OSGi Events for Communities Components

package com.mycompany.recipe;

import org.osgi.service.event.Event;
import com.adobe.cq.social.scf.core.SocialEvent;
import com.adobe.granite.activitystreams.ObjectTypes;
import com.adobe.granite.activitystreams.Verbs;

/* 
 * The Recipe type, passed to RecipeEvent(), would be a custom Recipe class 
 * that extends either 
 *    com.adobe.cq.social.scf.SocialComponent 
 * or
 *    com.adobe.cq.social.scf.SocialCollectionComponent
 * See https://docs.adobe.com/docs/en/aem/6-2/develop/communities/scf/server-customize.html
 */

/**
 * Defines events that are triggered on a custom component, "Recipe".
 */
public class RecipeEvent extends SocialEvent<RecipeEvent.RecipeActions> {

    private static final long serialVersionUID = 1L;
    protected static final String PARENT_PATH = "PARENT_PATH";

    /**
     * The event topic suffix for Recipe events
     */
    public static final String RECIPE_TOPIC = "recipe";

    /**
     * @param recipe - the recipe resource on which the event was triggered
     * @param userId - the user id of the user who triggered the action
     * @param action - the recipe action that triggered this event
     */
    public RecipeEvent(final Recipe recipe, final String userId, final RecipeEvent.RecipeActions action) {
        String recipePath = recipe.getResource().getPath();
        String parentPath = (recipe.getParentComponent() != null) ? 
                             recipe.getParentComponent().getResource().getPath() : 
                             recipe.getSourceComponentId();
        this(recipePath, userId, parentPath, action);
    }

    /**
     * @param recipePath - the path to the recipe resource (jcr node) on which the event was triggered
     * @param userId - the user id of the user who triggered the action
     * @param parentPath - the path to the parent node of the recipe resource
     * @param action - the recipe action that triggered this event
     */
    public RecipeEvent(final String recipePath, final String userId, final String parentPath) {
        super(RECIPE_TOPIC, recipePath, userId, action, 
              new BaseEventObject(recipePath, ObjectTypes.ARTICLE), 
              new BaseEventObject(parentPath, ObjectTypes.COLLECTION),
              new HashMap<String, Object>(1) {
            private static final long serialVersionUID = 1L;
            {
                if (parentPath != null) {
                    this.put(PARENT_PATH, parentPath);
                }

            }
        });
    }

    private RecipeEvent (final Event event) {
      super(event);
    }

    /**
     * List of available recipe actions that can trigger a recipe event.
     */
    public static enum RecipeActions implements SocialEvent.SocialActions {
        RecipeAdded, 
        RecipeModified, 
        RecipeDeleted;


        @Override
        public String getVerb() {
            switch (this) {
                case RecipeAdded:
                    return Verbs.POST;
                case RecipeModified:
                    return Verbs.UPDATE;
                case RecipeDeleted:
                    return Verbs.DELETE;
                default:
                    throw new IllegalArgumentException("Unsupported action");
            }
        }
    }

}

package my.company.comments;

import java.util.Collections;
import java.util.Map;

import org.apache.commons.lang.StringUtils;
import org.apache.felix.scr.annotations.Activate;
import org.apache.felix.scr.annotations.Component;
import org.apache.felix.scr.annotations.Modified;
import org.apache.felix.scr.annotations.Property;
import org.apache.felix.scr.annotations.Service;
import org.apache.sling.api.resource.Resource;
import org.apache.sling.commons.osgi.PropertiesUtil;
import org.osgi.service.component.ComponentContext;

import com.adobe.cq.social.activitystreams.listener.api.ActivityStreamProviderExtension;
import com.adobe.cq.social.commons.events.CommentEvent.CommentActions;
import com.adobe.cq.social.scf.core.SocialEvent;

@Service
@Component(metatype = true, label = "My Comment Delete Event Filter",
        description = "Prevents comment DELETE events from showing up in activity streams")
public class CommentDeleteEventActivityFilter implements ActivityStreamProviderExtension {

    @Property(name = "ranking", intValue = 10)
    protected int ranking;

    @Activate
    public void activate(final ComponentContext ctx) {
        ranking = PropertiesUtil.toInteger(ctx.getProperties().get("ranking"), 10);
    }

    @Modified
    public void update(final Map<String, Object> props) {
        ranking = PropertiesUtil.toInteger(props.get("ranking"), 10);
    }

    @Override
    public boolean evaluate(final SocialEvent<?> evt, final Resource resource) {
        if (evt.getAction() != null && evt.getAction() instanceof SocialEvent.SocialActions) {
            final SocialEvent.SocialActions action = evt.getAction();
            if (StringUtils.equals(action.getVerb(), CommentActions.DELETED.getVerb())) {
                return false;
            }
        }
        return true;
    }

    @Override
    public Map<String, ? extends Object> getActivityProperties(final SocialEvent<?> arg0, final Resource arg1) {
        return Collections.<String, Object>emptyMap();
    }

    @Override
    public Map<String, ? extends Object> getActorProperties(final SocialEvent<?> arg0, final Resource arg1) {
        return Collections.<String, Object>emptyMap();
    }

    @Override
    public String getName() {
        return "My Comment Delete Event Filter";
    }

    @Override
    public Map<String, ? extends Object> getObjectProperties(final SocialEvent<?> arg0, final Resource arg1) {
        return Collections.<String, Object>emptyMap();
    }

    /* Ensure a custom extension is registered with a ranking lower than any existing implementation in the product. */
    @Override
    public int getRanking() {
        return this.ranking;
    }

    @Override
    public Map<String, ? extends Object> getTargetProperties(final SocialEvent<?> arg0, final Resource arg1) {
        return Collections.<String, Object>emptyMap();
    }

    @Override
    public String[] getStreamProviderPid() {
        return new String[]{"*"};
    }

}