/*

 * Copyright (c) 2019, 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 jdk.jfr.internal.consumer;

import java.time.Instant;

import java.util.ArrayList;

import java.util.List;

import java.util.function.Consumer;

import jdk.jfr.EventType;

import jdk.jfr.consumer.RecordedEvent;

import jdk.jfr.internal.LongMap;

import jdk.jfr.internal.consumer.ChunkParser.ParserConfiguration;

final class Dispatcher {

    final static class EventDispatcher {

        private final static EventDispatcher[] NO_DISPATCHERS = new EventDispatcher[0];

        private final String eventName;

        private final Consumer<RecordedEvent> action;

        public EventDispatcher(String eventName, Consumer<RecordedEvent> action) {

            this.eventName = eventName;

            this.action = action;

        }

        private void offer(RecordedEvent event) {

            action.accept(event);

        }

        private boolean accepts(EventType eventType) {

            return (eventName == null || eventType.getName().equals(eventName));

        }

        public Consumer<RecordedEvent> getAction() {

            return action;

        }

    }

    private final Consumer<Throwable>[] errorActions;

    private final Runnable[] flushActions;

    private final Runnable[] closeActions;

    private final EventDispatcher[] dispatchers;

    private final LongMap<EventDispatcher[]> dispatcherLookup = new LongMap<>();

    final ParserConfiguration parserConfiguration;

    final Instant startTime;

    final Instant endTime;

    final long startNanos;

    final long endNanos;

    // Cache

    private EventType cacheEventType;

    private EventDispatcher[] cacheDispatchers;

    @SuppressWarnings({"rawtypes", "unchecked"})

    public Dispatcher(StreamConfiguration c) {

        this.flushActions = c.flushActions.toArray(new Runnable[0]);

        this.closeActions = c.closeActions.toArray(new Runnable[0]);

        this.errorActions = c.errorActions.toArray(new Consumer[0]);

        this.dispatchers = c.eventActions.toArray(new EventDispatcher[0]);

        this.parserConfiguration = new ParserConfiguration(0, Long.MAX_VALUE, c.reuse, c.ordered, buildFilter(dispatchers));

        this.startTime = c.startTime;

        this.endTime = c.endTime;

        this.startNanos = c.startNanos;

        this.endNanos = c.endNanos;

    }

    public void runFlushActions() {

        Runnable[] flushActions = this.flushActions;

        for (int i = 0; i < flushActions.length; i++) {

            try {

                flushActions[i].run();

            } catch (Exception e) {

                handleError(e);

            }

        }

    }

    public void runCloseActions() {

        Runnable[] closeActions = this.closeActions;

        for (int i = 0; i < closeActions.length; i++) {

            try {

                closeActions[i].run();

            } catch (Exception e) {

                handleError(e);

            }

        }

    }

    private static ParserFilter buildFilter(EventDispatcher[] dispatchers) {

        ParserFilter ef = new ParserFilter();

        for (EventDispatcher ed : dispatchers) {

            String name = ed.eventName;

            if (name == null) {

                return ParserFilter.ACCEPT_ALL;

            }

            ef.setThreshold(name, 0);

        }

        return ef;

    }

    void dispatch(RecordedEvent event) {

        EventType type = event.getEventType();

        EventDispatcher[] dispatchers = null;

        if (type == cacheEventType) {

            dispatchers = cacheDispatchers;

        } else {

            dispatchers = dispatcherLookup.get(type.getId());

            if (dispatchers == null) {

                List<EventDispatcher> list = new ArrayList<>();

                for (EventDispatcher e : this.dispatchers) {

                    if (e.accepts(type)) {

                        list.add(e);

                    }

                }

                dispatchers = list.isEmpty() ? EventDispatcher.NO_DISPATCHERS : list.toArray(new EventDispatcher[0]);

                dispatcherLookup.put(type.getId(), dispatchers);

            }

            cacheDispatchers = dispatchers;

        }

        // Expected behavior if exception occurs in onEvent:

        //

        // Synchronous:

        //  - User has added onError action:

        //     Catch exception, call onError and continue with next event

        //     Let Errors propagate to caller of EventStream::start

        //  - Default action

        //     Catch exception, e.printStackTrace() and continue with next event

        //     Let Errors propagate to caller of EventStream::start

        //

        // Asynchronous

        //  - User has added onError action

        //     Catch exception, call onError and continue with next event

        //     Let Errors propagate, shutdown thread and stream

        //  - Default action

        //    Catch exception, e.printStackTrace() and continue with next event

        //    Let Errors propagate and shutdown thread and stream

        //

        for (int i = 0; i < dispatchers.length; i++) {

            try {

                dispatchers[i].offer(event);

            } catch (Exception e) {

                handleError(e);

            }

        }

    }

    private void handleError(Throwable e) {

        Consumer<?>[] consumers = this.errorActions;

        if (consumers.length == 0) {

            defaultErrorHandler(e);

            return;

        }

        for (int i = 0; i < consumers.length; i++) {

            @SuppressWarnings("unchecked")

            Consumer<Throwable> consumer = (Consumer<Throwable>) consumers[i];

            consumer.accept(e);

        }

    }

    private void defaultErrorHandler(Throwable e) {

        e.printStackTrace();

    }

}