/*
 * (C) Copyright 2006-2016 Nuxeo SA (http://nuxeo.com/) and others.
 *
 * 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.
 *
 * Contributors:
 *     Bogdan Stefanescu
 *     Thierry Delprat
 *     Florent Guillaume
 *     Andrei Nechaev
 */
package org.nuxeo.ecm.core.event.impl;

import java.rmi.dgc.VMID;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.stream.Collectors;

import javax.naming.NamingException;
import javax.transaction.RollbackException;
import javax.transaction.Status;
import javax.transaction.Synchronization;
import javax.transaction.SystemException;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.nuxeo.common.logging.SequenceTracer;
import org.nuxeo.ecm.core.api.NuxeoException;
import org.nuxeo.ecm.core.api.RecoverableClientException;
import org.nuxeo.ecm.core.event.Event;
import org.nuxeo.ecm.core.event.EventBundle;
import org.nuxeo.ecm.core.event.EventContext;
import org.nuxeo.ecm.core.event.EventListener;
import org.nuxeo.ecm.core.event.EventService;
import org.nuxeo.ecm.core.event.EventServiceAdmin;
import org.nuxeo.ecm.core.event.EventStats;
import org.nuxeo.ecm.core.event.PostCommitEventListener;
import org.nuxeo.ecm.core.event.ReconnectedEventBundle;
import org.nuxeo.ecm.core.event.jms.AsyncProcessorConfig;
import org.nuxeo.ecm.core.event.pipe.EventPipeDescriptor;
import org.nuxeo.ecm.core.event.pipe.EventPipeRegistry;
import org.nuxeo.ecm.core.event.pipe.dispatch.EventBundleDispatcher;
import org.nuxeo.ecm.core.event.pipe.dispatch.EventDispatcherDescriptor;
import org.nuxeo.ecm.core.event.pipe.dispatch.EventDispatcherRegistry;
import org.nuxeo.runtime.api.Framework;
import org.nuxeo.runtime.transaction.TransactionHelper;

/**
 * Implementation of the event service.
 */
public class EventServiceImpl implements EventService, EventServiceAdmin, Synchronization {

    public static final VMID VMID = new VMID();

    private static final Log log = LogFactory.getLog(EventServiceImpl.class);

    protected static final ThreadLocal<CompositeEventBundle> threadBundles = new ThreadLocal<CompositeEventBundle>() {
        @Override
        protected CompositeEventBundle initialValue() {
            return new CompositeEventBundle();
        }
    };

    private static class CompositeEventBundle {

        boolean registeredSynchronization;

        final Map<String, EventBundle> byRepository = new HashMap<>();

        void push(Event event) {
            String repositoryName = event.getContext().getRepositoryName();
            if (!byRepository.containsKey(repositoryName)) {
                byRepository.put(repositoryName, new EventBundleImpl());
            }
            byRepository.get(repositoryName).push(event);
        }

    }

    protected final EventListenerList listenerDescriptors;

    protected PostCommitEventExecutor postCommitExec;

    protected volatile AsyncEventExecutor asyncExec;

    protected final List<AsyncWaitHook> asyncWaitHooks = new CopyOnWriteArrayList<>();

    protected boolean blockAsyncProcessing = false;

    protected boolean blockSyncPostCommitProcessing = false;

    protected boolean bulkModeEnabled = false;

    protected EventPipeRegistry registeredPipes = new EventPipeRegistry();

    protected EventDispatcherRegistry dispatchers = new EventDispatcherRegistry();

    protected EventBundleDispatcher pipeDispatcher;

    public EventServiceImpl() {
        listenerDescriptors = new EventListenerList();
        postCommitExec = new PostCommitEventExecutor();
        asyncExec = new AsyncEventExecutor();
    }

    public void init() {
        asyncExec.init();

        EventDispatcherDescriptor dispatcherDescriptor = dispatchers.getDispatcherDescriptor();
        if (dispatcherDescriptor != null) {
            List<EventPipeDescriptor> pipes = registeredPipes.getPipes();
            if (!pipes.isEmpty()) {
                pipeDispatcher = dispatcherDescriptor.getInstance();
                pipeDispatcher.init(pipes, dispatcherDescriptor.getParameters());
            }
        }
    }

    public EventBundleDispatcher getEventBundleDispatcher() {
        return pipeDispatcher;
    }

    public void shutdown(long timeoutMillis) throws InterruptedException {
        postCommitExec.shutdown(timeoutMillis);
        Set<AsyncWaitHook> notTerminated = asyncWaitHooks.stream().filter(hook -> !hook.shutdown()).collect(
                Collectors.toSet());
        if (!notTerminated.isEmpty()) {
            throw new RuntimeException("Asynch services are still running : " + notTerminated);
        }

        if (!asyncExec.shutdown(timeoutMillis)) {
            throw new RuntimeException("Async executor is still running, timeout expired");
        }
        if (pipeDispatcher != null) {
            pipeDispatcher.shutdown();
        }
    }

    public void registerForAsyncWait(AsyncWaitHook callback) {
        asyncWaitHooks.add(callback);
    }

    public void unregisterForAsyncWait(AsyncWaitHook callback) {
        asyncWaitHooks.remove(callback);
    }

    @Override
    public void waitForAsyncCompletion() {
        waitForAsyncCompletion(Long.MAX_VALUE);
    }

    @Override
    public void waitForAsyncCompletion(long timeout) {
        Set<AsyncWaitHook> notCompleted = asyncWaitHooks.stream()
                                                        .filter(hook -> !hook.waitForAsyncCompletion())
                                                        .collect(Collectors.toSet());
        if (!notCompleted.isEmpty()) {
            throw new RuntimeException("Async tasks are still running : " + notCompleted);
        }
        try {
            if (!asyncExec.waitForCompletion(timeout)) {
                throw new RuntimeException("Async event listeners thread pool is not terminated");
            }
        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
            // TODO change signature
            throw new RuntimeException(e);
        }
        if (pipeDispatcher != null) {
            try {
                pipeDispatcher.waitForCompletion(timeout);
            } catch (InterruptedException e) {
                Thread.currentThread().interrupt();
                throw new RuntimeException(e);
            }
        }
    }

    @Override
    public void addEventListener(EventListenerDescriptor listener) {
        listenerDescriptors.add(listener);
        log.debug("Registered event listener: " + listener.getName());
    }

    public void addEventPipe(EventPipeDescriptor pipeDescriptor) {
        registeredPipes.addContribution(pipeDescriptor);
        log.debug("Registered event pipe: " + pipeDescriptor.getName());
    }

    public void addEventDispatcher(EventDispatcherDescriptor dispatcherDescriptor) {
        dispatchers.addContrib(dispatcherDescriptor);
        log.debug("Registered event dispatcher: " + dispatcherDescriptor.getName());
    }

    @Override
    public void removeEventListener(EventListenerDescriptor listener) {
        listenerDescriptors.removeDescriptor(listener);
        log.debug("Unregistered event listener: " + listener.getName());
    }

    public void removeEventPipe(EventPipeDescriptor pipeDescriptor) {
        registeredPipes.removeContribution(pipeDescriptor);
        log.debug("Unregistered event pipe: " + pipeDescriptor.getName());
    }

    public void removeEventDispatcher(EventDispatcherDescriptor dispatcherDescriptor) {
        dispatchers.removeContrib(dispatcherDescriptor);
        log.debug("Unregistered event dispatcher: " + dispatcherDescriptor.getName());
    }

    @Override
    public void fireEvent(String name, EventContext context) {
        fireEvent(new EventImpl(name, context));
    }

    @Override
    public void fireEvent(Event event) {

        String ename = event.getName();
        EventStats stats = Framework.getService(EventStats.class);
        for (EventListenerDescriptor desc : listenerDescriptors.getEnabledInlineListenersDescriptors()) {
            if (!desc.acceptEvent(ename)) {
                continue;
            }
            try {
                long t0 = System.currentTimeMillis();
                SequenceTracer.start("Fire sync event " + event.getName());
                desc.asEventListener().handleEvent(event);
                long elapsed = System.currentTimeMillis() - t0;
                SequenceTracer.stop("done in " + elapsed + " ms");
                if (stats != null) {
                    stats.logSyncExec(desc, elapsed);
                }
                if (event.isCanceled()) {
                    // break loop
                    return;
                }
            } catch (RuntimeException e) {
                // get message
                SequenceTracer.destroy("failure");
                String message = "Exception during " + desc.getName() + " sync listener execution, ";
                if (event.isBubbleException()) {
                    message += "other listeners will be ignored";
                } else if (event.isMarkedForRollBack()) {
                    message += "transaction will be rolled back";
                    if (event.getRollbackMessage() != null) {
                        message += " (" + event.getRollbackMessage() + ")";
                    }
                } else {
                    message += "continuing to run other listeners";
                }
                // log
                if (e instanceof RecoverableClientException) {
                    log.info(message + "\n" + e.getMessage());
                    log.debug(message, e);
                } else {
                    log.error(message, e);
                }
                // rethrow or swallow
                if (event.isBubbleException()) {
                    throw e;
                } else if (event.isMarkedForRollBack()) {
                    Exception ee;
                    if (event.getRollbackException() != null) {
                        ee = event.getRollbackException();
                    } else {
                        ee = e;
                    }
                    // when marked for rollback, throw a generic
                    // RuntimeException to make sure nobody catches it
                    throw new RuntimeException(message, ee);
                } else {
                    // swallow exception
                }
            }
        }

        if (!event.isInline()) { // record the event
            // don't record the complete event, only a shallow copy
            ShallowEvent shallowEvent = ShallowEvent.create(event);
            if (event.isImmediate()) {
                EventBundleImpl b = new EventBundleImpl();
                b.push(shallowEvent);
                fireEventBundle(b);
            } else {
                recordEvent(shallowEvent);
            }
        }
    }

    @Override
    public void fireEventBundle(EventBundle event) {
        boolean comesFromJMS = false;

        if (event instanceof ReconnectedEventBundle) {
            if (((ReconnectedEventBundle) event).comesFromJMS()) {
                comesFromJMS = true;
            }
        }

        List<EventListenerDescriptor> postCommitSync = listenerDescriptors.getEnabledSyncPostCommitListenersDescriptors();
        List<EventListenerDescriptor> postCommitAsync = listenerDescriptors.getEnabledAsyncPostCommitListenersDescriptors();

        if (bulkModeEnabled) {
            // run all listeners synchronously in one transaction
            List<EventListenerDescriptor> listeners = new ArrayList<>();
            if (!blockSyncPostCommitProcessing) {
                listeners = postCommitSync;
            }
            if (!blockAsyncProcessing) {
                listeners.addAll(postCommitAsync);
            }
            if (!listeners.isEmpty()) {
                postCommitExec.runBulk(listeners, event);
            }
            return;
        }

        // run sync listeners
        if (blockSyncPostCommitProcessing) {
            log.debug("Dropping PostCommit handler execution");
        } else if (comesFromJMS) {
            // when called from JMS we must skip sync listeners
            // - postComit listeners should be on the core
            // - there is no transaction started by JMS listener
            log.debug("Deactivating sync post-commit listener since we are called from JMS");
        } else {
            if (!postCommitSync.isEmpty()) {
                postCommitExec.run(postCommitSync, event);
            }
        }

        if (blockAsyncProcessing) {
            log.debug("Dopping bundle");
            return;
        }

        // fire async listeners
        if (AsyncProcessorConfig.forceJMSUsage() && !comesFromJMS) {
            log.debug("Skipping async exec, this will be triggered via JMS");
        } else {
            if (pipeDispatcher == null) {
                asyncExec.run(postCommitAsync, event);
            } else {
                // rather than sending to the WorkManager: send to the Pipe
                pipeDispatcher.sendEventBundle(event);
            }
        }
    }

    @Override
    public void fireEventBundleSync(EventBundle event) {
        for (EventListenerDescriptor desc : listenerDescriptors.getEnabledSyncPostCommitListenersDescriptors()) {
            desc.asPostCommitListener().handleEvent(event);
        }
        for (EventListenerDescriptor desc : listenerDescriptors.getEnabledAsyncPostCommitListenersDescriptors()) {
            desc.asPostCommitListener().handleEvent(event);
        }
    }

    @Override
    public List<EventListener> getEventListeners() {
        return listenerDescriptors.getInLineListeners();
    }

    @Override
    public List<PostCommitEventListener> getPostCommitEventListeners() {
        List<PostCommitEventListener> result = new ArrayList<>();

        result.addAll(listenerDescriptors.getSyncPostCommitListeners());
        result.addAll(listenerDescriptors.getAsyncPostCommitListeners());

        return result;
    }

    public EventListenerList getEventListenerList() {
        return listenerDescriptors;
    }

    @Override
    public EventListenerDescriptor getEventListener(String name) {
        return listenerDescriptors.getDescriptor(name);
    }

    // methods for monitoring

    @Override
    public EventListenerList getListenerList() {
        return listenerDescriptors;
    }

    @Override
    public void setListenerEnabledFlag(String listenerName, boolean enabled) {
        if (!listenerDescriptors.hasListener(listenerName)) {
            return;
        }

        for (EventListenerDescriptor desc : listenerDescriptors.getAsyncPostCommitListenersDescriptors()) {
            if (desc.getName().equals(listenerName)) {
                desc.setEnabled(enabled);
                synchronized (this) {
                    listenerDescriptors.recomputeEnabledListeners();
                }
                return;
            }
        }

        for (EventListenerDescriptor desc : listenerDescriptors.getSyncPostCommitListenersDescriptors()) {
            if (desc.getName().equals(listenerName)) {
                desc.setEnabled(enabled);
                synchronized (this) {
                    listenerDescriptors.recomputeEnabledListeners();
                }
                return;
            }
        }

        for (EventListenerDescriptor desc : listenerDescriptors.getInlineListenersDescriptors()) {
            if (desc.getName().equals(listenerName)) {
                desc.setEnabled(enabled);
                synchronized (this) {
                    listenerDescriptors.recomputeEnabledListeners();
                }
                return;
            }
        }
    }

    @Override
    public int getActiveThreadsCount() {
        return asyncExec.getActiveCount();
    }

    @Override
    public int getEventsInQueueCount() {
        return asyncExec.getUnfinishedCount();
    }

    @Override
    public boolean isBlockAsyncHandlers() {
        return blockAsyncProcessing;
    }

    @Override
    public boolean isBlockSyncPostCommitHandlers() {
        return blockSyncPostCommitProcessing;
    }

    @Override
    public void setBlockAsyncHandlers(boolean blockAsyncHandlers) {
        blockAsyncProcessing = blockAsyncHandlers;
    }

    @Override
    public void setBlockSyncPostCommitHandlers(boolean blockSyncPostComitHandlers) {
        blockSyncPostCommitProcessing = blockSyncPostComitHandlers;
    }

    @Override
    public boolean isBulkModeEnabled() {
        return bulkModeEnabled;
    }

    @Override
    public void setBulkModeEnabled(boolean bulkModeEnabled) {
        this.bulkModeEnabled = bulkModeEnabled;
    }

    protected void recordEvent(Event event) {
        CompositeEventBundle b = threadBundles.get();
        b.push(event);
        if (TransactionHelper.isTransactionActive()) {
            if (!b.registeredSynchronization) {
                // register as synchronization
                try {
                    TransactionHelper.lookupTransactionManager().getTransaction().registerSynchronization(this);
                } catch (NamingException | SystemException | RollbackException e) {
                    throw new RuntimeException("Cannot register Synchronization", e);
                }
                b.registeredSynchronization = true;
            }
        } else if (event.isCommitEvent()) {
            handleTxCommited();
        }
    }

    @Override
    public void beforeCompletion() {
    }

    @Override
    public void afterCompletion(int status) {
        if (status == Status.STATUS_COMMITTED) {
            handleTxCommited();
        } else if (status == Status.STATUS_ROLLEDBACK) {
            handleTxRollbacked();
        } else {
            log.error("Unexpected afterCompletion status: " + status);
        }
    }

    protected void handleTxRollbacked() {
        threadBundles.remove();
    }

    protected void handleTxCommited() {
        CompositeEventBundle b = threadBundles.get();
        threadBundles.remove();

        // notify post commit event listeners
        for (EventBundle bundle : b.byRepository.values()) {
            try {
                fireEventBundle(bundle);
            } catch (NuxeoException e) {
                log.error("Error while processing " + bundle, e);
            }
        }
    }

}