package com.temp.foundation.widgets.support;

import java.util.*;

import com.google.gwt.event.shared.*;
import com.temp.foundation.widgets.support.events.*;
import com.temp.shared.utils.*;

/**
 * @param <H> interface implemented by handlers of this kind of event
 */
public class NonDomHandlerManager<H extends EventHandler> implements HasHandlers {

    private final List<H> handlers = new ArrayList<H>();
    private final Object source;

    public NonDomHandlerManager(Object source) {
        this.source = source;
    }

    @Override
    public void fireEvent(GwtEvent<?> event) {
        if (!(event instanceof NonDomEvent)) {
            throw new IllegalStateException("NonDomHandlerManager can currently only dispatch Events than implement NonDomEvent");
        }
        NonDomEvent<H> ndEvent = ObjectUtils.cast(event);
        ndEvent.setSource(source);
        for (H handler : handlers) {
            if (handler != null) {
                ndEvent.dispatch(handler);
            }
        }
    }

    /**
     * Adds a handler.
     *
     * @param handler the handler
     * @return the handler registration
     */
    public HandlerRegistration addHandler(H handler) {
        if (handler == null) {
            return null;
        }
        int index = handlers.size();
        handlers.add(handler);
        return new IndexHandlerRegistration(index);
    }

    private class IndexHandlerRegistration implements HandlerRegistration {
        private final int index;

        private IndexHandlerRegistration(int index) {
            this.index = index;
        }

        @Override
        public void removeHandler() {
            if (index < handlers.size()) {
                handlers.set(index, null);
            }
        }
    }
}