOffset, endingOffset - startingOffset);

    }

    @Override

    public final DoubleStream sorted() {

        return SortedOps.makeDouble(this);

    }

    @Override

    public final DoubleStream distinct() {

        // While functional and quick to implement, this approach is not very efficient.

        // An efficient version requires a double-specific map/set implementation.

        return boxed().distinct().mapToDouble(i -> (double) i);

    }

    // Terminal ops from DoubleStream

    @Override

    public void forEach(DoubleConsumer consumer) {

        evaluate(ForEachOps.makeDouble(consumer, false));

    }

    @Override

    public void forEachOrdered(DoubleConsumer consumer) {

        evaluate(ForEachOps.makeDouble(consumer, true));

    }

    @Override

    public final double sum() {

        // TODO: better algorithm to compensate for errors

        return reduce(0.0, Double::sum);

    }

    @Override

    public final OptionalDouble min() {

        return reduce(Math::min);

    }

    @Override

    public final OptionalDouble max() {

        return reduce(Math::max);

    }

    @Override

    public final OptionalDouble average() {

        double[] avg = collect(() -> new double[2],

                               (ll, i) -> {

                                   ll[0]++;

                                   ll[1] += i;

                               },

                               (ll, rr) -> {

                                   ll[0] += rr[0];

                                   ll[1] += rr[1];

                               });

        return avg[0] > 0

               ? OptionalDouble.of(avg[1] / avg[0])

               : OptionalDouble.empty();

    }

    @Override

    public final long count() {

        return mapToObj(e -> null).mapToInt(e -> 1).sum();

    }

    @Override

    public final DoubleSummaryStatistics summaryStatistics() {

        return collect(DoubleSummaryStatistics::new, DoubleSummaryStatistics::accept,

                       DoubleSummaryStatistics::combine);

    }

    @Override

    public final double reduce(double identity, DoubleBinaryOperator op) {

        return evaluate(ReduceOps.makeDouble(identity, op));

    }

    @Override

    public final OptionalDouble reduce(DoubleBinaryOperator op) {

        return evaluate(ReduceOps.makeDouble(op));

    }

    @Override

    public final <R> R collect(Supplier<R> resultFactory,

                               ObjDoubleConsumer<R> accumulator,

                               BiConsumer<R, R> combiner) {

        BinaryOperator<R> operator = (left, right) -> {

            combiner.accept(left, right);

            return left;

        };

        return evaluate(ReduceOps.makeDouble(resultFactory, accumulator, operator));

    }

    @Override

    public final boolean anyMatch(DoublePredicate predicate) {

        return evaluate(MatchOps.makeDouble(predicate, MatchOps.MatchKind.ANY));

    }

    @Override

    public final boolean allMatch(DoublePredicate predicate) {

        return evaluate(MatchOps.makeDouble(predicate, MatchOps.MatchKind.ALL));

    }

    @Override

    public final boolean noneMatch(DoublePredicate predicate) {

        return evaluate(MatchOps.makeDouble(predicate, MatchOps.MatchKind.NONE));

    }

    @Override

    public final OptionalDouble findFirst() {

        return evaluate(FindOps.makeDouble(true));

    }

    @Override

    public final OptionalDouble findAny() {

        return evaluate(FindOps.makeDouble(false));

    }

    @Override

    public final double[] toArray() {

        return Nodes.flattenDouble((Node.OfDouble) evaluateToArrayNode(Double[]::new))

                        .asDoubleArray();

    }

    //

    /**

     * Source stage of a DoubleStream

     *

     * @param <E_IN> type of elements in the upstream source

     */

    static class Head<E_IN> extends DoublePipeline<E_IN> {

        /**

         * Constructor for the source stage of a DoubleStream.

         *

         * @param source {@code Supplier<Spliterator>} describing the stream

         *               source

         * @param sourceFlags the source flags for the stream source, described

         *                    in {@link StreamOpFlag}

         * @param parallel {@code true} if the pipeline is parallel

         */

        Head(Supplier<? extends Spliterator<Double>> source,

             int sourceFlags, boolean parallel) {

            super(source, sourceFlags, parallel);

        }

        /**

         * Constructor for the source stage of a DoubleStream.

         *

         * @param source {@code Spliterator} describing the stream source

         * @param sourceFlags the source flags for the stream source, described

         *                    in {@link StreamOpFlag}

         * @param parallel {@code true} if the pipeline is parallel

         */

        Head(Spliterator<Double> source,

             int sourceFlags, boolean parallel) {

            super(source, sourceFlags, parallel);

        }

        @Override

        final boolean opIsStateful() {

            throw new UnsupportedOperationException();

        }

        @Override

        final Sink<E_IN> opWrapSink(int flags, Sink<Double> sink) {

            throw new UnsupportedOperationException();

        }

        // Optimized sequential terminal operations for the head of the pipeline

        @Override

        public void forEach(DoubleConsumer consumer) {

            if (!isParallel()) {

                adapt(sourceStageSpliterator()).forEachRemaining(consumer);

            }

            else {

                super.forEach(consumer);

            }

        }

        @Override

        public void forEachOrdered(DoubleConsumer consumer) {

            if (!isParallel()) {

                adapt(sourceStageSpliterator()).forEachRemaining(consumer);

            }