/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF 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.apache.camel.processor;

import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;

import org.apache.camel.AsyncCallback;
import org.apache.camel.AsyncProcessor;
import org.apache.camel.CamelContext;
import org.apache.camel.Exchange;
import org.apache.camel.ExchangePattern;
import org.apache.camel.Message;
import org.apache.camel.Ordered;
import org.apache.camel.Predicate;
import org.apache.camel.Processor;
import org.apache.camel.Route;
import org.apache.camel.Traceable;
import org.apache.camel.support.ServiceSupport;
import org.apache.camel.support.SynchronizationAdapter;
import org.apache.camel.util.AsyncProcessorHelper;
import org.apache.camel.util.ExchangeHelper;
import org.apache.camel.util.ServiceHelper;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import static org.apache.camel.util.ObjectHelper.notNull;

/**
 * Processor implementing <a href="http://camel.apache.org/oncompletion.html">onCompletion</a>.
 *
 * @version 
 */
public class OnCompletionProcessor extends ServiceSupport implements AsyncProcessor, Traceable {

    private static final Logger LOG = LoggerFactory.getLogger(OnCompletionProcessor.class);
    private final CamelContext camelContext;
    private final Processor processor;
    private final ExecutorService executorService;
    private final boolean shutdownExecutorService;
    private final boolean onCompleteOnly;
    private final boolean onFailureOnly;
    private final Predicate onWhen;
    private final boolean useOriginalBody;
    private final boolean afterConsumer;

    public OnCompletionProcessor(CamelContext camelContext, Processor processor, ExecutorService executorService, boolean shutdownExecutorService,
                                 boolean onCompleteOnly, boolean onFailureOnly, Predicate onWhen, boolean useOriginalBody, boolean afterConsumer) {
        notNull(camelContext, "camelContext");
        notNull(processor, "processor");
        this.camelContext = camelContext;
        this.processor = processor;
        this.executorService = executorService;
        this.shutdownExecutorService = shutdownExecutorService;
        this.onCompleteOnly = onCompleteOnly;
        this.onFailureOnly = onFailureOnly;
        this.onWhen = onWhen;
        this.useOriginalBody = useOriginalBody;
        this.afterConsumer = afterConsumer;
    }

    @Override
    protected void doStart() throws Exception {
        ServiceHelper.startService(processor);
    }

    @Override
    protected void doStop() throws Exception {
        ServiceHelper.stopService(processor);
    }

    @Override
    protected void doShutdown() throws Exception {
        ServiceHelper.stopAndShutdownService(processor);
        if (shutdownExecutorService) {
            getCamelContext().getExecutorServiceManager().shutdownNow(executorService);
        }
    }

    public CamelContext getCamelContext() {
        return camelContext;
    }

    public void process(Exchange exchange) throws Exception {
        AsyncProcessorHelper.process(this, exchange);
    }

    public boolean process(Exchange exchange, AsyncCallback callback) {
        if (processor != null) {
            // register callback
            if (afterConsumer) {
                exchange.getUnitOfWork().addSynchronization(new OnCompletionSynchronizationAfterConsumer());
            } else {
                exchange.getUnitOfWork().addSynchronization(new OnCompletionSynchronizationBeforeConsumer());
            }
        }

        callback.done(true);
        return true;
    }

    protected boolean isCreateCopy() {
        // we need to create a correlated copy if we run in parallel mode or is in after consumer mode (as the UoW would be done on the original exchange otherwise)
        return executorService != null || afterConsumer;
    }

    /**
     * Processes the exchange by the processors
     *
     * @param processor the processor
     * @param exchange the exchange
     */
    protected static void doProcess(Processor processor, Exchange exchange) {
        // must remember some properties which we cannot use during onCompletion processing
        // as otherwise we may cause issues
        Object stop = exchange.removeProperty(Exchange.ROUTE_STOP);
        Object failureHandled = exchange.removeProperty(Exchange.FAILURE_HANDLED);
        Object caught = exchange.removeProperty(Exchange.EXCEPTION_CAUGHT);
        Object errorhandlerHandled = exchange.removeProperty(Exchange.ERRORHANDLER_HANDLED);
        Object rollbackOnly = exchange.removeProperty(Exchange.ROLLBACK_ONLY);
        Object rollbackOnlyLast = exchange.removeProperty(Exchange.ROLLBACK_ONLY_LAST);

        Exception cause = exchange.getException();
        exchange.setException(null);

        try {
            processor.process(exchange);
        } catch (Exception e) {
            exchange.setException(e);
        } finally {
            // restore the options
            if (stop != null) {
                exchange.setProperty(Exchange.ROUTE_STOP, stop);
            }
            if (failureHandled != null) {
                exchange.setProperty(Exchange.FAILURE_HANDLED, failureHandled);
            }
            if (caught != null) {
                exchange.setProperty(Exchange.EXCEPTION_CAUGHT, caught);
            }
            if (errorhandlerHandled != null) {
                exchange.setProperty(Exchange.ERRORHANDLER_HANDLED, errorhandlerHandled);
            }
            if (rollbackOnly != null) {
                exchange.setProperty(Exchange.ROLLBACK_ONLY, rollbackOnly);
            }
            if (rollbackOnlyLast != null) {
                exchange.setProperty(Exchange.ROLLBACK_ONLY, rollbackOnlyLast);
            }
            if (cause != null) {
                exchange.setException(cause);
            }
        }
    }

    /**
     * Prepares the {@link Exchange} to send as onCompletion.
     *
     * @param exchange the current exchange
     * @return the exchange to be routed in onComplete
     */
    protected Exchange prepareExchange(Exchange exchange) {
        Exchange answer;

        if (isCreateCopy()) {
            // for asynchronous routing we must use a copy as we dont want it
            // to cause side effects of the original exchange
            // (the original thread will run in parallel)
            answer = ExchangeHelper.createCorrelatedCopy(exchange, false);
            if (answer.hasOut()) {
                // move OUT to IN (pipes and filters)
                answer.setIn(answer.getOut());
                answer.setOut(null);
            }
            // set MEP to InOnly as this onCompletion is a fire and forget
            answer.setPattern(ExchangePattern.InOnly);
        } else {
            // use the exchange as-is
            answer = exchange;
        }

        if (useOriginalBody) {
            LOG.trace("Using the original IN message instead of current");

            Message original = exchange.getUnitOfWork().getOriginalInMessage();
            answer.setIn(original);
        }

        // add a header flag to indicate its a on completion exchange
        answer.setProperty(Exchange.ON_COMPLETION, Boolean.TRUE);

        return answer;
    }

    private final class OnCompletionSynchronizationAfterConsumer extends SynchronizationAdapter implements Ordered {

        public int getOrder() {
            // we want to be last
            return Ordered.LOWEST;
        }

        @Override
        public void onComplete(final Exchange exchange) {
            if (onFailureOnly) {
                return;
            }

            if (onWhen != null && !onWhen.matches(exchange)) {
                // predicate did not match so do not route the onComplete
                return;
            }

            // must use a copy as we dont want it to cause side effects of the original exchange
            final Exchange copy = prepareExchange(exchange);

            if (executorService != null) {
                executorService.submit(new Callable<Exchange>() {
                    public Exchange call() throws Exception {
                        LOG.debug("Processing onComplete: {}", copy);
                        doProcess(processor, copy);
                        return copy;
                    }
                });
            } else {
                // run without thread-pool
                LOG.debug("Processing onComplete: {}", copy);
                doProcess(processor, copy);
            }
        }

        public void onFailure(final Exchange exchange) {
            if (onCompleteOnly) {
                return;
            }

            if (onWhen != null && !onWhen.matches(exchange)) {
                // predicate did not match so do not route the onComplete
                return;
            }


            // must use a copy as we dont want it to cause side effects of the original exchange
            final Exchange copy = prepareExchange(exchange);
            final Exception original = copy.getException();
            final boolean originalFault = copy.hasOut() ? copy.getOut().isFault() : copy.getIn().isFault();
            // must remove exception otherwise onFailure routing will fail as well
            // the caused exception is stored as a property (Exchange.EXCEPTION_CAUGHT) on the exchange
            copy.setException(null);
            // must clear fault otherwise onFailure routing will fail as well
            if (copy.hasOut()) {
                copy.getOut().setFault(false);
            } else {
                copy.getIn().setFault(false);
            }

            if (executorService != null) {
                executorService.submit(new Callable<Exchange>() {
                    public Exchange call() throws Exception {
                        LOG.debug("Processing onFailure: {}", copy);
                        doProcess(processor, copy);
                        // restore exception after processing
                        copy.setException(original);
                        return null;
                    }
                });
            } else {
                // run without thread-pool
                LOG.debug("Processing onFailure: {}", copy);
                doProcess(processor, copy);
                // restore exception after processing
                copy.setException(original);
                // restore fault after processing
                if (copy.hasOut()) {
                    copy.getOut().setFault(originalFault);
                } else {
                    copy.getIn().setFault(originalFault);
                }
            }
        }

        @Override
        public String toString() {
            if (!onCompleteOnly && !onFailureOnly) {
                return "onCompleteOrFailure";
            } else if (onCompleteOnly) {
                return "onCompleteOnly";
            } else {
                return "onFailureOnly";
            }
        }
    }

    private final class OnCompletionSynchronizationBeforeConsumer extends SynchronizationAdapter implements Ordered {

        public int getOrder() {
            // we want to be last
            return Ordered.LOWEST;
        }

        @Override
        public void onAfterRoute(Route route, Exchange exchange) {
            if (exchange.isFailed() && onCompleteOnly) {
                return;
            }

            if (!exchange.isFailed() && onFailureOnly) {
                return;
            }

            if (onWhen != null && !onWhen.matches(exchange)) {
                // predicate did not match so do not route the onComplete
                return;
            }

            // must use a copy as we dont want it to cause side effects of the original exchange
            final Exchange copy = prepareExchange(exchange);

            if (executorService != null) {
                executorService.submit(new Callable<Exchange>() {
                    public Exchange call() throws Exception {
                        LOG.debug("Processing onAfterRoute: {}", copy);
                        doProcess(processor, copy);
                        return copy;
                    }
                });
            } else {
                // run without thread-pool
                LOG.debug("Processing onAfterRoute: {}", copy);
                doProcess(processor, copy);
            }
        }

        @Override
        public String toString() {
            return "onAfterRoute";
        }
    }

    @Override
    public String toString() {
        return "OnCompletionProcessor[" + processor + "]";
    }

    public String getTraceLabel() {
        return "onCompletion";
    }
}