package org.apidesign.openfixed;

import java.util.HashSet;

import java.util.List;

import java.util.Set;

import java.util.concurrent.CopyOnWriteArrayList;

import java.util.concurrent.Executor;

import java.util.concurrent.Executors;

/**

 *

 * @author Jaroslav Tulach <jtulach@netbeans.org>

 */

final class PostEventSupport implements EventSupport, Runnable {

    private final List<ModificationListener> listeners = new CopyOnWriteArrayList<ModificationListener>();

    private final List<Deliverable> deliverables = new CopyOnWriteArrayList<Deliverable>();

    private static final Executor EXEC = Executors.newSingleThreadExecutor();

    PostEventSupport() {

    }

    @Override

    public void fireModificationEvent(ModificationEvent ev) {

        synchronized (deliverables) {

            final Deliverable d = new Deliverable(ev, listeners.toArray(new ModificationListener[0]));

            deliverables.add(d);

            EXEC.execute(this);

        }

    }

    @Override

    public void add(ModificationListener l) {

        listeners.add(l);

    }

    @Override

    public void remove(ModificationListener l) {

        listeners.remove(l);

    }

    @Override

    public void run() {

        Deliverable[] pending;

        synchronized (deliverables) {

            if (deliverables.isEmpty()) {

                return;

            }

            pending = deliverables.toArray(new Deliverable[0]);

            deliverables.clear();

        }

        Calculator calc = null;

        Set<PostModificationListener> notify = new HashSet<PostModificationListener>();

        int pendingCount = pending.length;

        for (Deliverable d : pending) {

            calc = (Calculator)d.ev.getSource();

            d.ev.pending = --pendingCount;

            d.ev.posts = notify;

            for (ModificationListener l : d.listeners) {

                l.modification(d.ev);

            }

            d.ev.posts = null;

        }

        for (PostModificationListener pml : notify) {

            pml.postProcess(new PostModificationEvent(calc));

        }

    }

    private static class Deliverable {

        final ModificationEvent ev;

        final ModificationListener[] listeners;

        public Deliverable(ModificationEvent ev, ModificationListener[] listeners) {

            this.ev = ev;

            this.listeners = listeners;

        }

    }

}