package com.temp.client.foundation.widget.input.support;

import com.google.gwt.event.shared.*;
import com.temp.client.foundation.widget.input.support.events.*;
import com.temp.shared.utils.*;

import java.util.*;

/**
 * @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 );
            }
        }
    }
}