/*
 * Licensed to Elasticsearch under one or more contributor
 * license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright
 * ownership. Elasticsearch licenses this file to you 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 org.elasticsearch.action.ingest;

import org.elasticsearch.action.ActionListener;
import org.elasticsearch.action.ActionRunnable;
import org.elasticsearch.ingest.CompoundProcessor;
import org.elasticsearch.ingest.IngestDocument;
import org.elasticsearch.ingest.Pipeline;
import org.elasticsearch.threadpool.ThreadPool;

import java.util.List;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.function.BiConsumer;

import static org.elasticsearch.ingest.TrackingResultProcessor.decorate;

class SimulateExecutionService {

    private static final String THREAD_POOL_NAME = ThreadPool.Names.MANAGEMENT;

    private final ThreadPool threadPool;

    SimulateExecutionService(ThreadPool threadPool) {
        this.threadPool = threadPool;
    }

    void executeDocument(Pipeline pipeline, IngestDocument ingestDocument, boolean verbose,
                         BiConsumer<SimulateDocumentResult, Exception> handler) {
        if (verbose) {
            List<SimulateProcessorResult> processorResultList = new CopyOnWriteArrayList<>();
            CompoundProcessor verbosePipelineProcessor = decorate(pipeline.getCompoundProcessor(), null, processorResultList);
            Pipeline verbosePipeline = new Pipeline(pipeline.getId(), pipeline.getDescription(), pipeline.getVersion(),
                verbosePipelineProcessor);
            ingestDocument.executePipeline(verbosePipeline, (result, e) -> {
                handler.accept(new SimulateDocumentVerboseResult(processorResultList), e);
            });
        } else {
            ingestDocument.executePipeline(pipeline, (result, e) -> {
                if (e == null) {
                    handler.accept(new SimulateDocumentBaseResult(result), null);
                } else {
                    handler.accept(new SimulateDocumentBaseResult(e), null);
                }
            });
        }
    }

    public void execute(SimulatePipelineRequest.Parsed request, ActionListener<SimulatePipelineResponse> listener) {
        threadPool.executor(THREAD_POOL_NAME).execute(ActionRunnable.wrap(listener, l -> {
            final AtomicInteger counter = new AtomicInteger();
            final List<SimulateDocumentResult> responses =
                new CopyOnWriteArrayList<>(new SimulateDocumentBaseResult[request.getDocuments().size()]);

            if (request.getDocuments().isEmpty()) {
                l.onResponse(new SimulatePipelineResponse(request.getPipeline().getId(),
                    request.isVerbose(), responses));
                return;
            }

            int iter = 0;
            for (IngestDocument ingestDocument : request.getDocuments()) {
                final int index = iter;
                executeDocument(request.getPipeline(), ingestDocument, request.isVerbose(), (response, e) -> {
                    if (response != null) {
                        responses.set(index, response);
                    }
                    if (counter.incrementAndGet() == request.getDocuments().size()) {
                        listener.onResponse(new SimulatePipelineResponse(request.getPipeline().getId(),
                            request.isVerbose(), responses));
                    }
                });
                iter++;
            }
        }));
    }
}
