/*
 * 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 com.facebook.presto.operator;

import com.facebook.presto.execution.buffer.OutputBuffer;
import com.facebook.presto.execution.buffer.PagesSerde;
import com.facebook.presto.execution.buffer.PagesSerdeFactory;
import com.facebook.presto.execution.buffer.SerializedPage;
import com.facebook.presto.spi.Page;
import com.facebook.presto.spi.type.Type;
import com.facebook.presto.sql.planner.plan.PlanNodeId;
import com.google.common.collect.ImmutableList;
import com.google.common.util.concurrent.ListenableFuture;

import java.util.List;
import java.util.function.Function;

import static com.facebook.presto.execution.buffer.PageSplitterUtil.splitPage;
import static com.facebook.presto.spi.block.PageBuilderStatus.DEFAULT_MAX_PAGE_SIZE_IN_BYTES;
import static com.google.common.base.Preconditions.checkState;
import static com.google.common.collect.ImmutableList.toImmutableList;
import static java.util.Objects.requireNonNull;

public class TaskOutputOperator
        implements Operator
{
    public static class TaskOutputFactory
            implements OutputFactory
    {
        private final OutputBuffer outputBuffer;

        public TaskOutputFactory(OutputBuffer outputBuffer)
        {
            this.outputBuffer = requireNonNull(outputBuffer, "outputBuffer is null");
        }

        @Override
        public OperatorFactory createOutputOperator(int operatorId, PlanNodeId planNodeId, List<Type> types, Function<Page, Page> pagePreprocessor, PagesSerdeFactory serdeFactory)
        {
            return new TaskOutputOperatorFactory(operatorId, planNodeId, outputBuffer, pagePreprocessor, serdeFactory);
        }
    }

    public static class TaskOutputOperatorFactory
            implements OperatorFactory
    {
        private final int operatorId;
        private final PlanNodeId planNodeId;
        private final OutputBuffer outputBuffer;
        private final Function<Page, Page> pagePreprocessor;
        private final PagesSerdeFactory serdeFactory;

        public TaskOutputOperatorFactory(int operatorId, PlanNodeId planNodeId, OutputBuffer outputBuffer, Function<Page, Page> pagePreprocessor, PagesSerdeFactory serdeFactory)
        {
            this.operatorId = operatorId;
            this.planNodeId = requireNonNull(planNodeId, "planNodeId is null");
            this.outputBuffer = requireNonNull(outputBuffer, "outputBuffer is null");
            this.pagePreprocessor = requireNonNull(pagePreprocessor, "pagePreprocessor is null");
            this.serdeFactory = requireNonNull(serdeFactory, "serdeFactory is null");
        }

        @Override
        public List<Type> getTypes()
        {
            return ImmutableList.of();
        }

        @Override
        public Operator createOperator(DriverContext driverContext)
        {
            OperatorContext operatorContext = driverContext.addOperatorContext(operatorId, planNodeId, TaskOutputOperator.class.getSimpleName());
            return new TaskOutputOperator(operatorContext, outputBuffer, pagePreprocessor, serdeFactory);
        }

        @Override
        public void close()
        {
        }

        @Override
        public OperatorFactory duplicate()
        {
            return new TaskOutputOperatorFactory(operatorId, planNodeId, outputBuffer, pagePreprocessor, serdeFactory);
        }
    }

    private final OperatorContext operatorContext;
    private final OutputBuffer outputBuffer;
    private final Function<Page, Page> pagePreprocessor;
    private final PagesSerde serde;
    private ListenableFuture<?> blocked = NOT_BLOCKED;
    private boolean finished;

    public TaskOutputOperator(OperatorContext operatorContext, OutputBuffer outputBuffer, Function<Page, Page> pagePreprocessor, PagesSerdeFactory serdeFactory)
    {
        this.operatorContext = requireNonNull(operatorContext, "operatorContext is null");
        this.outputBuffer = requireNonNull(outputBuffer, "outputBuffer is null");
        this.pagePreprocessor = requireNonNull(pagePreprocessor, "pagePreprocessor is null");
        this.serde = requireNonNull(serdeFactory, "serdeFactory is null").createPagesSerde();
    }

    @Override
    public OperatorContext getOperatorContext()
    {
        return operatorContext;
    }

    @Override
    public List<Type> getTypes()
    {
        return ImmutableList.of();
    }

    @Override
    public void finish()
    {
        finished = true;
    }

    @Override
    public boolean isFinished()
    {
        if (blocked != NOT_BLOCKED && blocked.isDone()) {
            blocked = NOT_BLOCKED;
        }

        return finished && blocked == NOT_BLOCKED;
    }

    @Override
    public ListenableFuture<?> isBlocked()
    {
        if (blocked != NOT_BLOCKED && blocked.isDone()) {
            blocked = NOT_BLOCKED;
        }
        return blocked;
    }

    @Override
    public boolean needsInput()
    {
        if (blocked != NOT_BLOCKED && blocked.isDone()) {
            blocked = NOT_BLOCKED;
        }
        return !finished && blocked == NOT_BLOCKED;
    }

    @Override
    public void addInput(Page page)
    {
        requireNonNull(page, "page is null");
        if (page.getPositionCount() == 0) {
            return;
        }
        checkState(blocked == NOT_BLOCKED, "output is already blocked");

        page = pagePreprocessor.apply(page);

        List<SerializedPage> serializedPages = splitPage(page, DEFAULT_MAX_PAGE_SIZE_IN_BYTES).stream()
                .map(serde::serialize)
                .collect(toImmutableList());

        ListenableFuture<?> future = outputBuffer.enqueue(serializedPages);
        if (!future.isDone()) {
            this.blocked = future;
        }
        operatorContext.recordGeneratedOutput(page.getSizeInBytes(), page.getPositionCount());
    }

    @Override
    public Page getOutput()
    {
        return null;
    }
}